Hannover 2013 – scientific programme
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MO: Fachverband Molekülphysik
MO 2: Electronic Spectroscopy I
MO 2.4: Talk
Monday, March 18, 2013, 11:45–12:00, F 107
Spectroscopic study of weak molecular interactions: benzene- phenol- and pyrazine-acetylene — •Benjamin Stuhlmann1, Markus Böning1, Gernot Engler1, Georg Jansen2, Michael Schmitt1, and Karl Kleinermanns1 — 1Heinrich Heine-Universität, Institut für Physikalische Chemie I, Düsseldorf — 2Universität Duisburg-Essen, Institut für Theoretische Organische Chemie
The stepwise aggregation of individual molecules from small clusters to highly ordered crystals is a fascinating process.
The structures of different aromate-acetylene aggregates are assigned and compared to that of the co-crystal. These structures are determinded by the interactions between the conjugated π-systems and hydrogen atoms.
Acetylene can either be the hydrogen-donor or the hydrogen-acceptor in those π-H-bonded aggregates, depending on the nature of its partner. The resulting binding motive leads to a different distribution of electron density and thus to a different frequency shift of characteristic vibrations, depending on which molecule is the donor and which molecule is the acceptor in the cluster.
The spectroscopic investigation of the electronic origin of the aromate via UV-spectroscopy and characteristic infrared active vibrations (asymmetric C-H-stretch, O-H-stretch in phenol) via IR-spectroscopy gives direct evidence of the binding motive in the observed cluster.