Login In
2018 Volume 76 Issue 3
2018, 76(3): 161-167
doi: 10.6023/A17120537
Abstract:
Terpenoids represent one of the largest and most diverse classes of secondary metabolites and widely exist in nature. Among them, sesquiterpene lactones are ubiquitous in a variety of medicinal plants, which are the main active ingredients of many traditional Chinese herbal medicines. However, it is extremely challenging to accomplish the total synthesis of these natural compounds. Photochemical rearrangement of santonin is an effective strategy to construct the guaianolide skeleton. Furthermore, as a renewable natural resource, santonin was extensively used in natural product total synthesis, especially complex terpenoids. In this review, a brief overview of application of photochemical rearrangement of santonin in total synthesis of natural terpenoids is presented, which mainly includes:(1) the synthesis of sesquiterpene and its oligomers, and (2) the core structure construction of some diterpenoids.
Terpenoids represent one of the largest and most diverse classes of secondary metabolites and widely exist in nature. Among them, sesquiterpene lactones are ubiquitous in a variety of medicinal plants, which are the main active ingredients of many traditional Chinese herbal medicines. However, it is extremely challenging to accomplish the total synthesis of these natural compounds. Photochemical rearrangement of santonin is an effective strategy to construct the guaianolide skeleton. Furthermore, as a renewable natural resource, santonin was extensively used in natural product total synthesis, especially complex terpenoids. In this review, a brief overview of application of photochemical rearrangement of santonin in total synthesis of natural terpenoids is presented, which mainly includes:(1) the synthesis of sesquiterpene and its oligomers, and (2) the core structure construction of some diterpenoids.
2018, 76(3): 168-176
doi: 10.6023/A17110499
Abstract:
Since its discovery in 2004, the new frontier materials graphene and its derivatives have attracted a great deal of attention on the fields of new batteries, sensors, new energy and biomedicine, due to their unique electrical, optical and mechanical properties. Specifically, it has been developed rapidly in the biomedical field. The good biocompatibility has endowed graphene and its derivatives great prospects for their biological applications. In order to realize the in vivo application of graphene materials and improve the safety of the environment and life system, it is crucial to consider and study on the biodegradation behaviors of graphene. The research on biodegradation of graphene currently mainly focuses on the enzymatic degradation. The degradation behaviors can be tuned by the modification via a series of methods, such as heterogeneous atom doping and surface functionalization, etc. The progress of biodegradation of graphene and their derivatives, especially the enzymatic degradation and their biomedical applications is discussed. The important basis and guidance to further promote the in vivo study of graphene materials will be provided.
Since its discovery in 2004, the new frontier materials graphene and its derivatives have attracted a great deal of attention on the fields of new batteries, sensors, new energy and biomedicine, due to their unique electrical, optical and mechanical properties. Specifically, it has been developed rapidly in the biomedical field. The good biocompatibility has endowed graphene and its derivatives great prospects for their biological applications. In order to realize the in vivo application of graphene materials and improve the safety of the environment and life system, it is crucial to consider and study on the biodegradation behaviors of graphene. The research on biodegradation of graphene currently mainly focuses on the enzymatic degradation. The degradation behaviors can be tuned by the modification via a series of methods, such as heterogeneous atom doping and surface functionalization, etc. The progress of biodegradation of graphene and their derivatives, especially the enzymatic degradation and their biomedical applications is discussed. The important basis and guidance to further promote the in vivo study of graphene materials will be provided.
2018, 76(3): 177-189
doi: 10.6023/A17110484
Abstract:
Natural products are rich sources of drugs for the treatment of human diseases, while identification of the protein targets and mode of actions is one of the most significant and challenging steps in drug discovery across bioactive natural products. This review describes recent progresses in the methodology of target identification of natural products, highlights examples of target identification utilizing chemical proteomics and biophysical strategies, and discusses the advantages, limitations, applications, and challenges of each strategy.
Natural products are rich sources of drugs for the treatment of human diseases, while identification of the protein targets and mode of actions is one of the most significant and challenging steps in drug discovery across bioactive natural products. This review describes recent progresses in the methodology of target identification of natural products, highlights examples of target identification utilizing chemical proteomics and biophysical strategies, and discusses the advantages, limitations, applications, and challenges of each strategy.
