Rostock 2019 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 3: Ultrafast Processes in Solution

MO 3.3: Vortrag

Montag, 11. März 2019, 11:15–11:30, S HS 001 Biologie

Broadband Ultrafast Transient Absorption Spectroscopy of Triplet Phenylpentadiynylidene and Diphenylpropynylidene — •Lea Ress, Engelbert Reusch, Hans-Christian Schmitt, Ingo Fischer, and Tobias Brixner — Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg

The chemical and physical properties of unsaturated carbon-rich chain molecules like phenylpentadiynylidene (PhC₅H) and diphenylpropynylidene (PhC₃Ph) are of significance in research areas such as astrochemistry and combustion processes, wherein biradical or rather carbenic structures and their electronic characteristics play an important role. Those molecules were previously generated by photolysis and characterized by matrix isolated EPR, IR and UV/Vis spectroscopy [1],[2]. Their precursors (5-diazopenta-1,3-diyn-1-yl)benzene (PhC₅N₂H) and (3-diazoprop-1-yne-1,3-diyl)dibenzene (PhC₃N₂Ph) have not been characterized via ultrafast transient absorption spectroscopy in liquid phase at room temperature. In this contribution, we investigate the photolysis of the diazo group with ultrashort laser pulses by excitation at 260 nm to generate triplet PhC₅H and PhC₃Ph. We study the ultrafast photochemistry of these triplet species in dichloromethane and ethanol as aprotic and protic solvents, respectively, and further discuss reaction pathways and ultrafast dynamics up to three nanoseconds within these solvents.

[1] S. N. Knezz et al., J. Am. Chem. Soc., 138, 12596-12604 (2016)

[2] P. S. Thomas et al., J. Org. Chem., 75, 6372-6381 (2010)