中国科学院化学研究所张德清报道了以二氰亚甲基和三苯基膦为端盖的新型不对称形式醌式分子。相关研究成果于2024年8月13日发表在《德国应用化学》。

研究人员已经合成了许多具有对称封端基团的醌式分子，特别是二氰基亚甲基单元，用于有机光电材料。相比之下，以不同基团封端为特征的不对称醌式分子探索较少。

该文中，研究人员提出了新形式醌式分子一种意想不到的合成，这些分子被二氰基亚甲基和三苯基鏻部分封端。这些不对称醌式分子的结构通过单晶结构分析得到了有力的验证。基于控制实验和DFT计算，研究人员提出了这些不对称醌式分子形成的反应机理。

根据对它们的键长和芳香性的分析以及Mayer bond Orbital（MBO）计算，相应的两性离子形式应该对这些醌式分子的基态结构做出贡献。这与观察到这些醌式分子具有负溶剂化显色性的事实非常吻合。

尽管这些新的醌式分子在溶液和结晶状态下都是不发光的，但在提高溶剂粘度或将其分散在PMMA基质中后，它们会以高达51.4%的量子产率发射。有趣的是，它们的发光也可以在与某些蛋白质结合时开启，特别是与人血清白蛋白结合时。

附：英文原文

Title: Novel Dissymmetric Formal Quinoidal Molecules End-capped by Dicyanomethylene and Triphenylphosphonium

Author: Wansong Shang, Wei Meng, Lingfang Chen, Zhichun Shangguan, Yanyan Huang, Xi-Sha Zhang, Cheng Li, Shuming Bai, Guanxin Zhang, Deqing Zhang

Issue&Volume: 2024-08-13

Abstract: A number of quinoidal molecules with symmetric end-capping groups, particularly dicyanomethylene units, have been synthesized for organic optoelectronic materials. In comparison, dissymmetric quinoidal molecules, characterized by end-capping with different groups, are less explored. In this paper, we present the unexpected formation of new formal quinoidal molecules, which are end-capped with both dicyanomethylene and triphenylphosphonium moieties. The structures of these dissymmetric quinoidal molecules were firmly verified by single crystal structural analyses. On the basis of the control experiments and DFT calculations, we proposed the reaction mechanism for the formation of these dissymmetric quinoidal molecules. The respective zwitterionic forms should make contributions to the ground state structures of these quinoidal molecules based on the analysis of their bond lengths and aromaticity and Mayer Bond Orbital (MBO) calculation. This agrees well with the fact that negative solvatochromism was observed for these quinoidal molecules. Although these new quinoidal molecules are non-emissive both in solutions and crystalline states, they become emissive with quantum yields up to 51.4% after elevating the solvent viscosity or dispersing them in a PMMA matrix. Interestingly, their emissions can also be switched on upon binding with certain proteins, in particular with human serum albumin.

DOI: 10.1002/anie.202412704

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202412704