2018, 76(3): 190-195
doi: 10.6023/A17110511
Abstract:
Lots of research has indicated that materials contain Arg-Gly-Asp (RGD) sequence can promote cell attachment and proliferation on them. Although Antheraea pernyi silk fibroin is a natural structural protein which contains RGD sequence, there are few studies on this kind of protein materials, for the regeneration of Antheraea pernyi silk fibroin from silk fibers is complicated and it is hard to be processed. In this paper, we present a water-insoluble Antheraea pernyi/Bombyx mori silk fibroin blending scaffold. The regenerated Antheraea pernyi silk fibroin (RASF) solution was prepared by dissolving degummed silk fibers at 100℃ and dialyzing at 4℃. The regenerated Bombyx mori silk fibroin (RBSF) solution was prepared by dissolving degummed silk fibers at 60℃ and dialyzing at 20℃. Regenerated silk fibroin solution was concentrated to 6 wt% solution in 10 wt% PEG solution. Based on RASF and RBSF solution, RBSF porous scaffold and RASF/RBSF blending scaffolds with different ratios were prepared through treating 1-butanol/SF solution under freezing at -20℃. The volume ratio of 1-butanol to solution was 1:2. RASF porous scaffold was not hard enough to hold itself, therefore the maximum content of RASF in blending scaffold was 70 wt%. With increasing of RASF content, pore sizes of scaffolds decreased from 250 μm to 150 μm and compressive strengths decreased from 280 kPa to 108 kPa, while the thermal stabilities increased. FTIR results demonstrated that the molecular conformation of silk fibroin was proven to be β-sheet, β-turn and α-helix. The biocompatibilities of scaffolds were demonstrated with in vitro cell culture. The results showed that L929 fibroblast and MC3t3-E1 osteoblast adhered, proliferated and migrated well into the scaffolds. The speed of cell proliferation accelerated with the increase of RASF content. Obviously, these regenerated silk fibroin scaffolds with good bio-compatibility could be used in tissue engineering field further.
Lots of research has indicated that materials contain Arg-Gly-Asp (RGD) sequence can promote cell attachment and proliferation on them. Although Antheraea pernyi silk fibroin is a natural structural protein which contains RGD sequence, there are few studies on this kind of protein materials, for the regeneration of Antheraea pernyi silk fibroin from silk fibers is complicated and it is hard to be processed. In this paper, we present a water-insoluble Antheraea pernyi/Bombyx mori silk fibroin blending scaffold. The regenerated Antheraea pernyi silk fibroin (RASF) solution was prepared by dissolving degummed silk fibers at 100℃ and dialyzing at 4℃. The regenerated Bombyx mori silk fibroin (RBSF) solution was prepared by dissolving degummed silk fibers at 60℃ and dialyzing at 20℃. Regenerated silk fibroin solution was concentrated to 6 wt% solution in 10 wt% PEG solution. Based on RASF and RBSF solution, RBSF porous scaffold and RASF/RBSF blending scaffolds with different ratios were prepared through treating 1-butanol/SF solution under freezing at -20℃. The volume ratio of 1-butanol to solution was 1:2. RASF porous scaffold was not hard enough to hold itself, therefore the maximum content of RASF in blending scaffold was 70 wt%. With increasing of RASF content, pore sizes of scaffolds decreased from 250 μm to 150 μm and compressive strengths decreased from 280 kPa to 108 kPa, while the thermal stabilities increased. FTIR results demonstrated that the molecular conformation of silk fibroin was proven to be β-sheet, β-turn and α-helix. The biocompatibilities of scaffolds were demonstrated with in vitro cell culture. The results showed that L929 fibroblast and MC3t3-E1 osteoblast adhered, proliferated and migrated well into the scaffolds. The speed of cell proliferation accelerated with the increase of RASF content. Obviously, these regenerated silk fibroin scaffolds with good bio-compatibility could be used in tissue engineering field further.
