Fundamental studies on the structures and spectroscopic properties of imidazo[1,2-a]pyrazin-3(7H)-one derivatives
Fundamental studies on the structures and spectroscopic properties of imidazo[1,2-a]pyrazin-3(7H)-one derivatives
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DOI：
10.1246/bcsj.76.2361
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发表时间：
2003-12-01
影响因子：
4
通讯作者：
Hirano, T
中科院分区：
文献类型：
--
作者：
Nakai, S;Yasui, M;Hirano, T
2-甲基和2-苯基咪唑并[1，2-a]-吡嗪-3(7H)-酮1和2及其N-和O-烷基衍生物3-6的基本物理性质已通过X-射线结晶学、UV/Vis吸收光谱、核磁共振和AML-Cosmo计算进行了研究。3和4的晶体结构表明，咪唑并[1，2-a]吡嗪-3(7H)-酮(咪唑并吡嗪酮)pi-体系具有平面环状结构，C3-O10键的羰基特征减弱，表明咪唑并[1，2-a]吡嗪-3(7H)-酮(咪唑并吡嗪酮)pi-体系具有双离子共振结构，从而增加了芳香性。关于1-4的键长变化和核磁共振化学位移的数据也支持它们的咪唑并吡嗪酮环具有少量的芳香性。此外，咪唑并吡嗪酮衍生物1-4由于与氢键供体溶剂分子发生氢键作用而表现出溶致变色性；在互变异构平衡中，衍生物1和2更倾向于作为NH形式的异构体。这些观察结果通过MO计算得到了一致的评估。还确定了质子化物种1-6和阴离子物种1和2的物理性质。咪唑并吡嗪酮pi-体系的基本性质解释了咪唑并吡嗪酮类化合物的化学和生物发光反应活性以及生物发光超分子的构建等问题。
The fundamental physical properties of 2-methyl and 2-phenylimidazo[1,2-a]pyrazin-3(7H)-one 1 and 2, and their N- and O-alkylated derivatives 3-6 have been investigated by X-ray crystallography, UV/vis absorption spectroscopy, NMR, and AMl-COSMO calculations. The crystal structures of 3 and 4 showed that the imidazo[1,2-a]pyrazin-3(7H)-one (imidazopyrazinone) pi-system has a planar ring structure and a weakened carbonyl character of the C3-O10 bond, suggesting that the imidazopyrazinone pi-system has the character of a zwitter-ionic resonance structure to increase the aromaticity. The data concerning the bond length alternations and the NMR chemical shifts of 1-4 also support that their imidazopyrazinone rings have small portions of aromatic character. In addition, imidazopyrazinone derivatives 1-4 showed solvatochromism originating by hydrogen-bonding interactions with hydrogen-bond donor solvent molecules; derivatives 1 and 2 prefer to be the NH form isomers in their tautomeric equilibriums. These observations were consistently evaluated by MO calculations. The physical properties of protonated species of 1-6 and anion species of 1 and 2 were also established. The fundamental properties of the imidazopyrazinone pi-system explain the several problems of the chemi- and bioluminescence reactivities of imidazopyrazi none derivatives and of the construction of a bioluminescent supramolecule.