Boron containing π-electron chromophores represented by tri(9-anthryl)borane show quite unique spectroscopic and photophysical properties, owing to the presence of the vacant p-orbital on the boron atom. In practice, we demonstrated that the excited states of arylborane derivatives were characterized by charge transfer from the π-orbital of the aryl group to the vacant p-orbital on the boron atom: π(Ar) – p(B) CT. If such π(Ar) – p(B) CT interactions are introduced to the MLCT excited state of a transition metal complex, new and novel aspects into photophysics of the metal complexes could be demonstrated. We have previously reported our experiments on the platinum(II) complexes having arylborane-appended 2,2’:6’,2”-terpyridine (tpy) ligands to demonstrate synergetic metal(M) – ligand and π(Ar) – p(B) CT interactions.

In the present study, we focus on donor-acceptor interaction using an arylborane substituent and discussed about the charge separation on the spectroscopic and photophysical properties of their metal complexes. Then, we synthesized a novel cyclometalated-type platinum (II) complex using an NCN tridentate ligand with boron substituents, which is thought to cause intermolecular interactions, and investigated its spectroscopic properties.