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2019 Volume 77 Issue 5
2019, 77(5): 397-405
doi: 10.6023/A19010039
Abstract:
Polyfluorenes are not only a class of classical blue conjugated polymers with high fluorescence efficiency and good thermal stability, but also a hairy-rod polymer model due to their rigid main chain and flexible side chain. Therefore, PFs have received attention and related reports are continuing. Most of the research on PFs has focused on the synthesis of new functional materials and the improvement of device structure to improve their photoelectric properties. However, the research on single chain conformation, chain aggregation structure, film condensed structure and photovoltaic devices performance in the process of precursor solution to film are rarely reported. In recent years, our research group focused on the quantitative structure-property relationship of polyfluorene conjugated polymers condensed state from solution to film. The complex single chain and aggregate shape characteristics of PFs precursor solutions were studied by static/dynamic laser scattering and other methods. Combining spectroscopy, electron microscopy and other methods, the kinetic evolution of PFs in isolated single chain, aggregation condensed-structures, transition state and the mechanism and regularity of β-conformation are revealed. Quantitative structure-property relationship of single-chain conformation of precursor solution, aggregate structure of thin film and optoelectronic device performance is established. The aim is to improve the photoelectric efficiency of the polymer from the intrinsic properties. The research will have important guiding significance not only for polyfluorene-based polymers but also for the design and processing of the entire conjugated polymer materials.
Polyfluorenes are not only a class of classical blue conjugated polymers with high fluorescence efficiency and good thermal stability, but also a hairy-rod polymer model due to their rigid main chain and flexible side chain. Therefore, PFs have received attention and related reports are continuing. Most of the research on PFs has focused on the synthesis of new functional materials and the improvement of device structure to improve their photoelectric properties. However, the research on single chain conformation, chain aggregation structure, film condensed structure and photovoltaic devices performance in the process of precursor solution to film are rarely reported. In recent years, our research group focused on the quantitative structure-property relationship of polyfluorene conjugated polymers condensed state from solution to film. The complex single chain and aggregate shape characteristics of PFs precursor solutions were studied by static/dynamic laser scattering and other methods. Combining spectroscopy, electron microscopy and other methods, the kinetic evolution of PFs in isolated single chain, aggregation condensed-structures, transition state and the mechanism and regularity of β-conformation are revealed. Quantitative structure-property relationship of single-chain conformation of precursor solution, aggregate structure of thin film and optoelectronic device performance is established. The aim is to improve the photoelectric efficiency of the polymer from the intrinsic properties. The research will have important guiding significance not only for polyfluorene-based polymers but also for the design and processing of the entire conjugated polymer materials.
2019, 77(5): 406-417
doi: 10.6023/A18120504
Abstract:
In recent years, the use of gas therapy has been more and more concerned by researchers in biomedical applications. Carbon monoxide (CO) is a diatomic gas messenger molecule with the function of transmitting intercellular information and regulating cellular signals. CO is found to play an extremely important physiological role in multiple systems, including cardiovascular system, nervous system, immune system, endocrine system and respiratory system, cancer therapy, coagulation and fibrinolysis system, organ transplantation and preservation, and so on. The biological functions of carbon monoxide molecule greatly depend on the its concentration, position, and duration. However, the existing carbon monoxide donors including Mn2(CO)10, Ru2Cl4(CO)6, Ru(CO)3Cl(glycinato), CORM-F, CORM-A1 have some disadvantages, such as poor stability, difficulties in dose control, lack of targeting, potential toxic and side effects on normal cells and tissues, which limited their further applications. How to control the concentration of carbon monoxide in the specific region has always been a big challenge in the field of biomedical applications. With the rapid development of nanoscience and technology, researchers have constructed a series of multifunctional carbon monoxide releasing nanomaterials, provided a new idea for CO controlled release, and applied them in the field of biomedicine. In this paper, several kinds of endogenous/exogenous stimulus-responsive CO releasing nanomaterials with the unique advantages are introduced based on the stimuli source. Then, the applications of these controlled CO releasing nanomaterials in biomedical fields, such as inhibiting inflammation, anti-bacte- rial and cancer therapy, are summarized. Finally, the challenges and prospects of CO releasing nanomaterials are discussed.
In recent years, the use of gas therapy has been more and more concerned by researchers in biomedical applications. Carbon monoxide (CO) is a diatomic gas messenger molecule with the function of transmitting intercellular information and regulating cellular signals. CO is found to play an extremely important physiological role in multiple systems, including cardiovascular system, nervous system, immune system, endocrine system and respiratory system, cancer therapy, coagulation and fibrinolysis system, organ transplantation and preservation, and so on. The biological functions of carbon monoxide molecule greatly depend on the its concentration, position, and duration. However, the existing carbon monoxide donors including Mn2(CO)10, Ru2Cl4(CO)6, Ru(CO)3Cl(glycinato), CORM-F, CORM-A1 have some disadvantages, such as poor stability, difficulties in dose control, lack of targeting, potential toxic and side effects on normal cells and tissues, which limited their further applications. How to control the concentration of carbon monoxide in the specific region has always been a big challenge in the field of biomedical applications. With the rapid development of nanoscience and technology, researchers have constructed a series of multifunctional carbon monoxide releasing nanomaterials, provided a new idea for CO controlled release, and applied them in the field of biomedicine. In this paper, several kinds of endogenous/exogenous stimulus-responsive CO releasing nanomaterials with the unique advantages are introduced based on the stimuli source. Then, the applications of these controlled CO releasing nanomaterials in biomedical fields, such as inhibiting inflammation, anti-bacte- rial and cancer therapy, are summarized. Finally, the challenges and prospects of CO releasing nanomaterials are discussed.
