NUCLEAR-QUADRUPOLE INTERACTIONS IN COPPER(II) DIETHYLENETRIAMINE-SUBSTITUTED IMIDAZOLE COMPLEXES AND IN COPPER(II) PROTEINS
NUCLEAR-QUADRUPOLE INTERACTIONS IN COPPER(II) DIETHYLENETRIAMINE-SUBSTITUTED IMIDAZOLE COMPLEXES AND IN COPPER(II) PROTEINS
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DOI：
10.1021/ja00181a002
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发表时间：
1990-12-05
影响因子：
15
通讯作者：
PEISACH, J
中科院分区：
文献类型：
--
作者：
JIANG, F;MCCRACKEN, J;PEISACH, J
用电子自旋回波包络调制光谱研究了Cu（II）-二乙烯三胺配位的14 N取代咪唑类化合物的核四极相互作用。取代在邻近远程氮的碳只有轻微改变的四极耦合参数，而烷基化在远程氮改变他们显着。通过应用改进的Townes-Dailey模型，我们能够将远程氮的四极耦合参数的变化与咪唑环外部的sp2杂化轨道中的电子占据的变化联系起来，并将其与N.sbd.H或N.sbd.C键极化联系起来。这些研究表明，以前观察到的Cu（II）蛋白质中的四极耦合常数的变化可能会出现在远程氮的配位组氨酸咪唑侧链的氢键的变化。
Electron spin echo envelope modulation spectroscopy was used to study the nuclear quadrupole interactions of the remote 14N of substituted imidazoles coordinated to Cu(II)-diethylenetriamine. Substitution at the carbon adjacent to the remote nitrogen only slightly altered the quadrupole coupling parameters, while alkylation at the remote nitrogen altered them significantly. By applying modified Townes-Dailey model, we were able to relate the change of quadrupole coupling parameters of the remote nitrogen to the change of electron occupancy in the sp2 hybrid orbital that is external to the imidazole ring and to relate this to N.sbd.H or N.sbd.C bond polarization. These studies suggest that the variation of quadrupole coupling constants previously observed in Cu(II) proteins may arise from the variations in hydrogen bonding at the remote nitrogen of the coordinated histidine imidazole side chain.