Synthesis, Photophysical, And Computational Studies Of A Bridged Ir-Iota Iota Iota-Pt-Iota Iota Heterodimetallic Complex

An Ir-III-Pt-II heterodimetallic complex [(ppy)(2)Ir(dapz)PtCl2]Cl (4), together with the corresponding monometallic complexes [(dapz)PtCl2] (2) and [(ppy)(2)Ir(dapz)]Cl (3) was designed and prepared, where dapz is 2,5-di(N-methyl-N '-(pyrid-2-yl)amino)pyrazine and ppy is 2-phenylpyridine, respectively. Single-crystal X-ray analysis was carried out for complex 4, displaying the intermolecular Pt center dot center dot center dot Pt and aromatic plane center dot center dot center dot plane distances of 3.839 and 3.886 angstrom, respectively. The monometallic complex 2 exhibits a single emission maximum at 432 nm with a shorter excited-state lifetime (tau) of 6 ns, while complex 3 exhibits an emission band at 454 nm with a longer excited-state lifetime of 135 ns in CH3CN (N-2-saturated) under ambient conditions. In contrast, the heterodimetallic complex 4 displays intriguing excitation wavelength-dependent dual singlet and triplet emissions. Theoretical calculations of the electronic structures and absorption spectra of these complexes were carried out to assist the interpretation of these experimental findings.