Rausch Rodger, Schmidt David, Bialas David, Krummenacher Ivo, Braunschweig Holger, Würthner Frank
Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
Center for Nanosystems Chemistry, Universität Würzburg, Theodor-Boveri-Weg, 97074, Würzburg, Germany.
Chemistry. 2018 Mar 7;24(14):3420-3424. doi: 10.1002/chem.201706002. Epub 2018 Feb 15.
The first isoindigo (bi)radicals were obtained by proton coupled oxidation of their 4-hydroxyaryl substituted precursors. Optical and magnetic spectroscopic studies revealed a singlet open-shell biradicaloid electronic ground state for the bisphenoxyl-isoindigo (=1.20) with a small singlet-triplet energy gap of 0.065 eV and a large biradical character of y=0.79 that was corroborated by temperature-dependent EPR spectroscopy and quantum chemical calculations. The concept of kinetic blocking of the radical centers and delocalization of spin density into the electron-withdrawing chromophore core of isoindigo offers an entry into a new class of exceptionally stable open-shell functional materials based on organic colorants.
首个异靛蓝（双）自由基是通过其4-羟基芳基取代前体的质子耦合氧化得到的。光学和磁光谱研究表明，双酚氧基异靛蓝（=1.20）具有单重态开壳双自由基类电子基态，其单重态-三重态能隙小，为0.065 eV，双自由基特征大，y = 0.79，这一点得到了变温电子顺磁共振光谱和量子化学计算的证实。自由基中心的动力学阻断以及自旋密度离域到异靛蓝的吸电子发色团核心中的概念，为基于有机染料的一类新型异常稳定的开壳功能材料提供了切入点。
