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Synthesis and characterization of new bridged tolanes

Kozhemyakin, Yury

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Approaches to novel diphenylacetylene derivatives and related compounds with restricted rotation of the phenyl rings have been developed. Since mutual overlapping of molecular orbitals specifies the electronic communication between aromatic π-systems, regulation of the conformation within a molecule gives control over conductive and photophysical properties of tolane. Amide- and ester bound tethers have been used. The first one resists aggressive factors better, compared with ester. Introduction of amide-functionalized tethers have been demonstrated by synthesis of two bridged tolanes; a novel double-bridged 1,4-bis(phenylethynyl)benzene (I) was prepared.

In addition, synthetic approaches leading to multi-gram amounts of bifunctional tolanophanes are shown, ready for further derivatization. TIPS-acetylene derivatives possessed not only outstanding emissive, but also interest-evoking structural properties, expressed in folded cyclic dimers with electronically interacting chromophore units by means of π-π-stacking. Considering this, series of cyclic oligomers have been synthesized and investigated.

From previous studies it was known, that in the solid state twisted tolanophanes planarize after excitation due to a special arrangement of the electronic states. Introduction of the second tether into the tolanophane molecule gives a more rigid molecule (II) and leads to a better understanding of the emissive properties of tolane chromophores. Compound II showed a twisted conformation in the excited state. Figure I. Selected synthesized and studied molecules.

Further, bifunctional tolanophanes have been used for copolymerization (III). Bridged derivatives of 1,4-diphenyldiacetylene have been investigated, as they are usual defects in poly(para-phenyleneethynylene)s and can significantly affect their properties. Emissive ability of these substances appeared to be not distinct; they showed weak photophysical response on twisting.

Item Type: Dissertation
Supervisor: Bunz, Prof. Dr. Uwe
Date of thesis defense: 13 July 2018
Date Deposited: 23 Jul 2018 12:53
Date: 2018
Faculties / Institutes: Fakultät für Chemie und Geowissenschaften > Institute of Organic Chemistry
Subjects: 540 Chemistry and allied sciences
Controlled Keywords: Diphenylacetylene, Tolane, Twisted
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