title: Solvatochromic Stokes shift and determination of excited state dipole moments of free base and zinc octaethylporphyrin.
abstract: Solvent effects on the photophysical properties of free base octaethylporphyrin and zinc octaethylporphyrin are investigated at the ambient temperature (300 K). Steady state electronic absorption and emission spectra of the porphyrins are recorded in different organic solvents of varying polarity. By using solvatochromic Stokes shift method, the dipole moments associated with the first excited singlet states of the presently used porphyrin molecules are determined for the first time, to the best of our knowledge, from Lippert-Mataga, Bakhshiev and Reichardt equations. The dipole moments associated with the singlet ground state of the porphyrin molecules are calculated theoretically by using density functional theory (DFT) method by adopting B3LYP/6-31G(d,p) level using Gaussian 03 package. Moreover, some other photophysical properties (fluorescence quantum yield, fluorescence lifetime, decay rates, etc.) of the porphyrins are measured in different solvents of varying polarity.
authors.affiliation: Integrated Science Education and Research Centre, Siksha-Bhavana, Visva-Bharati, Santiniketan 731 235, India.
authors.forename: Mihir
authors.initials: M
authors.lastname: Ghosh
authors.affiliation: Integrated Science Education and Research Centre, Siksha-Bhavana, Visva-Bharati, Santiniketan 731 235, India. Electronic address: subratasinha67@rediffmail.com.
authors.forename: Subrata
authors.initials: S
authors.lastname: Sinha
mesh_terms: D008665:Metalloporphyrins / Q000737:chemistry*; D008958:Models, Molecular; D011166:Porphyrins / Q000737:chemistry*; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence
chemical_list: D008665:Metalloporphyrins; D011166:Porphyrins; C488938:octaethylporphyrin; C526613:zinc octaethylporphyrin
keywords: Excited state dipole moment; Ground state dipole moment; Octaethylporphyrin; Stokes shift