title: Synthesis and characterization of new bridged tolanes
creator: Kozhemyakin, Yury
subject: ddc-540
subject: 540 Chemistry and allied sciences
description: 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.
date: 2018
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/25115/1/Dissertation_Kozhemyakin_Yury_PDF-A.pdf
identifier: DOI:10.11588/heidok.00025115
identifier: urn:nbn:de:bsz:16-heidok-251151
identifier:   Kozhemyakin, Yury  (2018) Synthesis and characterization of new bridged tolanes.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/25115/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng