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2024 Volume 39 Issue 5
2024, 39(5): 1-10
doi: 10.3866/PKU.DXHX202309053
Abstract:
外消旋体的拆分是制备光学活性化合物的重要方法，利用拆分试剂通过结晶进行的物理拆分，往往只能得到一种高光学活性的化合物。作为重要的不对称合成技术，动力学拆分可以获得高光学活性的产物，同时回收高光学活性的原料。我们综合光催化和动力学拆分技术，设计了一例基于激发态手性铜催化的烯烃E→Z异构的动力学拆分实验，实验包括底物的制备和纯化、光催化反应、动力学拆分曲线的绘制以及对照实验等内容，包含无水无氧操作、柱层析和pTLC分离、GC和手性HPLC分析等多项实验操作，涵盖了化学合成、表征、动力学测量等。本实验综合性高，操作性强，总时长24学时，分为三天完成，也可开设为三个8学时的独立实验，适合在有机化学实验或综合化学实验课程中开设。通过本实验可以锻炼学生的综合实验技能，让学生了解学科前沿，感受到动力学拆分、光催化和激发态过渡金属催化技术的优越性和重要性，并激发学生进一步推动该领域的发展。
外消旋体的拆分是制备光学活性化合物的重要方法，利用拆分试剂通过结晶进行的物理拆分，往往只能得到一种高光学活性的化合物。作为重要的不对称合成技术，动力学拆分可以获得高光学活性的产物，同时回收高光学活性的原料。我们综合光催化和动力学拆分技术，设计了一例基于激发态手性铜催化的烯烃E→Z异构的动力学拆分实验，实验包括底物的制备和纯化、光催化反应、动力学拆分曲线的绘制以及对照实验等内容，包含无水无氧操作、柱层析和pTLC分离、GC和手性HPLC分析等多项实验操作，涵盖了化学合成、表征、动力学测量等。本实验综合性高，操作性强，总时长24学时，分为三天完成，也可开设为三个8学时的独立实验，适合在有机化学实验或综合化学实验课程中开设。通过本实验可以锻炼学生的综合实验技能，让学生了解学科前沿，感受到动力学拆分、光催化和激发态过渡金属催化技术的优越性和重要性，并激发学生进一步推动该领域的发展。
2024, 39(5): 11-19
doi: 10.3866/PKU.DXHX202309073
Abstract:
This experiment addresses the challenge of understanding the abstract concept of “living” in living radical polymerization within the undergraduate teaching of polymer chemistry course. We conducted a 3D printing experiment using photo-induced reversible addition-fragmentation chain transfer (RAFT) polymerization. Initially, we synthesized O-(ethyl)-S-(2-propyl ethanoate thio) xanthate (EXEP) under optimized conditions. Subsequently, 3D printing was performed with commercial photosensitive resin under conditions with and without EXEP. The printed structures were then subjected to post-modification with a fluorescent monomer, and a comparative experiment on polymer welding was conducted. By analyzing and comparing the experimental results, we aimed to visually demonstrate the mechanism of living radical polymerization and its impact on post-functionalization. This experiment seamlessly integrates foundational theory into an engaging practical context. It is characterized by its reasonable duration, simplicity in operation, significant outcomes, and alignment with basic requirements for undergraduate teaching experiments. Furthermore, it contributes to enhancing students’ comprehensive analytical abilities, sparking their interest in deeper research, and cultivating their innovative awareness and extension capabilities.
This experiment addresses the challenge of understanding the abstract concept of “living” in living radical polymerization within the undergraduate teaching of polymer chemistry course. We conducted a 3D printing experiment using photo-induced reversible addition-fragmentation chain transfer (RAFT) polymerization. Initially, we synthesized O-(ethyl)-S-(2-propyl ethanoate thio) xanthate (EXEP) under optimized conditions. Subsequently, 3D printing was performed with commercial photosensitive resin under conditions with and without EXEP. The printed structures were then subjected to post-modification with a fluorescent monomer, and a comparative experiment on polymer welding was conducted. By analyzing and comparing the experimental results, we aimed to visually demonstrate the mechanism of living radical polymerization and its impact on post-functionalization. This experiment seamlessly integrates foundational theory into an engaging practical context. It is characterized by its reasonable duration, simplicity in operation, significant outcomes, and alignment with basic requirements for undergraduate teaching experiments. Furthermore, it contributes to enhancing students’ comprehensive analytical abilities, sparking their interest in deeper research, and cultivating their innovative awareness and extension capabilities.
2024, 39(5): 20-26
doi: 10.3866/PKU.DXHX202309055
Abstract:
Preparation of cyclohexanone is a classic “hands-on” organic chemistry experiment widely used in undergraduate teaching. However, conventional experiments often involve the use of non-environmentally friendly high-cost heavy metal oxidants, limiting the teaching process to the development of students’ experimental skills. In response to this, we have transformed the experiment into a design-oriented approach. Students are tasked with consulting literature, researching, and exploring greener and more environmentally friendly oxidation systems. By evaluating the merits of various oxidation systems, determining the types of oxidants, and designing experimental procedures, students complete the experiment. This innovative approach enhances the experiment’s complexity, promotes innovation, and introduces challenges. It not only solidifies students’ practical laboratory skills but also cultivates their ability to discover, analyze, and solve problems, fostering innovative thinking and awareness of green chemistry.
Preparation of cyclohexanone is a classic “hands-on” organic chemistry experiment widely used in undergraduate teaching. However, conventional experiments often involve the use of non-environmentally friendly high-cost heavy metal oxidants, limiting the teaching process to the development of students’ experimental skills. In response to this, we have transformed the experiment into a design-oriented approach. Students are tasked with consulting literature, researching, and exploring greener and more environmentally friendly oxidation systems. By evaluating the merits of various oxidation systems, determining the types of oxidants, and designing experimental procedures, students complete the experiment. This innovative approach enhances the experiment’s complexity, promotes innovation, and introduces challenges. It not only solidifies students’ practical laboratory skills but also cultivates their ability to discover, analyze, and solve problems, fostering innovative thinking and awareness of green chemistry.
2024, 39(5): 27-36
doi: 10.3866/PKU.DXHX202309107
Abstract:
This experiment employs the coordination reaction between epigallocatechin gallate (EGCG) from persimmon extract and ferrous sulfate. The study investigates the responsive changes of the complex solution at different pH, aiming to achieve a portable differentiation application for common acidic and alkaline substances in daily life. The experiment utilizes readily available raw materials, ensures a safe process, and demonstrates observable phenomena, allowing the audience to appreciate the beauty of chemical transformations and fostering a strong interest in the field of chemistry.
This experiment employs the coordination reaction between epigallocatechin gallate (EGCG) from persimmon extract and ferrous sulfate. The study investigates the responsive changes of the complex solution at different pH, aiming to achieve a portable differentiation application for common acidic and alkaline substances in daily life. The experiment utilizes readily available raw materials, ensures a safe process, and demonstrates observable phenomena, allowing the audience to appreciate the beauty of chemical transformations and fostering a strong interest in the field of chemistry.
2024, 39(5): 37-43
doi: 10.3866/PKU.DXHX202309085
Abstract:
Blowing bubbles is a universally enjoyable activity. However, commercially available bubble solutions often contain unknown ingredients that can be irritating to the skin. In this study, we utilized common household items to develop a green, safe, and non-toxic bubble solution using the single variable method, enabling the creation of giant bubbles. The experiment progresses systematically, from basic to advanced, fostering curiosity and exploration. Suitable for individuals of all ages, this endeavor aims to ignite and nurture interest and passion for chemistry experiments. Participants can engage in the delightful experience of concocting their own giant bubble solution.
Blowing bubbles is a universally enjoyable activity. However, commercially available bubble solutions often contain unknown ingredients that can be irritating to the skin. In this study, we utilized common household items to develop a green, safe, and non-toxic bubble solution using the single variable method, enabling the creation of giant bubbles. The experiment progresses systematically, from basic to advanced, fostering curiosity and exploration. Suitable for individuals of all ages, this endeavor aims to ignite and nurture interest and passion for chemistry experiments. Participants can engage in the delightful experience of concocting their own giant bubble solution.
2024, 39(5): 44-51
doi: 10.3866/PKU.DXHX202309092
Abstract:
There is a dearth of experiments on the synthesis of binuclear bridging complexes in current experimental textbooks, and limited knowledge exists regarding secondary amine synthesis and Cu(II) oxidation. In this study, drawing from the foundational reactions in organic chemistry theory, two routes were devised to synthesize the target secondary amine ligand. Route 1 is predicated on nucleophilic substitution reactions, while Route 2 involves nucleophilic addition condensation and reduction. Leveraging the principles of coordination chemistry and the conjugated drive effect in organic chemistry, Cu(II), with its weak oxidizing properties, oxidized secondary amines into conjugated aromatic imines (Schiff base) structures. Concurrently, the coordination of Schiff base and the bridging coordination of chloride ions were harnessed to form stable chlorine-bridged binuclear Cu(I) complexes. To suit the experimental teaching conditions in tertiary institutions, a straightforward operational set-up was designed to visually illustrate the identification of copper ion valence states in Cu(I) complexes. The experimental principles herein encompass not only fundamental chemical reaction knowledge but also embody the latest scientific research findings. With mild reaction conditions, intuitive experimental observations, good reproducibility, and high yields, this experiment effectively enhances students’ comprehensive experimental operation skills and cultivates their abilities in organic synthesis and coordination chemistry.
There is a dearth of experiments on the synthesis of binuclear bridging complexes in current experimental textbooks, and limited knowledge exists regarding secondary amine synthesis and Cu(II) oxidation. In this study, drawing from the foundational reactions in organic chemistry theory, two routes were devised to synthesize the target secondary amine ligand. Route 1 is predicated on nucleophilic substitution reactions, while Route 2 involves nucleophilic addition condensation and reduction. Leveraging the principles of coordination chemistry and the conjugated drive effect in organic chemistry, Cu(II), with its weak oxidizing properties, oxidized secondary amines into conjugated aromatic imines (Schiff base) structures. Concurrently, the coordination of Schiff base and the bridging coordination of chloride ions were harnessed to form stable chlorine-bridged binuclear Cu(I) complexes. To suit the experimental teaching conditions in tertiary institutions, a straightforward operational set-up was designed to visually illustrate the identification of copper ion valence states in Cu(I) complexes. The experimental principles herein encompass not only fundamental chemical reaction knowledge but also embody the latest scientific research findings. With mild reaction conditions, intuitive experimental observations, good reproducibility, and high yields, this experiment effectively enhances students’ comprehensive experimental operation skills and cultivates their abilities in organic synthesis and coordination chemistry.
2024, 39(5): 52-62
doi: 10.3866/PKU.DXHX202309097
Abstract:
This study presents an improvement to the analytical chemistry experiment “Determination of total phosphorus in water and wastewater by spectrophotometry”. Maifannite, a green and non-toxic material, was modified with ZnFe-LDHs (layered double hydroxides) to create an adsorption material. The modified Maifannite was characterized using FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-ray Diffraction), SEM (Scanning Electron Microscope), and EDS-mapping (Energy Dispersive X-ray Spectroscopy Mapping). Optimal adsorption conditions for total phosphorus by ZnFe-LDHs modified Maifannite were explored, achieving a removal rate of over 98.4%. After treatment with modified Maifannite, the concentration of phosphorus in wastewater was reduced to less than 0.08 mg·L−1, meeting the first-level discharge standard for phosphorus. This enhanced experiment is rich in content, comprehensive, and cultivates students’ research and teamwork abilities while practicing the concept of “green chemistry”. It is suitable for extension to higher-grade undergraduate teaching.
This study presents an improvement to the analytical chemistry experiment “Determination of total phosphorus in water and wastewater by spectrophotometry”. Maifannite, a green and non-toxic material, was modified with ZnFe-LDHs (layered double hydroxides) to create an adsorption material. The modified Maifannite was characterized using FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-ray Diffraction), SEM (Scanning Electron Microscope), and EDS-mapping (Energy Dispersive X-ray Spectroscopy Mapping). Optimal adsorption conditions for total phosphorus by ZnFe-LDHs modified Maifannite were explored, achieving a removal rate of over 98.4%. After treatment with modified Maifannite, the concentration of phosphorus in wastewater was reduced to less than 0.08 mg·L−1, meeting the first-level discharge standard for phosphorus. This enhanced experiment is rich in content, comprehensive, and cultivates students’ research and teamwork abilities while practicing the concept of “green chemistry”. It is suitable for extension to higher-grade undergraduate teaching.
2024, 39(5): 63-69
doi: 10.3866/PKU.DXHX202309098
Abstract:
Visible light irradiation is a crucial factor in modern synthetic organic chemistry, yet it is often overlooked in undergraduate organic experiment textbooks. This innovative experiment introduces a microscale approach, inspired by the principles of photosynthesis, to catalyze the oxidation of p-cyanophenylboronic acid to p-hydroxybenzonitrile using extracts from spinach leaves under red-light irradiation. The incorporation of this comprehensive experiment into our school’s organic chemistry laboratory teaching offers several advantages: (1) The environmentally friendly catalyst is easily accessible, and the synthesis process is safe and reliable with low experimental costs. (2) Microscale experiments contribute to reducing environmental pollution, enhancing laboratory safety, saving reagents and time, minimizing instrument wear and tear, and fostering students’ meticulous experimental style and habits. (3) Beyond expanding students’ knowledge and horizons, this experiment also ignites their interest in learning and boosts their learning enthusiasm.
Visible light irradiation is a crucial factor in modern synthetic organic chemistry, yet it is often overlooked in undergraduate organic experiment textbooks. This innovative experiment introduces a microscale approach, inspired by the principles of photosynthesis, to catalyze the oxidation of p-cyanophenylboronic acid to p-hydroxybenzonitrile using extracts from spinach leaves under red-light irradiation. The incorporation of this comprehensive experiment into our school’s organic chemistry laboratory teaching offers several advantages: (1) The environmentally friendly catalyst is easily accessible, and the synthesis process is safe and reliable with low experimental costs. (2) Microscale experiments contribute to reducing environmental pollution, enhancing laboratory safety, saving reagents and time, minimizing instrument wear and tear, and fostering students’ meticulous experimental style and habits. (3) Beyond expanding students’ knowledge and horizons, this experiment also ignites their interest in learning and boosts their learning enthusiasm.
2024, 39(5): 70-79
doi: 10.3866/PKU.DXHX202309090
Abstract:
Photodynamic therapy (PDT) emerges as a novel approach to treat tumors utilizing “photosensitizers” and “light”. This method involves exposing the tumor site to specific wavelengths of light, activating photosensitizers concentrated in the tumor to generate highly oxidizing reactive oxygen species, ultimately dismantling the tumor. In comparison to surgery, chemotherapy, and radiation therapy, PDT boasts simplicity in operation, precise targeting, minimal invasiveness, lack of drug resistance, and the ability to trigger systemic immunity. While PDT has gained widespread adoption in developed nations, its promotion in China is still underway, hampered by a lack of public understanding. In response, we present a popular science experiment elucidating tumor-targeted photodynamic therapy using a laboratory-synthesized selenium-Rhodamine photosensitizer. The experiment encompasses enzyme activation of targeted photosensitizers, visual detection of singlet oxygen, and the photodynamic eradication of cancer cells. This experiment vividly illustrates the scientific principles behind targeted photodynamic therapy, enhancing public awareness of photodynamic cancer treatment. Such efforts are crucial for advancing the adoption of photodynamic therapy in our country, underscoring the pivotal role of chemistry in cancer treatment. The entire popular science experiment is straightforward, visually intuitive, and has demonstrated effective results in science outreach.
Photodynamic therapy (PDT) emerges as a novel approach to treat tumors utilizing “photosensitizers” and “light”. This method involves exposing the tumor site to specific wavelengths of light, activating photosensitizers concentrated in the tumor to generate highly oxidizing reactive oxygen species, ultimately dismantling the tumor. In comparison to surgery, chemotherapy, and radiation therapy, PDT boasts simplicity in operation, precise targeting, minimal invasiveness, lack of drug resistance, and the ability to trigger systemic immunity. While PDT has gained widespread adoption in developed nations, its promotion in China is still underway, hampered by a lack of public understanding. In response, we present a popular science experiment elucidating tumor-targeted photodynamic therapy using a laboratory-synthesized selenium-Rhodamine photosensitizer. The experiment encompasses enzyme activation of targeted photosensitizers, visual detection of singlet oxygen, and the photodynamic eradication of cancer cells. This experiment vividly illustrates the scientific principles behind targeted photodynamic therapy, enhancing public awareness of photodynamic cancer treatment. Such efforts are crucial for advancing the adoption of photodynamic therapy in our country, underscoring the pivotal role of chemistry in cancer treatment. The entire popular science experiment is straightforward, visually intuitive, and has demonstrated effective results in science outreach.
2024, 39(5): 80-89
doi: 10.3866/PKU.DXHX202310004
Abstract:
Organophosphorus pesticides rank among the most extensively used pesticides in agriculture, leading to widespread contamination of water bodies, soil, and vegetation, thereby disrupting ecosystems and posing health risks. Consequently, rapid and precise detection of organophosphorus pesticide residues is crucial for effective pesticide management. Conventional analytical methods such as chromatography and spectroscopy rely on sophisticated equipment and specialized personnel, incurring high costs and time consumption. In response, this study presents an innovative approach involving the development of aptamer-based colloidal gold lateral flow test strips for the swift and accurate detection of residual organophosphorus pesticides in fruits and vegetables. These test strips offer advantages such as sensitivity, portability, and ease of operation, enabling on-site application in real sample detection and demonstrating excellent applicability. Furthermore, the logical operation process of these test strips facilitates science popularization and education. Diverse experimental processes and schemes tailored for different audiences serve to stimulate interest in chemistry and science while enhancing awareness of food safety.
Organophosphorus pesticides rank among the most extensively used pesticides in agriculture, leading to widespread contamination of water bodies, soil, and vegetation, thereby disrupting ecosystems and posing health risks. Consequently, rapid and precise detection of organophosphorus pesticide residues is crucial for effective pesticide management. Conventional analytical methods such as chromatography and spectroscopy rely on sophisticated equipment and specialized personnel, incurring high costs and time consumption. In response, this study presents an innovative approach involving the development of aptamer-based colloidal gold lateral flow test strips for the swift and accurate detection of residual organophosphorus pesticides in fruits and vegetables. These test strips offer advantages such as sensitivity, portability, and ease of operation, enabling on-site application in real sample detection and demonstrating excellent applicability. Furthermore, the logical operation process of these test strips facilitates science popularization and education. Diverse experimental processes and schemes tailored for different audiences serve to stimulate interest in chemistry and science while enhancing awareness of food safety.
2024, 39(5): 90-97
doi: 10.3866/PKU.DXHX202310001
Abstract:
Luminescence lifetime is a crucial concept in photochemistry, serving as a significant parameter that characterizes the properties of luminescent materials. Despite the widespread applications of luminescent materials in various fields such as human production, military, aerospace, the general public often lacks a clear understanding of the scientific notion that “Luminescence lifetime can vary”. This project takes everyday light as a starting point and utilizes long afterglow materials with human-recognizable lifetimes (> 100 ms) as a medium of demonstration. By investigating the self-assembly of melamine and phthalic acid in an aqueous medium, a class of organic long afterglow materials with extended lifetimes and high brightness is designed and synthesized. The simplicity of the synthesis method, cost-effectiveness of raw materials, clear experimental phenomena, and high reproducibility make it an ideal theme for science popularization. Additionally, the project explores luminescence phenomena in daily life, introducing innovative and engaging modes of science communication such as original animations and “afterglow graffiti”. By leveraging platforms like Bilibili and TikTok, the outreach of chemical knowledge is broadened. The science popularization content includes several independent interactive modules tailored to the characteristics and needs of different audience groups, aiming for broad coverage and high acceptance. This approach ensures that luminescence lifetime becomes intimately connected with everyday life and reaches a wide audience.
Luminescence lifetime is a crucial concept in photochemistry, serving as a significant parameter that characterizes the properties of luminescent materials. Despite the widespread applications of luminescent materials in various fields such as human production, military, aerospace, the general public often lacks a clear understanding of the scientific notion that “Luminescence lifetime can vary”. This project takes everyday light as a starting point and utilizes long afterglow materials with human-recognizable lifetimes (> 100 ms) as a medium of demonstration. By investigating the self-assembly of melamine and phthalic acid in an aqueous medium, a class of organic long afterglow materials with extended lifetimes and high brightness is designed and synthesized. The simplicity of the synthesis method, cost-effectiveness of raw materials, clear experimental phenomena, and high reproducibility make it an ideal theme for science popularization. Additionally, the project explores luminescence phenomena in daily life, introducing innovative and engaging modes of science communication such as original animations and “afterglow graffiti”. By leveraging platforms like Bilibili and TikTok, the outreach of chemical knowledge is broadened. The science popularization content includes several independent interactive modules tailored to the characteristics and needs of different audience groups, aiming for broad coverage and high acceptance. This approach ensures that luminescence lifetime becomes intimately connected with everyday life and reaches a wide audience.
2024, 39(5): 98-107
doi: 10.3866/PKU.DXHX202310026
Abstract:
Addressing the challenges in teaching the Nernst equation in inorganic chemistry, this experiment introduces the cutting-edge zinc-air battery as a teaching model. By altering the concentration of oxidizing and reducing materials, students explore the key factors of the Nernst equation, enhancing their understanding of electrochemical processes. Simultaneously, the experiment incorporates flexible electronics technology, using carrageenan as a safe and environmentally friendly solid electrolyte to guide students in learning and constructing solid zinc-air batteries. The batteries are tested for voltage performance at various bending angles to assess their flexibility. Moreover, to foster creativity, students design and build various forms of solid zinc-air batteries to power electronic devices. This experiment is closely aligned with fundamental electrochemical knowledge and state-of-the-art technology, allowing students to deepen their understanding of the Nernst equation while gaining practical experience in creating flexible electronic devices. This approach sparks students’ interest in electrochemistry and proves cost-effective with promising results.
Addressing the challenges in teaching the Nernst equation in inorganic chemistry, this experiment introduces the cutting-edge zinc-air battery as a teaching model. By altering the concentration of oxidizing and reducing materials, students explore the key factors of the Nernst equation, enhancing their understanding of electrochemical processes. Simultaneously, the experiment incorporates flexible electronics technology, using carrageenan as a safe and environmentally friendly solid electrolyte to guide students in learning and constructing solid zinc-air batteries. The batteries are tested for voltage performance at various bending angles to assess their flexibility. Moreover, to foster creativity, students design and build various forms of solid zinc-air batteries to power electronic devices. This experiment is closely aligned with fundamental electrochemical knowledge and state-of-the-art technology, allowing students to deepen their understanding of the Nernst equation while gaining practical experience in creating flexible electronic devices. This approach sparks students’ interest in electrochemistry and proves cost-effective with promising results.
