Classification of the hydrogen-bonding species in a series of novel hydrazide based azobenzene derivatives investigated by two-dimensional correlation infrared spectroscopy and molecular modeling

摘要

Classification of hydrogen-bonding species in a series of novel hydrazide modified p-methoxyazobenzene derivatives, 4-{n-[4-(4-methoxyphenylazo)-phenoxy]-alkoxy}-benzoic acid hydrazide (D-n, n = 3, 6, 10) are performed in the present study. Temperature-dependent infrared (IR) spectra of D. have been measured to investigate the thermal stability of the weak intermolecular interactions, such as hydrogen bonding among hydrazide moieties, pi-pi stacking among aromatic groups, and hydrophobic interaction between alkyl chains. In order to reveal the hydrogen bonding formed between -NH-, -NH2, and -CONH- groups efficiently, two-dimensional (2D) correlation spectra have been constructed in the thermal sensitive spectral regions of (a) 3500-3100 cm(-1) and (b) 1700-1450 cm(-1) separately, and it have also been constructed between these two spectral regions. Based on the experimental data, the ab initio computational models have been developed to the proposed patterns of hydrogen bonding related to intermolecular interactions in D-n. The intermolecular hydrogen bondings and molecular alignments patterns result from both the experimental data and the computational models are performed for D-3, D-6, and D-10 respectively, in the present study. (c) 2005 Published by Elsevier B.V.