Reduced rate constants of photoinduced electron transfer in intramolecular fluorescence quenching of donor-acceptor podands induced by cation-complexation are observed in the highly exothermic reactions.
At room temperature,the conversion of greenhouse gases into valuable chemicals using metal-free catalysts for dry reforming of methane(DRM) is quite promising and challenging.Herein,we developed a novel covalent organ...At room temperature,the conversion of greenhouse gases into valuable chemicals using metal-free catalysts for dry reforming of methane(DRM) is quite promising and challenging.Herein,we developed a novel covalent organic porous polymer (TPE-COP) with rapid charge separation of the electron–hole pairs for DRM driven by visible light at room temperature,which can efficiently generate syngas (CO and H_(2)).Both electron donor (tris(4-aminophenyl)amine,TAPA) and acceptor (4,4',4'',4'''-((1 E,1'E,1''E,1'''E)-(ethene-1,1,2,2-tetrayltetrakis (benzene-4,1-diyl))tetrakis (ethene-2,1-diyl))tetrakis (1-(4-formylbenzyl)quinolin-1-ium),TPE-CHO) were existed in TPE-COP,in which the push–pull effect between them promoted the separation of photogenerated electron–hole,thus greatly improving the photocatalytic activity.Density functional theory (DFT) simulation results show that TPE-COP can form charge-separating species under light irradiation,leading to electrons accumulation in TPE-CHO unit and holes in TAPA,and thus efficiently initiating DRM.After 20 h illumination,the photocatalytic results show that the yields reach 1123.6 and 30.8μmol g^(-1)for CO and H_(2),respectively,which are significantly higher than those of TPE-CHO small molecules.This excellent result is mainly due to the increase of specific surface area,the enhancement of light absorption capacity,and the improvement of photoelectron-generating efficiency after the formation of COP.Overall,this work contributes to understanding the advantages of COP materials for photocatalysis and fundamentally pushes metal-free catalysts into the door of DRM field.展开更多
In this work, the excited states of the title compounds are calculated by using time-dependent density functional theory (TDDFT). Firstly, the variation of the sequences of intramolecular charge local excitation (LE) ...In this work, the excited states of the title compounds are calculated by using time-dependent density functional theory (TDDFT). Firstly, the variation of the sequences of intramolecular charge local excitation (LE) and intramolecular charge transfer (CT) in the gas phase is studied by changing electron donors or acceptors. Then, the effects of Polarized Continuum Model (PCM) and Self-consistent Isodensity Polarized Continuum Model (SCI-PCM) in solvents on the calculated results are discussed. It is shown that the calculated results obtained by the PCM are in more agreement with the experimental data. Finally, the excited states of compounds in different solvents were calculated by PCM. Compared with the results obtained in gas phase, the absorption spectra of the CT state in the solvents have a larger red shift; however, the spectra for the LE state are hardly changed.展开更多
After the separation of the donor, the acceptor, and the σ-type bridge from the π-σ-π system, the geometries of biphenyl, biphenyl anion radical, naphthalene, and naphthalene anion radical are optimized, and then ...After the separation of the donor, the acceptor, and the σ-type bridge from the π-σ-π system, the geometries of biphenyl, biphenyl anion radical, naphthalene, and naphthalene anion radical are optimized, and then the reorganization energy for the intermolecular electron transfer (ET) at the levels of HF/4-31G and HF/DZP is calculated. The ET matrix elements of the self-exchange reactions of theπ-σ-π systems have been calculated by means of both the direct calculation based on the variational principle, and the transition energy between the molecular orbitals at the linear coordinateR = 0.5. For the cross reactions, the ET matrix element and the geometry of the transition state are determined by searching the minimum energy splitting Δmin along the reaction coordinate. In the evaluation of the solvent reorganization energy of the ET in solution, the Marcus’ two- sphere model has been invoked. A few of ET rate constants for the intramolecular ET reactions for the π-σ-π systems, which contain the biphenylyl as the donor and both biphenylyl and naphthyl as the acceptor, have been obtained.展开更多
Biological processes have been widely used for the treatment of both domestic and industrial wastewaters.In such biological processes,pollutants are converted into pollution-free substances by microorganisms through o...Biological processes have been widely used for the treatment of both domestic and industrial wastewaters.In such biological processes,pollutants are converted into pollution-free substances by microorganisms through oxidation-reduction reactions.Thus,how to quantify the internal oxidation-reduction properties wastewaters and seek out targeted countermeasures is essential to understand,operate,and optimize biological wastewater treatment systems.So far,no such approach is available yet.In this work,a novel concept of electron neutralization-based evaluation is proposed to describe the internal oxidation-reduction properties of wastewater.Pollutants in wastewater are defined as electron donor substances(EDSs)or electron acceptor substances(EASs),which could give or accept electrons,respectively.With such an electron neutralization concept,several parameters,i.e.,electron residual concentration(R),economy-related index(E and E r),and economical evaluation index(Y and Y r),are defined.Then,these parameters are used to evaluate the performance and economic aspects of currently applied wastewater treatment processes and even optimize systems.Three case studies demonstrate that the proposed concept could be effectively used to reduce wastewater treatment costs,assess energy recovery,and evaluate process performance.Therefore,a new,simple,and reliable methodology is established to describe the oxidation-reduction properties of wastewater and assess the biological wastewater treatment processes.展开更多
The studies on model systems XAuPH3 (X=H, F, Cl, Br, I, CN, CH3 ) have been carried out by using ab intio HF and DFT B3LYP methods at pseudopotential and dou-ble-zeta LANL2DZ level. The results are compared with those...The studies on model systems XAuPH3 (X=H, F, Cl, Br, I, CN, CH3 ) have been carried out by using ab intio HF and DFT B3LYP methods at pseudopotential and dou-ble-zeta LANL2DZ level. The results are compared with those of MP2. The properties of the models, i.e. the atomic net charge populations, the frontier molecular orbitals and nonlinear optical (NLO) properties have been investigated under an applied electric field on the basis of optimized structures. The computational results show that for these models characterized as electron acceptor-metal-electron donor (A-M-D) system, the NLO properties are due to in-tramolecular charge-transfer interaction between the accep-tor and the donor. The more charges transfer gives, the bet-ter NLO properties. In the selected model systems, IAuPH3 has the biggest bvec and g of 1184.1942 a.u. and 17341.9214 a.u., whereas IC6H4PH3+, a typical A--D organic conjugated system, has bvec and of 710.7697 and 11664.1405 a.u. respec-tively. In comparison, IAuPH3 has significant NLO proper-ties.展开更多
The behavior of photon-gated spectral hole burning with meso-phenyl-tetrabenzoporphyrinato-zinc as electron donor and dicyanobenzene as electron acceptor dispersed in polymethylmethacrylate was investigated.The data o...The behavior of photon-gated spectral hole burning with meso-phenyl-tetrabenzoporphyrinato-zinc as electron donor and dicyanobenzene as electron acceptor dispersed in polymethylmethacrylate was investigated.The data of absorption spectrum of the photoproduct acquired through photon-gated hole burning process by high power density and long hole burning time at 20 K were given The mechanism of photomduced donor-acceptor electron transfer for the iarget system in photon-gated spectral hole burning was demonstrated.展开更多
基金We are grateful to the National NatUral Science Foundation of China for support this work.!(grantNO. 29733100)
文摘Reduced rate constants of photoinduced electron transfer in intramolecular fluorescence quenching of donor-acceptor podands induced by cation-complexation are observed in the highly exothermic reactions.
基金supported by National Natural Science Foundation of China (Nos. 22274039 and 22178089)Hunan Provincial Innovation Foundation for Postgraduate (No.CX20220392)。
文摘At room temperature,the conversion of greenhouse gases into valuable chemicals using metal-free catalysts for dry reforming of methane(DRM) is quite promising and challenging.Herein,we developed a novel covalent organic porous polymer (TPE-COP) with rapid charge separation of the electron–hole pairs for DRM driven by visible light at room temperature,which can efficiently generate syngas (CO and H_(2)).Both electron donor (tris(4-aminophenyl)amine,TAPA) and acceptor (4,4',4'',4'''-((1 E,1'E,1''E,1'''E)-(ethene-1,1,2,2-tetrayltetrakis (benzene-4,1-diyl))tetrakis (ethene-2,1-diyl))tetrakis (1-(4-formylbenzyl)quinolin-1-ium),TPE-CHO) were existed in TPE-COP,in which the push–pull effect between them promoted the separation of photogenerated electron–hole,thus greatly improving the photocatalytic activity.Density functional theory (DFT) simulation results show that TPE-COP can form charge-separating species under light irradiation,leading to electrons accumulation in TPE-CHO unit and holes in TAPA,and thus efficiently initiating DRM.After 20 h illumination,the photocatalytic results show that the yields reach 1123.6 and 30.8μmol g^(-1)for CO and H_(2),respectively,which are significantly higher than those of TPE-CHO small molecules.This excellent result is mainly due to the increase of specific surface area,the enhancement of light absorption capacity,and the improvement of photoelectron-generating efficiency after the formation of COP.Overall,this work contributes to understanding the advantages of COP materials for photocatalysis and fundamentally pushes metal-free catalysts into the door of DRM field.