2019, 77(5): 418-421
doi: 10.6023/A19020061
Abstract:
In this paper, a metal-free catalytic method for synthesis of 2-picolinamide derivatives is reported. Under the promotion of proton acid, simple pyridines react with isocyanides to provide 2-picolinamides by means of the aminocarbonylation of the aryl C-H bond in the C2 position of pyridines. The product formation involves in the electrophilic addition of isocyanide to pyridine ring, hydrolysis and the oxidative aromatization regenerating pyridine ring in the presence of Di-t-butyl peroxide (DTBP) and oxalic acid dihydrate. Control experiments in the optimization section disclose the fact that the proton acid and oxidant are both indispensable for this C-H bond aminocarbonylation reaction. Generally, the synthetic reactions run smoothly under air atmosphere by heating all the substrates and reagents in one-pot at 100℃. The pyridine substrates containing methyl, t-butyl, cyclic dialkyl, methoxyl, halogen substituents at different site of the pyridine ring have displayed fine tolerance to the synthesis of corresponding products with diverse substructures in the pyridine ring. On the other hand, both alkyl and aryl functionalized isocyanides have also been found applicable to this synthetic protocol to provide 2-picolinamides containing correspondingly various N-alkyl and N-aryl fragment. The primary results indicate that the stability of the isocyanide substrate evidently influence the reaction result. The reactions employing relatively more stable 2, 6-dimethylphenyl isocyanide give corresponding products with higher yield than those ones using other isocyanides. Comparing with those reported methods employing transition metal catalyst such as silver or palladium salt to activate the C2-H bond in pyridines for the synthesis of analogous products, the present method benefits from the distinctive features of totally metal-free catalysis, broad substrate tolerance, specific regioselectivity in transforming C2-H bond, and high atom economy. Therefore, such a synthetic method will reasonably be a practical approach in complementing those already known strategies for the synthesis of structurally diverse and useful 2-picolinamide scaffolds.
In this paper, a metal-free catalytic method for synthesis of 2-picolinamide derivatives is reported. Under the promotion of proton acid, simple pyridines react with isocyanides to provide 2-picolinamides by means of the aminocarbonylation of the aryl C-H bond in the C2 position of pyridines. The product formation involves in the electrophilic addition of isocyanide to pyridine ring, hydrolysis and the oxidative aromatization regenerating pyridine ring in the presence of Di-t-butyl peroxide (DTBP) and oxalic acid dihydrate. Control experiments in the optimization section disclose the fact that the proton acid and oxidant are both indispensable for this C-H bond aminocarbonylation reaction. Generally, the synthetic reactions run smoothly under air atmosphere by heating all the substrates and reagents in one-pot at 100℃. The pyridine substrates containing methyl, t-butyl, cyclic dialkyl, methoxyl, halogen substituents at different site of the pyridine ring have displayed fine tolerance to the synthesis of corresponding products with diverse substructures in the pyridine ring. On the other hand, both alkyl and aryl functionalized isocyanides have also been found applicable to this synthetic protocol to provide 2-picolinamides containing correspondingly various N-alkyl and N-aryl fragment. The primary results indicate that the stability of the isocyanide substrate evidently influence the reaction result. The reactions employing relatively more stable 2, 6-dimethylphenyl isocyanide give corresponding products with higher yield than those ones using other isocyanides. Comparing with those reported methods employing transition metal catalyst such as silver or palladium salt to activate the C2-H bond in pyridines for the synthesis of analogous products, the present method benefits from the distinctive features of totally metal-free catalysis, broad substrate tolerance, specific regioselectivity in transforming C2-H bond, and high atom economy. Therefore, such a synthetic method will reasonably be a practical approach in complementing those already known strategies for the synthesis of structurally diverse and useful 2-picolinamide scaffolds.
2019, 77(5): 422-426
doi: 10.6023/A19010018
Abstract:
Cancer is a major cause of death and its early diagnosis has been a research goal for many decades. For males, prostatic carcinoma has become the second leading cause of cancer death worldwide. Prostate specific membrane antigen (PSMA) has been widely recognized as a prostate cancer marker. Thus, measurement of PSMA would be more valuable for the early diagnosis of prostate cancer. Nanomaterials have the characteristics of small size effect, quantum size effect, macroscopic quantum tunneling effect and surface effect, and have been widely used in various fields, such as cell imaging, analysis and detection, drug release and treatment. Gold nanoparticles have been widely used in biosensing and medical diagnosis due to their simple preparation, high stability and unique photoelectric properties. In this paper, a new colorimetric approach is proposed for simple detection of PSMA based on gold nanoparticles. In the experiment, we synthesized gold nanoparticles with positive charges, and the polyanionic peptide as the substrate of PSMA. The detection of PSMA was based on the property that different aggregation states of gold nanoparticles can lead to the change of color and the specific recognition of PSMA for its substrate. The positively charged gold nanoparticles interact electrostatically with polyanionic peptide, resulting in aggregation of gold nanoparticles. In the presence of PSMA, however, the polyanionic peptide are hydrolyzed into glutamic acid fragment due to the reaction between the PSMA and the polyanionic peptide, resulting in the dispersion of gold nanoparticles. This behaviour leads to the development of a rapid and simple colorimetric method for assaying PSMA activity, with a detection limit of 0.5 nmol/L and the linear range of 2~10 nmol/L. This approach is simple compared to the existing ones since the gold nanoparticles-peptide based sensor is easy to be assembled and the detection can be achieved without the involvement of complicated procedures. Moreover, the applicability of the method has been demonstrated by detecting PSMA spiked into urine samples.
