Lithium/sulfur （Li/S） cells have great potential to become mainstream secondary batteries due to their ultra-high theoretical specific energy. The major challenge for Li/S cells is the unstable cycling performance c...Lithium/sulfur （Li/S） cells have great potential to become mainstream secondary batteries due to their ultra-high theoretical specific energy. The major challenge for Li/S cells is the unstable cycling performance caused by the sulfur＇s insulating nature and the high-solubility of the intermediate polysulfide products. Several years of efforts to develop various fancy carbon nanostructures, trying to physically encapsulate the polysulfides, did not yet push the cell＇s cycle life long enough to compete with current Li ion cells. The focus of this review is on the recent progress in chemical bonding strategy for trapping polysulfides through employing functional groups and additives in carbon matrix. Research results on understanding the working mechanism of chemical interaction between polysulfides and functional groups （e.g. 0-, B-, N- and S-） in carbon matrix, metal-based additives, or polymer additives during charge/discharge are discussed.展开更多
Many organic molecules with various functional groups have been used to passivate the perovskite surface for improving the efficiency and stability of perovskite solar cell(PSCs).However,the intrinsic attributes of th...Many organic molecules with various functional groups have been used to passivate the perovskite surface for improving the efficiency and stability of perovskite solar cell(PSCs).However,the intrinsic attributes of the passivation effect based on different chemical bonds are rarely studied.Here,we comparatively investigate the passivation effect among 12 types of functional groups on para-tertbutylbenzene for PSCs and find that the open circuit voltage(VOC) tends to increase with the chemical bonding strength between perovskite and these passivation additive molecules.Particularly,the paratert-butylbenzoic acid(tB-COOH),with the extra intermolecular hydrogen bonding,can stabilize the surface passivation of perovskite films exceptionally well through formation of a crystalline interlayer with water-insoluble property and high melting point.As a result,the tB-COOH device achieves a champion power conversion efficiency(PCE) of 21.46%.More importantly,such devices,which were stored in ambient air with a relative humidity of ~45%,can retain 88% of their initial performance after a testing period of more than 1 year(10,080 h).This work provides a case study to understand chemical bonding effects on passivation of perovskite.展开更多
Background:Hydrogen bonding interaction was considered to play a critical role in controlling drug release from transdermal patch.However,the quantitative evaluation of hydrogen bonding strength between drug and polar...Background:Hydrogen bonding interaction was considered to play a critical role in controlling drug release from transdermal patch.However,the quantitative evaluation of hydrogen bonding strength between drug and polar functional group was rarely reported,and the relationship between hydrogen bonding strength and controlled release capacity of pressure sensitive adhesive(PSA)was not well understood.The present study shed light on this relationship.Methods:Acrylate PSAs with amide group were synthesized by a free radical-initiated solution polymerization.Six drugs,i.e.,etodolac,ketoprofen,gemfibrozil,zolmitriptan,propranolol and lidocaine,were selected as model drugs.In vitro drug release and skin permeation experiments and in vivo pharmacokinetic experiment were performed.Partial correlation analysis,fourier-transform infrared spectroscopy and molecular simulation were conducted to provide molecular details of drug-PSA interactions.Mechanical test,rheology study,and modulated differential scanning calorimetry study were performed to scrutinize the free volume and molecular mobility of PSAs.Results:Release rate of all six drugs from amide PSAs decreased with the increase of amide group concentrations;however,only zolmitriptan and propranolol showed decreased skin permeation rate.It was found that drug release was controlled by amide group through hydrogen bonding,and controlled release extent was positively correlated with hydrogen bonding strength.Conclusion:From these results,we concluded that drugs with strong hydrogen bond forming ability and high skin permeation were suitable to use amide PSAs to regulate their release rate from patch.展开更多
Excited-state intramolecular proton transfer(ESIPT) molecules are broadly applied to UV absorbers, fluorescence sensing, and lighting materials. In previous work, the fluorescence colors of oxazoline-substituted hydro...Excited-state intramolecular proton transfer(ESIPT) molecules are broadly applied to UV absorbers, fluorescence sensing, and lighting materials. In previous work, the fluorescence colors of oxazoline-substituted hydroxyfluorenes and hydroxylated benzoxazole were diversified by adding the π-conjugation. There is intriguing that the mechanism of diversified fluorescence colors induced by ESIPT. Here, the density functional theory(DFT) and time-dependent DFT(TDDFT)are advised to identify the effects of π-conjugation on ESIPT and photophysical properties. The stabilized geometrical configurations, frontier molecular orbitals(FMOs) isosurfaces, and O–H stretching vibration frequency analysis demonstrate that PT processes are more active in S1state. Constructing the minimum energy pathways of ESIPT processes, we find that the calculated peak of enol and keto fluorescence of naphthoxazole(NO–OH) is distinctly bathochromic-shift relative to the oxazoline-substituted hydroxyfluorenes(Oxa–OH) configuration when adding π-conjugation-substitution, and it means that π-conjugation-substitution can diversify the fluorescence color. We hope our studies can establish new channels to devise the ESIPT-based molecules.展开更多
