title: DFT/TD-DFT study of solvent effect as well the substituents influence on the different features of TPP derivatives for PDT application.
abstract: Spectral characteristics study of meso-tetraphenylporphyrin derivatives (TPP1 and TPP2) used as photosensitizers for utilization in photodynamic therapy (PDT) has been performed by density functional theory (DFT) and time dependent DFT (TD-DFT) calculations at B3LYP/6-31 G(d) level of theory using PCM solvation model. The geometrical parameters of porphyrins have been studied for ground and excited-state geometry to deduce the influence of various substituents as well as solvent effect on the deformation of porphyrin ring. Two theoretical approaches - linear response (LR) and external iteration (EI) - have been performed to replicate absorption and fluorescence emission spectra. Experimental and theoretical investigations have shown that EI method reproduces the absorption energies very well for both singlet-singlet and triplet-triplet transitions, whereas the LR approach is more coherent with experimental fluorescence emission spectra. Spectral features and HOMO-LUMO band gap analysis have shown that TPP1 can be more useful in PDT. Calculations have revealed that two the highest occupied and two the lowest unoccupied molecular orbitals are responsible for the Q-band absorption and are located mainly on the porphyrin ring. In order to verify the substituent effect on the activity of tested compounds in their ground and excited states, the molecular electrostatic potential surfaces have been analyzed.
authors.affiliation: A. Chełkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland. mdulski@us.edu.pl
authors.forename: Mateusz
authors.initials: M
authors.lastname: Dulski
authors.forename: Marta
authors.initials: M
authors.lastname: Kempa
authors.forename: Patrycja
authors.initials: P
authors.lastname: Kozub
authors.forename: Justyna
authors.initials: J
authors.lastname: Wójcik
authors.forename: Marcin
authors.initials: M
authors.lastname: Rojkiewicz
authors.forename: Piotr
authors.initials: P
authors.lastname: Kuś
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Szurko
authors.forename: Alicja
authors.initials: A
authors.lastname: Ratuszna
authors.forename: Roman
authors.initials: R
authors.lastname: Wrzalik
mesh_terms: D000042:Absorption; D000096:Acetone / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D010778:Photochemotherapy; D011166:Porphyrins / Q000737:chemistry*; D011789:Quantum Theory; D012996:Solutions; D012997:Solvents / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013194:Staining and Labeling; D055672:Static Electricity; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D011166:Porphyrins; D012996:Solutions; D012997:Solvents; C409084:tetraphenylporphyrin; D000096:Acetone