Catalán Javier, Díaz Cristina, Pérez Pilar, de Paz José L G
Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
J Phys Chem A. 2006 Jul 27;110(29):9116-22. doi: 10.1021/jp0613788.
The concerted double proton transfer undergone by the C(2)(h) dimer of 7-azaindole upon electronic excitation has also been reported to occur in 3-methyl-7-azaindole monocrystals and in dimers of this compound under free-jet conditions. However, the results obtained in this work for the 3-methyl-7-azaindole dimer formed in a 10(-4) M solution of the compound in 2-methylbutane suggest that the dimer produces no fluorescent signal consistent with a double proton transfer in the liquid phase or in a matrix. In this paper, the spectroscopic behavior of the doubly hydrogen bonded dimer of 3-methyl-7-azaindole is shown to provide a prominent example of molecular symmetry control over the spectroscopy of a substance. This interpretation opens up a new, interesting research avenue for exploring the ability of molecular symmetry to switch between proton-transfer mechanisms. It should be noted that symmetry changes in the 3-methyl-7-azaindole dimer are caused by an out-of-phase internal rotation of the two methyl groups.
据报道，7-氮杂吲哚的C(2)(h)二聚体在电子激发时发生的协同双质子转移，在3-甲基-7-氮杂吲哚单晶以及该化合物在自由喷射条件下的二聚体中也会出现。然而，在这项工作中，对于在2-甲基丁烷中10(-4) M该化合物溶液中形成的3-甲基-7-氮杂吲哚二聚体所获得的结果表明，该二聚体在液相或基质中未产生与双质子转移一致的荧光信号。本文表明，3-甲基-7-氮杂吲哚双氢键二聚体的光谱行为为分子对称性对物质光谱的控制提供了一个突出的例子。这种解释为探索分子对称性在质子转移机制之间切换的能力开辟了一条新的、有趣的研究途径。需要注意的是，3-甲基-7-氮杂吲哚二聚体中的对称性变化是由两个甲基的异相内旋转引起的。
