Université Lille, CNRS, UMR 8516 - LASIR - Laboratoire de Spectrochimie Infrarouge et Raman , F-59000 Lille , France.
Université Lille, CNRS, INRA, ENSCL, UMR 8207 - UMET - Unité Matériaux et Transformations , F-59000 Lille , France.
J Phys Chem A. 2018 Apr 12;122(14):3572-3582. doi: 10.1021/acs.jpca.7b10767. Epub 2018 Mar 28.
The photoswitching and competitive processes of two photochromic dithienylethenes (DTEs) functionalized at both sides with 2-ureido-4[1H]-pyrimidone (UPy) quadruple hydrogen-bonding recognition patterns have been investigated with NMR experiments, ultrafast spectroscopy, and density functional theory (DFT) calculations. The originality of these molecules is their ability to form large supramolecular assemblies induced by light for the closed form (CF) species while the open form (OF) species exist as small oligomers. Photochromic parameters have been determined and photochemical pathways have been rationalized with clear distinction between the antiparallel (OF-AP) and parallel (OF-P) species. A new photocyclization pathway via triplet manifold has been evidenced. The effect of the supramolecular assembly on the photochemical response is discussed. Unlike the photoreversion process, which is unaffected by supramolecular assembly, rate constants of the photocyclization reaction and intersystem crossing process are sensitive to the presence of small OF oligomers.
我们研究了两个双噻吩乙烯（DTE）的光致变色和竞争过程，它们的两侧都用 2-尿嘧啶-4[1H]-嘧啶酮（UPy）四重氢键识别模式进行了功能化。通过 NMR 实验、超快光谱和密度泛函理论（DFT）计算进行了研究。这些分子的新颖之处在于它们能够在光的诱导下形成大的超分子组装体，用于闭环形式（CF）物种，而开环形式（OF）物种则存在于小的低聚物中。已经确定了光致变色参数，并通过明确区分反平行（OF-AP）和平行（OF-P）物种来合理化光化学反应途径。已经证明了一种通过三重态态的新的环化途径。讨论了超分子组装对光化学响应的影响。与不受超分子组装影响的光致恢复过程不同，环化反应和系间窜越过程的速率常数对小 OF 低聚物的存在敏感。
