Nitronyl Nitroxide Bifunctionalized Electron-Poor Chromophores: Synthesis of Stable Dye Biradicals by Lewis Acid Promoted Desilylation
作者:Rodger Rausch、Ana-Maria Krause、Ivo Krummenacher、Holger Braunschweig、Frank Würthner
DOI:10.1021/acs.joc.0c02613
日期:2021.2.5
regard, nitronyl nitroxides are promising candidates for stable (bi-)radicals due to their high degree of spin delocalization along the O–N–C–N–O pentad unit. Unfortunately, they are limited to electron-rich systems so far. To overcome this limitation, we developed a synthetic procedure for the twofold spin decoration of electron-poor chromophores (Ered = −1158 mV) with nitronyl nitroxide radical moieties
带有π核的开壳有机分子对于光学,电子和磁性应用非常感兴趣,但经常会快速分解或缺乏合成方法。在这方面,由于硝酰基硝基氧化物沿O–N–C–N–O五单元单元的高度自旋离域化,因此它们有望成为稳定(双)自由基的候选物。不幸的是,到目前为止,它们仅限于富电子系统。为了克服这一限制,我们开发了一种用于贫电子发色团(E红通过用氟化硼对各自的甲硅烷基化的前体进行选择性脱保护/氧化反应,然后用原硅酸四乙酯淬灭,通过氧化亚硝酰基的氮自由基基团得到= -1158mV)。最终获得了由per双酰亚胺(PBI),异靛蓝(IIn)和二酮吡咯并吡咯(DPP)桥接的亚硝基硝基氧自由基PBI–NN,IIn–NN,PhDPP–NN,ThDPP–NN和FuDPP–NN经过高碘酸盐氧化后,产率为60-81%。发色团的吸收光谱特征保留在开壳状态,并与原始母体化合物相匹配,从而可以先验光学特性的预测。因此,我们实现了双重自旋标记,同时保持了缺电子发色团的固有特性。