Cyclometalated platinum(II) complexes with sterically bulky camphor-derived groups as β-diketonate ancillary ligand: a new route to efficiently reducing π-π interactions and Pt-Pt interactions

Abstract

A new series of mono-cyclometalated square planar platinum(II) complexes have been synthesized and the single-crystal X-ray structures of complex 1 and 2 have been determined. The complexes have the general formula ppyPt(O∧O), where ppy is 2-phenylpyridyl, and O∧O is β-diketonate ancillary ligands with the acyl substituent group in position 3 of (D)-(+)-camphor. Although, like the many Pt(II) complexes with square-planar geometry, these complexes have plane stacking modes in crystal structure, the sterically bulky camphor-derived groups compel extensive slipping of the molecular stacking planes, resulting in the negligible overlapping of the aromatic ring fragments between molecules and the considerable Pt-Pt distance. The resolved spectra and a little shifted emission in solid state of complexes show that there is significant reduction of π-π interactions and Pt-Pt interactions, and suggest these complexes may be good candidates for doped phosphorescent organic light emitting diodes (PhOLEDs) and even for nondoped PhOLEDs.