Cancer is a major cause of death and its early diagnosis has been a research goal for many decades. For males, prostatic carcinoma has become the second leading cause of cancer death worldwide. Prostate specific membrane antigen (PSMA) has been widely recognized as a prostate cancer marker. Thus, measurement of PSMA would be more valuable for the early diagnosis of prostate cancer. Nanomaterials have the characteristics of small size effect, quantum size effect, macroscopic quantum tunneling effect and surface effect, and have been widely used in various fields, such as cell imaging, analysis and detection, drug release and treatment. Gold nanoparticles have been widely used in biosensing and medical diagnosis due to their simple preparation, high stability and unique photoelectric properties. In this paper, a new colorimetric approach is proposed for simple detection of PSMA based on gold nanoparticles. In the experiment, we synthesized gold nanoparticles with positive charges, and the polyanionic peptide as the substrate of PSMA. The detection of PSMA was based on the property that different aggregation states of gold nanoparticles can lead to the change of color and the specific recognition of PSMA for its substrate. The positively charged gold nanoparticles interact electrostatically with polyanionic peptide, resulting in aggregation of gold nanoparticles. In the presence of PSMA, however, the polyanionic peptide are hydrolyzed into glutamic acid fragment due to the reaction between the PSMA and the polyanionic peptide, resulting in the dispersion of gold nanoparticles. This behaviour leads to the development of a rapid and simple colorimetric method for assaying PSMA activity, with a detection limit of 0.5 nmol/L and the linear range of 2~10 nmol/L. This approach is simple compared to the existing ones since the gold nanoparticles-peptide based sensor is easy to be assembled and the detection can be achieved without the involvement of complicated procedures. Moreover, the applicability of the method has been demonstrated by detecting PSMA spiked into urine samples.
2019, 77(5): 427-433
doi: 10.6023/A19010003
Abstract:
x mol/L-Ag/BaTiO3 (x=0.01, 0.02, 0.04, where x is concentration of Ag) plasmonic photocatalysts were fabricated by precipitating Au nanoparticles on BaTiO3 nano-piezoelectric through a photochemical reducing approach. The plasmonic piezo-photocatalytic composite material can simultaneously solve the problems of low photocatalytic efficiency and narrow light absorption range in the photocatalysis process. BaTiO3 nano-piezoelectric were synthesized by a hydrothermal synthesis, Ag nanoparticles were deposited on the surface of BaTiO3 powder using a photoreduction reaction. Subsequently, the effects of microtopography, optical properties and degradation of dye were discussed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray photoelectron spectroscopy (XPS), UV-visible absorption spectra, photocurrent, photoelectrocatalytic, etc. The mechanism of piezoelectric photocatalysis and the effect of the concentration of ionic particles on the properties of the composite photocatalyst were investigated. The intensity and excitation mode of localized surface plasmon resonance (LSPR) vary on account of the different densities of nanoparticles, the 0.02 mol/L Ag-BaTiO3 showed an excellent photocatalytic performance for degrading 91% RhB in 75 min under full-spectrum light irradiation with ultrasonic excitation which can produce piezoelectric charges on the surfaces of the BaTiO3 nanocubes, and the degradation efficiency is increased by 21%. The effects of hybrid structure piezoelectric potential in nano-piezoelectric has been confirmed to express a great influence on surface plasmon resonance photocatalytic activity. The improvement of catalytic performance is due to the synergistic effect of piezoelectric effect and surface plasmon resonance effect. The LSPR of Ag nanoparticles that uniformly decorated on the surface of BaTiO3 nano-piezoelectric, widen the range of light absorption from ultraviolet to visible light. With introducing ultrasonic excitation to renew the piezoelectric charges on the surfaces of the BaTiO3 nanocubes, the piezoelectric field originated from the deformation of BaTiO3 nanotubes can further enhance the separation of photo-carriers induced by the localized surface plasmon resonance (LSPR), and promote the generation of hydroxyl radicals with strong oxidizing ability and accelerate the degradation of organic dyes. This work based on the piezotronic effect of the BaTiO3 nanocubes, assisting the surface plasmon resonance in photocatalysis improved the degradation efficiency of Rh B significantly. In addition, this discovery could be extended to other material systems to provide an effective technology for environment purification.
