In search of excited-state proton transfer in the lumichrome dimer in the solid state: theoretical and experimental approach.
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.
Sikorska
Ewa
E
Faculty of Commodity Science, Poznań University of Economics, al. Niepodleglości 10, 60-967 Poznań, Poland.
Khmelinskii
Igor
I
Kubicki
Maciej
M
Prukała
Wiesław
W
Hoffmann
Marcin
M
Machado
Isabel F
IF
Ferreira
Luis F V
LF
Karolczak
Jerzy
J
Worrall
David R
DR
Krawczyk
Alina
A
Insińska-Rak
Małgorzata
M
Sikorski
Marek
M
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
D005415:Flavins; D011522:Protons; C001559:7,8-dimethylalloxazine