2018, 76(3): 196-201
doi: 10.6023/A17110509
Abstract:
Light-driven molecular motors have attracted overwhelming attention due to their potential applications in a wide range of fields. Despite of the great successes obtained in alkene-based light-driven molecular motors and switches, scientists pursuing high-efficient alternatives with superior working mechanisms have never suspended. In this report, a promising model of light-driven rotary motor, namely BN-stilbene motor, constructed by replacing the central C=C axis of a CC-stilbene rotary motor with a polar B=N bond, was rationally designed. Multireference Complete Active Space Self-Consistent Field (CASSCF) method and Time-Dependent Density Functional (TDDFT) theory were applied to study the mechanism of BN-stilbene, along with the Complete Active Space Second-Order Perturbation Theory (CASPT2) energy corrections. Our calculations show that the B=N axis well preserves the conjugation of between the rotor and stator, leading to four ground-state helical conformers (i.e., cis-stable, trans-unstable, trans-stable and cis-unstable), whose geometries and energies are in line with their counterparts in CC-stilbene motor; in addition, BN-stilbene has similar absorption spectra and more slopped excited-state potential energy curves at Franck-Condon region, which can fascinate a spontaneous rotary motion around B=N axis, thus generates directional photo-induced isomerization from cis-stable to trans-unstable (or from trans-stable to cis-unstable). Moreover, the barriers for helical inversions (trans-unstable → trans-stable or cis-unstable → cis-stable) are found to be lower than those of the reversed thermal rotations (i.e., cis-stable → trans-unstable and trans-stable → cis-unstable), which further insures the unidirectionality of rotation. These features sufficiently allow BN-stilbene to serve as a candidate for light-driven molecular rotary motor. Finally and most importantly, as compared with that of CC-stilbene, the photoisomerization mechanism of BN-stilbene motor shows advantages in nonadiabatic transition:Due to the introducing of polar B=N axis, the S1/S0 conical intersections of BN system are both geometrically and energetically closer to the excited-state intermediate, which is thus expected to improve the nonadiabatic transition probabilities and the unidirectionality of the rotation. Therefore, the BN-stilbene motor is expected to perform a unidirectional, repetitive 360° rotation upon sequential applying of photo and thermal inputs. The findings suggest BN-hetero stilbene as a promising type of light-driven rotary motor and may inspire the design and synthesis of novel molecular motors.
Light-driven molecular motors have attracted overwhelming attention due to their potential applications in a wide range of fields. Despite of the great successes obtained in alkene-based light-driven molecular motors and switches, scientists pursuing high-efficient alternatives with superior working mechanisms have never suspended. In this report, a promising model of light-driven rotary motor, namely BN-stilbene motor, constructed by replacing the central C=C axis of a CC-stilbene rotary motor with a polar B=N bond, was rationally designed. Multireference Complete Active Space Self-Consistent Field (CASSCF) method and Time-Dependent Density Functional (TDDFT) theory were applied to study the mechanism of BN-stilbene, along with the Complete Active Space Second-Order Perturbation Theory (CASPT2) energy corrections. Our calculations show that the B=N axis well preserves the conjugation of between the rotor and stator, leading to four ground-state helical conformers (i.e., cis-stable, trans-unstable, trans-stable and cis-unstable), whose geometries and energies are in line with their counterparts in CC-stilbene motor; in addition, BN-stilbene has similar absorption spectra and more slopped excited-state potential energy curves at Franck-Condon region, which can fascinate a spontaneous rotary motion around B=N axis, thus generates directional photo-induced isomerization from cis-stable to trans-unstable (or from trans-stable to cis-unstable). Moreover, the barriers for helical inversions (trans-unstable → trans-stable or cis-unstable → cis-stable) are found to be lower than those of the reversed thermal rotations (i.e., cis-stable → trans-unstable and trans-stable → cis-unstable), which further insures the unidirectionality of rotation. These features sufficiently allow BN-stilbene to serve as a candidate for light-driven molecular rotary motor. Finally and most importantly, as compared with that of CC-stilbene, the photoisomerization mechanism of BN-stilbene motor shows advantages in nonadiabatic transition:Due to the introducing of polar B=N axis, the S1/S0 conical intersections of BN system are both geometrically and energetically closer to the excited-state intermediate, which is thus expected to improve the nonadiabatic transition probabilities and the unidirectionality of the rotation. Therefore, the BN-stilbene motor is expected to perform a unidirectional, repetitive 360° rotation upon sequential applying of photo and thermal inputs. The findings suggest BN-hetero stilbene as a promising type of light-driven rotary motor and may inspire the design and synthesis of novel molecular motors.
