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.