The Paulie’s principle is used for development of the orbital-free (OF) version of the density functional theory. On the example of the three-atomic clusters, Al<sub>3</sub>, Si<sub>3</sub>, a...The Paulie’s principle is used for development of the orbital-free (OF) version of the density functional theory. On the example of the three-atomic clusters, Al<sub>3</sub>, Si<sub>3</sub>, and C<sub>3</sub>, it is shown that the OF approach may lead to equilibrium configurations of atomic systems with both the metallic and covalent bonding. The equilibrium interatomic distances, interbonding angles and binding energies are found in good accordance with the known data. Results will be useful for developing of theoretical study of huge molecules and nanoparticles.展开更多
A series of mono-functional benzoxazine monomers with different N-substituents were synthesized from phenol, formaldehyde, and various amines （ammonia, methylamine, n-butylamine, dodecylamine）, named P-am, P-m, P-b,...A series of mono-functional benzoxazine monomers with different N-substituents were synthesized from phenol, formaldehyde, and various amines （ammonia, methylamine, n-butylamine, dodecylamine）, named P-am, P-m, P-b, and P-da, respectively. The surface properties of these polybenzoxazine films were proven by contact angle measurements. The hydrogen bond network of the polybenzoxazine systems was studied using the FTIR spectra. And the results showed that the surface free energy increased with increasing the fraction of intermolecular hydrogen bonding when the N-substituent was an alkyl chain. However, the rule was not suitable when the N-substituent was H. That was because there was one more kind of intramolecular hydrogen bond in the poly（P-am）. Based on these findings, we proposed that both the N-substituent alkyl group and the fraction of intermolecular hydrogen bonding had effects on the surface free energy.展开更多
Low-lying electronic states of the lutetium dimer （Lu2） were studied based on density functional theory （DFT） using ten different density functionals together with three different relativistic effective core pseud...Low-lying electronic states of the lutetium dimer （Lu2） were studied based on density functional theory （DFT） using ten different density functionals together with three different relativistic effective core pseudopotentials （RECPs）. Relative state energies, equilibrium bond lengths, vibrational frequencies, and ground-state dissociation energies were evaluated. It was found that the ground state is a triplet state irrespective of the type of functional and RECP used. This result is in contrast with a previous DFT calculation which gave a singlet ground state for Lu2. By comparing with the high-level ab initio and available experimental results, it is evident that the hybrid-GGA functionals combined with the Stuttgart smallcore RECP yield the best overall agreement for the properties under study. The effects of Hartree-Fock exchange in B3LYP functional on the calculated bond length and dissociation energy of the ground state were examined, and rationalized in terms of 5d participation in Lu-Lu covalent bonding.展开更多
Vanadium oxide clusters VxOy^q（x≤8, q=0, ±1） are classified according to the oxidation index （△=2y＋q-5x） of each cluster. Density functional calculations indicate that clusters with the same oxidation inde...Vanadium oxide clusters VxOy^q（x≤8, q=0, ±1） are classified according to the oxidation index （△=2y＋q-5x） of each cluster. Density functional calculations indicate that clusters with the same oxidation index tend to have similar bonding characters, electronic structures, and reactivities. This general rule leads to the findings of new possible ground state struc- tures for V206 and V3O6＋ clusters. This successful application of the classification method on vanadium oxide clusters proves that this method is very effective in studying the bonding properties of early transition metal oxide clusters.展开更多
Transition metal phosphoraniminato derivatives of Keggin-type polyoxometalates(POMs) are important intermediates in N-transfer reactions.Density functional theory(DFT) has been employed to calculate the electronic str...Transition metal phosphoraniminato derivatives of Keggin-type polyoxometalates(POMs) are important intermediates in N-transfer reactions.Density functional theory(DFT) has been employed to calculate the electronic structures,bonding features and redox properties of the iron and ruthenium phosphoraniminato derivatives of Keggin-type POMs,[PW11O39{MVNPPh3}] 3-(M = Fe,Ru).Our DFT calculations show that both anions have the same qualitative M-N single bond features.However,the calculations predict that the FeN system possesses a lower energy and more accessible metalnitrogen antibonding orbital than the RuN system.This results in a greater weakening of the Fe-N bond in the reduction process,and thus enhances its N-transfer reactivity.展开更多
文摘Lithium/sulfur （Li/S） cells have great potential to become mainstream secondary batteries due to their ultra-high theoretical specific energy. The major challenge for Li/S cells is the unstable cycling performance caused by the sulfur＇s insulating nature and the high-solubility of the intermediate polysulfide products. Several years of efforts to develop various fancy carbon nanostructures, trying to physically encapsulate the polysulfides, did not yet push the cell＇s cycle life long enough to compete with current Li ion cells. The focus of this review is on the recent progress in chemical bonding strategy for trapping polysulfides through employing functional groups and additives in carbon matrix. Research results on understanding the working mechanism of chemical interaction between polysulfides and functional groups （e.g. 0-, B-, N- and S-） in carbon matrix, metal-based additives, or polymer additives during charge/discharge are discussed.
