LC-wPBE: an appropriate OFT functional for a reliable description of transition energies in phthalocyanines

Phthalocyanine derivatives have been used in many fields as an important functional material1-3. Catalysis, optical disks, photodynamic therapy, are some applications of devices involving such compounds. Their useful properties are correlated to efficient electron transfer abilities1, related to 1(π-π*) transitions involving Q and B bands.1 In a previous study4, in order to define a most appropriate TD-OFT methodology to study the photoinduced charge transfer from phthalocyanines to semiconductor oxides5, the LC-wPBE hybrid functional,6 among a series of OFT functionals, showed to be the most suitable. Adjusting the range separation parameter (w)6 it was possible to estimate with minimum discrepancy compared to the experimental data, the energies of the highest intensity electronic transitions related to Q and B bands (Eo and Es). In this communication, we present results on the implementation of this methodology to Zinc (II) phthalocyanine (ZnPc) and some tetrasubstituted derivatives. The solvated structures (DMS0)7 were optimized using the M068 functional combined with the DZP-DKH atomic basis set9. For ZnPc the w capable to give a good convergence for Eo and Es was estimated as being 0.17 bohr1. This value was then applied for the other phthalocyanines, Table 1. Similar estimates using the CAM-B3L YP10 exchange-correlation hybrid functional resulted in high deviations for Es. All calculations were performed in Gaussian0912. The results suggests that LC-mPBE with the proper fit of the m parameter, furn ishes with controlled discrepancy the energies of the highest intensity electronic transitions related to Q and B bands.