Coupling D(6) Ir(Iii) And D(8) Pt(Ii) Chromophores

Two classes of widely studied luminescent metal complexes are octahedral d(6) (i.e., Ir3+) and square planar d(8) (i.e., Pt2+) polypyridyl complexes, which have distinctly different photophysics and photoreactivity. In this study we report a series of d(6)-d(8) Ir-III-Pt-II hybrid complexes arising from coordination of metalloligands IrL2(benzene-1-thioether-2-thiolate) or Ir(L)(2)(benzene-1,2-dithio-late) anion [L = 2-phenylpyridine (ppy), 2-(2,4-difluorophenyl)pyridine (dfppy), or 1-phenylisoquinoline (piq)] to Pt(terpy)(2+) (terpy = 2,2':6',2''terpyridine). X-ray crystal structures of the Ir-Pt complexes show the IrL2 and Pt(terpy) chromophores are cofacially oriented with interplanar distances of 3.268-3.442 <(A) over circle>. Density functional theory (DFT) calculations show that the highest occupied molecular orbital and the lowest unoccupied molecular orbital are localized in the IrL2 and the Pt(terpy), respectively. All the complexes display a low-energy absorption band (lambda(max) = 460-534 nm, epsilon(max) = (0.75-2.13) x 10(3) M-1 cm(-1)), which is attributed to interchromophore-charge-transfer (ICCT) transition, according to time-dependent DFT calculations. The (ICCT)-I-3 excited state is emissive, giving long-lived phosphorescence that reaches as low as near-infrared (lambda(max) = 668-710 nm, tau = 0.17-0.79 mu s).