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Theoretical Study on the Ion-pair Formation Mechanism for the Li+I_2 →Li^+ + I_2^- System

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Chinese Journal of Structural Chemistry 2004年第5期23卷 498-501页

作者： SUNXiao-Min FENGDa-Cheng CAIZheng-Ting instituteoftheoreticalchemistry ShandongUniversityJinan250100China

For the Li + I2 →Li+ + I2- system, theoretical study has been performed on the QCISD(T) level by using the ab initio method. The collision complex in ion-pair formation process was found and optimized. These results show that the crossed molecule beam (CMB) experimental phenomenon is verified and the detailed geometry is given for the first time. A mechanism for ion-pair formation was proposed in detail. The position where the collision complex occurs affects the reaction path. Specifically, the process has threshold when the collision complex appeared before the crossing point between the covalent and ionic state potential energy surfaces. On the contrary, the process has no threshold after the crossing point. Theoretically, the title system belongs to the former case.

关键词： nonadiabatic transition two-state potential energy surface ion-pair formation

The Study of One Carbon Unit Transfer from Imidazolidine to dUMP Analogue with ONIOM Theory

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Chinese Chemical Letters 2004年第1期15卷 123-126页

作者： ChuanSongQI DaChengFENG ZhengTingCAI instituteoftheoreticalchemistry ShandongUniversityJinan250100

ONIOM quantum mechanics method is used in this paper to study one-carbon unit transfer from imidazolidine to 6-aminouracil derivates. The computation results show that this reaction can be completed via three paths owing to the three different proton transfer modes. By calculation and analysis, we can find the direct proton transfer is the preferable pathway.

关键词： H4folate one-carbon unit transfer dUMP.

Theoretical Study on the Long-lived Complexes for the Na +I_2Collision System

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Chinese Chemical Letters 2004年第6期15卷 749-752页

作者： XiaoMinSUN DaChengFENG ZhengTingCAI instituteoftheoreticalchemistry ShandongUniversityJinan250100

For the Na + I2 collision system, theoretical study is performed on the QCISD(T) level by using ab initio method. The ab initio potential energy surfaces are got and on them the long-lived complexes are found and optimized. These results verify the crossed molecule beam experimental phenomenon and the detailed geometry structures are given for the first time. The role of the complexes in the reaction path is also described in detail.

关键词： Nonadiabatic transition ion-pair formation two-state potential energy surface long-lived complex.

1, 4-Pyrone Effects on O-H Bond Dissociation Energies of Catechols in Flavonoids: A Density Functional Theory Study

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Chinese Chemical Letters 2002年第6期13卷 531-534页

作者： HongYuZHANG YouMinSUN 等 LaboratoryofComputationalBiology ShandongProvincialResearchCenterforBioinformaticEngineeringandTechniqueShandongUniversityofTechnologyZibo255091 instituteoftheoreticalchemistry Sh

Through B3LYP/6-31G** calculations, the 1, 4-pyrone effects on O-H bond dissociation energies (BDEs) of catechols in rings A or B of flavonoids were investigated. For the catechol in ring A, although 1, 4-pyrone enlarged the conjugation system, its electron-withdrawing property increased the O-H BDE ∼ 3 × 4.184 kJ/mol compared with that of catechol. However, for the catechol in ring B, 1,4-pyrone was poorly conjugated with the moiety, and therefore, had little effect on the O-H BDE.

关键词： Antioxidant density functional theory flavonoid O-H bond dissociation energy structure-activity relationships.

A DFT Study on Intramolecular Hydrogen Bond in Substituted Catechols and Their Radicals

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Chinese Chemical Letters 2003年第2期14卷 209-212页

作者： Hong Yu ZHANG You Min SUN 等 LaboratoryforComputationalBiology ShandongProvincialResearchCenterforBioinformaticEngineeringandTechniqueShandongUniversityofTechnologyZibo255049 instituteoftheoreticalchemistry S

Density functional theory (DFT) at B3LYP/6-31G(d,p) level was employed to calculate intramolecular hydrogen bond enthalpies (HIHB), O-H charge differences, O-H bond lengths and bond orders for various substituted catechols and their radicals generated after H-abstraction. It was found that although the charge difference between hydrogen-bonded H and O played a role in determining HIHB, HIHB was mainly governed by the hydrogen bond length. As the oxygen-centered radical has great tendency to form a chemical bond with the H atom, hydrogen bond lengths in catecholic radicals are systematically shorter than those in catechols. Hence, the HIHB for the former are higher than those for the latter.