2024, 39(5): 108-115
doi: 10.3866/PKU.DXHX202310032
Abstract:
Test paper, a type of paper product chemically treated to produce color changes in response to specific substances, serves as a valuable tool for rapid detection and analysis. This experiment, based on the surface modification of glass fiber filter paper, introduces a heavy metal ion detection test paper designed with the fluorescence sensing characteristics of rare earth complexes. The test paper demonstrates its effectiveness and convenience in detecting heavy metal ions in water sources. The innovative test paper proves highly useful in addressing heavy metal ion contamination in water, emphasizing the significant role of chemistry in advancing ecological civilization. The simplified, safe, and environmentally friendly process of creating the test paper yields a practical and user-friendly product. This experiment not only educates on the general production and testing principles of test papers but also sparks students’ interest in scientific exploration and application. The experiment, characterized by its simplicity, repeatability, low entry barrier, environmental friendliness, and safety, possesses a unique color aesthetic, leaving a lasting impression. It is suitable for conducting popular science experiments in public places and promoting awareness in experimental teaching across various educational levels.
Test paper, a type of paper product chemically treated to produce color changes in response to specific substances, serves as a valuable tool for rapid detection and analysis. This experiment, based on the surface modification of glass fiber filter paper, introduces a heavy metal ion detection test paper designed with the fluorescence sensing characteristics of rare earth complexes. The test paper demonstrates its effectiveness and convenience in detecting heavy metal ions in water sources. The innovative test paper proves highly useful in addressing heavy metal ion contamination in water, emphasizing the significant role of chemistry in advancing ecological civilization. The simplified, safe, and environmentally friendly process of creating the test paper yields a practical and user-friendly product. This experiment not only educates on the general production and testing principles of test papers but also sparks students’ interest in scientific exploration and application. The experiment, characterized by its simplicity, repeatability, low entry barrier, environmental friendliness, and safety, possesses a unique color aesthetic, leaving a lasting impression. It is suitable for conducting popular science experiments in public places and promoting awareness in experimental teaching across various educational levels.
2024, 39(5): 116-124
doi: 10.3866/PKU.DXHX202310056
Abstract:
he issue of oil-water separation in the treatment of produced water by ternary composite flooding (ASP-PW) has emerged as a technical bottleneck in the widespread adoption of ternary composite flooding technology. This paper introduces a method that utilizes ultrasonic-enhanced polymeric aluminum chloride (PAC) for the synergistic treatment of ASP-PW, significantly improving the efficiency of oil-water separation. Experimental findings reveal that, at an ultrasound frequency of 40 kHz and a duration of 60 min, the particle size of emulsified oil droplets increased from 349 nm to 3639 nm, indicating the consolidating effect of ultrasound on emulsified oil droplets. When ultrasonic and PAC are employed in tandem to process ASP-PW, with ultrasound duration at 60 min, dosage at 850 mg∙L−1, and a settling time of 30 min in a 40°C water bath, the oil removal rate reached 95.82%. This rate surpasses the individual oil removal rates of ultrasound alone (86.12%) and PAC (90.87%) under the same conditions, demonstrating a significant synergistic effect. The experiment’s practical content is a crucial manifestation of science and education integration. Following the principles of green and sustainable development, the experimental process enhances students’ ability for independent exploration. This experiment, spanning from problem investigation and program design to result acquisition, underscores the pivotal role of teamwork. Additionally, it opens up new possibilities for the processing of ASP-PW.
he issue of oil-water separation in the treatment of produced water by ternary composite flooding (ASP-PW) has emerged as a technical bottleneck in the widespread adoption of ternary composite flooding technology. This paper introduces a method that utilizes ultrasonic-enhanced polymeric aluminum chloride (PAC) for the synergistic treatment of ASP-PW, significantly improving the efficiency of oil-water separation. Experimental findings reveal that, at an ultrasound frequency of 40 kHz and a duration of 60 min, the particle size of emulsified oil droplets increased from 349 nm to 3639 nm, indicating the consolidating effect of ultrasound on emulsified oil droplets. When ultrasonic and PAC are employed in tandem to process ASP-PW, with ultrasound duration at 60 min, dosage at 850 mg∙L−1, and a settling time of 30 min in a 40°C water bath, the oil removal rate reached 95.82%. This rate surpasses the individual oil removal rates of ultrasound alone (86.12%) and PAC (90.87%) under the same conditions, demonstrating a significant synergistic effect. The experiment’s practical content is a crucial manifestation of science and education integration. Following the principles of green and sustainable development, the experimental process enhances students’ ability for independent exploration. This experiment, spanning from problem investigation and program design to result acquisition, underscores the pivotal role of teamwork. Additionally, it opens up new possibilities for the processing of ASP-PW.
2024, 39(5): 125-133
doi: 10.3866/PKU.DXHX202310050
Abstract:
In this paper, the experimental design of undergraduate teaching was conducted based on the hot research fields of molecular switches and aggregation-induced luminescence. Photochromic diarylethene was skillfully integrated into a tetraarylethene system with aggregation-induced luminescence performance, and a new type of photoswitchable fluorescent molecular switch with both color-changing and luminescence functions was prepared. By integrating science and education, the scientific research frontier was introduced into undergraduate experimental teaching. A comprehensive experimental exploration was carried out from the aspects of material preparation, separation and purification, structure characterization and performance test. The molecular design of this experiment is concise and novel, the content is rich, and the phenomenon is obvious. On the basis of comprehensively applying and consolidating the basic theories and basic operations of undergraduate learning, this work can stimulate students’ interest in scientific research and cultivate the scientific spirit of unity and cooperation, breakthrough and innovation.
In this paper, the experimental design of undergraduate teaching was conducted based on the hot research fields of molecular switches and aggregation-induced luminescence. Photochromic diarylethene was skillfully integrated into a tetraarylethene system with aggregation-induced luminescence performance, and a new type of photoswitchable fluorescent molecular switch with both color-changing and luminescence functions was prepared. By integrating science and education, the scientific research frontier was introduced into undergraduate experimental teaching. A comprehensive experimental exploration was carried out from the aspects of material preparation, separation and purification, structure characterization and performance test. The molecular design of this experiment is concise and novel, the content is rich, and the phenomenon is obvious. On the basis of comprehensively applying and consolidating the basic theories and basic operations of undergraduate learning, this work can stimulate students’ interest in scientific research and cultivate the scientific spirit of unity and cooperation, breakthrough and innovation.
2024, 39(5): 134-143
doi: 10.3866/PKU.DXHX202310093
Abstract:
Photocatalytic oxidation, distinguished by its safety, controllability, mild conditions, and environmental friendliness compared to traditional oxidation reactions, has emerged as a prominent research focus in the forefront of chemistry, garnering widespread attention. However, its application in undergraduate teaching experiments has been limited by experimental conditions and equipment constraints. In this experiment, we devised a simple photoreaction device using conventional laboratory instruments. Employing a high-efficiency, low-energy sodium lamp as the light source to catalyze the oxidation of phosphate intermediates, we achieved the laboratory-scale synthesis of 1,2-dioxocycloethane-type medical chemiluminescence reagents, diversifying the application of photochemical reactions in experimental teaching. The materials and reagents used in this experiment are inexpensive and readily available, the operation is straightforward, and the yield of the product is high. The experiment allows for both independent single-bottle operations and the execution of multiple-bottle series reactions. Considering the experimental cost and teaching efficiency, we conducted group experimental teaching with a two-bottle series, fostering diverse teaching forms and nurturing students’ cooperative skills. This approach is well-suited for undergraduate experimental teaching, aiding students in enhancing their comprehensive experimental operational abilities and deepening their understanding of reaction mechanisms such as radical coupling.
Photocatalytic oxidation, distinguished by its safety, controllability, mild conditions, and environmental friendliness compared to traditional oxidation reactions, has emerged as a prominent research focus in the forefront of chemistry, garnering widespread attention. However, its application in undergraduate teaching experiments has been limited by experimental conditions and equipment constraints. In this experiment, we devised a simple photoreaction device using conventional laboratory instruments. Employing a high-efficiency, low-energy sodium lamp as the light source to catalyze the oxidation of phosphate intermediates, we achieved the laboratory-scale synthesis of 1,2-dioxocycloethane-type medical chemiluminescence reagents, diversifying the application of photochemical reactions in experimental teaching. The materials and reagents used in this experiment are inexpensive and readily available, the operation is straightforward, and the yield of the product is high. The experiment allows for both independent single-bottle operations and the execution of multiple-bottle series reactions. Considering the experimental cost and teaching efficiency, we conducted group experimental teaching with a two-bottle series, fostering diverse teaching forms and nurturing students’ cooperative skills. This approach is well-suited for undergraduate experimental teaching, aiding students in enhancing their comprehensive experimental operational abilities and deepening their understanding of reaction mechanisms such as radical coupling.
2024, 39(5): 144-153
doi: 10.3866/PKU.DXHX202309084
Abstract:
With the continued implementation of national “Double Carbon” strategies, carbon dioxide (CO2) has emerged as a focal point of attention. However, a comprehensive and in-depth understanding of CO2 cycling and carbon emission reduction is lacking among the general public. This experiment introduces a set of carbon cycle experiments covering the properties, generation, transformation, and capture of CO2. It simulates natural and industrial carbon sequestration processes through processes like photosynthesis and chemical absorption, achieving carbon emission reduction and carbon neutrality. The dynamic changes in CO2 are demonstrated through various forms such as color changes in indicators, fountains, and precipitation. Raw materials for the experiment are sourced from daily life, ensuring simplicity in operation. The experiment incorporates diverse interactive elements, enhancing its appeal and effectively conveying the chemical principles of the carbon cycle. It serves to popularize knowledge related to the “Double Carbon” strategy, fostering a deep-seated understanding of low-carbon energy-saving concepts.
With the continued implementation of national “Double Carbon” strategies, carbon dioxide (CO2) has emerged as a focal point of attention. However, a comprehensive and in-depth understanding of CO2 cycling and carbon emission reduction is lacking among the general public. This experiment introduces a set of carbon cycle experiments covering the properties, generation, transformation, and capture of CO2. It simulates natural and industrial carbon sequestration processes through processes like photosynthesis and chemical absorption, achieving carbon emission reduction and carbon neutrality. The dynamic changes in CO2 are demonstrated through various forms such as color changes in indicators, fountains, and precipitation. Raw materials for the experiment are sourced from daily life, ensuring simplicity in operation. The experiment incorporates diverse interactive elements, enhancing its appeal and effectively conveying the chemical principles of the carbon cycle. It serves to popularize knowledge related to the “Double Carbon” strategy, fostering a deep-seated understanding of low-carbon energy-saving concepts.
2024, 39(5): 154-162
doi: 10.3866/PKU.DXHX202310074
Abstract:
The proline-catalyzed asymmetric aldol reaction stands as a classic experiment illustrating the concept of enantiomerism. However, due to substrate reactivity limitations and experimental constraints, the stereochemical concepts of diastereoisomerism and racemization have not been adequately addressed. To bridge this gap between experimental and theoretical teaching and enhance students’ understanding of stereochemistry in Organic Chemistry, we have innovated and expanded the proline-catalyzed asymmetric aldol reaction. Firstly, by upgrading the conventional two-component reaction to a three-component reaction, we efficiently generate diastereomers through the conversion of arylaldehydes to highly reactive aldimines. Secondly, we introduce the stereoselective control of proline through the use of catalysts with opposite chiral configurations, while also incorporating the concept of racemization by mixing products with opposite configurations. Thirdly, we employ nuclear magnetic resonance (NMR) technology to elucidate the diastereoisomerism ratio of the products, facilitating a deeper understanding of diastereoisomerism concepts. Our results demonstrate that this experiment offers excellent repeatability, appropriate duration, and a balance of exploration and innovation. Implementation of this project not only enhances students’ scientific inquiry and innovative thinking but also cultivates their ability to conduct innovative experiments.
