Institute of Chemistry, University of Silesia, 9 Szkolna Street, Pl-40 006 Katowice, Poland.
J Phys Chem A. 2011 Jul 7;115(26):7511-20. doi: 10.1021/jp2016903. Epub 2011 Jun 9.
This paper presents the investigation results of the polarized IR spectra of the hydrogen bond in crystals of 3- and 4-methylthioacetanilide. The spectra were measured at 293 and 77 K by a transmission method, with the use of polarized light. The main spectral properties of the crystals can be interpreted satisfactorily in terms of the "strong-coupling" theory, on the basis of the hydrogen bond centrosymmetric dimer model. The spectra revealed that the strongest vibrational exciton coupling involved the closely spaced hydrogen bonds, each belonging to a different chain of associated 3- and 4-methylthioacetanilide molecules. A weaker exciton coupling involved the adjacent hydrogen bonds in each individual chain. It was proven that a nonrandom distribution of the protons and deuterons took place in the lattices of isotopically diluted crystalline samples of 3- and 4-methylthioacetanilide. In each case, the H/D isotopic "self-organization" mechanism involved all four hydrogen bonds from each unit cell.
本文介绍了 3- 和 4- 甲基硫代乙酰胺晶体中氢键的偏振红外光谱研究结果。在 293 和 77 K 下，采用透射法和偏振光测量了光谱。基于氢键对称二聚体模型，根据“强耦合”理论，可以很好地解释晶体的主要光谱特性。光谱表明，最强的振动激子耦合涉及到相互靠近的氢键，每个氢键都属于不同的 3- 和 4- 甲基硫代乙酰胺分子链。较弱的激子耦合涉及到每个单独链中的相邻氢键。证明了在 3- 和 4- 甲基硫代乙酰胺的同位素稀释晶体样品的晶格中，质子和氘的分布是非随机的。在每种情况下，H/D 同位素“自组织”机制都涉及到每个单元晶格中的四个氢键。
