title: In search of excited-state proton transfer in the lumichrome dimer in the solid state: theoretical and experimental approach.
abstract: Quantum chemical density functional theory (DFT) calculations and spectral data were employed to investigate the possibility of the excited-state double proton transfer (ESDPT) in lumichrome crystals. The calculations in a lumichrome dimer predict a transfer of a proton in the first excited state, leading to a cation-anion pair. The presently reported X-ray structure of 1,3-dimethyllumichrome and its complex solid-state luminescence indicate that also in this molecule intermolecular hydrogen bonds might be involved in the photophysics. The long-wavelength emission in lumichrome crystals peaked at 530 nm is attributed to excited-state proton transfer, whereas a wider emission band in methylated lumichrome derivatives peaked at 560 nm is attributed to ions formed upon photoexcitation of the crystals.
authors.affiliation: Faculty of Commodity Science, Poznań University of Economics, al. Niepodleglości 10, 60-967 Poznań, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Sikorska
authors.forename: Igor
authors.initials: I
authors.lastname: Khmelinskii
authors.forename: Maciej
authors.initials: M
authors.lastname: Kubicki
authors.forename: Wiesław
authors.initials: W
authors.lastname: Prukała
authors.forename: Marcin
authors.initials: M
authors.lastname: Hoffmann
authors.forename: Isabel F
authors.initials: IF
authors.lastname: Machado
authors.forename: Luis F V
authors.initials: LF
authors.lastname: Ferreira
authors.forename: Jerzy
authors.initials: J
authors.lastname: Karolczak
authors.forename: David R
authors.initials: DR
authors.lastname: Worrall
authors.forename: Alina
authors.initials: A
authors.lastname: Krawczyk
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Insińska-Rak
authors.forename: Marek
authors.initials: M
authors.lastname: Sikorski
mesh_terms: D000465:Algorithms; D018360:Crystallography, X-Ray; D019281:Dimerization; D005415:Flavins / Q000737:chemistry*; D007834:Lasers; D008956:Models, Chemical; D015394:Molecular Structure; D010777:Photochemistry; D011522:Protons; D011789:Quantum Theory; D013057:Spectrum Analysis
chemical_list: D005415:Flavins; D011522:Protons; C001559:7,8-dimethylalloxazine