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Stereospecific Synthesis and Photophysical Properties of Propeller-Shaped C90H48 PAH

submitted on 07.10.2019, 14:15 and posted on 11.10.2019, 20:13 by Fangyuan Zhang, Evripidis Michail, Fridolin Saal, Ana-Maria Krause, Prince Ravat
Highly twisted large PAHs offer, in addition to physical properties, a feature of chirality, which results in non-super imposable mirror-image structures of these compounds that can be resolved into optically active enantiomers. This process, however, is cumbersome, which largely restricts the available quantity of materials in optically active form and represents a great hurdle for their applications. Herein, we have synthesized an enantiomerically pure propeller-shaped PAH, C90H48, possessing three [7]helicene and three [5]helicene subunits. This compound can be obtained in gram quantities in a straight-forward manner. The photophysical and chiroptical properties were investigated using UV−vis absorption and emission, optical rotation and circular dichroism spectroscopy, supported by DFT calculations. The non-linear optical properties were investigated by two-photon absorption measurements using linearly and circularly polarized light. The extremely twisted structure and packing of the homochiral compound were investigated by single crystal X-ray diffraction analysis


Julius-Maximilians-Universität Würzburg within the “Excellent Ideas” programme


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Institute of Organic Chemistry, University of Würzburg



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Declaration of Conflict of Interest

The authors declare no competing financial interest.