Muñoz M A, Ferrero R, Carmona C, Balón M
Departamento de Química Física, Facultad de Farmacia, Universidad de Sevilla, 41012 Seville, Spain.
Spectrochim Acta A Mol Biomol Spectrosc. 2004 Jan;60(1-2):193-200. doi: 10.1016/s1386-1425(03)00206-3.
The NH-pi interactions of indole with benzene, naphthalene, phenanthrene, toluene, m-xylene, and mesitilene, in carbon tetrachloride solutions, have been studied by Fourier transform infrared spectroscopy. The experiments, carried out on the NH stretching band of indole, prove the formation of 1:1 complexes in which the NH bond of indole is engaged. The NH frequency shifts are independent of the number of rings in the base, but they progressively increase as the electron density is enhanced by methylation. The association constants increase with the increase of both, the number of rings and the methyl groups on the base. At higher base concentrations, further shifts on the free NH and associated bands indicate the formation of 1:2 complexes, which suggest hybride NH-pi and van der Waals interactions between one indole ring and two benzene acceptor molecules.
通过傅里叶变换红外光谱研究了在四氯化碳溶液中吲哚与苯、萘、菲、甲苯、间二甲苯和均三甲苯的N-H…π相互作用。对吲哚的N-H伸缩带进行的实验证明形成了1:1配合物，其中吲哚的N-H键参与其中。N-H频率位移与碱中环的数量无关，但随着甲基化增强电子密度，它们会逐渐增加。缔合常数随着碱上环的数量和甲基数量的增加而增加。在较高的碱浓度下，游离N-H和缔合带的进一步位移表明形成了1:2配合物，这表明一个吲哚环与两个苯受体分子之间存在混合的N-H…π和范德华相互作用。