2018, 76(3): 202-208
doi: 10.6023/A17110477
Abstract:
Lithium ion batteries (LIBs) have been recognized as one of the most popular and promising energy storage devices because of their high energy density and cyclability. The leading electrode materials for LIBs are mainly based on inorganic compounds materials because of their excellent electrochemical performances. Compared with inorganic compounds or metal-based electrode materials, organic electrode materials have been less explored for LIBs, but they are promising because of their synthetic diversity, flexible framework, low cost and environmental benignity. Unlike organic small molecules and linear polymers electrodes, which show low surface area and are soluble in electrolyte leading to the low electrochemical performance, conjugated microporous polymers (CMPs) feature with large specific surface area, good physicochemical stability, unique extended π-conjugation along the polymer skeleton and high crosslinked degree, which make CMPs great potential as electrodes for LIBs. In this work, a pyrene-based conjugated microporous polymer (PyDB) has been synthesized via palladium-catalyzed Suzuki cross-coupling reaction from tetrabromopyrene and 1, 4-benzenediboronic acid. PyDB is insoluble in common organic solvents tested because of its highly crosslinked polymer structure. Thermogravimetric analysis indicated that the polymer is thermally stable up to 430℃ in nitrogen atmosphere. Nitrogen adsorption-desorption measurement revealed that PyDB has a high Brunauer-Emmet-Teller specific surface area of up to 1283 m2·g-1. PyDB based electrode for LIBs exhibited excellent electrochemical performance. The assembled LIB from PyDB as cathode material shows a discharge capacity of 163 mAh·g-1 at a current density of 50 mA·g-1 with a high capacitance retention of 167 mAh·g-1 after 300 cycles at a current density of 100 mA·g-1. When PyDB was used as anode material, the assembled LIB also exhibits a high capacity of 495 mAh·g-1 at 50 mA·g-1 with a high capacitance retention of 245 mAh·g-1 after 300 cycles at 200 mA·g-1. The excellent electrochemical performance of PyDB could be attributed to its extended π-conjugation structure and porous structure with high surface area, the extended π-conjugation is beneficial to the doping reaction and electronic conduction, while porous structure with high surface area can provide plentiful active sites and promote the transmission of ions.
Lithium ion batteries (LIBs) have been recognized as one of the most popular and promising energy storage devices because of their high energy density and cyclability. The leading electrode materials for LIBs are mainly based on inorganic compounds materials because of their excellent electrochemical performances. Compared with inorganic compounds or metal-based electrode materials, organic electrode materials have been less explored for LIBs, but they are promising because of their synthetic diversity, flexible framework, low cost and environmental benignity. Unlike organic small molecules and linear polymers electrodes, which show low surface area and are soluble in electrolyte leading to the low electrochemical performance, conjugated microporous polymers (CMPs) feature with large specific surface area, good physicochemical stability, unique extended π-conjugation along the polymer skeleton and high crosslinked degree, which make CMPs great potential as electrodes for LIBs. In this work, a pyrene-based conjugated microporous polymer (PyDB) has been synthesized via palladium-catalyzed Suzuki cross-coupling reaction from tetrabromopyrene and 1, 4-benzenediboronic acid. PyDB is insoluble in common organic solvents tested because of its highly crosslinked polymer structure. Thermogravimetric analysis indicated that the polymer is thermally stable up to 430℃ in nitrogen atmosphere. Nitrogen adsorption-desorption measurement revealed that PyDB has a high Brunauer-Emmet-Teller specific surface area of up to 1283 m2·g-1. PyDB based electrode for LIBs exhibited excellent electrochemical performance. The assembled LIB from PyDB as cathode material shows a discharge capacity of 163 mAh·g-1 at a current density of 50 mA·g-1 with a high capacitance retention of 167 mAh·g-1 after 300 cycles at a current density of 100 mA·g-1. When PyDB was used as anode material, the assembled LIB also exhibits a high capacity of 495 mAh·g-1 at 50 mA·g-1 with a high capacitance retention of 245 mAh·g-1 after 300 cycles at 200 mA·g-1. The excellent electrochemical performance of PyDB could be attributed to its extended π-conjugation structure and porous structure with high surface area, the extended π-conjugation is beneficial to the doping reaction and electronic conduction, while porous structure with high surface area can provide plentiful active sites and promote the transmission of ions.
