SAMOP 2023 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 6: Poster I
MO 6.15: Poster
Dienstag, 7. März 2023, 16:30–19:00, Empore Lichthof
Bidirectional photorearrangement reaction of a xanthine derivative — •Thomas Rittner1, Karina Heilmeier1, Rafael E. Rodríguez-Lugo2, Simon Dietzmann2, Svenja Wortmann1, Roger Jan Kutta1, Robert Wolf2, and Patrick Nuernberger1 — 1Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93053 Regensburg — 2Institut für Anorganische Chemie, Universität Regensburg, 93053 Regensburg
7-Aryl-8-pyridyl substituted theophyllines exhibit a remarkable photoreaction. Our studies show that upon excitation with ultraviolet light, the anisyl substituted 7-(4-methoxyphenyl)-1,3-dimethyl-8-(pyridin-2-yl)-3,7,8,9-tetrahydro-1H-purine-2,6-dione undergoes a rearrangement. The anisol moiety migrates from the 7-nitrogen on the purine skeleton of the theophylline to the 1'-nitrogen of the pyridine, yielding a zwitterionic isomer. Both isomers could be isolated and subsequently characterized by NMR spectroscopy and single-crystal X-ray scattering. Time-resolved and steady-state absorption and emission spectroscopies in the visible spectral range were used to investigate the photorearrangement mechanism. Together with quantum-chemical calculations a detailed picture on a molecular level could be obtained. We further demonstrate that also a photo-induced back-isomerization is feasible, enabling in principle a general design for photo-switchable molecular structures.