We analysed the photooxidation reaction in the electro-(1O2) and nucleophilic (O2•−) reaction of 2-pyridone azo derivatives. First, we calculated the energy (enthalpies) of tautomers formation, which is a measure of d...We analysed the photooxidation reaction in the electro-(1O2) and nucleophilic (O2•−) reaction of 2-pyridone azo derivatives. First, we calculated the energy (enthalpies) of tautomers formation, which is a measure of durability and the probability of their formation. We performed the light fastness calculations of the monoazopyridone dyes. Using the semi-empirical methods of quantum chemistry AM1 and PM3, the reactivity indicators of superdelocalisability (SrE(N)) and the electron density distribution in ground state on the highest occupied HOMO orbital and the lowest unoccupied excited state LUMO in 2-pyridone phenylazo derivatives were calculated. Superdelocalisability coefficients enable the stability to oxidising agents of various chemical molecules depending on the tautomeric forms in which they may occur. The results of the electron density calculations at the HOMO and LUMO boundary orbitals allow to determine the tendency to electrophilic attack with singlet oxygen 1O2 or nucleophilic attack of the superoxide anion O2•−on a specific atom in the molecule. The structure of the dyes was optimised with MM+, MD and AM1 or PM3 until a constant energy value was achieved with a convergence criterion of 0.01 kcal/mol.展开更多
The inclusion behavior of 4, 4＇ -Thiodiphenol （TDP）, a typical bisphenol and endocrine disruptor, reacts with β-cyclodextrin （β-CD） in aqueous solutions has been investigated by means of UV absorption spectrum ...The inclusion behavior of 4, 4＇ -Thiodiphenol （TDP）, a typical bisphenol and endocrine disruptor, reacts with β-cyclodextrin （β-CD） in aqueous solutions has been investigated by means of UV absorption spectrum and quantum-chemical calculation with Gaussian 98 software. The results show that the inclusion behavior of TDP is quite different in acidic solutions （pH 5.9） from that in alkaline solutions （pH 10.0）. This behavior difference is attributed to the different formula structures in aqueous solutions at acidic and alkaline pH values that are demonstrated by quantum- chemical modeling and calculation. TDP forms a 1 ： 1 fl-CD inclusion complex in aqueous solutions. The equiiibrium constant K was calculated to be 553.49 L/mol at pH 5.9 and 1 318.20 L/mol at pH 10.0 respectively for the inclusion complex reaction by using the modified Benesi-Heldbrand equation. After inclusion TDP＇s structure is changed especially at the inclusion part with the bond order becoming larger, which results in inhibitive photodegradation during direct photooxidation and H2O2 assisted photooxidation.展开更多
AM 1 and PM 3 SCF MO calculation have been performed to obtain molecular geometries of 7 1 isopropyl silacyclohexane based liquid crystal compounds biphenyl ethane series by energy gradient completed optimization.For ...AM 1 and PM 3 SCF MO calculation have been performed to obtain molecular geometries of 7 1 isopropyl silacyclohexane based liquid crystal compounds biphenyl ethane series by energy gradient completed optimization.For all optimized configurations,there is no imaginary frequency in vibrational analysis.The stable configuration,electronic structure,and some molecular properties of title compounds(heat of formation,dipole moment and energy level of frontal molecule orbital,etc) are frist reported.The calculated results are fully discussed with rspect to the organic structure theory.展开更多
The catalytic activity of trimethyl phosphite modified HZSM-5 zeolite and un-modified HZSM-5zeolite treated with 100% steam at 673,773,873,973 and 1073K, respectively, were investigated using heptanecracking as a prob...The catalytic activity of trimethyl phosphite modified HZSM-5 zeolite and un-modified HZSM-5zeolite treated with 100% steam at 673,773,873,973 and 1073K, respectively, were investigated using heptanecracking as a probe reaction. The results showed that the heptane conversion of both trimethyl phosphitetreated samples and un-phosphated samples decreased with an increase in treating temperature, but trimethylphosphite modified samples showed higher activity in comparison with the un-modified samples, which weresteam-treated at a higher temperature. The results were firstly elucidated by the model cluster method andcomputational quantum chemistry method. Full optimization and frequency analysis of all cluster model havebeen carried out using the Gaussian 94 software-package with the PM 3 semi-empirical method performed onsmall cluster models. The computational results showed that the dealumination of trimethyl phosphite modi-fied zeolite model cluster was more difficult than that of un-modified zeolite model cluster when they weretreated with steam while investigating the heat of reaction.展开更多
AM1 and PM3 methods using the unrestricted Hartree-Fock (UHF) calculations have been applied to study the thermolysis of dicyanofuroxan. The results obtained show that the reaction proceeds to product through a two-st...AM1 and PM3 methods using the unrestricted Hartree-Fock (UHF) calculations have been applied to study the thermolysis of dicyanofuroxan. The results obtained show that the reaction proceeds to product through a two-step pathway where the second one is the rate-determining step.展开更多
We present here a systematically theoretical study on the nonlinearities and their structure-property relationship of cyanovinyl-substituted donor-acceptor molecules by virtue of semiempirical PM3/AM1-FF approach. Goo...We present here a systematically theoretical study on the nonlinearities and their structure-property relationship of cyanovinyl-substituted donor-acceptor molecules by virtue of semiempirical PM3/AM1-FF approach. Good consistency between measured and calculated hyperpolarizabilities is obtained. Results show that conformation has a significant effect on hyperpolarizabilities. The torsion angle change between two conjugated parts of the molecular systems can substantially alter the nonlinearities. The total amount of charge transfer difference from donor to acceptor has been introduced to understand the microscopic nature of the nonlinear optical properties for the title molecules. General guidelines may be sought out in the search of molecules with large values of beta. Some molecules with large molecular hyperpolarizabilities can be predicted by the optimization for the longer pi-electron systems with both acceptor and donor groups.展开更多