Template-Assisted Preparation and Lithium Storage Performance of Nitrogen Doped Porous Carbon Sheets
2018, 76(3): 209-214
doi: 10.6023/A17090425
Abstract:
Nitrogen doped porous carbon sheets (NPCSs) having high lithium storage performance were successfully prepared by a template-assisted approach using magnesium oxide/melamine/polyethylene glycol (MgO/melamine/PEG) as raw materials. In a typical procedure, the precursor, which consisted of MgO, melamine and PEG in a mass ratio of 7:3:10, was carbonized at 700℃ for 3 h in a temperature-programmed tubular furnace under N2 flow with a heating rate of 5℃·min-1. The intermediate was immersed into 3 mol·L-1 HCl solution for several times to remove MgO. Subsequently, the sample was rinsed with water and ethanol until a neutral pH was obtained, and then dried at 80℃ in a vacuum oven. The sample was systematically characterized and analyzed by Fourier transform infrared spectrometer (FTIR), X-ray powder diffractometer (XRD), X-ray photoelectron spectrometer (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The results indicated that NPCSs showed an interconnected porous carbon sheet networks, showing relatively high specific surface area (370.8 m2·g-1), hierarchical pore channels, and high nitrogen content (8.5 at%). Such a continuous porous structure could enhance the electron transport on three-dimensional direction, shorten the diffusion distance of lithium ions, enlarge the interface area between lithium ion and electrolyte, and provide the place for the accommodation of lithium ions. Additionally, high N-doping level in NPCSs could provide numerous activated sites for the intercalation and deintercalation of lithium ions, and enhance the electronic conductivity. Based on the unique structure, NPCSs electrode could exhibit high initial reversible specific capacities (after excluding the contribution of acetylene black, 914 mAh·g-1 at 100 mA·g-1) and good cycling stability (still remaining a specific capacity of 523 mAh·g-1 at 1000 mA·g-1 up to 300 cycles). Moreover, NPCSs displayed high rate capability with a reversible capacity of 355 mAh·g-1 at a current density of 3000 mA·g-1. Therefore, the NPCSs obtained are expectable to be widely used as anode material in lithium-ion batteries.
Nitrogen doped porous carbon sheets (NPCSs) having high lithium storage performance were successfully prepared by a template-assisted approach using magnesium oxide/melamine/polyethylene glycol (MgO/melamine/PEG) as raw materials. In a typical procedure, the precursor, which consisted of MgO, melamine and PEG in a mass ratio of 7:3:10, was carbonized at 700℃ for 3 h in a temperature-programmed tubular furnace under N2 flow with a heating rate of 5℃·min-1. The intermediate was immersed into 3 mol·L-1 HCl solution for several times to remove MgO. Subsequently, the sample was rinsed with water and ethanol until a neutral pH was obtained, and then dried at 80℃ in a vacuum oven. The sample was systematically characterized and analyzed by Fourier transform infrared spectrometer (FTIR), X-ray powder diffractometer (XRD), X-ray photoelectron spectrometer (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The results indicated that NPCSs showed an interconnected porous carbon sheet networks, showing relatively high specific surface area (370.8 m2·g-1), hierarchical pore channels, and high nitrogen content (8.5 at%). Such a continuous porous structure could enhance the electron transport on three-dimensional direction, shorten the diffusion distance of lithium ions, enlarge the interface area between lithium ion and electrolyte, and provide the place for the accommodation of lithium ions. Additionally, high N-doping level in NPCSs could provide numerous activated sites for the intercalation and deintercalation of lithium ions, and enhance the electronic conductivity. Based on the unique structure, NPCSs electrode could exhibit high initial reversible specific capacities (after excluding the contribution of acetylene black, 914 mAh·g-1 at 100 mA·g-1) and good cycling stability (still remaining a specific capacity of 523 mAh·g-1 at 1000 mA·g-1 up to 300 cycles). Moreover, NPCSs displayed high rate capability with a reversible capacity of 355 mAh·g-1 at a current density of 3000 mA·g-1. Therefore, the NPCSs obtained are expectable to be widely used as anode material in lithium-ion batteries.