关键词： Catechol catecholic radical density functional theory intramolecular hydrogen bond.

Molecular Exchanging Energy of Anionic/Cationic Surfactants System on the Surface of Solution

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Chinese Chemical Letters 2003年第10期14卷 1077-1080页

作者： DongYangHUANG XiZhangYI ZhengWuWANG MedicalSchoolofShantouUniversity Shantou515031 instituteoftheoreticalchemistry ShandongUniversityJinan250100

In order to study synergism of the mixed surfactants system with molecular exchanging energy (E), the Lennard-Jones formula has been firstly introduced to evaluate the E of the mixed system, CH3(CH2)nOSO 3 /CH3(CH2)nN+(CH3)3 directly from their molecular structure. The comparison of the calculated and the observed results showed that this method is practical.

关键词： Surfactant molecule exchanging energy dimensional crystal model.

A Possible Reaction Channel from BrONO to BrNO_2

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Chinese Chemical Letters 2002年第11期13卷 1138-1140页

作者： HaiTaoYU XuRiHUANG 等 CollegeofChemistryandChemicalEngineering HeilongjiangUniversityHarbin150080 StateKeyLaboratoryofTheoreticalandComputationalChemistry InstituteofTheoreticalChemistryJilinUniversit

A possible isomerization channel from BrONO (bromine nitrite) to BrNO2 (nitryl bromide) is predicted by means of MP2 and QCISD(T) (single-point) methods. The channel is a direct bromine abstraction reaction from BrONO molecule by NO2 in which the forward reaction barrier is 89.30 kJ/mol at final UQCISD(T)/6-311+G(2df)//UMP2/6-311G(d) level of theory with zero-point energies included. The result can explain the available experiments very well.

关键词： BrNO2 BrONO isomerization abstraction.

Three Novel Isomers of FCH_2CP System

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Chinese Chemical Letters 2004年第2期15卷 250-252页

作者： MingXiaLI HaiTaoYU HongGangFU ZeShengLI JiaZhongSUN CollegeofChemistryandChemicalEngineering HeilongiangUniversityHarbin150080 StateKeyLaboratoryofTheoreticalandComputationalChemistry InstituteofTheoreticalChemistryJilinUniversityChangchun130023

Three new isomers of FCH2CP system, F(H)CCPH (1), F-cCPC-H(H) (2) and F-cCC(H)P-H (3), are predicted by means of B3LYP and CCSD(T) (single-point) methods with 6-311++G(d,p) and 6-311++G(2df,2p) basis sets, respectively. The three calculated isomers can isomerize into thermodynamically the most stable species F-cPC(H)C-H, which has been suggested in previous theoretical studies, with relatively higher reaction barriers. In view of their higher thermodynamic and kinetic stability, we believe that the three species can be detected in future experiments.

关键词： FCH2CP system stability isomer.

Singlet H-cCNC-C: A Potential Interstellar Molecule

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Chinese Chemical Letters 2004年第4期15卷 498-500页

作者： HalTaoYU MingXiaLI HongGangFU BaiFuXING JiaZhongSUN CollegeofChemistryandChemicalEngineering HeilongjiangUniversityHarbin150080 StateKeyLaboratoryofTheoreticalandComputationalChemistry InstituteofTheoreticalChemistryJilinUniversityChangchun130023

A new planar isomer of HNC3 system, H-cCNC-C, is theoretically predicted by means of B3LYP and CCSD(T) methods. The suggested species can isomerize into other five kinetically more stable isomers, which have been experimentally identified, with relatively higher reaction barriers. In view of its higher kinetic stability, we can reasonably believe that the obtained species H-cCNC-C can be experimentally observed in future studies.

关键词： HNC_3 system stability isomer isomerization.