The density functional theory and the cluster model methods have been employed to investigate the interactions between thiophene and the HZSM-5 zeolites. The molecular complexes formed by the adsorption of thiophene o...The density functional theory and the cluster model methods have been employed to investigate the interactions between thiophene and the HZSM-5 zeolites. The molecular complexes formed by the adsorption of thiophene on silanol H3SiOH with two coordination forms, and the model Brrnsted acid sites of zeolite cluster H3Si（OH）AI（OH）2SiH3 upon the interaction with thiophene have been comparatively studied. Full optimization and frequency analysis of all cluster models have been carried out using the B3LYP hybrid method at 6-31G basis level for hydrogen atoms and 6-31＋G（d） basis set level for silicon, aluminum, oxygen, carbon, and sulfur atoms. The calculated results showed that the nature of interactions leading to the formation of the zeolite cluster-thiophene and silanol-thiophene complexes was associated with the van der Waals force confirmed by a slight change of geometric structures and properties. Thiophene is adsorbed on bridging hydroxyl group prior to silanol OH group judging from the magnitude of adsorption heat. The cluster model calculation reproducing the experimental prediction to form the experimental adsorption spectra of thiophene in HZSM-5 zeolite has illustrated the validity of the proposed adsorption models.展开更多
Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of...Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of Dinaphtho[2,3-b:2’,3’-d]thiophene-5,7,12,13-tetraone (DNTTRA) and its 36 derivatives containing azobenzene were calculated by using density functional theory B3LYP and M06-2X methods at 6-311++g(d, p) level, respectively. Besides, the atomic charges of natural bond orbitals (NBO) were analyzed. The frontier orbitals and electron absorption spectra of A-G5 molecule were calculated by TD-DFT (TD-B3LYP/6-311++g(d, p) and TD-M06-2X/6-311++g(d, p)). The NLO properties were calculated by effective finite field FF method and self-compiled program. The results show that 36 molecules of these six series are D-π-A-π-D structures. The third-order NLO coefficients γ (second-order hyperpolarizability) of the D series molecules are the largest among the six series, reaching 10<sup>7</sup> atomic units (10<sup><span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#ffffff;"="">-</span>33</sup> esu) of order of magnitude, showing good third-order NLO properties. Last, the third-order NLO properties of the azobenzene ring can be improved by introducing strong electron donor groups (e.g. -N(CH<sub>3</sub>)<sub>2</sub> or -NHCH<sub>3</sub>) in the azobenzene ring, so that the third-order NLO materials with good performance can be obtained.展开更多
Brønsted acidic ionic liquids(ILs),N-methylimidazole hydrogen sulfate([HMIm]HSO_(4))and N-methylpyrrolidone hydrogen sulfate([HNMP]HSO_(4)),are synthesized and employed as extractants to extract thiophene from mo...Brønsted acidic ionic liquids(ILs),N-methylimidazole hydrogen sulfate([HMIm]HSO_(4))and N-methylpyrrolidone hydrogen sulfate([HNMP]HSO_(4)),are synthesized and employed as extractants to extract thiophene from model gasoline(thiophene dissolved in noctane).The effect of extraction temperature,extraction time and volume ratio of ILs to model gasoline on desulfurization rates is investigated.Then,the optimal desulfurization conditions are obtained:the ratio of ILs to model gasoline is 1∶1,extraction temperature is 50℃ for[HMIm]HSO_(4)and 60℃ for[HNMP]HSO_(4),extraction time is 60 min.Meanwhile,the desulfurization rate of[HNMP]HSO_(4)for model gasoline is 62.8%,which is higher than that of[HMIm]HSO_(4)(55.5%)under optimal conditions.The reason is discussed on the basis of the interaction energy between thiophene and ILs at the B3LYP/6-311++G(d,p)level.Furthermore,the total desulfurization rate of[HNMP]HSO_(4)and[HMIm]HSO_(4)reaches 96.4%and 94.4%,respectively,by multistage extraction.Finally,the used ILs can be reused by vacuum drying,and their desulfurization rates are not significantly decreased after recycling 7 times in single-stage desulfurization.展开更多