2018, 76(3): 215-223
doi: 10.6023/A17120543
Abstract:
Dye-sensitized solar cells (DSSCs), as an emerging solar energy conversion technology, have attracted increasing attention for their ease of fabrication, low production cost, wide variety of dye structure, and high power conversion efficiency (PCE). As the critical component of DSSCs, photosensitizers play an important role in photon capturing, charge generation and separation, as well as electron injection at the semiconductor interface. Efforts on the design and synthesis of photosensitizers are thus an effective and straightforward way to tune the photovoltaic performance. In this article, three novel phenothiazine-based D-A-π-A type organic dyes (JY50~JY52) featuring benzothiadiazole units as auxiliary acceptors have been synthesized and applied in DSSCs. The introduction of auxiliary acceptor would take the advantages of the optimization of the dyes' energy levels and light absorption. To get more impressive device efficiency, 4-hexylbenzene group was decorated onto phenothiazine donor and has proved to be effective for improving the molar absorption coefficient and suppressing the charge recombination, finally resulting in the enhancement of photocurrent (Jsc) and photovoltage (Voc). In order to investigate the effect of different electron acceptor/anchoring group, benzoic acid and cyanoacrylic acid, which are widely applied in porphyrin-based dyes and metal-free organic dyes, respectively, are employed here to construct the target dyes. As we can see from the obtained photovoltaic performance data, dyes (JY50 and JY51) with benzoic acid anchor seem more beneficial to gain a higher Voc, this may be ascribed to its nearly vertical adsorption geometry on the TiO2 interface and the resulting decrease of the charge recombination. As for dye (JY52) with cyanoacrylic acid anchor, a better Jsc value is achieved because cyanoacrylic acid endows dye an extended conjugated system and an enhanced intramolecular charge transfer. Under AM 1.5 solar light conditions, the dye JY51 with 4-hexylbenzene unit and benzoic acid acceptor exhibited the highest PCE of 7.61%, with Voc of 797 mV and Jsc of 14.21 mA·cm-2.
Dye-sensitized solar cells (DSSCs), as an emerging solar energy conversion technology, have attracted increasing attention for their ease of fabrication, low production cost, wide variety of dye structure, and high power conversion efficiency (PCE). As the critical component of DSSCs, photosensitizers play an important role in photon capturing, charge generation and separation, as well as electron injection at the semiconductor interface. Efforts on the design and synthesis of photosensitizers are thus an effective and straightforward way to tune the photovoltaic performance. In this article, three novel phenothiazine-based D-A-π-A type organic dyes (JY50~JY52) featuring benzothiadiazole units as auxiliary acceptors have been synthesized and applied in DSSCs. The introduction of auxiliary acceptor would take the advantages of the optimization of the dyes' energy levels and light absorption. To get more impressive device efficiency, 4-hexylbenzene group was decorated onto phenothiazine donor and has proved to be effective for improving the molar absorption coefficient and suppressing the charge recombination, finally resulting in the enhancement of photocurrent (Jsc) and photovoltage (Voc). In order to investigate the effect of different electron acceptor/anchoring group, benzoic acid and cyanoacrylic acid, which are widely applied in porphyrin-based dyes and metal-free organic dyes, respectively, are employed here to construct the target dyes. As we can see from the obtained photovoltaic performance data, dyes (JY50 and JY51) with benzoic acid anchor seem more beneficial to gain a higher Voc, this may be ascribed to its nearly vertical adsorption geometry on the TiO2 interface and the resulting decrease of the charge recombination. As for dye (JY52) with cyanoacrylic acid anchor, a better Jsc value is achieved because cyanoacrylic acid endows dye an extended conjugated system and an enhanced intramolecular charge transfer. Under AM 1.5 solar light conditions, the dye JY51 with 4-hexylbenzene unit and benzoic acid acceptor exhibited the highest PCE of 7.61%, with Voc of 797 mV and Jsc of 14.21 mA·cm-2.
