Photoluminescence of a Platinum(II) Complex Containing Multiresonance B–N Motif in the Cyclometalated Ligand

N- and B-Embedded polycyclic aromatic hydrocarbons with
a multiresonance
(MR) character have fascinating photophysical properties including
high photoluminescence quantum yields and ultrapure emission color
purity. The combination of MR character and heavy metal atom for developing
photoluminescent transition metal complexes is of great interest but
has rarely been investigated. Herein a platinum(II) complex, namely, Pt(BICPy)(acac), containing a MR moiety in the cyclometalated
ligand has been synthesized and characterized. The complex displays
strong narrowband phosphorescence with a quantum yield of 53% and
a lifetime of 26 μs. Theoretical calculations unveiled the enhanced
spin–orbit coupling effect induced by metal coordination.
This work provides a way for harvesting the triplet excitons of MR
type molecules.