Intramolecular Electron Transfer in the Photochemistry of Some Nitrophenyldihydropyridines
作者:Elisa Fasani、Maurizio Fagnoni、Daniele Dondi、Angelo Albini
DOI:10.1021/jo052463z
日期:2006.3.1
The lowest singlet is localized on the dihydropyridine moiety (1PyH2-Ph) and emits a blue fluorescence (with close to unitary efficiency in glass at 77 K). In 3-nitrophenyl derivatives (PyH2-PhNO2, some of which are photolabile drugs) the fluorescence is completely quenched. Reasonably, this is due to intramolecular electron transfer between the close-lying donor and acceptor moieties to give the charge-separated
4-苯基-1,4-二氢吡啶-3,5-二羧酸酯包含两个被sp 3碳隔开的π发色团。最低的单峰位于二氢吡啶部分(1 PyH 2 -Ph)上,并发出蓝色荧光(在77 K的玻璃中具有接近统一的效率)。在3-硝基苯基衍生物(PyH 2 -PhNO 2,其中一些是对光不稳定的药物)中,荧光被完全淬灭。合理地,这是由于在紧密的供体和受体部分之间进行分子内电子转移,从而产生了电荷分离的物质(PyH 2 • + -PhNO 2 • -)。在77 K的EPA玻璃中,背电子转移产生二氢吡啶定位的三重态(3 PyH 2 -PhNO 2),发出黄色磷光。在溶液中,从上二氢吡啶部分发起rearomatization,最后得到PY-PHNO的自由基阳离子脱质子化2具有低量子产率(5×10 - 4〜5×10 - 3,通过在254 nm处照射而增加至0.013,其中硝基苯基发色团的直接激发起作用)。在三乙胺的存在下,反应变