The proline-catalyzed asymmetric aldol reaction stands as a classic experiment illustrating the concept of enantiomerism. However, due to substrate reactivity limitations and experimental constraints, the stereochemical concepts of diastereoisomerism and racemization have not been adequately addressed. To bridge this gap between experimental and theoretical teaching and enhance students’ understanding of stereochemistry in Organic Chemistry, we have innovated and expanded the proline-catalyzed asymmetric aldol reaction. Firstly, by upgrading the conventional two-component reaction to a three-component reaction, we efficiently generate diastereomers through the conversion of arylaldehydes to highly reactive aldimines. Secondly, we introduce the stereoselective control of proline through the use of catalysts with opposite chiral configurations, while also incorporating the concept of racemization by mixing products with opposite configurations. Thirdly, we employ nuclear magnetic resonance (NMR) technology to elucidate the diastereoisomerism ratio of the products, facilitating a deeper understanding of diastereoisomerism concepts. Our results demonstrate that this experiment offers excellent repeatability, appropriate duration, and a balance of exploration and innovation. Implementation of this project not only enhances students’ scientific inquiry and innovative thinking but also cultivates their ability to conduct innovative experiments.
2024, 39(5): 163-171
doi: 10.3866/PKU.DXHX202310084
Abstract:
Crystal field theory stands as a cornerstone in coordination chemistry and poses a pivotal challenge in undergraduate inorganic chemistry education. Leveraging recent advancements in the synthesis of nickel macrocyclic coordination compounds, we introduce a highly adaptable and multifaceted comprehensive experiment. Students engage in synthesizing a series of nickel complexes, observing their colors, and analyzing their infrared absorption spectra, UV-visible absorption spectra, and effective magnetic moments. By integrating classroom instruction with literature review, students deduce the ligand composition and central ion crystal field configuration of the complexes. Spanning 8 class hours, this experiment amalgamates theoretical knowledge and experimental skills across inorganic, analytical, and physical chemistry domains. It exhibits conspicuous experimental phenomena, excellent reproducibility, low cost, and high safety standards. Moreover, it extensively cultivates students’ analytical prowess in tackling real-world problems within a problem-oriented learning framework, thereby enhancing their fundamental chemical literacy.
Crystal field theory stands as a cornerstone in coordination chemistry and poses a pivotal challenge in undergraduate inorganic chemistry education. Leveraging recent advancements in the synthesis of nickel macrocyclic coordination compounds, we introduce a highly adaptable and multifaceted comprehensive experiment. Students engage in synthesizing a series of nickel complexes, observing their colors, and analyzing their infrared absorption spectra, UV-visible absorption spectra, and effective magnetic moments. By integrating classroom instruction with literature review, students deduce the ligand composition and central ion crystal field configuration of the complexes. Spanning 8 class hours, this experiment amalgamates theoretical knowledge and experimental skills across inorganic, analytical, and physical chemistry domains. It exhibits conspicuous experimental phenomena, excellent reproducibility, low cost, and high safety standards. Moreover, it extensively cultivates students’ analytical prowess in tackling real-world problems within a problem-oriented learning framework, thereby enhancing their fundamental chemical literacy.
2024, 39(5): 172-183
doi: 10.3866/PKU.DXHX202310125
Abstract:
Smart hydrogels, characterized by their highly hydrophilic three-dimensional network structures, possess the ability to swiftly sense and respond to changes in their environment. This project harnesses alginate extracted from edible kelp, cross-linking it with various metal ions to craft alginate hydrogels. These hydrogels exhibit remarkable responsiveness, effectively distinguishing between hard and soft water while also facilitating the analysis of vitamin C and metal ion concentrations. Through a series of engaging experiments, this endeavor elucidates the formation mechanisms and practical applications of intelligent hydrogels. Preschoolers and primary school students engage in simple yet colorful hydrogel preparations, fostering a sense of excitement. Meanwhile, middle school students and the general public can participate in extracting alginic acid from kelp using everyday kitchen utensils, subsequently utilizing the resulting hydrogels for water hardness recognition and vitamin C analysis in fruits. Such hands-on experiences not only ignite curiosity but also promote the integration of chemistry into daily life, stimulating interest and enthusiasm for the subject. College students, through advanced experiments, delve into the analysis of iron ion concentrations and vitamin C content using photometric methods. This project seamlessly merges entertainment, practicality, and scientific inquiry, offering a feasible and enriching educational experience. It is poised to bridge the gap between chemistry and everyday life, serving the public, and fostering broader understanding and engagement with the field.
Smart hydrogels, characterized by their highly hydrophilic three-dimensional network structures, possess the ability to swiftly sense and respond to changes in their environment. This project harnesses alginate extracted from edible kelp, cross-linking it with various metal ions to craft alginate hydrogels. These hydrogels exhibit remarkable responsiveness, effectively distinguishing between hard and soft water while also facilitating the analysis of vitamin C and metal ion concentrations. Through a series of engaging experiments, this endeavor elucidates the formation mechanisms and practical applications of intelligent hydrogels. Preschoolers and primary school students engage in simple yet colorful hydrogel preparations, fostering a sense of excitement. Meanwhile, middle school students and the general public can participate in extracting alginic acid from kelp using everyday kitchen utensils, subsequently utilizing the resulting hydrogels for water hardness recognition and vitamin C analysis in fruits. Such hands-on experiences not only ignite curiosity but also promote the integration of chemistry into daily life, stimulating interest and enthusiasm for the subject. College students, through advanced experiments, delve into the analysis of iron ion concentrations and vitamin C content using photometric methods. This project seamlessly merges entertainment, practicality, and scientific inquiry, offering a feasible and enriching educational experience. It is poised to bridge the gap between chemistry and everyday life, serving the public, and fostering broader understanding and engagement with the field.
2024, 39(5): 184-192
doi: 10.3866/PKU.DXHX202310127
Abstract:
Centered on “unveiling the magical potential of titanium”, this experiment commenced by employing electrochemical anodization to craft vibrant titanium oxide (TiO2) films. By meticulously adjusting applied voltages, electrolytes, and anodization durations, we achieved precise control over the coloration of these films, showcasing the captivating visual allure of chemistry. Subsequent X-ray photoelectron spectroscopy elucidated the composition of these intriguing layers, confirming their pure and non-toxic nature as titanium dioxide. Detailed discussions ensued regarding the refinement of oxide film quality processes and the adoption of environmentally friendly cycling techniques. Furthermore, we explored the application of anodized TiO2 films in dye wastewater treatment and NaCl corrosion resistance tests, unveiling their multifaceted capabilities encompassing degradation, antibacterial properties, and corrosion resistance. This endeavor underscores the beauty of applied chemistry. Finally, we devised a multifaceted science popularization plan aimed at disseminating knowledge to audiences of diverse backgrounds, dispelling concerns regarding the safety of titanium-colored film layers, and enabling participants to fully appreciate the enchantment of chemistry.
Centered on “unveiling the magical potential of titanium”, this experiment commenced by employing electrochemical anodization to craft vibrant titanium oxide (TiO2) films. By meticulously adjusting applied voltages, electrolytes, and anodization durations, we achieved precise control over the coloration of these films, showcasing the captivating visual allure of chemistry. Subsequent X-ray photoelectron spectroscopy elucidated the composition of these intriguing layers, confirming their pure and non-toxic nature as titanium dioxide. Detailed discussions ensued regarding the refinement of oxide film quality processes and the adoption of environmentally friendly cycling techniques. Furthermore, we explored the application of anodized TiO2 films in dye wastewater treatment and NaCl corrosion resistance tests, unveiling their multifaceted capabilities encompassing degradation, antibacterial properties, and corrosion resistance. This endeavor underscores the beauty of applied chemistry. Finally, we devised a multifaceted science popularization plan aimed at disseminating knowledge to audiences of diverse backgrounds, dispelling concerns regarding the safety of titanium-colored film layers, and enabling participants to fully appreciate the enchantment of chemistry.
2024, 39(5): 193-200
doi: 10.3866/PKU.DXHX202311021
Abstract:
The apparatus for moving-boundary method is upgraded by digital technique. The conductivity-time curve is measured, and the moving velocity of the boundary through two pairs of conductive electrodes can be determined precisely and objectively. This method eliminates the subjective deviation from manual observation. No indicator is needed to mark the boundary, and the problem of unobservable boundary at low concentration is therefore solved. The experimental object is also extended from traditional acidic electrolyte solution (e.g., aqueous HCl) to neutral electrolyte solution (e.g., aqueous NaCl, KCl, etc.). In the range of experimental concentrations (approx. 0.01 mol∙L−1 to 0.1 mol∙L−1), the transference number of H+ can be obtained with a reasonable deviation (0.8230–0.8350) by this method. The improved apparatus can be used to determine the transference numbers and mobilities of electrolytes, which provides a new way for physical chemistry experiment teaching.
The apparatus for moving-boundary method is upgraded by digital technique. The conductivity-time curve is measured, and the moving velocity of the boundary through two pairs of conductive electrodes can be determined precisely and objectively. This method eliminates the subjective deviation from manual observation. No indicator is needed to mark the boundary, and the problem of unobservable boundary at low concentration is therefore solved. The experimental object is also extended from traditional acidic electrolyte solution (e.g., aqueous HCl) to neutral electrolyte solution (e.g., aqueous NaCl, KCl, etc.). In the range of experimental concentrations (approx. 0.01 mol∙L−1 to 0.1 mol∙L−1), the transference number of H+ can be obtained with a reasonable deviation (0.8230–0.8350) by this method. The improved apparatus can be used to determine the transference numbers and mobilities of electrolytes, which provides a new way for physical chemistry experiment teaching.
2024, 39(5): 201-208
doi: 10.3866/PKU.DXHX202311033
Abstract:
This experiment integrates cutting-edge research from the field of organic photochemistry into undergraduate laboratory instruction. Utilizing benzaldehyde, aniline, and 4-isopropyl-1,4-dihydropyridines as starting materials, a visible-light-mediated one-pot multicomponent reaction was conducted under mild conditions to yield secondary amines efficiently. The experiment features cost-effective and readily available reagents, simple operation, and mild reaction conditions, alongside incorporating principles of green chemistry and organic synthesis methodology. Suitable for undergraduate laboratory teaching, it provides students with practical skills while deepening their comprehension of topics such as photochemical reactions, one-pot tandem reactions, and free radical processes. This experiment bridges the gap between cutting-edge research and talent cultivation, enhancing students’ abilities in scientific research, innovation, and practical application.
This experiment integrates cutting-edge research from the field of organic photochemistry into undergraduate laboratory instruction. Utilizing benzaldehyde, aniline, and 4-isopropyl-1,4-dihydropyridines as starting materials, a visible-light-mediated one-pot multicomponent reaction was conducted under mild conditions to yield secondary amines efficiently. The experiment features cost-effective and readily available reagents, simple operation, and mild reaction conditions, alongside incorporating principles of green chemistry and organic synthesis methodology. Suitable for undergraduate laboratory teaching, it provides students with practical skills while deepening their comprehension of topics such as photochemical reactions, one-pot tandem reactions, and free radical processes. This experiment bridges the gap between cutting-edge research and talent cultivation, enhancing students’ abilities in scientific research, innovation, and practical application.
