title: Structures and electronic absorption spectra of a recently synthesised class of photodynamic therapy agents.
abstract: A theoretical study was performed on a novel class of boron-containing molecules (various substituted tetraarylazadipyrromethenes), which show in vitro activity for application in photodynamic therapy. Geometric optimisation of the structures for the singlet and triplet electronic states was carried out on compounds in vacuo at the density functional level of theory, by employing the PBE0 hybrid functional and the split-valence plus polarisation basis set. The absorbance properties in the UV-visible region were examined by means of time-dependent density functional response theory, using the same functional as mentioned above. To evaluate the influence of the solvent on the excitation energies, the continuum polarisable model was applied. Calculated electronic excitations, such as those regarding the Q-like band, were found to be in good agreement (within 0.01-0.1 eV) with experimental values and experimental trends on changing both the substituents and solvent.
authors.affiliation: Dipartimento di Chimica and Centro di Calcolo ad Alte Prestazioni per Elaborazioni Parallele e Distribuite, Centro d'Eccellenza MURST, Università della Calabria, 87030 Arcavacata di Rende, Italy.
authors.forename: Angelo Domenico
authors.initials: AD
authors.lastname: Quartarolo
authors.forename: Nino
authors.initials: N
authors.lastname: Russo
authors.forename: Emilia
authors.initials: E
authors.lastname: Sicilia
mesh_terms: D001372:Aza Compounds / Q000737:chemistry / Q000494:pharmacology; D001896:Boron Compounds / Q000737:chemistry* / Q000494:pharmacology; D008958:Models, Molecular; D008968:Molecular Conformation; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000737:chemistry* / Q000494:pharmacology; D011162:Porphobilinogen / Q000031:analogs & derivatives / Q000737:chemistry; D011166:Porphyrins / Q000737:chemistry; D011758:Pyrroles / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D001372:Aza Compounds; D001896:Boron Compounds; D017319:Photosensitizing Agents; D011166:Porphyrins; D011758:Pyrroles; D011162:Porphobilinogen