title: Halogen atom effect on the photophysical properties of substituted aza-BODIPY derivatives.
abstract: The influence of halogen atom substitution (Br and I), in different amounts and positions in an aza-BODIPY skeleton, on the photophysical properties of some aza-BODIPY derivatives has been investigated by using density functional theory and its time-dependent extension. The heavy atom effect on excitation energies, singlet-triplet energy gaps and spin-orbit matrix elements has been considered. The maximum absorption within the therapeutic window has been confirmed for all the aza-BODIPY derivatives. The feasible intersystem spin crossing pathways for the population of the lowest triplet state, that will depend on the values of the spin-orbit matrix elements, the energy gap as well as the orbital composition of the involved states have been found to most likely involve the S1and T1or T2states. The outcomes of computations support the potential therapeutic use of these compounds as photosensitizers in photodynamic therapy.
authors.affiliation: Dipartimento di Chimica e Tecnologie Chimiche, Università della Calabria, I-87036 Arcavacata di Rende, Italy. gloria.mazzone@unical.it.
authors.forename: B C
authors.initials: BC
authors.lastname: De Simone
authors.affiliation: Dipartimento di Chimica e Tecnologie Chimiche, Università della Calabria, I-87036 Arcavacata di Rende, Italy. gloria.mazzone@unical.it.
authors.forename: G
authors.identifier: http://orcid.org/0000-0002-4686-6876
authors.initials: G
authors.lastname: Mazzone
authors.affiliation: Dipartimento di Chimica e Tecnologie Chimiche, Università della Calabria, I-87036 Arcavacata di Rende, Italy. gloria.mazzone@unical.it.
authors.forename: J
authors.initials: J
authors.lastname: Pirillo
authors.affiliation: Dipartimento di Chimica e Tecnologie Chimiche, Università della Calabria, I-87036 Arcavacata di Rende, Italy. gloria.mazzone@unical.it.
authors.forename: N
authors.initials: N
authors.lastname: Russo
authors.affiliation: Dipartimento di Chimica e Tecnologie Chimiche, Università della Calabria, I-87036 Arcavacata di Rende, Italy. gloria.mazzone@unical.it.
authors.forename: E
authors.initials: E
authors.lastname: Sicilia