title: Spectroscopy and Photophysics of Monomethyl-Substituted Derivatives of 5-Deazaalloxazine and 10-Ethyl-5-Deaza-Isoalloxazine.
abstract: Steady-state and time-resolved spectra were used to describe the singlet and triplet states of 8-methyl-5-deazaalloxazine (8-Me-5-DAll), 9-methyl-5-deazaalloxazine (9-Me-5-DAll) and 10-ethyl-5-deaza-isoalloxazine (10-Et-5-DIAll). Solvatochromic properties were described using different polarity scales, including Δf and the four-parameter scale proposed by Catalán. The results indicate that the Catalán scale shows a strong influence of solvent acidity (hydrogen-bond donating ability) on the emission properties of 8-Me-5-DAll and 9-Me-5-DAll. These results indicate the importance of intermolecular solute-solvent hydrogen-bonding interactions in the excited state of these compounds. Contrary to deazaalloxazines, solvent acidity affects the absorption spectra of 10-Et-5-DIAll. Fluorescence lifetimes and quantum yields and also transient absorption spectra were determined for all of the compounds studied. Electronic structure and S(0)-S(i), S(0)-T(i ), T(1)-T(i) transitions energies and oscillator strengths were calculated using the TD-DFT methods. Theoretical calculations were compared to experimental data.
authors.affiliation: Faculty of Chemistry, A. Mickiewicz University, Umultowska 89B, 61-614, Poznań, Poland. dprukala@amu.edu.pl.
authors.forename: Dorota
authors.initials: D
authors.lastname: Prukała
authors.affiliation: Faculty of Chemistry, A. Mickiewicz University, Umultowska 89B, 61-614, Poznań, Poland.|FT/ICR MS Laboratory, Department of Earth Sciences, The University of Hong Kong, Hong Kong, Hong Kong.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Taczkowska
authors.affiliation: Faculty of Chemistry, A. Mickiewicz University, Umultowska 89B, 61-614, Poznań, Poland.
authors.forename: Mateusz
authors.initials: M
authors.lastname: Gierszewski
authors.affiliation: Faculty of Chemistry, A. Mickiewicz University, Umultowska 89B, 61-614, Poznań, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Pędziński
authors.affiliation: Faculty of Chemistry, A. Mickiewicz University, Umultowska 89B, 61-614, Poznań, Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Sikorski
mesh_terms: D010078:Oxazines / Q000737:chemistry*; D066244:Proton Magnetic Resonance Spectroscopy; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D010078:Oxazines
keywords: 5-deaza-isoalloxazine; 5-deazaalloxazine; Photophysics; Spectroscopy; TD-DFT study; Transient absorption spectra