eprintid: 25115
rev_number: 14
eprint_status: archive
userid: 3889
dir: disk0/00/02/51/15
datestamp: 2018-07-23 12:53:55
lastmod: 2018-08-31 09:12:55
status_changed: 2018-07-23 12:53:55
type: doctoralThesis
metadata_visibility: show
creators_name: Kozhemyakin, Yury
title: Synthesis and characterization of new bridged tolanes
subjects: ddc-540
divisions: i-120100
adv_faculty: af-12
cterms_swd: Diphenylacetylene
cterms_swd: Tolane
cterms_swd: Twisted
abstract: 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
id_scheme: DOI
id_number: 10.11588/heidok.00025115
ppn_swb: 1655391178
own_urn: urn:nbn:de:bsz:16-heidok-251151
date_accepted: 2018-07-13
advisor: HASH(0x561a62873928)
language: eng
bibsort: KOZHEMYAKISYNTHESISA2018
full_text_status: public
citation:   Kozhemyakin, Yury  (2018) Synthesis and characterization of new bridged tolanes.  [Dissertation]     
document_url: https://archiv.ub.uni-heidelberg.de/volltextserver/25115/1/Dissertation_Kozhemyakin_Yury_PDF-A.pdf