Pushing Pentacene-Based Fluorescence to the Near-Infrared Region by Platination

A series of binuclear platinum complexes of pentacenyl-6,13-diacetylide with different auxiliary ligands were synthesized to probe the effect of metal coordination on electronic spectroscopy and photophysics, to determine the solid-state packing of the complexes, and to tune emission energy. The complexes with anionic, π-donating ligands showed absorption (687–696 nm) and fluorescence (710–726 nm) lower in energy than those with neutral, π-accepting ligands (662–666, 675–686 nm). Our work showed that coordination of Pt ions with π-donating anionic ligands to pentacenyl-6,13-diacetylide could move the fluorescence of the organic chromophore to the near-infrared region (λem 710–726 nm). The combined perturbations of alkynation and platination lowered the HOMO → LUMO transition up to 0.34 eV.