Pyrolysis is an efficient and economical method for the utilization of waste rubber,but the high sulfur content limits its industrial application.Currently,the migration and transformation of the element S during pyro...Pyrolysis is an efficient and economical method for the utilization of waste rubber,but the high sulfur content limits its industrial application.Currently,the migration and transformation of the element S during pyrolysis of waste rubber is far from well known.In this work,a density functional theory(DFT)method was employed to explore the possible formation pathways of H_(2)S and its precursors(radicals HS·and S·)during the pyrolysis of thiophene,which is an important primary pyrolytic product of rubber.In particular,the influence of reactive hydrogen radicals was carefully investigated in the thiophene pyrolysis process.The calculation results indicate that the decomposition of thiophene tends to be initiated by hydrogen transfer between adjacent carbon atoms,which needs to overcome an energy barrier of 312.4 kJ/mol.The optimal pathway to generate H_(2)S in thiophene pyrolysis involves initial H migration and S-C bond cleavage,with an overall energy barrier of 525.8 kJ/mol.In addition,a thiol intermediate that bears unsaturated C-C bonds is essential for thiophene pyrolysis to generate H_(2)S,which exists in multiple critical reaction pathways.Moreover,the presence of hydrogen radicals significantly changes the decomposition patterns and reduces the energy barriers for thiophene decomposition,thus promoting the formation of H_(2)S.The current work on H_(2)S formation from thiophene can provide some theoretical support to explore clean utilization technologies for waste rubber.展开更多
As a widely used herbicide, the threat of atrazine to both environment and health of people has become the focus. Therefore, the research and analysis of atrazine are getting more important. In this work, the MIT was ...As a widely used herbicide, the threat of atrazine to both environment and health of people has become the focus. Therefore, the research and analysis of atrazine are getting more important. In this work, the MIT was used to detect atrazine theoretically. Atrazine was taken as a template molecule. MAA, MMA and TFMAA were taken as the functional monomers, respectively. The geometry optimization, the nature of hydrogen bonds, the NBO charge, and the binding energies of the imprinted molecule with the functional monomers were investigated at the B3LYP/6-31g（d,p） level. Results indicated that atrazine had the strongest interaction with TFMAA. When the ratio of atrazine and TFMAA was 1：6, the amount of H-bond formed from atrazine and TFMAA was the largest. Moreover, TFMAA owned the largest binding energy with atrazine while MMA owned the smallest. The study is helpful to interpret experiment phenomena of molecular imprinting and select better functional monomers.展开更多
Composite materials composed of LiMnO2, a typical electrode material for lithium ion battery, and a chiral cyanide-bridged Ni（Ⅱ）-Fe（Ⅲ） coordination polymer [NiL2][Fe（CN）6]·4H2O （Ni-Fe, H-form） （L = （1...Composite materials composed of LiMnO2, a typical electrode material for lithium ion battery, and a chiral cyanide-bridged Ni（Ⅱ）-Fe（Ⅲ） coordination polymer [NiL2][Fe（CN）6]·4H2O （Ni-Fe, H-form） （L = （1R,2R）-（-）-1,2-cyclohexane-diamine） or its deuterium isomer, [NiL2][Fe（CN）6]·4D2O （Ni-Fe, D-form） have been prepared by the various ratios （w/w） of Ni-Fe：LiMnO2 = 10：0 （pure Ni-Fe）, 9：1, 8：2, 7：3, 6：4, 5：5, 4：6, 3：7, 2：8, 1：9 and 0：10 （pure LiMnO2）. Gradual shift of IR （infrared） spectra by changing the ratios and losing difference between H-form and D-form of Ni-Fe due to isotope effects revealed adsorption of Ni-Fe onto LiMnO2 to form composite materials. Formation of composite materials of Ni-Fe and LiMnO2 could be also proved losing ferromagnetic behavior of LiMnO2 on increasing of the ratios of Ni-Fe in each composite. In contrast to smoothly positive thermal expansion of pure LiMnO2 along the crystallographic b axis, variable temperature powder XRD （X-ray diffraction） patterns at 100-300 K of the composite materials exhibited thermally-accessible lattice distortion along the b axis with different ratios. It is also proved deviation of ideal linear correlation of an evaluation function, In K = a/T ＋ b （where, K = （d（T） - d（0））/d（T）, d（T） denotes nλ/（sin 2θ） at T （K））.展开更多