x mol/L-Ag/BaTiO3 (x=0.01, 0.02, 0.04, where x is concentration of Ag) plasmonic photocatalysts were fabricated by precipitating Au nanoparticles on BaTiO3 nano-piezoelectric through a photochemical reducing approach. The plasmonic piezo-photocatalytic composite material can simultaneously solve the problems of low photocatalytic efficiency and narrow light absorption range in the photocatalysis process. BaTiO3 nano-piezoelectric were synthesized by a hydrothermal synthesis, Ag nanoparticles were deposited on the surface of BaTiO3 powder using a photoreduction reaction. Subsequently, the effects of microtopography, optical properties and degradation of dye were discussed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray photoelectron spectroscopy (XPS), UV-visible absorption spectra, photocurrent, photoelectrocatalytic, etc. The mechanism of piezoelectric photocatalysis and the effect of the concentration of ionic particles on the properties of the composite photocatalyst were investigated. The intensity and excitation mode of localized surface plasmon resonance (LSPR) vary on account of the different densities of nanoparticles, the 0.02 mol/L Ag-BaTiO3 showed an excellent photocatalytic performance for degrading 91% RhB in 75 min under full-spectrum light irradiation with ultrasonic excitation which can produce piezoelectric charges on the surfaces of the BaTiO3 nanocubes, and the degradation efficiency is increased by 21%. The effects of hybrid structure piezoelectric potential in nano-piezoelectric has been confirmed to express a great influence on surface plasmon resonance photocatalytic activity. The improvement of catalytic performance is due to the synergistic effect of piezoelectric effect and surface plasmon resonance effect. The LSPR of Ag nanoparticles that uniformly decorated on the surface of BaTiO3 nano-piezoelectric, widen the range of light absorption from ultraviolet to visible light. With introducing ultrasonic excitation to renew the piezoelectric charges on the surfaces of the BaTiO3 nanocubes, the piezoelectric field originated from the deformation of BaTiO3 nanotubes can further enhance the separation of photo-carriers induced by the localized surface plasmon resonance (LSPR), and promote the generation of hydroxyl radicals with strong oxidizing ability and accelerate the degradation of organic dyes. This work based on the piezotronic effect of the BaTiO3 nanocubes, assisting the surface plasmon resonance in photocatalysis improved the degradation efficiency of Rh B significantly. In addition, this discovery could be extended to other material systems to provide an effective technology for environment purification.
2019, 77(5): 434-441
doi: 10.6023/A18120511
Abstract:
In this work, a newly UiO-66/CoSO4 composite was prepared by introducing UiO-66 as precursor carrier. The morphology and structure of the presented UiO-66/CoSO4 composite were characterized by scanning electron microscopy, elemental analysis, specific surface area analysis and X-ray diffraction. The adsorption performance of UiO-66/CoSO4 towards levofloxacin hydrochloride (LV) in aqueous solution was investigated, and some parameters, such as pH value, temperature, contact time and initial concentration have been optimized. The results showed that the UiO-66/CoSO4 composite has significant adsorption performance for levofloxacin hydrochloride. Compared with the control material UiO-66, the removal efficiency of the composite towards levofloxacin hydrochloride increased by 20% under the same conditions, which indicated that the properties of the composites have been greatly improved. Within 5 min, 95.3% of levofloxacin hydrochloride can be removed, and the equilibrium adsorption (99.8%) was achieved within 30 min and the adsorption process could be described by pseudo-second-order kinetic model. The adsorption isotherm verified that the maximum adsorption capacity was up to 108.42 mg·g-1 and fitted well with the Langmuir isotherm model, which indicated that monolayer coverage of levofloxacin hydrochloride was formed on the surface of UiO-66/CoSO4 composite. Data obtained from thermodynamic study showed that the adsorption process is spontaneous endothermic reaction and the chemical adsorption might play major role to control step. The UiO-66/CoSO4 composite was easy to prepare with good reusability, and the adsorption efficiency is still higher than 92.2% after five cycles. Additionally, under the optimized condition, the UiO-66/CoSO4 composite was successfully applied for the removal of levofloxacin hydrochloride from environmental water and soil samples. It was found that above 94.7% of target can be removed by the as-prepared UiO-66/CoSO4 composite. This result proved that the composite with excellent recognition has been synthesized. The new UiO-66/CoSO4 composite prepared in this work provided a way to treatment levofloxacin hydrochloride in environment with broad application prospect.
In this work, a newly UiO-66/CoSO4 composite was prepared by introducing UiO-66 as precursor carrier. The morphology and structure of the presented UiO-66/CoSO4 composite were characterized by scanning electron microscopy, elemental analysis, specific surface area analysis and X-ray diffraction. The adsorption performance of UiO-66/CoSO4 towards levofloxacin hydrochloride (LV) in aqueous solution was investigated, and some parameters, such as pH value, temperature, contact time and initial concentration have been optimized. The results showed that the UiO-66/CoSO4 composite has significant adsorption performance for levofloxacin hydrochloride. Compared with the control material UiO-66, the removal efficiency of the composite towards levofloxacin hydrochloride increased by 20% under the same conditions, which indicated that the properties of the composites have been greatly improved. Within 5 min, 95.3% of levofloxacin hydrochloride can be removed, and the equilibrium adsorption (99.8%) was achieved within 30 min and the adsorption process could be described by pseudo-second-order kinetic model. The adsorption isotherm verified that the maximum adsorption capacity was up to 108.42 mg·g-1 and fitted well with the Langmuir isotherm model, which indicated that monolayer coverage of levofloxacin hydrochloride was formed on the surface of UiO-66/CoSO4 composite. Data obtained from thermodynamic study showed that the adsorption process is spontaneous endothermic reaction and the chemical adsorption might play major role to control step. The UiO-66/CoSO4 composite was easy to prepare with good reusability, and the adsorption efficiency is still higher than 92.2% after five cycles. Additionally, under the optimized condition, the UiO-66/CoSO4 composite was successfully applied for the removal of levofloxacin hydrochloride from environmental water and soil samples. It was found that above 94.7% of target can be removed by the as-prepared UiO-66/CoSO4 composite. This result proved that the composite with excellent recognition has been synthesized. The new UiO-66/CoSO4 composite prepared in this work provided a way to treatment levofloxacin hydrochloride in environment with broad application prospect.