2024, 39(5): 209-217
doi: 10.3866/PKU.DXHX202311024
Abstract:
we establish a relay catalysis strategy utilizing Pd(OAc)2/chiral phosphoric acid catalyst for the efficient synthesis of optically active 2-phenyl tetrahydroquinoline via a one-pot three-step domino reaction of 2-iodoaniline with allylic alcohol, eliminating the need for intermediate isolation. Compared to conventional single catalysis methods, this cooperative relay catalysis offers advantages of simplicity and high efficiency. Introducing scientific frontiers such as cooperative relay catalysis into experimental teaching, along with principles of green chemistry and energy saving, broadens students’ scientific perspectives, ignites their passion for learning, and enhances their innovation capabilities. Furthermore, this experiment encompasses fundamental theoretical knowledge including Grignard reactions, Heck reactions, imine condensations, and asymmetric hydrogen transfers, alongside practical analytical techniques such as thin-layer chromatography (TLC), column chromatography, nuclear magnetic resonance (NMR), rotary evaporation, high-performance liquid chromatography (HPLC), and polarimetry. Through this comprehensive experiment, students’ theoretical understanding, experimental skills, and scientific reasoning abilities are enriched, fostering the integration of scientific research and teaching.
we establish a relay catalysis strategy utilizing Pd(OAc)2/chiral phosphoric acid catalyst for the efficient synthesis of optically active 2-phenyl tetrahydroquinoline via a one-pot three-step domino reaction of 2-iodoaniline with allylic alcohol, eliminating the need for intermediate isolation. Compared to conventional single catalysis methods, this cooperative relay catalysis offers advantages of simplicity and high efficiency. Introducing scientific frontiers such as cooperative relay catalysis into experimental teaching, along with principles of green chemistry and energy saving, broadens students’ scientific perspectives, ignites their passion for learning, and enhances their innovation capabilities. Furthermore, this experiment encompasses fundamental theoretical knowledge including Grignard reactions, Heck reactions, imine condensations, and asymmetric hydrogen transfers, alongside practical analytical techniques such as thin-layer chromatography (TLC), column chromatography, nuclear magnetic resonance (NMR), rotary evaporation, high-performance liquid chromatography (HPLC), and polarimetry. Through this comprehensive experiment, students’ theoretical understanding, experimental skills, and scientific reasoning abilities are enriched, fostering the integration of scientific research and teaching.
2024, 39(5): 218-227
doi: 10.3866/PKU.DXHX202311046
Abstract:
Surface chemistry permeates various aspects of our daily lives, from the natural phenomenon of the “lotus leaf effect” to the functionalities of specialized industrial products like waterproofing, anti-freezing, and anti-fouling coatings. While these phenomena may seem commonplace and straightforward, they harbor intricate principles of interfacial science. In this experiment, we employ a layer-by-layer self-assembly technique to deposit a hydrophilic coating composed of plant polyphenol tannic acid (TA) and iron (Fe(III)) coordination complex onto the surface of a melt-blown fabric membrane. Subsequent oxidation of catechol groups using sodium periodate (NaIO4) facilitates the fixation of the polyphenol-metal coordination complex network at the fabric interface, thereby achieving a transition from hydrophobic to hydrophilic modification. Finally, we demonstrate the efficacy of the modified melt-blown fabric membrane in oil-water separation processes. Through this endeavor, we not only showcase the modification process of materials and the resulting property alterations but also delve into the underlying physical and chemical principles layer by layer. The reagents utilized in this educational experiment are environmentally friendly, facilitating simple operation, offering aesthetic appeal, and encouraging interaction. Moreover, the modified membrane boasts recyclability advantages. Employing a gradient approach to science communication, we elucidate the principles and essence behind these phenomena in a comprehensible manner, enabling the public to appreciate the magic and beauty of surface chemistry while acquiring knowledge. This experiment holds promise not only for popular science dissemination and classroom teaching but also for its excellent application prospects.
Surface chemistry permeates various aspects of our daily lives, from the natural phenomenon of the “lotus leaf effect” to the functionalities of specialized industrial products like waterproofing, anti-freezing, and anti-fouling coatings. While these phenomena may seem commonplace and straightforward, they harbor intricate principles of interfacial science. In this experiment, we employ a layer-by-layer self-assembly technique to deposit a hydrophilic coating composed of plant polyphenol tannic acid (TA) and iron (Fe(III)) coordination complex onto the surface of a melt-blown fabric membrane. Subsequent oxidation of catechol groups using sodium periodate (NaIO4) facilitates the fixation of the polyphenol-metal coordination complex network at the fabric interface, thereby achieving a transition from hydrophobic to hydrophilic modification. Finally, we demonstrate the efficacy of the modified melt-blown fabric membrane in oil-water separation processes. Through this endeavor, we not only showcase the modification process of materials and the resulting property alterations but also delve into the underlying physical and chemical principles layer by layer. The reagents utilized in this educational experiment are environmentally friendly, facilitating simple operation, offering aesthetic appeal, and encouraging interaction. Moreover, the modified membrane boasts recyclability advantages. Employing a gradient approach to science communication, we elucidate the principles and essence behind these phenomena in a comprehensible manner, enabling the public to appreciate the magic and beauty of surface chemistry while acquiring knowledge. This experiment holds promise not only for popular science dissemination and classroom teaching but also for its excellent application prospects.
2024, 39(5): 228-237
doi: 10.3866/PKU.DXHX202311059
Abstract:
Intelligent actuators have garnered significant attention for their applications in diverse fields such as soft robotics, artificial muscles, sensors, and intelligent skins. In this innovative experiment, we successfully synthesized a superhydrophobic actuation material by employing a layer-by-layer assembly approach, incorporating polyimide film (PI), polydimethylsiloxane (PDMS), and graphene. This material exhibits responsive behaviors to stimuli including light, electricity, and heat. Drawing inspiration from traditional Chinese paper-cutting techniques, we fashioned claw-shaped structures and deformable water collection devices, enabling intelligent programming even in challenging environments such as strong acids and alkalis. Serving as an effective educational tool, this experiment facilitates students’ understanding of fundamental scientific principles across multiple disciplines, spanning inorganic and polymer chemistry, instrumental analysis, and materials science, while emphasizing the seamless integration of theory and application. The selection of raw materials, which are non-toxic, cost-effective, and eco-friendly, aligns with the principles of green chemistry, underscoring the experiment’s sustainability. Notably, the experimental phenomenon is readily observable, and the operation process is engaging, fostering students’ enthusiasm for scientific research and innovation. This experiment offers a stimulating and enriching learning experience, nurturing students’ curiosity, and proficiency in scientific inquiry.
Intelligent actuators have garnered significant attention for their applications in diverse fields such as soft robotics, artificial muscles, sensors, and intelligent skins. In this innovative experiment, we successfully synthesized a superhydrophobic actuation material by employing a layer-by-layer assembly approach, incorporating polyimide film (PI), polydimethylsiloxane (PDMS), and graphene. This material exhibits responsive behaviors to stimuli including light, electricity, and heat. Drawing inspiration from traditional Chinese paper-cutting techniques, we fashioned claw-shaped structures and deformable water collection devices, enabling intelligent programming even in challenging environments such as strong acids and alkalis. Serving as an effective educational tool, this experiment facilitates students’ understanding of fundamental scientific principles across multiple disciplines, spanning inorganic and polymer chemistry, instrumental analysis, and materials science, while emphasizing the seamless integration of theory and application. The selection of raw materials, which are non-toxic, cost-effective, and eco-friendly, aligns with the principles of green chemistry, underscoring the experiment’s sustainability. Notably, the experimental phenomenon is readily observable, and the operation process is engaging, fostering students’ enthusiasm for scientific research and innovation. This experiment offers a stimulating and enriching learning experience, nurturing students’ curiosity, and proficiency in scientific inquiry.
2024, 39(5): 238-242
doi: 10.3866/PKU.DXHX202311066
Abstract:
In university organic chemistry experiments, the classic teaching project of synthesizing triphenylmethanol by reacting Grignard reagent with benzoate often encounters challenges with the conventional method of initiating the reaction using iodine heating. This approach is difficult to control and prone to generating by-products like biphenyl, leading to low yields. Furthermore, some students may fail to obtain the Grignard reagent, resulting in experiment failure. In this study, we propose a photoinitiated method for synthesizing the Grignard reagent, eliminating the need for iodine heating. Under 520 nm LED irradiation, bromobenzene reacts directly with magnesium to form phenylmagnesium bromide without requiring external heating, even at temperatures as low as−10°C. This cost-effective and readily available light source significantly shortens synthesis time, improves yield, and enhances experimental success rates. Therefore, this innovative approach holds promise for wider adoption and application in university settings.
In university organic chemistry experiments, the classic teaching project of synthesizing triphenylmethanol by reacting Grignard reagent with benzoate often encounters challenges with the conventional method of initiating the reaction using iodine heating. This approach is difficult to control and prone to generating by-products like biphenyl, leading to low yields. Furthermore, some students may fail to obtain the Grignard reagent, resulting in experiment failure. In this study, we propose a photoinitiated method for synthesizing the Grignard reagent, eliminating the need for iodine heating. Under 520 nm LED irradiation, bromobenzene reacts directly with magnesium to form phenylmagnesium bromide without requiring external heating, even at temperatures as low as−10°C. This cost-effective and readily available light source significantly shortens synthesis time, improves yield, and enhances experimental success rates. Therefore, this innovative approach holds promise for wider adoption and application in university settings.
2024, 39(5): 243-250
doi: 10.3866/PKU.DXHX202311074
Abstract:
The experiment for synthesizing cinnamic acid is a crucial foundational experiment in the current “Organic Chemistry Experiment” curriculum in higher education. However, during its implementation, several issues have emerged, including the unpleasant odor of residual benzaldehyde, sensitivity of raw materials to water, procurement challenges, and the generation of numerous high-temperature by-products. In response to these challenges, this paper proposes improvements to the classic cinnamic acid synthesis experiment. A homogeneous reaction system comprising benzaldehyde/malonic acid/triethylenediamine was employed to synthesize cinnamic acid. Additionally, a post-treatment method involving washing with sodium bisulfite was introduced to eliminate residual benzaldehyde, thereby aligning the experiment with modern teaching practices and the principles of green chemistry. The enhanced experiment not only effectively mitigates the odor issue associated with residual benzaldehyde but also offers advantages such as improved raw material stability, lower costs, and simplified post-treatment procedures. Furthermore, by incorporating spectroscopic characterization and column chromatography, the experiment can be expanded into a comprehensive 8-hour laboratory session targeting the synthesis of the fine chemical ferulic acid, thus enhancing the development of students’ overall chemical proficiency.
The experiment for synthesizing cinnamic acid is a crucial foundational experiment in the current “Organic Chemistry Experiment” curriculum in higher education. However, during its implementation, several issues have emerged, including the unpleasant odor of residual benzaldehyde, sensitivity of raw materials to water, procurement challenges, and the generation of numerous high-temperature by-products. In response to these challenges, this paper proposes improvements to the classic cinnamic acid synthesis experiment. A homogeneous reaction system comprising benzaldehyde/malonic acid/triethylenediamine was employed to synthesize cinnamic acid. Additionally, a post-treatment method involving washing with sodium bisulfite was introduced to eliminate residual benzaldehyde, thereby aligning the experiment with modern teaching practices and the principles of green chemistry. The enhanced experiment not only effectively mitigates the odor issue associated with residual benzaldehyde but also offers advantages such as improved raw material stability, lower costs, and simplified post-treatment procedures. Furthermore, by incorporating spectroscopic characterization and column chromatography, the experiment can be expanded into a comprehensive 8-hour laboratory session targeting the synthesis of the fine chemical ferulic acid, thus enhancing the development of students’ overall chemical proficiency.