文摘The density functional theory and the cluster model methods have been employed to investigate the interactions between thiophene and the HZSM-5 zeolites. The molecular complexes formed by the adsorption of thiophene on silanol H3SiOH with two coordination forms, and the model Brrnsted acid sites of zeolite cluster H3Si（OH）AI（OH）2SiH3 upon the interaction with thiophene have been comparatively studied. Full optimization and frequency analysis of all cluster models have been carried out using the B3LYP hybrid method at 6-31G basis level for hydrogen atoms and 6-31＋G（d） basis set level for silicon, aluminum, oxygen, carbon, and sulfur atoms. The calculated results showed that the nature of interactions leading to the formation of the zeolite cluster-thiophene and silanol-thiophene complexes was associated with the van der Waals force confirmed by a slight change of geometric structures and properties. Thiophene is adsorbed on bridging hydroxyl group prior to silanol OH group judging from the magnitude of adsorption heat. The cluster model calculation reproducing the experimental prediction to form the experimental adsorption spectra of thiophene in HZSM-5 zeolite has illustrated the validity of the proposed adsorption models.
文摘Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of Dinaphtho[2,3-b:2’,3’-d]thiophene-5,7,12,13-tetraone (DNTTRA) and its 36 derivatives containing azobenzene were calculated by using density functional theory B3LYP and M06-2X methods at 6-311++g(d, p) level, respectively. Besides, the atomic charges of natural bond orbitals (NBO) were analyzed. The frontier orbitals and electron absorption spectra of A-G5 molecule were calculated by TD-DFT (TD-B3LYP/6-311++g(d, p) and TD-M06-2X/6-311++g(d, p)). The NLO properties were calculated by effective finite field FF method and self-compiled program. The results show that 36 molecules of these six series are D-π-A-π-D structures. The third-order NLO coefficients γ (second-order hyperpolarizability) of the D series molecules are the largest among the six series, reaching 10<sup>7</sup> atomic units (10<sup><span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#ffffff;"="">-</span>33</sup> esu) of order of magnitude, showing good third-order NLO properties. Last, the third-order NLO properties of the azobenzene ring can be improved by introducing strong electron donor groups (e.g. -N(CH<sub>3</sub>)<sub>2</sub> or -NHCH<sub>3</sub>) in the azobenzene ring, so that the third-order NLO materials with good performance can be obtained.
基金This research was financially supported by the Natural Science Fund for Colleges and Universities of Jiangsu Province(09KJB530002).
文摘Brønsted acidic ionic liquids(ILs),N-methylimidazole hydrogen sulfate([HMIm]HSO_(4))and N-methylpyrrolidone hydrogen sulfate([HNMP]HSO_(4)),are synthesized and employed as extractants to extract thiophene from model gasoline(thiophene dissolved in noctane).The effect of extraction temperature,extraction time and volume ratio of ILs to model gasoline on desulfurization rates is investigated.Then,the optimal desulfurization conditions are obtained:the ratio of ILs to model gasoline is 1∶1,extraction temperature is 50℃ for[HMIm]HSO_(4)and 60℃ for[HNMP]HSO_(4),extraction time is 60 min.Meanwhile,the desulfurization rate of[HNMP]HSO_(4)for model gasoline is 62.8%,which is higher than that of[HMIm]HSO_(4)(55.5%)under optimal conditions.The reason is discussed on the basis of the interaction energy between thiophene and ILs at the B3LYP/6-311++G(d,p)level.Furthermore,the total desulfurization rate of[HNMP]HSO_(4)and[HMIm]HSO_(4)reaches 96.4%and 94.4%,respectively,by multistage extraction.Finally,the used ILs can be reused by vacuum drying,and their desulfurization rates are not significantly decreased after recycling 7 times in single-stage desulfurization.
