Quantum chemistry density-functional theory (DFT)B3LYP method with 6-31G+* basis set has been empolyed to study the electronic structure and IR spectrum of Huperzine A. The calculation result showed that the character...Quantum chemistry density-functional theory (DFT)B3LYP method with 6-31G+* basis set has been empolyed to study the electronic structure and IR spectrum of Huperzine A. The calculation result showed that the characteristic of the predicted IR bands was in general consistent with the experimental spectrum. 45 vibration modes were assigned clearly from the total of 102 vibration bands. The strongest IR-intensive band corresponds to the stretching vibration of the C O bond of the pyridone ring, and the highest frequency band belongs to the pyridone N H stretch. The investigation showed that the obvious differences between the calculated bands and the experimental spectrum existed at the bands involving the hydrogen atoms of amino and pyridone amide groups, which could form intermolecular hydrogen bond with other Huperzine A in the crystal structure. The hydrogen bonds can not only affect the orientation of these hydrogen atoms, but also can affect the force property of the chemical bond, which can change the vibrational frequencies.展开更多
首次以天然红辉沸石水热合成了 Y 型、P 型分子筛,以 IR 研究了水热合成体系中分子筛结构的演变及晶相分布规律。研究表明,在高 H_2O/Na_2O、低Ca^(2+)/Na^+体系中,主晶相为 Y 型分子筛,在低 H_2O/Na_2O、高 Ca^(2+)/Na^+体系中,主晶相...首次以天然红辉沸石水热合成了 Y 型、P 型分子筛,以 IR 研究了水热合成体系中分子筛结构的演变及晶相分布规律。研究表明,在高 H_2O/Na_2O、低Ca^(2+)/Na^+体系中,主晶相为 Y 型分子筛,在低 H_2O/Na_2O、高 Ca^(2+)/Na^+体系中,主晶相为 P 型分子筛。展开更多
文摘Quantum chemistry density-functional theory (DFT)B3LYP method with 6-31G+* basis set has been empolyed to study the electronic structure and IR spectrum of Huperzine A. The calculation result showed that the characteristic of the predicted IR bands was in general consistent with the experimental spectrum. 45 vibration modes were assigned clearly from the total of 102 vibration bands. The strongest IR-intensive band corresponds to the stretching vibration of the C O bond of the pyridone ring, and the highest frequency band belongs to the pyridone N H stretch. The investigation showed that the obvious differences between the calculated bands and the experimental spectrum existed at the bands involving the hydrogen atoms of amino and pyridone amide groups, which could form intermolecular hydrogen bond with other Huperzine A in the crystal structure. The hydrogen bonds can not only affect the orientation of these hydrogen atoms, but also can affect the force property of the chemical bond, which can change the vibrational frequencies.
文摘首次以天然红辉沸石水热合成了 Y 型、P 型分子筛,以 IR 研究了水热合成体系中分子筛结构的演变及晶相分布规律。研究表明,在高 H_2O/Na_2O、低Ca^(2+)/Na^+体系中,主晶相为 Y 型分子筛,在低 H_2O/Na_2O、高 Ca^(2+)/Na^+体系中,主晶相为 P 型分子筛。