2024, 39(5): 251-257
doi: 10.3866/PKU.DXHX202311084
Abstract:
This experiment addresses the pressing issue of milk safety, integrating cutting-edge molecular imprinting technology into undergraduate laboratory classes. A comprehensive experiment is designed, combining molecular imprinting, protein exclusion, and magnetic separation techniques to synthesize lightweight magnetic molecularly imprinted polymers. The polymers’ performance is evaluated, and they are utilized as solid-phase extraction adsorbents in conjunction with high-performance liquid chromatography to establish a novel method for the direct and selective detection of trace tetracycline in milk samples. This interdisciplinary study spans materials chemistry, analytical chemistry, instrumental chemistry, and food chemistry, fostering students’ scientific literacy, problem-solving abilities, and innovative thinking. The innovative design of the imprinting material and magnetic separation process ensures cost-effectiveness, ease of operation, and high safety throughout the experiment. Through this hands-on experience, students gain insight into molecular imprinting technology, learn new detection methods, refine basic laboratory skills, enhance data collection and analysis capabilities, and deepen their understanding of the interplay between components, performance, and application.
This experiment addresses the pressing issue of milk safety, integrating cutting-edge molecular imprinting technology into undergraduate laboratory classes. A comprehensive experiment is designed, combining molecular imprinting, protein exclusion, and magnetic separation techniques to synthesize lightweight magnetic molecularly imprinted polymers. The polymers’ performance is evaluated, and they are utilized as solid-phase extraction adsorbents in conjunction with high-performance liquid chromatography to establish a novel method for the direct and selective detection of trace tetracycline in milk samples. This interdisciplinary study spans materials chemistry, analytical chemistry, instrumental chemistry, and food chemistry, fostering students’ scientific literacy, problem-solving abilities, and innovative thinking. The innovative design of the imprinting material and magnetic separation process ensures cost-effectiveness, ease of operation, and high safety throughout the experiment. Through this hands-on experience, students gain insight into molecular imprinting technology, learn new detection methods, refine basic laboratory skills, enhance data collection and analysis capabilities, and deepen their understanding of the interplay between components, performance, and application.
2024, 39(5): 258-265
doi: 10.3866/PKU.DXHX202311085
Abstract:
Coordination chemistry, fundamental to understanding molecular interactions, has played a pivotal role in various fields from ancient dyeing techniques to modern industrial applications. However, public awareness of coordination chemistry remains limited. This interdisciplinary experiment integrates traditional mordant dyeing techniques with coordination chemistry to elucidate the rich colors and complexities behind dyeing processes. Utilizing plant pigments like alizarin and hematoxylin, the experiment showcases the formation of complex compounds through metal ion coordination, emphasizing the pivotal role of coordination chemistry in dyeing and fixation effects. Inspired by China’s intangible cultural heritage, tie-dyeing, the experiment further demonstrates the fusion of chemistry, art, and culture through the creation of tie-dye works, showcasing both the beauty of chemistry and the craftsmanship of traditional Chinese handicrafts. Additionally, a home experiment plan utilizing onion skin to produce dyes promotes hands-on experimentation and highlights the experiment’s accessibility and applicability to diverse audiences. This comprehensive science popularization initiative caters to young children, students at different educational levels, and the general public, promoting a deeper understanding of chemistry while emphasizing sustainability and safety.
Coordination chemistry, fundamental to understanding molecular interactions, has played a pivotal role in various fields from ancient dyeing techniques to modern industrial applications. However, public awareness of coordination chemistry remains limited. This interdisciplinary experiment integrates traditional mordant dyeing techniques with coordination chemistry to elucidate the rich colors and complexities behind dyeing processes. Utilizing plant pigments like alizarin and hematoxylin, the experiment showcases the formation of complex compounds through metal ion coordination, emphasizing the pivotal role of coordination chemistry in dyeing and fixation effects. Inspired by China’s intangible cultural heritage, tie-dyeing, the experiment further demonstrates the fusion of chemistry, art, and culture through the creation of tie-dye works, showcasing both the beauty of chemistry and the craftsmanship of traditional Chinese handicrafts. Additionally, a home experiment plan utilizing onion skin to produce dyes promotes hands-on experimentation and highlights the experiment’s accessibility and applicability to diverse audiences. This comprehensive science popularization initiative caters to young children, students at different educational levels, and the general public, promoting a deeper understanding of chemistry while emphasizing sustainability and safety.
2024, 39(5): 266-273
doi: 10.3866/PKU.DXHX202311101
Abstract:
The preparation of nano zinc oxide is a classic inorganic chemistry experiment with distinctive characteristics. In this paper, an innovative improvement is made to solve the existing problems in the experimental process of basic chemistry experiment “preparation of nano zinc oxide powder”. The preparation and photocatalytic activity of zinc oxide nanoparticles based on the microemulsion method were designed. This experiment features a mild reaction, simple operation, obvious phenomenon, and environmental friendliness. It can not only cultivate students’ basic operation skills but also stimulate students’ interest in experiments, and exercise students’ comprehensive ability. Compared to the traditional experiment for the preparation of nano zinc oxide, this approach has higher time efficiency and a scientifically reasonable experimental arrangement. The phenomena are more apparent, and it is more interesting. It is comprehensive and exploratory, as it not only consolidates students’ basic experimental skills but also nurtures their scientific research thinking and expands their research skills.
The preparation of nano zinc oxide is a classic inorganic chemistry experiment with distinctive characteristics. In this paper, an innovative improvement is made to solve the existing problems in the experimental process of basic chemistry experiment “preparation of nano zinc oxide powder”. The preparation and photocatalytic activity of zinc oxide nanoparticles based on the microemulsion method were designed. This experiment features a mild reaction, simple operation, obvious phenomenon, and environmental friendliness. It can not only cultivate students’ basic operation skills but also stimulate students’ interest in experiments, and exercise students’ comprehensive ability. Compared to the traditional experiment for the preparation of nano zinc oxide, this approach has higher time efficiency and a scientifically reasonable experimental arrangement. The phenomena are more apparent, and it is more interesting. It is comprehensive and exploratory, as it not only consolidates students’ basic experimental skills but also nurtures their scientific research thinking and expands their research skills.
2024, 39(5): 274-286
doi: 10.3866/PKU.DXHX202311067
Abstract:
As a classical physical chemistry experiment, traditional Fe(OH)3 colloid electrophoresis has suffered from the following shortcomings, such as the waste of Fe(OH)3 colloid, the long dialysis operation time, and the lack of inquiry learning. To overcome such shortcomings, we have made the following improvements on the original experiment: 1) realizing the recycling of Fe(OH)3 colloid by regenerating Fe(OH)3 colloid waste via colloid redissolution route; 2) improving the purification efficiency of coarse Fe(OH)3 colloid through optimizing the dialysis procedure; 3) introducing AgI colloid exploratory investigation to enhance the innovation and interestingness of this experiment; 4) introducing paper electrophoresis to cultivate the ability to connect fundamental experiments with practical applications. The above improvements have been fully confirmed and already applied in the colloid electrophoresis experiment performed in our university. As expected, such improvements have aroused enthusiastic responses from the students attended this course, thus providing a valuable reference for us to improve other classical experiments.
As a classical physical chemistry experiment, traditional Fe(OH)3 colloid electrophoresis has suffered from the following shortcomings, such as the waste of Fe(OH)3 colloid, the long dialysis operation time, and the lack of inquiry learning. To overcome such shortcomings, we have made the following improvements on the original experiment: 1) realizing the recycling of Fe(OH)3 colloid by regenerating Fe(OH)3 colloid waste via colloid redissolution route; 2) improving the purification efficiency of coarse Fe(OH)3 colloid through optimizing the dialysis procedure; 3) introducing AgI colloid exploratory investigation to enhance the innovation and interestingness of this experiment; 4) introducing paper electrophoresis to cultivate the ability to connect fundamental experiments with practical applications. The above improvements have been fully confirmed and already applied in the colloid electrophoresis experiment performed in our university. As expected, such improvements have aroused enthusiastic responses from the students attended this course, thus providing a valuable reference for us to improve other classical experiments.
2024, 39(5): 287-295
doi: 10.3866/PKU.DXHX202311096
Abstract:
Fluorescence detection has found extensive applications in various fields such as chemical analysis and biological testing. Therefore, conducting experiments related to fluorescence detection is of significant importance in undergraduate laboratory education. This experiment successfully developed a low-cost, compact open-source fluorescence spectrometer, whose performance was comprehensively evaluated and applied to the detection of real samples. The aim is to foster students’ awareness and confidence in designing and creating instruments.
Fluorescence detection has found extensive applications in various fields such as chemical analysis and biological testing. Therefore, conducting experiments related to fluorescence detection is of significant importance in undergraduate laboratory education. This experiment successfully developed a low-cost, compact open-source fluorescence spectrometer, whose performance was comprehensively evaluated and applied to the detection of real samples. The aim is to foster students’ awareness and confidence in designing and creating instruments.
2024, 39(5): 296-306
doi: 10.3866/PKU.DXHX202311087
Abstract:
This experiment introduces undergraduate students to the forefront of organic chemistry and new synthetic methodologies through the synthesis of isoquinolinone guided by photochemistry. By integrating organic photochemistry and continuous flow chemistry, the experiment aims to broaden the scope of undergraduate organic chemistry laboratory teaching. Carbon nitride (g-C3N4) is employed as a heterogeneous photocatalyst, while oxygen serves as a safe and atom-economic oxidant, enabling the synthesis of isoquinolinone under visible-light irradiation in a continuous flow setup. The experiment encompasses both batch and continuous flow photochemical synthesis of isoquinolinone, as well as the preparation of the natural product corydaldine. Students are involved in various aspects of the experiment, including the installation of a simple flow photochemical reactor, reaction monitoring, product purification, and characterization. Through this project, students not only gain insights into photochemical reactions but also cultivate their creativity and research skills in the realm of green and sustainable chemistry. They acquire hands-on experience in thin-layer chromatography, column chromatography, and spectroscopic analysis techniques like IR and NMR, enhancing their practical skills and environmental awareness. This innovative experiment aligns with the principles of green chemistry and miniaturization and is suitable for incorporation into undergraduate laboratory courses such as Organic Chemistry Laboratory and Comprehensive Chemistry Laboratory. Its introduction into laboratory teaching can enrich teaching practices, promote active learning, and elevate the quality of practical education.
This experiment introduces undergraduate students to the forefront of organic chemistry and new synthetic methodologies through the synthesis of isoquinolinone guided by photochemistry. By integrating organic photochemistry and continuous flow chemistry, the experiment aims to broaden the scope of undergraduate organic chemistry laboratory teaching. Carbon nitride (g-C3N4) is employed as a heterogeneous photocatalyst, while oxygen serves as a safe and atom-economic oxidant, enabling the synthesis of isoquinolinone under visible-light irradiation in a continuous flow setup. The experiment encompasses both batch and continuous flow photochemical synthesis of isoquinolinone, as well as the preparation of the natural product corydaldine. Students are involved in various aspects of the experiment, including the installation of a simple flow photochemical reactor, reaction monitoring, product purification, and characterization. Through this project, students not only gain insights into photochemical reactions but also cultivate their creativity and research skills in the realm of green and sustainable chemistry. They acquire hands-on experience in thin-layer chromatography, column chromatography, and spectroscopic analysis techniques like IR and NMR, enhancing their practical skills and environmental awareness. This innovative experiment aligns with the principles of green chemistry and miniaturization and is suitable for incorporation into undergraduate laboratory courses such as Organic Chemistry Laboratory and Comprehensive Chemistry Laboratory. Its introduction into laboratory teaching can enrich teaching practices, promote active learning, and elevate the quality of practical education.
