Basicity and Solvatochromism of Concave Pyridines with Extended π-Systems in Protic and Nonprotic Solvents
作者:Ole Storm、Ulrich Lüning
DOI:10.1002/ejoc.200300053
日期:2003.8
4-positions of concave pyridines to give substituted concave pyridines 3, which possess absorption maxima above 300 nm in their UV spectra. Their protonation and their interaction with polar solvents have been studied. Firstly, with strong acids, protonation occurs, and relative basicities (logKass) have been determined. Substitution at the remote aryl ring influences the basicity of the pyridine, and Hammett
芳炔取代基与凹吡啶的 4 位相连,得到取代的凹吡啶 3,其紫外光谱在 300 nm 以上具有最大吸收。已经研究了它们的质子化和它们与极性溶剂的相互作用。首先,使用强酸会发生质子化,并确定相对碱度 (logKass)。远程芳环上的取代会影响吡啶的碱性,哈米特图显示 logKass 与远程芳环的电子密度之间存在线性关系。其次,凹形吡啶 3 能够“感知”其吡啶氮原子和醇之间的氢键。当加入一定量的酒精时,观察到吸收最大值向更长波长的移动。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany,