Ru(II) complexes containing dihydro-1,1,3,3-tetramethyl-7,8-diazacyclopenta[1]phenanthren-2-ol ligand: Synthesis and their electrochemiluminescent characteristics

A series of new ruthenium(II) complexes containing dihydro-1,1,3,3-tetramethyl-7,8-diazacyclopenta[1]phenanthren-2-ol (DTDP-OH) ligand, such as [Ru(DTDP-OH)n(L)3−n]2+ (L = 2,2′-bipyridyl (bpy), o-phenanthroline (o-phen), 2,2′-bipyridine-4,4′-dicarboaldehyde (bpy-(CHO)2), 1,3-dihydro-1,1,3,3-tetramethyl-7,8-diazacyclopenta[1]phenanthren-2-one(DTDP), n = 1, 2, 3) were synthesized and their electrochemical and photophysical properties were studied. The synthesized Ru(II) complexes containing the DTDP-OH ligand showed strong MLCT absorptions at 420–487 nm. All the synthesized Ru(II) complexes containing the DTDP-OH ligand exhibited more intensive ECL emissions than the well-known [Ru(o-phen)3]2+ does. In particular, the ECL intensities of [Ru(DTDP-OH)2(o-phen)]2+ and [Ru(DTDP-OH)2(bpy-(CHO)2)]2+ were observed to be more than 2-fold greater than that of [Ru(o-phen)3]2+.