Electronic structures and spectra of porphyrin with fused benzoheterocycles: DFT and TDDFT-PCM investigations

Density functional theory (DFT) and time-dependent DFT (TDDFT) are applied to study seven asymmetric π-conjugated porphyrins with extended benzoheterocycles: quinoline, indole, benzoimidazole, benzothiazole, benzooxazole, 2,1,3-benzothiadiazole, and 2,1,3-benzoxadiazole. The solvation effects on the excitation energies for these porphyrin derivatives in chloroform are taken into account by using the continuum model (C-PCM) combined with TDDFT, and this method makes a closer agreement with the experimental values, especially for the B-bands of these objects. Great efforts have been made on investigating the influences of the fused aromatic units of the porphyrins on the absorption properties as these can be particularly important for many applications. Benzoheterocycle introduction and solvent effects have been systemically investigated, and close agreement is obtained between calculated and measured UV–vis spectra. These theoretical data could shed light on future synthetic chemistry. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007