Symmetry-Lowering of the Phthalocyanine Chromophore by a C2 Type Axial Ligand

By linking C2 type axial ligands such as 2,2‘-biphenoxy or 2,2‘-binaphthyloxy to the metal of a metallophthalocyanine (MtPc) as axial ligands, the effective symmetry of the chromophore was lowered, as manifested in the splitting of the Q00 band, which is reasonally explained by an excitonic interaction between the axial ligand and the Pc chromophore. The effective symmetry of MtPcs was thus lowered without modifying the Pc ligand with D4h symmetry.