Rostock 2019 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 3: Ultrafast Processes in Solution
MO 3.7: Vortrag
Montag, 11. März 2019, 12:15–12:30, S HS 001 Biologie
Experimental traces for ultrafast halogen-bond breaking in solution — •Bastian Geissler1, Christin Pflieger1, Claudio Beakovic1, Elric Engelage2, Stefan Huber2, and Patrick Nuernberger1 — 1Physikalische Chemie II, Ruhr-Universität Bochum, 44780 Bochum — 2Organische Chemie I, Ruhr-Universität Bochum, 44780 Bochum
Non-covalent halogen bonds between an iodine substituted organic compound and a Lewis base can play key roles in various chemical and biological processes. For instance, halogen bonds are already commonly used for crystal engineering. In the liquid phase, deciphering and exploiting the complex behavior of halogen bonds between solutes is an emerging area of research, still mostly focused on organic synthesis, catalysis, supramolecular self-assembly or molecular recognition processes.
In this study, we address the photophysical properties of compounds capable of halogen bonding by employing ultrafast time-resolved fluorescence upconversion and transient absorption techniques. Benzoimidazole derivates serve as halogen bond donors and pyridine derivates as Lewis base acceptors. Absorption studies suggest the existence of iodine halogen bonds in acetonitrile solution, indicative of a modified charge distribution along the halogen bond which is only observable in the presence of the donor-acceptor pair. Upon excitation, signals assigned to the halogen bond rapidly disappear, suggesting that the halogen bond breaks reversibly within a few picoseconds.