The synthesis and characterization of mixed ligand Ru(II) complexes with dipyrido(2,3-a:3 ',2 '-j) phenazine (dpop ') and 2,3,5,6-tetra(2-pyridyl)-pyrazine (tppz)

摘要

The synthesis of the mixed ligand mono metallic [Ru(dpop')(tppz)](2+) and bimetallic [(dpop') Ru(tppz)Ru(dpop')](4+) (dpop' = dipyrido(2,3-a:3',2'- j) phenazine; tppz = 2,3,5,6 tetra-(2-pyridyl)pyrazine) complexes is described. The [Ru(dpop')(tppz)](2+) complex display an intense absorption at 518 nm which is assigned to a Ru(d pi) -> dpop' (pi*) MLCT transition, and at 447 nm which is assigned to a Ru(d pi) -> tppz(pi*) MLCT transition. It undergoes emission at RT in CH3CN with lambda(em) = 722 nm. The bimetallic [(dpop')Ru(tppz)Ru(dpop')](4+) complex shows a low energy absorption shoulder near 635 nm assigned to a Ru(d pi)-> tppz(pi*) MLCT transition and an intense peak at 542 nm due to Ru(d pi) -> dpop' (pi*) MLCT transition. The bimetallic complex also emits at RT in CH3CN with lambda(em) = 785 nm. Cyclic voltammetry shows reversible Ru+2/+3 oxidations at 1.68 V for the monometallic complex and Ru+2/+3 oxidation couples at +1.94 and +1.70 V for the bimetallic complex.