VIBRATIONAL ANALYSIS OF BILIVERDIN DIMETHYL ESTER
VIBRATIONAL ANALYSIS OF BILIVERDIN DIMETHYL ESTER
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DOI：
10.1021/j100148a009
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发表时间：
1993-11-18
影响因子：
--
通讯作者：
MARK, F
中科院分区：
文献类型：
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作者：
SMIT, K;MATYSIK, J;MARK, F
本文测定了胆绿素二甲酯及其吡咯氮氘代异构体在固态和四氯化碳溶液中的傅里叶变换共振拉曼和红外光谱。的光谱的振动分析。力场是基于半经验AM 1方法通过两步程序得到的。首先，根据Pulay的缩放方法（Pulay，P.; Fogarasi，G.; Pongor，G.; Boggs，J. E.; Vargha，A. J. Am.化学分析1983，105，7037）。这些力场与从头算Hartree-Fock计算的力场进行了比较。优化的片段的比例因子被用作初始参数的胆绿素二甲酯的振动分析。在第二步中，通过使用频率和红外和共振拉曼强度作为标准来精炼它们。共振拉曼强度根据Peticolas及其同事（Peticolas，W. L.的; Strommen，D. P的; Lakshminarayanan，V.J.Chem.Phys.1980，73，4185）。正态模式分析的准确度优于20 cm（-1），这沿着评价强度，允许对大多数观察到的条带进行唯一分配。结果发现，大部分的振动模式是本地化的个别吡咯环和相邻的次甲基桥。
The Fourier-transform resonance Raman and infrared spectra of biliverdin dimethyl ester and the isotopomer deuterated at the pyrrole nitrogens were measured in the solid state and in CCl4 solution. A vibrational analysis of the spectra is presented. The force field was obtained on the basis of the semiempirical AM1 method by a two-step procedure. First, scaled AM1 force fields for fragments of the tetrapyrrole system were developed according to Pulay's scaling method (Pulay, P.; Fogarasi, G.; Pongor, G.; Boggs, J. E.; Vargha, A. J. Am. Chem. Sec. 1983, 105, 7037). These force fields were checked against those from ab-initio Hartree-Fock calculations. The scaling factors optimized for the fragments were used as initial parameters for the vibrational analysis of biliverdin dimethyl ester. They were refined in the second step by using both the frequencies and the infrared and resonance Raman intensities as criteria. The resonance Raman intensities were estimated according to the model introduced by Peticolas and co-workers (Peticolas, W. L.; Strommen, D. P.; Lakshminarayanan, V. J. Chem. Phys. 1980, 73, 4185). The accuracy of the normal mode analysis was better than 20 cm(-1) which along with the evaluated intensities allowed for a unique assignment of most of the observed bands. It was found that most of the vibrational modes are localized in the individual pyrrole rings and the adjacent methine bridges.