A Red-Emitting Light Switch Based on a Heteroleptic Ruthenium(II) Complex Containing a Tridentate dppz Analogue

Delocalization of the charge-transfer excitation in the series [Ru(NNN)(bpy)CN]+ [bpy = 2,2′-bipyridine; 1, NNN = 2,2′:6′,2′′-terpyridine; 2, NNN = 2-(2′-pyridyl)-1,10-phenanthroline or php; 3, NNN = 6′-(2′′-pyridyl)dipyrido[3,2-a:2′,3′-c]phenazine or dppzp] proves to be an effective way of tuning photophysical properties. Red-emitting 3 functions as a DNA “light switch”, shows emission from a state with charge-transfer-to-phenazine character, and exhibits a significantly enhanced emission signal relative to 1 and other dppzp-containing ruthenium(II) complexes.在配合物系列[Ru(NNN)(bpy)CN]+中，电荷转移激发的离域化被证实是调控光物理性质的有效途径。该系列中：1号配合物的NNN配体为2,2′:6′,2′′-三联吡啶(2,2′:6′,2′′-terpyridine)；2号配合物的NNN配体为2-(2′-吡啶基)-1,10-邻菲啰啉(2-(2′-pyridyl)-1,10-phenanthroline，简称php)；3号配合物的NNN配体为6′-(2′′-吡啶基)二吡啶并[3,2-a:2′,3′-c]吩嗪(6′-(2′′-pyridyl)dipyrido[3,2-a:2′,3′-c]phenazine，简称dppzp)。3号配合物可发射红光，兼具DNA"光开关"功能，其发射源自具有电荷转移至吩嗪特征的激发态，且相较于1号配合物及其他含dppzp的钌(II)配合物，其发射信号显著增强。