基金the National Natural Science Foundation of China(51922040,51821004)the China Postdoctoral Science Foundation(2019TQ0091)+1 种基金the Grants from Fok Ying Tung Education Foundation(161051)the Fundamental Research Funds for the Central Universities(2020MS020,2020DF01,2018ZD08).
文摘Pyrolysis is an efficient and economical method for the utilization of waste rubber,but the high sulfur content limits its industrial application.Currently,the migration and transformation of the element S during pyrolysis of waste rubber is far from well known.In this work,a density functional theory(DFT)method was employed to explore the possible formation pathways of H_(2)S and its precursors(radicals HS·and S·)during the pyrolysis of thiophene,which is an important primary pyrolytic product of rubber.In particular,the influence of reactive hydrogen radicals was carefully investigated in the thiophene pyrolysis process.The calculation results indicate that the decomposition of thiophene tends to be initiated by hydrogen transfer between adjacent carbon atoms,which needs to overcome an energy barrier of 312.4 kJ/mol.The optimal pathway to generate H_(2)S in thiophene pyrolysis involves initial H migration and S-C bond cleavage,with an overall energy barrier of 525.8 kJ/mol.In addition,a thiol intermediate that bears unsaturated C-C bonds is essential for thiophene pyrolysis to generate H_(2)S,which exists in multiple critical reaction pathways.Moreover,the presence of hydrogen radicals significantly changes the decomposition patterns and reduces the energy barriers for thiophene decomposition,thus promoting the formation of H_(2)S.The current work on H_(2)S formation from thiophene can provide some theoretical support to explore clean utilization technologies for waste rubber.
基金Supported by the Science and Technology Research Projects for Education Department ofJilin Province (No. 201130)the Natural Science Foundation of Jilin Province (No. 201215180)
文摘As a widely used herbicide, the threat of atrazine to both environment and health of people has become the focus. Therefore, the research and analysis of atrazine are getting more important. In this work, the MIT was used to detect atrazine theoretically. Atrazine was taken as a template molecule. MAA, MMA and TFMAA were taken as the functional monomers, respectively. The geometry optimization, the nature of hydrogen bonds, the NBO charge, and the binding energies of the imprinted molecule with the functional monomers were investigated at the B3LYP/6-31g（d,p） level. Results indicated that atrazine had the strongest interaction with TFMAA. When the ratio of atrazine and TFMAA was 1：6, the amount of H-bond formed from atrazine and TFMAA was the largest. Moreover, TFMAA owned the largest binding energy with atrazine while MMA owned the smallest. The study is helpful to interpret experiment phenomena of molecular imprinting and select better functional monomers.
文摘Composite materials composed of LiMnO2, a typical electrode material for lithium ion battery, and a chiral cyanide-bridged Ni（Ⅱ）-Fe（Ⅲ） coordination polymer [NiL2][Fe（CN）6]·4H2O （Ni-Fe, H-form） （L = （1R,2R）-（-）-1,2-cyclohexane-diamine） or its deuterium isomer, [NiL2][Fe（CN）6]·4D2O （Ni-Fe, D-form） have been prepared by the various ratios （w/w） of Ni-Fe：LiMnO2 = 10：0 （pure Ni-Fe）, 9：1, 8：2, 7：3, 6：4, 5：5, 4：6, 3：7, 2：8, 1：9 and 0：10 （pure LiMnO2）. Gradual shift of IR （infrared） spectra by changing the ratios and losing difference between H-form and D-form of Ni-Fe due to isotope effects revealed adsorption of Ni-Fe onto LiMnO2 to form composite materials. Formation of composite materials of Ni-Fe and LiMnO2 could be also proved losing ferromagnetic behavior of LiMnO2 on increasing of the ratios of Ni-Fe in each composite. In contrast to smoothly positive thermal expansion of pure LiMnO2 along the crystallographic b axis, variable temperature powder XRD （X-ray diffraction） patterns at 100-300 K of the composite materials exhibited thermally-accessible lattice distortion along the b axis with different ratios. It is also proved deviation of ideal linear correlation of an evaluation function, In K = a/T ＋ b （where, K = （d（T） - d（0））/d（T）, d（T） denotes nλ/（sin 2θ） at T （K））.