基金supported by the Research Grants Council of Hong Kong (T23-407/13-N)Innovation and Technology Commission (ITS/088/17)+5 种基金Start-up funds from Central Organization Department and South China University of Technologyfund from the Guangdong Science and Technology Program (2020B121201003)the National Natural Science Foundation of China (21776315)Petro China Innovation Foundation (2017D5007-0402)the Pearl River Talent Program (2019ZT08L075, 2019QN01L118)Fundamental Research Funds for the Central Universities (19CX05001A)。
文摘Many organic molecules with various functional groups have been used to passivate the perovskite surface for improving the efficiency and stability of perovskite solar cell(PSCs).However,the intrinsic attributes of the passivation effect based on different chemical bonds are rarely studied.Here,we comparatively investigate the passivation effect among 12 types of functional groups on para-tertbutylbenzene for PSCs and find that the open circuit voltage(VOC) tends to increase with the chemical bonding strength between perovskite and these passivation additive molecules.Particularly,the paratert-butylbenzoic acid(tB-COOH),with the extra intermolecular hydrogen bonding,can stabilize the surface passivation of perovskite films exceptionally well through formation of a crystalline interlayer with water-insoluble property and high melting point.As a result,the tB-COOH device achieves a champion power conversion efficiency(PCE) of 21.46%.More importantly,such devices,which were stored in ambient air with a relative humidity of ~45%,can retain 88% of their initial performance after a testing period of more than 1 year(10,080 h).This work provides a case study to understand chemical bonding effects on passivation of perovskite.
基金supported by the National Natural Science Foundation of China(81773665)Natural Science Foundation of Liaoning Province(20170540861,China)
文摘Background:Hydrogen bonding interaction was considered to play a critical role in controlling drug release from transdermal patch.However,the quantitative evaluation of hydrogen bonding strength between drug and polar functional group was rarely reported,and the relationship between hydrogen bonding strength and controlled release capacity of pressure sensitive adhesive(PSA)was not well understood.The present study shed light on this relationship.Methods:Acrylate PSAs with amide group were synthesized by a free radical-initiated solution polymerization.Six drugs,i.e.,etodolac,ketoprofen,gemfibrozil,zolmitriptan,propranolol and lidocaine,were selected as model drugs.In vitro drug release and skin permeation experiments and in vivo pharmacokinetic experiment were performed.Partial correlation analysis,fourier-transform infrared spectroscopy and molecular simulation were conducted to provide molecular details of drug-PSA interactions.Mechanical test,rheology study,and modulated differential scanning calorimetry study were performed to scrutinize the free volume and molecular mobility of PSAs.Results:Release rate of all six drugs from amide PSAs decreased with the increase of amide group concentrations;however,only zolmitriptan and propranolol showed decreased skin permeation rate.It was found that drug release was controlled by amide group through hydrogen bonding,and controlled release extent was positively correlated with hydrogen bonding strength.Conclusion:From these results,we concluded that drugs with strong hydrogen bond forming ability and high skin permeation were suitable to use amide PSAs to regulate their release rate from patch.
基金supported by the National Natural Science Foundation of China (Grant No. 11974152)the Shenyang High level Innovative Talents Program (Grant No. RC200565)+1 种基金the Science program of Liaoning Provincial Department of Education (Grant No. LJKZ0097)the Intercollegiate cooperation project of colleges and universities of Liaoning Provincial Department of Education。
文摘Excited-state intramolecular proton transfer(ESIPT) molecules are broadly applied to UV absorbers, fluorescence sensing, and lighting materials. In previous work, the fluorescence colors of oxazoline-substituted hydroxyfluorenes and hydroxylated benzoxazole were diversified by adding the π-conjugation. There is intriguing that the mechanism of diversified fluorescence colors induced by ESIPT. Here, the density functional theory(DFT) and time-dependent DFT(TDDFT)are advised to identify the effects of π-conjugation on ESIPT and photophysical properties. The stabilized geometrical configurations, frontier molecular orbitals(FMOs) isosurfaces, and O–H stretching vibration frequency analysis demonstrate that PT processes are more active in S1state. Constructing the minimum energy pathways of ESIPT processes, we find that the calculated peak of enol and keto fluorescence of naphthoxazole(NO–OH) is distinctly bathochromic-shift relative to the oxazoline-substituted hydroxyfluorenes(Oxa–OH) configuration when adding π-conjugation-substitution, and it means that π-conjugation-substitution can diversify the fluorescence color. We hope our studies can establish new channels to devise the ESIPT-based molecules.
