手性(物理)
溶剂
超分子手性
化学
超分子化学
部分
溶剂效应
光化学
J-骨料
化学工程
有机化学
分子
物理
手征对称破缺
量子力学
Nambu–Jona Lasinio模型
工程类
夸克
作者
Kuthanapillil Jyothish,Mahesh Hariharan,Danaboyina Ramaiah
标识
DOI:10.1002/chem.200700130
摘要
Abstract We prepared novel cholesterol‐appended squaraine dye 1 and model squaraine dye 2 and investigated their aggregation behavior in solution and thin films using photophysical, chiroptical, and microscopic techniques. Investigations on the dependence of aggregation on solvent composition (good/poor, CHCl 3 /CH 3 CN) demonstrated that squaraine dye 1 forms two novel H‐type chiral supramolecular assemblies with opposite chirality at different good/poor solvent compositions. Model compound 2 formed J‐type achiral assemblies under similar conditions. The supramolecular assembly of 1 observed at lower fractions of the poor solvent could be assigned to the thermodynamically stable form, while a kinetically controlled assembly is formed at higher fractions of the poor solvent. This assignment is evidenced by temperature‐ and concentration‐dependent experiments. With increasing temperature, the chirality of the kinetically controlled aggregate was lost and, on cooling, the aggregate with the opposite chirality was formed. On further heating and cooling the aggregates thus formed resulted in no significant changes in chirality, that is they are thermodynamically stable. Similarly, at lower concentrations, the thermodynamically stable form exists, but at higher concentration aggregation was found to proceed with kinetic control. Based on these observations it can be assumed that formation of the kinetically controlled assembly might be largely dependent on the presence of the nonpolar cholesterol moiety as well as the amount of poor solvent present. However, under solvent‐free conditions, structurally different aggregates were observed when drop cast from solutions containing monomer, whereas a left‐handed CD signal corresponding to the thermodynamically controlled assemblies was observed from pre‐aggregated solutions.
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