Theoretical studies of zinc phthalocyanine monomer, dimer and trimer forms

A theoretical study of the electronic structure of zinc phthalocyanine (ZnPc) ground state was carried out using ab initio and DFT methods. The DFT and MP2 methods indicated a D4h structure, while HF predicted a slightly distorted geometry. The DFT infrared spectra with the corrected wave number values presented good agreement with experiment. The solvation influence on the geometrical parameters, atomic charges and HOMO-LUMO energies was estimated with the use of PCM method and DMSO as solvent. The presence of solvent did not alter these parameters, but affected the orbital energies. The aggregation phenomena were studied with ZnPc dimer and trimer structures. The previously unknown ZnPc dimer infrared spectrum was obtained and compared to the one from monomer. The dimer and trimer stabilization energies are indicative that the formation of stacked structures with several ZnPc is a favorable process.