基金This work was supported by the Startup Foundation of Scientific Research for the Elitists Introduced into Jinan University
文摘In this work, the excited states of the title compounds are calculated by using time-dependent density functional theory (TDDFT). Firstly, the variation of the sequences of intramolecular charge local excitation (LE) and intramolecular charge transfer (CT) in the gas phase is studied by changing electron donors or acceptors. Then, the effects of Polarized Continuum Model (PCM) and Self-consistent Isodensity Polarized Continuum Model (SCI-PCM) in solvents on the calculated results are discussed. It is shown that the calculated results obtained by the PCM are in more agreement with the experimental data. Finally, the excited states of compounds in different solvents were calculated by PCM. Compared with the results obtained in gas phase, the absorption spectra of the CT state in the solvents have a larger red shift; however, the spectra for the LE state are hardly changed.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 29706104 and 29573112)the State Key Laboratory of Theoretical and Computational Chemistry of Jilin University.
文摘After the separation of the donor, the acceptor, and the σ-type bridge from the π-σ-π system, the geometries of biphenyl, biphenyl anion radical, naphthalene, and naphthalene anion radical are optimized, and then the reorganization energy for the intermolecular electron transfer (ET) at the levels of HF/4-31G and HF/DZP is calculated. The ET matrix elements of the self-exchange reactions of theπ-σ-π systems have been calculated by means of both the direct calculation based on the variational principle, and the transition energy between the molecular orbitals at the linear coordinateR = 0.5. For the cross reactions, the ET matrix element and the geometry of the transition state are determined by searching the minimum energy splitting Δmin along the reaction coordinate. In the evaluation of the solvent reorganization energy of the ET in solution, the Marcus’ two- sphere model has been invoked. A few of ET rate constants for the intramolecular ET reactions for the π-σ-π systems, which contain the biphenylyl as the donor and both biphenylyl and naphthyl as the acceptor, have been obtained.
基金supported by the National Science Foundation of China(Nos.51978615)Science and Technology Planning Project from the Science and Technology Department in Zhejiang Province(No.LQ17E080002)the Innovative and Entrepreneurial Training Plan of National College Students(No.GJ201810353001)。
文摘Biological processes have been widely used for the treatment of both domestic and industrial wastewaters.In such biological processes,pollutants are converted into pollution-free substances by microorganisms through oxidation-reduction reactions.Thus,how to quantify the internal oxidation-reduction properties wastewaters and seek out targeted countermeasures is essential to understand,operate,and optimize biological wastewater treatment systems.So far,no such approach is available yet.In this work,a novel concept of electron neutralization-based evaluation is proposed to describe the internal oxidation-reduction properties of wastewater.Pollutants in wastewater are defined as electron donor substances(EDSs)or electron acceptor substances(EASs),which could give or accept electrons,respectively.With such an electron neutralization concept,several parameters,i.e.,electron residual concentration(R),economy-related index(E and E r),and economical evaluation index(Y and Y r),are defined.Then,these parameters are used to evaluate the performance and economic aspects of currently applied wastewater treatment processes and even optimize systems.Three case studies demonstrate that the proposed concept could be effectively used to reduce wastewater treatment costs,assess energy recovery,and evaluate process performance.Therefore,a new,simple,and reliable methodology is established to describe the oxidation-reduction properties of wastewater and assess the biological wastewater treatment processes.
基金This work was supported by the Foundation of Over-century Excellent Talent Training Plan of the Ministry of Educa-tion (MOE)([2001]3), the Foundation of Excellent Young Teacher of MOE([1999]5),the Foundation of Skeleton Teachers of
文摘The studies on model systems XAuPH3 (X=H, F, Cl, Br, I, CN, CH3 ) have been carried out by using ab intio HF and DFT B3LYP methods at pseudopotential and dou-ble-zeta LANL2DZ level. The results are compared with those of MP2. The properties of the models, i.e. the atomic net charge populations, the frontier molecular orbitals and nonlinear optical (NLO) properties have been investigated under an applied electric field on the basis of optimized structures. The computational results show that for these models characterized as electron acceptor-metal-electron donor (A-M-D) system, the NLO properties are due to in-tramolecular charge-transfer interaction between the accep-tor and the donor. The more charges transfer gives, the bet-ter NLO properties. In the selected model systems, IAuPH3 has the biggest bvec and g of 1184.1942 a.u. and 17341.9214 a.u., whereas IC6H4PH3+, a typical A--D organic conjugated system, has bvec and of 710.7697 and 11664.1405 a.u. respec-tively. In comparison, IAuPH3 has significant NLO proper-ties.
基金Project supported by the National Natural Science Foundation of China
文摘The behavior of photon-gated spectral hole burning with meso-phenyl-tetrabenzoporphyrinato-zinc as electron donor and dicyanobenzene as electron acceptor dispersed in polymethylmethacrylate was investigated.The data of absorption spectrum of the photoproduct acquired through photon-gated hole burning process by high power density and long hole burning time at 20 K were given The mechanism of photomduced donor-acceptor electron transfer for the iarget system in photon-gated spectral hole burning was demonstrated.