文摘The Paulie’s principle is used for development of the orbital-free (OF) version of the density functional theory. On the example of the three-atomic clusters, Al<sub>3</sub>, Si<sub>3</sub>, and C<sub>3</sub>, it is shown that the OF approach may lead to equilibrium configurations of atomic systems with both the metallic and covalent bonding. The equilibrium interatomic distances, interbonding angles and binding energies are found in good accordance with the known data. Results will be useful for developing of theoretical study of huge molecules and nanoparticles.
基金financially supported by the Nanotech Foundation of Science and Technology Commission of Shanghai Municipality(No.0652nm001)the National Natural Science Fundation of China(No.u1162110)+1 种基金the Fundamental Research Funds for the Central Universities(No.WA1514015)and China Postdoctoral Science Foundation(No.2015M571509)
文摘A series of mono-functional benzoxazine monomers with different N-substituents were synthesized from phenol, formaldehyde, and various amines （ammonia, methylamine, n-butylamine, dodecylamine）, named P-am, P-m, P-b, and P-da, respectively. The surface properties of these polybenzoxazine films were proven by contact angle measurements. The hydrogen bond network of the polybenzoxazine systems was studied using the FTIR spectra. And the results showed that the surface free energy increased with increasing the fraction of intermolecular hydrogen bonding when the N-substituent was an alkyl chain. However, the rule was not suitable when the N-substituent was H. That was because there was one more kind of intramolecular hydrogen bond in the poly（P-am）. Based on these findings, we proposed that both the N-substituent alkyl group and the fraction of intermolecular hydrogen bonding had effects on the surface free energy.
基金the National Natural Science Foundation of China，the Innovation Scientists and Technicians Troop Construction Projects of Henan Province of China，the Science and Technology Research Key Project of Education Department of Henan Province of China
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.10804001, No.10674002, and No.20773024）, the National High Technology Research and Development Program of China （863 Program） （No.2006AA09Z243-3）, and the Program for Innovative Research Team in Anhui Normal University of China.
文摘Low-lying electronic states of the lutetium dimer （Lu2） were studied based on density functional theory （DFT） using ten different density functionals together with three different relativistic effective core pseudopotentials （RECPs）. Relative state energies, equilibrium bond lengths, vibrational frequencies, and ground-state dissociation energies were evaluated. It was found that the ground state is a triplet state irrespective of the type of functional and RECP used. This result is in contrast with a previous DFT calculation which gave a singlet ground state for Lu2. By comparing with the high-level ab initio and available experimental results, it is evident that the hybrid-GGA functionals combined with the Stuttgart smallcore RECP yield the best overall agreement for the properties under study. The effects of Hartree-Fock exchange in B3LYP functional on the calculated bond length and dissociation energy of the ground state were examined, and rationalized in terms of 5d participation in Lu-Lu covalent bonding.
基金This work was supported by the Hundred Talents Fund of the Chinese Academy of Sciences and the National Natural Science Foundation of China （No.20803083 and No.20933008）.
文摘Vanadium oxide clusters VxOy^q（x≤8, q=0, ±1） are classified according to the oxidation index （△=2y＋q-5x） of each cluster. Density functional calculations indicate that clusters with the same oxidation index tend to have similar bonding characters, electronic structures, and reactivities. This general rule leads to the findings of new possible ground state struc- tures for V206 and V3O6＋ clusters. This successful application of the classification method on vanadium oxide clusters proves that this method is very effective in studying the bonding properties of early transition metal oxide clusters.
基金support from the National Natural Science Foundation of China (20971020)the Program for Changjiang Scholars and Innovative Research Team in University(IRT0714)+1 种基金the Scientific Research Foundation for Doctor of Northeast Dianli University (BSJXM-201110)the Department of Science and Technology of Jilin Province (20082103)
文摘Transition metal phosphoraniminato derivatives of Keggin-type polyoxometalates(POMs) are important intermediates in N-transfer reactions.Density functional theory(DFT) has been employed to calculate the electronic structures,bonding features and redox properties of the iron and ruthenium phosphoraniminato derivatives of Keggin-type POMs,[PW11O39{MVNPPh3}] 3-(M = Fe,Ru).Our DFT calculations show that both anions have the same qualitative M-N single bond features.However,the calculations predict that the FeN system possesses a lower energy and more accessible metalnitrogen antibonding orbital than the RuN system.This results in a greater weakening of the Fe-N bond in the reduction process,and thus enhances its N-transfer reactivity.
