Boddeda Anitha, Hossain Mohammad Mosharraf, Mirzaei M Saeed, Lindeman Sergey V, Mirzaei Saber, Rathore Rajendra
Department of Chemistry, Marquette University, Milwaukee, WI 53201-1414, United States.
Department of Organic Chemistry, Faculty of Chemistry, Razi University, Kermanshah, Iran.
Org Chem Front. 2020 Oct 21;7(20):3215-3222. doi: 10.1039/d0qo00924e. Epub 2020 Sep 16.
Herein, we report the synthesis of two new series of angular (all-syn) ladder-type -[n]phenylenes (LMP, n = 3-8). One series contains keto groups at the termini bridges, denoted angular keto (AKn), the second contains alkyl groups at all bridge sp carbons, denoted angular alkyl (AAn). Their electronic and structural properties were delineated by a combination of electrochemistry and spectroscopic (UV-Vis and emission) methods and further supported by DFT calculations. Interestingly, experimental and DFT data show that changing the bridging group at the termini from alkyl (AAn) to keto (AKn) gives an increase in the first reduction potentials and LUMO energies, as the π-system is extended. Also, the charge (de)localization behavior is different for these two species; while the AAn compounds stablize charge with Robin-Day class III, the AKn compounds show a clear switch from class III to class II. In comparison with the linear analogues (LKn and LAn), DFT results reveal a shape independency of the charge (de)localization mechanism in acceptor-π-acceptor series (AKn/LKn).
在此，我们报告了两个新系列的角型（全顺式）梯形 -[n]亚苯基（LMP，n = 3 - 8）的合成。一个系列在末端桥连处含有酮基，记为角型酮基（AKn），第二个系列在所有桥连sp碳上含有烷基，记为角型烷基（AAn）。它们的电子和结构性质通过电化学和光谱（紫外 - 可见和发射）方法相结合来描述，并通过密度泛函理论（DFT）计算进一步得到支持。有趣的是，实验和DFT数据表明，随着π体系的扩展，将末端的桥连基团从烷基（AAn）变为酮基（AKn）会使第一还原电位和最低未占分子轨道（LUMO）能量增加。此外，这两种物质的电荷（去）离域行为不同；虽然AAn化合物以罗宾 - 戴III类稳定电荷，但AKn化合物显示出从III类到II类的明显转变。与线性类似物（LKn和LAn）相比，DFT结果揭示了受体 - π - 受体系列（AKn/LKn）中电荷（去）离域机制与形状无关。
