Oligothiophenes incorporating metal-metal quadruple bonds (MM = Mo2, MoW and W2). A chemical approach for photon harvesting and spectral expansion

The syntheses, electronic structures as determined by calculations employing density functional theory, and the physic-chemical properties of oligothiophenes attached to MM quadruply bonded centers (MM = Mo₂, MoW and W₂) by carboxylate tethers are described. These materials absorb light across the spectral range 300-1000 nm due to intense ¹LLCT and ¹MLCT transitions. The MM¿ orbital is strongly coupled to the p-system of the oligothiophenes and the photoexcited states have relatively long lived singlet and triplet state which are on the order 10 ps and 50 ¿s, respectively. Electrochemical and Photophysical studies are reported.