Le Bras Laura, Berthin Roxanne, Hamdi Ismaïl, Louati Maroua, Aloïse Stéphane, Takeshita Michinori, Adamo Carlo, Perrier Aurélie
Chimie ParisTech, PSL Research University, CNRS, Institute of Chemistry for Life and Health Sciences (i-CLeHS), F-75005 Paris, France.
Phys Chem Chem Phys. 2020 Apr 7;22(13):6942-6952. doi: 10.1039/c9cp06590c. Epub 2020 Mar 17.
A dithienylethene (DTE) photochromic compound functionalized by ureidopyrimidinone (UPy) quadruple hydrogen bonding blocks was synthesized by Takeshita and coworkers [Takeshita et al., Chem. Commun., 2005, 761] in order to form a light-responsive supramolecular self-assembling system. In solution, the formation of supramolecular assemblies was only observed for one DTE isomer, namely the closed-form isomer. To rationalize this experimental finding, with the help of Molecular Dynamics (MD) and (time-dependent) DFT calculations, the behaviour of open-form and closed-form monomers, dimers, hexamers and π-stacked dimers in solution is investigated. Our simulations show that, for the open-form oligomers, the progression of the supramolecular assembly is hindered due to (i) the possible formation of a very stable cyclic dimer for the open-form parallel isomer, (ii) the relative flexibility of the open-form oligomers compared to their closed-form counterparts, and (iii) the possible existence of π-stacked dimers that constitute bottlenecks blocking the progression of the supramolecular self-assembly.
武下及其同事 [武下等人，《化学通讯》，2005年，第761页] 合成了一种由脲嘧啶酮（UPy）四重氢键模块功能化的二噻吩乙烯（DTE）光致变色化合物，以形成光响应超分子自组装体系。在溶液中，仅观察到一种DTE异构体（即闭环异构体）形成超分子聚集体。为合理解释这一实验结果，借助分子动力学（MD）和（含时）密度泛函理论（DFT）计算，研究了开环形式和闭环形式的单体、二聚体、六聚体以及π堆积二聚体在溶液中的行为。我们的模拟结果表明，对于开环形式的低聚物，超分子组装过程受到阻碍，原因如下：（i）开环形式的平行异构体可能形成非常稳定的环状二聚体；（ii）与闭环形式的低聚物相比，开环形式的低聚物具有相对较高的柔韧性；（iii）可能存在π堆积二聚体，它们构成了阻碍超分子自组装进程的瓶颈。