2024, 39(5): 307-314
doi: 10.3866/PKU.DXHX202311092
Abstract:
Based on the general process of synthetic chemistry methodology and the “scientific problem-oriented” principle in laboratory teaching, this paper has developed a basic experiment of organic chemistry derived from the green synthesis of 1,3-dibromoacetone, and firstly applied halogen exchange reaction to laboratory teaching. Starting with 1,3-dichloroacetone and lithium bromide, the halogen exchange equilibrium was broken efficiently using mixture solvent of dichloromethane and acetone (10 : 1). Therefore, in the presence of 3.5 equivalents of lithium bromide, the green synthesis of 1,3-dibromoacetone was achieved with 97% isolated yield after refluxing 1.5 hours at 40 °C. The purity of desired product was higher than 97%, and up to 98.8% after recrystallization. The all reagents used in this experiment are safe and environmentally benign. The teaching time is about 4 hours, which not only involves basic operations of various organic chemistry experiments, but also includes important aspects such as reaction monitoring, structure characterization, and purity analysis. It is very suitable for basic organic chemistry laboratory teaching. At the same time, based on this experimental scheme, combined with the micro-course learning and exercises on the development history of halogen exchange reaction in application and development of 1,3-dibromoacetone, the interaction between theoretical knowledge and synthetic practice was realized. This improved the comprehensive ability of undergraduate of chemistry majors to solve synthetic chemistry problems and solidified the quality of talent cultivation in the field of chemistry.
Based on the general process of synthetic chemistry methodology and the “scientific problem-oriented” principle in laboratory teaching, this paper has developed a basic experiment of organic chemistry derived from the green synthesis of 1,3-dibromoacetone, and firstly applied halogen exchange reaction to laboratory teaching. Starting with 1,3-dichloroacetone and lithium bromide, the halogen exchange equilibrium was broken efficiently using mixture solvent of dichloromethane and acetone (10 : 1). Therefore, in the presence of 3.5 equivalents of lithium bromide, the green synthesis of 1,3-dibromoacetone was achieved with 97% isolated yield after refluxing 1.5 hours at 40 °C. The purity of desired product was higher than 97%, and up to 98.8% after recrystallization. The all reagents used in this experiment are safe and environmentally benign. The teaching time is about 4 hours, which not only involves basic operations of various organic chemistry experiments, but also includes important aspects such as reaction monitoring, structure characterization, and purity analysis. It is very suitable for basic organic chemistry laboratory teaching. At the same time, based on this experimental scheme, combined with the micro-course learning and exercises on the development history of halogen exchange reaction in application and development of 1,3-dibromoacetone, the interaction between theoretical knowledge and synthetic practice was realized. This improved the comprehensive ability of undergraduate of chemistry majors to solve synthetic chemistry problems and solidified the quality of talent cultivation in the field of chemistry.
2024, 39(5): 315-324
doi: 10.3866/PKU.DXHX202311094
Abstract:
The experimental preparation of polyacrylic acid by free radical polymerization is an important and classic teaching content in the course of Polymer Chemistry Experiments. The monomer is easy to obtain and the reaction conditions are mild. As a representative experiment to master the free radical polymerization reaction and the preparation of porous adsorption materials, it is offered in many colleges and universities. However, in the preparation experiments of polyacrylic acid in existing textbooks, the reaction system is easy to gelate and produces more waste liquid. The process took 30.5 to 33 hours and could not be completed within one teaching session. The characterization process is complicated. Therefore, natural and cheap sodium alginate was used as thickener in this improved experiment to stabilize the viscosity of the reaction system and prevent the gelation of the reaction system caused by the sharp increase of local viscosity. Using the same natural and cheap porous diatomite as filler, the porous resin was prepared by co-precipitation with the polyacrylic acid solution prepared by free radical polymerization reaction, which greatly reduced the use and consumption of organic solvents. In addition, this improved experiment follows the academic frontier, and introduces the smartphone identification-colorimetric analysis to characterize the adsorption performance of the product, which is fast and convenient. The new method of hole formation and representation reduced the duration of the experiment to 5 hours, ensuring the continuity of teaching, while retaining the characteristics of the original experiment, making the experiment more meaningful and conducive to stimulate students’ interest in learning this experimental course.
The experimental preparation of polyacrylic acid by free radical polymerization is an important and classic teaching content in the course of Polymer Chemistry Experiments. The monomer is easy to obtain and the reaction conditions are mild. As a representative experiment to master the free radical polymerization reaction and the preparation of porous adsorption materials, it is offered in many colleges and universities. However, in the preparation experiments of polyacrylic acid in existing textbooks, the reaction system is easy to gelate and produces more waste liquid. The process took 30.5 to 33 hours and could not be completed within one teaching session. The characterization process is complicated. Therefore, natural and cheap sodium alginate was used as thickener in this improved experiment to stabilize the viscosity of the reaction system and prevent the gelation of the reaction system caused by the sharp increase of local viscosity. Using the same natural and cheap porous diatomite as filler, the porous resin was prepared by co-precipitation with the polyacrylic acid solution prepared by free radical polymerization reaction, which greatly reduced the use and consumption of organic solvents. In addition, this improved experiment follows the academic frontier, and introduces the smartphone identification-colorimetric analysis to characterize the adsorption performance of the product, which is fast and convenient. The new method of hole formation and representation reduced the duration of the experiment to 5 hours, ensuring the continuity of teaching, while retaining the characteristics of the original experiment, making the experiment more meaningful and conducive to stimulate students’ interest in learning this experimental course.
2024, 39(5): 325-335
doi: 10.3866/PKU.DXHX202311104
Abstract:
Uric acid is the final product of purine metabolism in the human body. Prolonged consumption of high-purine foods or various meats that are not fresh can lead to imbalance of uric acid in the body, resulting in high levels of uric acid in the blood and triggering a series of health problems. In this experiment, a novel Cd2In2S5 nanocrystal was prepared and combined with a screen-printed carbon flexible electrode for uric acid detection. Monitoring uric acid content can be used to assess human health and determine the freshness of meat. This experiment innovatively brings nano materials to the market, enabling elementary and secondary school students, university students, and the general public to understand the principles of uric acid detection. The materials used in the experiment are inexpensive and readily available, with simple operation, enabling home uric acid testing.
Uric acid is the final product of purine metabolism in the human body. Prolonged consumption of high-purine foods or various meats that are not fresh can lead to imbalance of uric acid in the body, resulting in high levels of uric acid in the blood and triggering a series of health problems. In this experiment, a novel Cd2In2S5 nanocrystal was prepared and combined with a screen-printed carbon flexible electrode for uric acid detection. Monitoring uric acid content can be used to assess human health and determine the freshness of meat. This experiment innovatively brings nano materials to the market, enabling elementary and secondary school students, university students, and the general public to understand the principles of uric acid detection. The materials used in the experiment are inexpensive and readily available, with simple operation, enabling home uric acid testing.
2024, 39(5): 336-344
doi: 10.3866/PKU.DXHX202312002
Abstract:
Electrophilic halogenation of arenes represents a fundamental method for synthesizing aryl halides, crucial in the construction of various agrochemicals, materials, and pharmaceuticals. However, achieving regioselectivity in the halogenation of electron-rich arenes has posed a persistent challenge. This experiment demonstrates a synergistic catalytic approach for halogenating arenes bearing electron-donating substituents under mild conditions, offering a highly selective pathway to aryl halides. The utilization of hydrogen bonding between a Brønsted acid and the protic solvent nitromethane facilitates this transformation, effectively addressing the aforementioned challenge. The experiment not only enhances students’ understanding of electrophilic halogenation reactions of arenes but also imparts knowledge on self-assembly, synergistic catalysis, and Lewis acid-base catalysis. Furthermore, it deepens students’ comprehension of reaction mechanisms and ionic intermediates. The experiment comprises three main components: synthesis of brominated aromatics, mechanism exploration, and applicability assessment. It encompasses various organic laboratory techniques, including reaction monitoring, purification, and product characterization. With a duration of 7 hours and ensuring high safety, this experiment is suitable for undergraduate teaching. Moreover, it serves to strengthen students’ fundamental experimental skills while fostering their capacity for scientific research innovation and practice, preparing them for future scientific endeavors.
Electrophilic halogenation of arenes represents a fundamental method for synthesizing aryl halides, crucial in the construction of various agrochemicals, materials, and pharmaceuticals. However, achieving regioselectivity in the halogenation of electron-rich arenes has posed a persistent challenge. This experiment demonstrates a synergistic catalytic approach for halogenating arenes bearing electron-donating substituents under mild conditions, offering a highly selective pathway to aryl halides. The utilization of hydrogen bonding between a Brønsted acid and the protic solvent nitromethane facilitates this transformation, effectively addressing the aforementioned challenge. The experiment not only enhances students’ understanding of electrophilic halogenation reactions of arenes but also imparts knowledge on self-assembly, synergistic catalysis, and Lewis acid-base catalysis. Furthermore, it deepens students’ comprehension of reaction mechanisms and ionic intermediates. The experiment comprises three main components: synthesis of brominated aromatics, mechanism exploration, and applicability assessment. It encompasses various organic laboratory techniques, including reaction monitoring, purification, and product characterization. With a duration of 7 hours and ensuring high safety, this experiment is suitable for undergraduate teaching. Moreover, it serves to strengthen students’ fundamental experimental skills while fostering their capacity for scientific research innovation and practice, preparing them for future scientific endeavors.
2024, 39(5): 345-353
doi: 10.3866/PKU.DXHX202312009
Abstract:
In the physical chemistry experiment “Colloid ζ potential measurement by electrophoresis”, there exist some issues affecting the effectiveness of experimental teaching, such as prolonged colloid purification time and low accuracy in interface position measurement. To address these challenges, this paper explores methods and conditions for the rapid, large-scale, and repeatable purification of Fe(OH)3 colloids using acid and alkali ion exchange resins. Additionally, an innovative device utilizing a digital scale and a light barrier for precise measurement of colloidal interface position has been designed. This device is integrated with the electrophoresis tube holder, forming a dedicated set of instrumentation. The increased accuracy in interface position measurement allows for a reduction in electrophoresis measurement time to 5 minutes, mitigating the impact of potential gradient changes caused by prolonged electrophoresis. The application of these improved methods and instruments in experimental teaching has resulted in enhanced efficiency, reduced measurement result deviation, and improved repeatability. This lays the groundwork for incorporating some exploratory experiments into the teaching program.
In the physical chemistry experiment “Colloid ζ potential measurement by electrophoresis”, there exist some issues affecting the effectiveness of experimental teaching, such as prolonged colloid purification time and low accuracy in interface position measurement. To address these challenges, this paper explores methods and conditions for the rapid, large-scale, and repeatable purification of Fe(OH)3 colloids using acid and alkali ion exchange resins. Additionally, an innovative device utilizing a digital scale and a light barrier for precise measurement of colloidal interface position has been designed. This device is integrated with the electrophoresis tube holder, forming a dedicated set of instrumentation. The increased accuracy in interface position measurement allows for a reduction in electrophoresis measurement time to 5 minutes, mitigating the impact of potential gradient changes caused by prolonged electrophoresis. The application of these improved methods and instruments in experimental teaching has resulted in enhanced efficiency, reduced measurement result deviation, and improved repeatability. This lays the groundwork for incorporating some exploratory experiments into the teaching program.