文摘We analysed the photooxidation reaction in the electro-(1O2) and nucleophilic (O2•−) reaction of 2-pyridone azo derivatives. First, we calculated the energy (enthalpies) of tautomers formation, which is a measure of durability and the probability of their formation. We performed the light fastness calculations of the monoazopyridone dyes. Using the semi-empirical methods of quantum chemistry AM1 and PM3, the reactivity indicators of superdelocalisability (SrE(N)) and the electron density distribution in ground state on the highest occupied HOMO orbital and the lowest unoccupied excited state LUMO in 2-pyridone phenylazo derivatives were calculated. Superdelocalisability coefficients enable the stability to oxidising agents of various chemical molecules depending on the tautomeric forms in which they may occur. The results of the electron density calculations at the HOMO and LUMO boundary orbitals allow to determine the tendency to electrophilic attack with singlet oxygen 1O2 or nucleophilic attack of the superoxide anion O2•−on a specific atom in the molecule. The structure of the dyes was optimised with MM+, MD and AM1 or PM3 until a constant energy value was achieved with a convergence criterion of 0.01 kcal/mol.
基金Supported by the National Natural Science Foundation of China (20177017 and 20477031).
文摘The inclusion behavior of 4, 4＇ -Thiodiphenol （TDP）, a typical bisphenol and endocrine disruptor, reacts with β-cyclodextrin （β-CD） in aqueous solutions has been investigated by means of UV absorption spectrum and quantum-chemical calculation with Gaussian 98 software. The results show that the inclusion behavior of TDP is quite different in acidic solutions （pH 5.9） from that in alkaline solutions （pH 10.0）. This behavior difference is attributed to the different formula structures in aqueous solutions at acidic and alkaline pH values that are demonstrated by quantum- chemical modeling and calculation. TDP forms a 1 ： 1 fl-CD inclusion complex in aqueous solutions. The equiiibrium constant K was calculated to be 553.49 L/mol at pH 5.9 and 1 318.20 L/mol at pH 10.0 respectively for the inclusion complex reaction by using the modified Benesi-Heldbrand equation. After inclusion TDP＇s structure is changed especially at the inclusion part with the bond order becoming larger, which results in inhibitive photodegradation during direct photooxidation and H2O2 assisted photooxidation.
文摘AM 1 and PM 3 SCF MO calculation have been performed to obtain molecular geometries of 7 1 isopropyl silacyclohexane based liquid crystal compounds biphenyl ethane series by energy gradient completed optimization.For all optimized configurations,there is no imaginary frequency in vibrational analysis.The stable configuration,electronic structure,and some molecular properties of title compounds(heat of formation,dipole moment and energy level of frontal molecule orbital,etc) are frist reported.The calculated results are fully discussed with rspect to the organic structure theory.
文摘The catalytic activity of trimethyl phosphite modified HZSM-5 zeolite and un-modified HZSM-5zeolite treated with 100% steam at 673,773,873,973 and 1073K, respectively, were investigated using heptanecracking as a probe reaction. The results showed that the heptane conversion of both trimethyl phosphitetreated samples and un-phosphated samples decreased with an increase in treating temperature, but trimethylphosphite modified samples showed higher activity in comparison with the un-modified samples, which weresteam-treated at a higher temperature. The results were firstly elucidated by the model cluster method andcomputational quantum chemistry method. Full optimization and frequency analysis of all cluster model havebeen carried out using the Gaussian 94 software-package with the PM 3 semi-empirical method performed onsmall cluster models. The computational results showed that the dealumination of trimethyl phosphite modi-fied zeolite model cluster was more difficult than that of un-modified zeolite model cluster when they weretreated with steam while investigating the heat of reaction.
文摘AM1 and PM3 methods using the unrestricted Hartree-Fock (UHF) calculations have been applied to study the thermolysis of dicyanofuroxan. The results obtained show that the reaction proceeds to product through a two-step pathway where the second one is the rate-determining step.
基金Project supported by the State Science and Technology Commission and the National Natural Science Foundation of China.
文摘We present here a systematically theoretical study on the nonlinearities and their structure-property relationship of cyanovinyl-substituted donor-acceptor molecules by virtue of semiempirical PM3/AM1-FF approach. Good consistency between measured and calculated hyperpolarizabilities is obtained. Results show that conformation has a significant effect on hyperpolarizabilities. The torsion angle change between two conjugated parts of the molecular systems can substantially alter the nonlinearities. The total amount of charge transfer difference from donor to acceptor has been introduced to understand the microscopic nature of the nonlinear optical properties for the title molecules. General guidelines may be sought out in the search of molecules with large values of beta. Some molecules with large molecular hyperpolarizabilities can be predicted by the optimization for the longer pi-electron systems with both acceptor and donor groups.
