A Panchromatic Cyclometalated Iridium Dye Based on 2-Thienyl-Perimidine

Though 2-arylperimidines have never been used in iridium(III) chemistry, the present study on structural, electronic and optical properties of N-unsubstituted and N-methylated 2-(2-thienyl)perimidines, supported by DFT/TDDFT calculations, has shown that these ligands are promising candidates for construction of light-harvesting iridium(III) complexes. In contrast to N-H perimidine, the N-methylated ligand gave the expected cyclometalated μ-chloro-bridged iridium(III) dimer which was readily converted to a cationic heteroleptic complex with 4,4'-dicarboxy-2,2'-bipyridine. The resulting iridium(III) dye exhibited panchromatic absorption up to 1000 nm and was tested in a dye-sensitized solar cell.