2019, 77(5): 442-446
doi: 10.6023/A19010005
Abstract:
Cyclic fluorene-based strained semiconductors which achieve both merits of hoop-shaped cycloparaphenylenes and fluorene-based emitters with high-efficiency feature have attracted increasing attention from synthetic chemists and theoreticians due to their aesthetic molecular structure, radial p orbitals and nanosized cavities. Compared with linear fluorene-based semiconductors, Cyclic fluorene-based strained semiconductors exhibit unique photoelectrical properties. For example, contrary to the deep blue emission of linear fluorene-based molecules, the controlled cyclic fluorene-based strained molecules show stronger green emission. However, the properties of molecular vibrations of cyclic fluorene-based strained materials have not been reported so far. In this article, [4]Cyclo-9, 9-dipropyl-2, 7-fluorene (CF) and linear quaterfluorenes (LF) were synthesized as modeling compounds to explore the differences of Raman spectra on structures by theoretical and experimental studies. Raman spectroscopy measurements have been presented on polymer poly(9, 9-dioctylfluorene) (PFO) and LF, and compare them with CF. In addition, we have calculated the theoretical Raman spectra of CF and LF based on time-dependent density functional theory (TDDFT), which are then compared to the experimental results for the assignment of different modes. All calculations were performed at 6-31G (d) basis set along with the range corrected B3LYP density functional. The results demonstrate that the Raman peak positions of CF which are analogous to those of carbon nanotubes such as G band are shifted. Compared to the Raman spectra of LF, G1 and G2 peaks of CF shifted to lower frequency region, however G3 peaks shifted to higher frequency region. The relative intensity of Raman peaks in CF especially in low frequency region has increased. These properties of Raman in CF can be assigned to the changed structure of conjugated backbone and electrical structure due to strain and every fluorene unit of CF has involved in vibration and the delocalization of π electrons gets higher. These results provide powerful basis for correlating structure and properties on strain organic semiconductors by Raman spectra.
Cyclic fluorene-based strained semiconductors which achieve both merits of hoop-shaped cycloparaphenylenes and fluorene-based emitters with high-efficiency feature have attracted increasing attention from synthetic chemists and theoreticians due to their aesthetic molecular structure, radial p orbitals and nanosized cavities. Compared with linear fluorene-based semiconductors, Cyclic fluorene-based strained semiconductors exhibit unique photoelectrical properties. For example, contrary to the deep blue emission of linear fluorene-based molecules, the controlled cyclic fluorene-based strained molecules show stronger green emission. However, the properties of molecular vibrations of cyclic fluorene-based strained materials have not been reported so far. In this article, [4]Cyclo-9, 9-dipropyl-2, 7-fluorene (CF) and linear quaterfluorenes (LF) were synthesized as modeling compounds to explore the differences of Raman spectra on structures by theoretical and experimental studies. Raman spectroscopy measurements have been presented on polymer poly(9, 9-dioctylfluorene) (PFO) and LF, and compare them with CF. In addition, we have calculated the theoretical Raman spectra of CF and LF based on time-dependent density functional theory (TDDFT), which are then compared to the experimental results for the assignment of different modes. All calculations were performed at 6-31G (d) basis set along with the range corrected B3LYP density functional. The results demonstrate that the Raman peak positions of CF which are analogous to those of carbon nanotubes such as G band are shifted. Compared to the Raman spectra of LF, G1 and G2 peaks of CF shifted to lower frequency region, however G3 peaks shifted to higher frequency region. The relative intensity of Raman peaks in CF especially in low frequency region has increased. These properties of Raman in CF can be assigned to the changed structure of conjugated backbone and electrical structure due to strain and every fluorene unit of CF has involved in vibration and the delocalization of π electrons gets higher. These results provide powerful basis for correlating structure and properties on strain organic semiconductors by Raman spectra.
2019, 77(5): 447-454
doi: 10.6023/A19010033
Abstract:
Nano-scale nickel oxide materials were prepared by solvothermal method using nickel acetylacetonate, oleic acid and oleylamine as raw materials, octadecene as solvent and polyvinylpyrrolidone as surfactant. The effects of the ratio of reactants ratio, insulation time, surfactant and the mass of oleylamine on the microstructure, particle size, morphology, optics and catalytic properties of the product were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), ultraviolet-visible spectroscopy (UV-Vis) spectral analysis, and Tafel test. The specific experimental operations were:the oleic acid (OA) and 1-octadecene (ODE) was added into four flasks (500 mL) with heating and stirring. Nickel acetylacetonate was added when the temperature raise to 50℃, then continuously stirring for 60 minutes at 120℃ before a certain amount of oleylamine (OAm) was added to the reaction system. The mixed solution was poured into the inner liner of the high temperature reactor. The reactor was covered and transferred to the electro-thermostatic blast oven for a period of time and then cooled to room temperature. The main research results were obtained:(1) The boundary of the original particles became smoothed after sintering, and the spherical particles become flake-shaped which might be attributed to the residual organic covering so the size of nickel oxide nanoparticles changed from the original 40~45 nm to 30~40 nm. (2) With the addition of PVP, the content of NiO phase increased and the particle size was controlled within 40~45 nm. The UV-Vis test showed that NiO belonged to direct band gap and the band gap width was 3.5~3.7 eV. (3) The Tafel analysis showed that the best catalytic activity with exchange current density J0 was 1.23×10-2 mA·cm-2, where pure NiO could be obtained when the reactant ratio of n[Ni(acac)2]:n(OA)=1:2, the additive PVP mass fraction was of 1.66%, the amount of oleylamine was of 30 mmol, and the temperature was of 200℃ for 8 h.
