Partigianoni Colleen M., Chodorowski-Kimmes Sandrine, Treadway Joseph A., Striplin Durwin, Trammell Scott A., Meyer Thomas J.
Department of Chemistry, University of North Carolina at Chapel Hill, CB# 3290, Chapel Hill, North Carolina 27599-3290.
Inorg Chem. 1999 Mar 22;38(6):1193-1198. doi: 10.1021/ic980544q.
A synthetic procedure has been devised for the preparation of the reductive quencher ligand 4-methyl-4'-(N-methyl-p-tolylaminomethyl)-2,2'-bipyridine (dmb-tol), which contains toluidine covalently bound to 2,2'-bipyridine. When bound to Re(I) in [Re(I)(dmb-tol)(CO)(3)Cl], laser flash Re(I) --> dmb metal-to-ligand charge-transfer (MLCT) excitation at 355 nm in CH(3)CN at 298 +/- 2 K is followed by efficient, rapid (<5 ns) appearance of a transient with an absorption feature at 470 nm. The transient spectrum is consistent with formation of the redox-separated state, [Re(I)(dmb(-)-tol(+))(CO)(3)Cl], which returns to the ground state by back electron transfer with k(ET) = (1.05 +/- 0.01) x 10(7) s(-)(1) (tau = 95 +/- 1 ns) at 298 +/- 2 K. Rapid, efficient quenching is also observed in the Ru(II) complex Ru(4,4'-(C(O)NEt(2))(2)bpy)(2)(dmb-tol). Based on transient absorption measurements, a rapid equilibrium appears to exist between the initial metal-to-ligand charge-transfer excited state and the redox-separated state, which lies at higher energy. Decay to the ground state is dominated by back electron transfer within the redox-separated state which occurs with k > 4 x 10(8) s(-)(1) at 298 +/- 2 K.
已设计出一种合成方法来制备还原猝灭剂配体4-甲基-4'-(N-甲基-对甲苯氨基甲基)-2,2'-联吡啶（dmb-tol），该配体含有与2,2'-联吡啶共价结合的甲苯胺。当与[Re(I)(dmb-tol)(CO)(3)Cl]中的Re(I)结合时，在298±2K的CH(3)CN中，355nm处的激光闪光Re(I)→dmb金属到配体电荷转移（MLCT）激发之后，会快速（<5ns）出现一个在470nm处有吸收特征的瞬态。该瞬态光谱与氧化还原分离态[Re(I)(dmb(-)-tol(+))(CO)(3)Cl]的形成一致，在298±2K时，它通过反向电子转移回到基态，k(ET)=(1.05±0.01)×10(7)s(-)(1)（τ=95±1ns）。在Ru(II)配合物Ru(4,4'-(C(O)NEt(2))(2)bpy)(2)(dmb-tol)中也观察到快速、有效的猝灭。基于瞬态吸收测量，初始金属到配体电荷转移激发态和能量更高的氧化还原分离态之间似乎存在快速平衡。衰减到基态主要由氧化还原分离态内的反向电子转移主导，在298±2K时k>4×10(8)s(-)(1)。
