Synthesis and characterization of phosphorescent platinum complexes containing phenylpyridazine

Synthesis and characterization of a series of square planar Pt(II)-phenylpyridazine complexes are reported. The complexes have the general structure of (C-N)Pt(O-O), where HC-N is 3-phenyl-pyridazine (ppdz), 3-(3'-trifluoromethylphenyl)pyridazine (3'tfmppdz), 3-(3'-methoxyphenyl)-pyridazine (3'meoppdz), 3-(4'-methoxyphenyl)pyridazine (4'meoppdz), or 3-phenyl-6-chloro-pyridazine (6Clppdz) and HO-O is acetylacetone (Hacac). Reaction of K2PtCl4 with a HC-N ligand forms the dimer, (C-N)Pt(mu-Cl)(2)Pt(C-N), which is cleaved with Hacac to give the corresponding monomer, (C-N)Pt(O-O). The emission characteristics of these complexes are governed by the substituents of the cyclometalating ligands, showing emission lambda(max) values from 508 to 610 nm. Strong spin-orbit coupling of the platinum atom allows for the formally forbidden mixing of the (MLCT)-M-1 with the (MCLT)-M-3 and (3)(pi-pi*) states. (C) 2003 Published by Elsevier B.V.