Nano-scale nickel oxide materials were prepared by solvothermal method using nickel acetylacetonate, oleic acid and oleylamine as raw materials, octadecene as solvent and polyvinylpyrrolidone as surfactant. The effects of the ratio of reactants ratio, insulation time, surfactant and the mass of oleylamine on the microstructure, particle size, morphology, optics and catalytic properties of the product were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), ultraviolet-visible spectroscopy (UV-Vis) spectral analysis, and Tafel test. The specific experimental operations were:the oleic acid (OA) and 1-octadecene (ODE) was added into four flasks (500 mL) with heating and stirring. Nickel acetylacetonate was added when the temperature raise to 50℃, then continuously stirring for 60 minutes at 120℃ before a certain amount of oleylamine (OAm) was added to the reaction system. The mixed solution was poured into the inner liner of the high temperature reactor. The reactor was covered and transferred to the electro-thermostatic blast oven for a period of time and then cooled to room temperature. The main research results were obtained:(1) The boundary of the original particles became smoothed after sintering, and the spherical particles become flake-shaped which might be attributed to the residual organic covering so the size of nickel oxide nanoparticles changed from the original 40~45 nm to 30~40 nm. (2) With the addition of PVP, the content of NiO phase increased and the particle size was controlled within 40~45 nm. The UV-Vis test showed that NiO belonged to direct band gap and the band gap width was 3.5~3.7 eV. (3) The Tafel analysis showed that the best catalytic activity with exchange current density J0 was 1.23×10-2 mA·cm-2, where pure NiO could be obtained when the reactant ratio of n[Ni(acac)2]:n(OA)=1:2, the additive PVP mass fraction was of 1.66%, the amount of oleylamine was of 30 mmol, and the temperature was of 200℃ for 8 h.
2019, 77(5): 455-460
doi: 10.6023/A19010017
Abstract:
In this paper, we predicted a superhard carbon phase (Pc-carbon) by using CALYPSO software. The crystal structure belongs to monoclinic system with the space group Pc. We have studied the electronic and mechanical properties of Pc-carbon by first principles calculations. The calculated total energy per atom of Pc-carbon have a minimum value of -8.08 eV, confirming that the optimized structure is stable. And the minimum total energy per atom of Pc-carbon is higher than diamond and graphite, suggesting that the Pc-carbon should be thermodynamically metastable comparing diamond and graphite. There are no imaginary frequency throughout the entire Brillouin zone in the phonon dispersion, confirming the dynamical stability of Pc-carbon up to 100 GPa. The elastic constants of Pc-carbon follow the Born mechanical stability criteria, demonstrating the mechanical stability of Pc-carbon. The calculated B/G value and Poisson's ratio show that Pc-carbon is brittle. The calculated Vickers hardness value of Pc-carbon is 87.6 GPa, which is much larger than the minimal value for a superhard materials (40 GPa), indicating Pc-carbon is a potential superhard material. The Vickers hardness of Pc-carbon is less than that of diamond and M-carbon, but is comparable to that of bct-C4 and Ibam-C. In addition, the ideal tensile and shear strengths of Pc-carbon (65.8 and 56.5 GPa) are comparable to those of c-BN (55.3 and 58.3 GPa), suggesting that Pc-carbon may have similar tensile and shear resistance to c-BN. The elastic anisotropy index AU is 0.35, indicating that Pc-carbon is elastic anisotropic; the fractional anisotropy ratio of bulk modulus AB and shear modulus AG are 0.010 and 0.032, suggesting that the bulk modulus and shear modulus of Pc-carbon are all elastic anisotropic. The hydrostatic calculations of Pc-carbon indicate that Pc-carbon have excellent incompressibility as the pressure is increased up to 100 GPa. And Pc-carbon is an ultra-incompressible material like other carbon allotropes. The calculated band gap of Pc-carbon is estimated to be 0.99 eV, indicating that Pc-carbon is an indirect band gap semiconductor. The PDOS of Pc-carbon reflects significant sp3 hybridization between atomic orbitals, which leads to the superhard properties of Pc-carbon. Therefore, Pc-carbon is a potential superhard semiconductor material.