2024, 39(5): 354-362
doi: 10.3866/PKU.DXHX202312014
Abstract:
Formylstyrylpyridinium salt (SBQ) is a water-soluble fluorescent diarylethene derivative. In aqueous solution, it undergoes a[2+2] photodimerization reaction under 365 nm ultraviolet light irradiation, yielding non-fluorescent photodimers. Upon exposure to 254 nm short-wavelength ultraviolet light, these photodimers can undergo photolysis of the cyclobutene ring, regenerating SBQ monomers and restoring fluorescence, making them suitable for optical information storage. In acidic aqueous solution, SBQ monomers can be grafted onto the polyvinyl alcohol skeleton through acetalization reaction, synthesizing a water-soluble photosensitive polymer material. When mixed with polyvinyl acetate emulsion, it forms a one-component silk screen printing photosensitive emulsion. Students can utilize the synthesized product to print patterns on paper and experimental clothing, as well as to fabricate printed circuit boards and explore additional applications. All synthetic reactions in this experiment are conducted in aqueous solution, offering safety, environmental friendliness, and adherence to green chemistry principles.
Formylstyrylpyridinium salt (SBQ) is a water-soluble fluorescent diarylethene derivative. In aqueous solution, it undergoes a[2+2] photodimerization reaction under 365 nm ultraviolet light irradiation, yielding non-fluorescent photodimers. Upon exposure to 254 nm short-wavelength ultraviolet light, these photodimers can undergo photolysis of the cyclobutene ring, regenerating SBQ monomers and restoring fluorescence, making them suitable for optical information storage. In acidic aqueous solution, SBQ monomers can be grafted onto the polyvinyl alcohol skeleton through acetalization reaction, synthesizing a water-soluble photosensitive polymer material. When mixed with polyvinyl acetate emulsion, it forms a one-component silk screen printing photosensitive emulsion. Students can utilize the synthesized product to print patterns on paper and experimental clothing, as well as to fabricate printed circuit boards and explore additional applications. All synthetic reactions in this experiment are conducted in aqueous solution, offering safety, environmental friendliness, and adherence to green chemistry principles.
2024, 39(5): 363-370
doi: 10.3866/PKU.DXHX202312017
Abstract:
Recently, mechanoluminescence materials have attracted considerable attention due to their unique optical properties induced by external stimulus, demonstrating the excellent potential for sensing impact, stress, tension, pressure, display and lighting, and imaging. Using dibenzoylmethane (DBM), Eu(NO3)3, and triethylamine (TEA) as raw materials, the ionic Eu3+ coordination complexes Eu(DBM)4TEA were obtained. The complexes were characterized by UV-vis absorption spectroscopy, infrared spectroscopy, X-ray diffraction, and solid fluorescence. Their mechanoluminescence properties are realized by grinding the sample powder. The designing experiment is developed based on the research results and consists of the synthesis and characterization of lanthanide-based organometallic materials. This experiment with a simple route includes a lot of knowledge and was beneficial to enhance students’ research capabilities, helping students learn the relationship between structure and function, and getting scientific research training.
Recently, mechanoluminescence materials have attracted considerable attention due to their unique optical properties induced by external stimulus, demonstrating the excellent potential for sensing impact, stress, tension, pressure, display and lighting, and imaging. Using dibenzoylmethane (DBM), Eu(NO3)3, and triethylamine (TEA) as raw materials, the ionic Eu3+ coordination complexes Eu(DBM)4TEA were obtained. The complexes were characterized by UV-vis absorption spectroscopy, infrared spectroscopy, X-ray diffraction, and solid fluorescence. Their mechanoluminescence properties are realized by grinding the sample powder. The designing experiment is developed based on the research results and consists of the synthesis and characterization of lanthanide-based organometallic materials. This experiment with a simple route includes a lot of knowledge and was beneficial to enhance students’ research capabilities, helping students learn the relationship between structure and function, and getting scientific research training.
2024, 39(5): 371-379
doi: 10.3866/PKU.DXHX202312015
Abstract:
The use of lacquer in China for thousands of years has resulted in the development of a unique lacquer art culture. The “lacquer” refers to urushi lacquer, which is collected from lacquer trees. Lacquer phenol undergoes series of chemical reactions to form a solid film with excellent properties, such as moisture resistance, high temperature resistance, and resistance to acid and alkali. Adding color powder into lacquer can produce a brilliant color paint, which is widely used in jewelry, anti-corrosion and cultural relics restoration. From the perspective of chemistry, the chemical composition, properties of lacquer and the chemical reaction of urushiol to lacquer film are introduced. Also, a series of popular science experiments are designed to verify what is lacquer and its excellent properties so that the people can deeply understand the ubiquity and importance of chemistry. The introduction of the history of lacquer, and the hands-on participation of primary and secondary school students in lacquerware production and lacquer painting drawing could exercise hands-on ability of young people, and convey the lacquer culture and the craftsman spirit of lacquer artists. The combination of lacquer art and chemistry can help the people to appreciate the beauty of lacquer art, realize the crucial role of chemistry in lacquer, and stimulate their interest in chemistry, therefore, realize the purpose of carrying forward the intangible cultural heritage of lacquer art and spreading the scientific knowledge of chemistry.
The use of lacquer in China for thousands of years has resulted in the development of a unique lacquer art culture. The “lacquer” refers to urushi lacquer, which is collected from lacquer trees. Lacquer phenol undergoes series of chemical reactions to form a solid film with excellent properties, such as moisture resistance, high temperature resistance, and resistance to acid and alkali. Adding color powder into lacquer can produce a brilliant color paint, which is widely used in jewelry, anti-corrosion and cultural relics restoration. From the perspective of chemistry, the chemical composition, properties of lacquer and the chemical reaction of urushiol to lacquer film are introduced. Also, a series of popular science experiments are designed to verify what is lacquer and its excellent properties so that the people can deeply understand the ubiquity and importance of chemistry. The introduction of the history of lacquer, and the hands-on participation of primary and secondary school students in lacquerware production and lacquer painting drawing could exercise hands-on ability of young people, and convey the lacquer culture and the craftsman spirit of lacquer artists. The combination of lacquer art and chemistry can help the people to appreciate the beauty of lacquer art, realize the crucial role of chemistry in lacquer, and stimulate their interest in chemistry, therefore, realize the purpose of carrying forward the intangible cultural heritage of lacquer art and spreading the scientific knowledge of chemistry.
2024, 39(5): 380-387
doi: 10.3866/PKU.DXHX202312024
Abstract:
In current undergraduate education for chemistry majors, the teaching experiments related to elemental analysis in the “Instrumental Analysis” course mainly rely on the use of commercial instruments such as Atomic Absorption Spectroscopy (AAS), Atomic Fluorescence Spectrometry (AFS), and Inductively Coupled Plasma Mass Spectrometry (ICP-OES). While these instruments effectively cover the teaching requirements for understanding the basic principles of analytical instruments, they are often expensive and have closed structures. To address these limitations, we designed a portable microplasma-atomic emission spectroscopy device based on Solution Cathode Glow Discharge (SCGD) technology, a cutting-edge development in the field. By constructing and utilizing this device, students can independently collect emission signals, thereby enhancing their practical skills and deepening their understanding of instrument structure and the principles of atomic emission spectroscopy. Furthermore, this experimental approach is not only interesting but also fosters students’ innovative thinking and scientific research abilities. Compared to traditional analytical instruments, the improved device is cost-effective and easily adaptable for laboratory teaching, thereby increasing students’ engagement and improving overall teaching effectiveness.
In current undergraduate education for chemistry majors, the teaching experiments related to elemental analysis in the “Instrumental Analysis” course mainly rely on the use of commercial instruments such as Atomic Absorption Spectroscopy (AAS), Atomic Fluorescence Spectrometry (AFS), and Inductively Coupled Plasma Mass Spectrometry (ICP-OES). While these instruments effectively cover the teaching requirements for understanding the basic principles of analytical instruments, they are often expensive and have closed structures. To address these limitations, we designed a portable microplasma-atomic emission spectroscopy device based on Solution Cathode Glow Discharge (SCGD) technology, a cutting-edge development in the field. By constructing and utilizing this device, students can independently collect emission signals, thereby enhancing their practical skills and deepening their understanding of instrument structure and the principles of atomic emission spectroscopy. Furthermore, this experimental approach is not only interesting but also fosters students’ innovative thinking and scientific research abilities. Compared to traditional analytical instruments, the improved device is cost-effective and easily adaptable for laboratory teaching, thereby increasing students’ engagement and improving overall teaching effectiveness.
2024, 39(5): 388-395
doi: 10.3866/PKU.DXHX202312016
Abstract:
Amidation synthesis stands as a significant area in organic chemistry. Incorporating cutting-edge amidation methods into basic organic chemistry laboratory teaching can enhance educational content and foster integration between undergraduate teaching and research achievements. Herein, we report an experiment focusing on the umpolung of aldehydes catalyzed by N-heterocyclic carbene (NHC) for amide synthesis. Utilizing benzaldehyde and nitrosobenzene as substrates, N-hydroxy-N-phenylbenzoylamide was efficiently synthesized under anhydrous and oxygen-free conditions. The reaction progress was monitored via thin-layer chromatography (TLC), and the product structure was confirmed by infrared and nuclear magnetic resonance spectroscopy. This experiment offers simplicity in operation, mild reaction conditions, high atom economy, and excellent repeatability, rendering it highly suitable for undergraduate laboratory teaching. By amalgamating the pivotal concept of umpolung with the cutting-edge science of N-heterocyclic carbene catalysis, this experiment aims to stimulate and nurture students’ interest in scientific inquiry.
Amidation synthesis stands as a significant area in organic chemistry. Incorporating cutting-edge amidation methods into basic organic chemistry laboratory teaching can enhance educational content and foster integration between undergraduate teaching and research achievements. Herein, we report an experiment focusing on the umpolung of aldehydes catalyzed by N-heterocyclic carbene (NHC) for amide synthesis. Utilizing benzaldehyde and nitrosobenzene as substrates, N-hydroxy-N-phenylbenzoylamide was efficiently synthesized under anhydrous and oxygen-free conditions. The reaction progress was monitored via thin-layer chromatography (TLC), and the product structure was confirmed by infrared and nuclear magnetic resonance spectroscopy. This experiment offers simplicity in operation, mild reaction conditions, high atom economy, and excellent repeatability, rendering it highly suitable for undergraduate laboratory teaching. By amalgamating the pivotal concept of umpolung with the cutting-edge science of N-heterocyclic carbene catalysis, this experiment aims to stimulate and nurture students’ interest in scientific inquiry.
2024, 39(5): 396-404
doi: 10.3866/PKU.DXHX202312021
Abstract:
“Luminescent sea” refers to the magical scene of blue light on the surface sea water at night or in a dark environment, also known as “blue tears”. This popular science experiment aims to guide people to gain an understanding of the world, and reveals the principles hidden behind natural phenomena and active experimentation. According to the principle of chemiluminescence energy transfer, the smart release material polysaccharide hydrogel entrapped with material was used to prepare sustainable luminescent hydrogel spheres. And a portable science popularization experiment box has been launched, which can reproduce your own surging “blue tears” anytime and anywhere. With the ability to interpret natural phenomena and promote applied research, this popular science experiment connects the knowledge of sugar chemistry, photochemistry and material chemistry, fully showing the romantic and wonderful chemical science to the public.
“Luminescent sea” refers to the magical scene of blue light on the surface sea water at night or in a dark environment, also known as “blue tears”. This popular science experiment aims to guide people to gain an understanding of the world, and reveals the principles hidden behind natural phenomena and active experimentation. According to the principle of chemiluminescence energy transfer, the smart release material polysaccharide hydrogel entrapped with material was used to prepare sustainable luminescent hydrogel spheres. And a portable science popularization experiment box has been launched, which can reproduce your own surging “blue tears” anytime and anywhere. With the ability to interpret natural phenomena and promote applied research, this popular science experiment connects the knowledge of sugar chemistry, photochemistry and material chemistry, fully showing the romantic and wonderful chemical science to the public.
