Magnetic circular dichroism spectroscopy and TD-DFT calculations of metal phthalocyanine anion and cation radical species

The results of INDO/s and TD-DFT calculations for neutral ZnPc(−2), unligated [ZnPc(−1)]+ and chloride anion ligated [(Cl)ZnPc(−1)] cation radicals, the [ZnPc(−3)]− radical anion and [ZnPc(−4)]2− dianion species, performed on a set of B3LYP geometry optimizations are compared with magnetic circular dichroism spectral data. The two calculation methods predict spectra that are broadly similar. The TD-DFT calculations provide a significantly closer agreement with the experimental band centers in the UV region than was previously the case with INDO/s based calculations. The assignment of several key spectral features remains problematic, however, when band polarization information derived from magnetic circular dichroism spectroscopy is taken into consideration.