In this paper, we predicted a superhard carbon phase (Pc-carbon) by using CALYPSO software. The crystal structure belongs to monoclinic system with the space group Pc. We have studied the electronic and mechanical properties of Pc-carbon by first principles calculations. The calculated total energy per atom of Pc-carbon have a minimum value of -8.08 eV, confirming that the optimized structure is stable. And the minimum total energy per atom of Pc-carbon is higher than diamond and graphite, suggesting that the Pc-carbon should be thermodynamically metastable comparing diamond and graphite. There are no imaginary frequency throughout the entire Brillouin zone in the phonon dispersion, confirming the dynamical stability of Pc-carbon up to 100 GPa. The elastic constants of Pc-carbon follow the Born mechanical stability criteria, demonstrating the mechanical stability of Pc-carbon. The calculated B/G value and Poisson's ratio show that Pc-carbon is brittle. The calculated Vickers hardness value of Pc-carbon is 87.6 GPa, which is much larger than the minimal value for a superhard materials (40 GPa), indicating Pc-carbon is a potential superhard material. The Vickers hardness of Pc-carbon is less than that of diamond and M-carbon, but is comparable to that of bct-C4 and Ibam-C. In addition, the ideal tensile and shear strengths of Pc-carbon (65.8 and 56.5 GPa) are comparable to those of c-BN (55.3 and 58.3 GPa), suggesting that Pc-carbon may have similar tensile and shear resistance to c-BN. The elastic anisotropy index AU is 0.35, indicating that Pc-carbon is elastic anisotropic; the fractional anisotropy ratio of bulk modulus AB and shear modulus AG are 0.010 and 0.032, suggesting that the bulk modulus and shear modulus of Pc-carbon are all elastic anisotropic. The hydrostatic calculations of Pc-carbon indicate that Pc-carbon have excellent incompressibility as the pressure is increased up to 100 GPa. And Pc-carbon is an ultra-incompressible material like other carbon allotropes. The calculated band gap of Pc-carbon is estimated to be 0.99 eV, indicating that Pc-carbon is an indirect band gap semiconductor. The PDOS of Pc-carbon reflects significant sp3 hybridization between atomic orbitals, which leads to the superhard properties of Pc-carbon. Therefore, Pc-carbon is a potential superhard semiconductor material.
2019, 77(5): 461-468
doi: 10.6023/A18120503
Abstract:
A series of BiOCl-ov/palygorskite (PGS) nanocomposites (abbreviated as x B/P, where x is the molar content of BiOCl-ov in the composites) were synthesized by simple one-step hydrothermal method. The structure, morphology and photoelectrochemical properties of the nanocomposites have been thoroughly characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption, Fourier infrared spectroscopy (FT-IR), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), fluorescence spectroscopy (PL) and electrochemical impedance (EIS) spectra. As a typical rodlike natural mineral, PGS was commonly used as absorbent in many fields. Its photocatalytic properties was always ascribed to the defects in its crystal lattice after the acidic treatment, which would give contribution to the photoinduced electron conductions in its bulky nanoparticles. On the other hand, as a typical layered p-typed semiconductor, BiOCl-ov was widely used in many oxidations due to the many of oxygen vacancies existed in its nanostructure. The combination of rodlike PGS and layered BiOCl-ov could be successfully carried out through the formation of the nanocomposites due to their respective crystal structure as well as their catalytic activity. So the BiOCl-ov/PGS nanocomposites were well prepared according to the advantages of PGS and BiOCl-ov. With the carefully investigation of the structure of the nanocomposites, the results showed that the catalysts were successfully prepared. The structures of BiOCl-ov and PGS were all well remained after the preparing process. The photocatalytic activity of the prepared BiOCl-ov/PGS was detected through the selective oxidation of aromatic alcohols under visible-light conditions. It found that BiOCl-ov/PGS showed promising activity for the photocatalytic oxidation of alcohols under the irradiation of visible light. The conversion of 78% of benzalcohol as well as the selectivity of 86% of benzaldehyde was reached with the catalysis of the nanocomposites in the photocatalytic oxidation of benzalcohol. Some of the other substrates, including the derivatives of benzalcohol as well as diphenylmethanol could be well oxidized. Moreover, the nonaromatic substrate, that is, phenethyl alcohol, it was always thought to be not easy to be oxidized one, could also be oxidized to corresponding phenylacetaldehyde with high conversion (89%) and selectivity (99%). Meanwhile, the catalyst possessed well light stability. The photocatalytic mechanism of the oxidation was also investigated through the active species capturing experiments. It showed that the major active species of the oxidation system was ·O2- and ·OH radicals.
A series of BiOCl-ov/palygorskite (PGS) nanocomposites (abbreviated as x B/P, where x is the molar content of BiOCl-ov in the composites) were synthesized by simple one-step hydrothermal method. The structure, morphology and photoelectrochemical properties of the nanocomposites have been thoroughly characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption, Fourier infrared spectroscopy (FT-IR), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), fluorescence spectroscopy (PL) and electrochemical impedance (EIS) spectra. As a typical rodlike natural mineral, PGS was commonly used as absorbent in many fields. Its photocatalytic properties was always ascribed to the defects in its crystal lattice after the acidic treatment, which would give contribution to the photoinduced electron conductions in its bulky nanoparticles. On the other hand, as a typical layered p-typed semiconductor, BiOCl-ov was widely used in many oxidations due to the many of oxygen vacancies existed in its nanostructure. The combination of rodlike PGS and layered BiOCl-ov could be successfully carried out through the formation of the nanocomposites due to their respective crystal structure as well as their catalytic activity. So the BiOCl-ov/PGS nanocomposites were well prepared according to the advantages of PGS and BiOCl-ov. With the carefully investigation of the structure of the nanocomposites, the results showed that the catalysts were successfully prepared. The structures of BiOCl-ov and PGS were all well remained after the preparing process. The photocatalytic activity of the prepared BiOCl-ov/PGS was detected through the selective oxidation of aromatic alcohols under visible-light conditions. It found that BiOCl-ov/PGS showed promising activity for the photocatalytic oxidation of alcohols under the irradiation of visible light. The conversion of 78% of benzalcohol as well as the selectivity of 86% of benzaldehyde was reached with the catalysis of the nanocomposites in the photocatalytic oxidation of benzalcohol. Some of the other substrates, including the derivatives of benzalcohol as well as diphenylmethanol could be well oxidized. Moreover, the nonaromatic substrate, that is, phenethyl alcohol, it was always thought to be not easy to be oxidized one, could also be oxidized to corresponding phenylacetaldehyde with high conversion (89%) and selectivity (99%). Meanwhile, the catalyst possessed well light stability. The photocatalytic mechanism of the oxidation was also investigated through the active species capturing experiments. It showed that the major active species of the oxidation system was ·O2- and ·OH radicals.
