Petrova Jasmina, Ivanova Anela, Tadjer Alia
Faculty of Chemistry and Pharmacy, University of Sofia , 1 James Bourchier Boulevard, 1164 Sofia, Bulgaria.
J Phys Chem A. 2017 Aug 24;121(33):6327-6335. doi: 10.1021/acs.jpca.7b04663. Epub 2017 Aug 9.
Crystallization water plays an important role in the self-organization of oligomer chains in conducting polyaniline. In order to quantify the interaction between emeraldine salt and such a water, models containing a tetramer in bipolaronic or polaronic form, chloride counterions, and an explicit water molecule are used. Different initial positions of water with respect to the oligomer chain-tangential and vertical-are considered. Various media are simulated by introducing an implicit solvent continuum of decreasing polarity. The DFT-D3/PCM computational approach is employed to examine the behavior of the systems in several aspects-the role of the explicit water position and the effect of the environment polarity on the spatial structure, energetics, charge distribution, and the frontier molecular orbital energies. The strength of hydrogen bonding and the patterns of charge redistribution invoked by the water molecule are discussed. The study establishes trend lines in the variation of the molecular characteristics upon change of milieu as a tool for control of the self-assembly process. The results show that chains interact more efficiently with tangentially placed water. The influence of the environment polarity is minor and is mainly expressed in slight shortening of the intermolecular distances and mild decrease of the group charges of the system components with reduction of polarity.
结晶水在导电聚苯胺中低聚物链的自组装过程中起着重要作用。为了量化翡翠盐与这种水之间的相互作用，使用了包含双极化子或极化子形式的四聚体、氯化物抗衡离子和一个明确水分子的模型。考虑了水相对于低聚物链的不同初始位置——切向和垂直方向。通过引入极性逐渐降低的隐式溶剂连续介质来模拟各种介质。采用DFT-D3/PCM计算方法从多个方面研究系统的行为——明确水分子位置的作用以及环境极性对空间结构、能量学、电荷分布和前沿分子轨道能量的影响。讨论了氢键的强度以及水分子引起的电荷重新分布模式。该研究建立了随着环境变化分子特性变化的趋势线，作为控制自组装过程的工具。结果表明，链与切向放置的水相互作用更有效。环境极性的影响较小，主要表现为随着极性降低，分子间距离略有缩短，系统组分的基团电荷略有减少。