2019, 77(5): 469-474
doi: 10.6023/A19010028
Abstract:
As a clean, safe, efficient, and economical energy, nuclear energy plays an irreplaceable role in the resource sector. However, uranium deposits on land will run out in the coming decades. The uranium content in seawater is huge but its concentration is as low as~3 ppb. So it is an urgent problem to design and synthesize adsorbent materials with high extraction efficiency. In this paper, taking the actual industrialization as the direction, we adopted biphenyl as the building block and synthesize the porous aromatic framework material (PAF-45) in a low price. Then porous aromatic framework material (PAF-45-PG) with phosphoric acid groups was prepared through a post-modification procedure. The structure and pore characteristics of the compound were investigated by FTIR, TGA, PXRD, SEM, TEM and N2 adsorption experiments. FTIR spectrum indicates that the emerging vibrational peaks at 900~1250 cm-1 can be ascribed to the successful decoration of phosphate groups in PAF-45-PG compared with pure PAF-45. Powder X-ray diffraction shows that PAF-45 and PAF-45-PG are amorphous. And transmission electron microscope (TEM) images also agree with the conclusion of PXRD that PAF materials possess disordered structure. Moreover, there is no significant weight loss before 400℃ demonstrated by thermogravimetric analysis, which indicates the high thermal stability of two PAF resultants. The porosity of PAF networks was characterized by measuring the N2 adsorption isotherm at 77 K. Calculated by Brunauer-Emmett-Teller (BET) adsorption model, the specific surface area of PAF-45-PG is 426 m2·g-1, which is lower than that of pure PAF-45 (828 m2·g-1). This reduction of surface area is attributed to the introduction of functional groups which increase the weight per constitutional unit and occupy the space in the porous structure. After that, we tested the UO22+ ion adsorption of PAFs in simulated seawater. The equilibrium adsorption capacity of PAF-45-PG increases with the increase of uranium concentration, and reaches the maximum value (101 mg·g-1) at about 8 ppm. Because the maximum capacity of PAF-45 is 5.9 mg·g-1, this result indicates that the adsorption of uranium ion in PAF-45-PG is mainly caused by the post-modified phosphate functional group on its pore surface. Due to the low cost and simple preparation process, the material (PAF-45-PG) has a great industrial prospect.
As a clean, safe, efficient, and economical energy, nuclear energy plays an irreplaceable role in the resource sector. However, uranium deposits on land will run out in the coming decades. The uranium content in seawater is huge but its concentration is as low as~3 ppb. So it is an urgent problem to design and synthesize adsorbent materials with high extraction efficiency. In this paper, taking the actual industrialization as the direction, we adopted biphenyl as the building block and synthesize the porous aromatic framework material (PAF-45) in a low price. Then porous aromatic framework material (PAF-45-PG) with phosphoric acid groups was prepared through a post-modification procedure. The structure and pore characteristics of the compound were investigated by FTIR, TGA, PXRD, SEM, TEM and N2 adsorption experiments. FTIR spectrum indicates that the emerging vibrational peaks at 900~1250 cm-1 can be ascribed to the successful decoration of phosphate groups in PAF-45-PG compared with pure PAF-45. Powder X-ray diffraction shows that PAF-45 and PAF-45-PG are amorphous. And transmission electron microscope (TEM) images also agree with the conclusion of PXRD that PAF materials possess disordered structure. Moreover, there is no significant weight loss before 400℃ demonstrated by thermogravimetric analysis, which indicates the high thermal stability of two PAF resultants. The porosity of PAF networks was characterized by measuring the N2 adsorption isotherm at 77 K. Calculated by Brunauer-Emmett-Teller (BET) adsorption model, the specific surface area of PAF-45-PG is 426 m2·g-1, which is lower than that of pure PAF-45 (828 m2·g-1). This reduction of surface area is attributed to the introduction of functional groups which increase the weight per constitutional unit and occupy the space in the porous structure. After that, we tested the UO22+ ion adsorption of PAFs in simulated seawater. The equilibrium adsorption capacity of PAF-45-PG increases with the increase of uranium concentration, and reaches the maximum value (101 mg·g-1) at about 8 ppm. Because the maximum capacity of PAF-45 is 5.9 mg·g-1, this result indicates that the adsorption of uranium ion in PAF-45-PG is mainly caused by the post-modified phosphate functional group on its pore surface. Due to the low cost and simple preparation process, the material (PAF-45-PG) has a great industrial prospect.
