Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation

Cyclic 6-membered aromatic compounds such as benzene and azabenzenes (pyridine, pyridazine, and pyrazine) are known to be light-sensitive, affording, in particular, the Dewar benzene type of intermediates. Pyridine is known to provide the only Dewar pyridine intermediate that undergoes reversible ri...

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Autores principales:	Evgenia Vaganova, Dror Eliaz, Ulyana Shimanovich, Gregory Leitus, Emad Aqad, Vladimir Lokshin, Vladimir Khodorkovsky
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	photochemistry aromatic heterocycle pyridine electroconducting polymer Organic chemistry QD241-441
Acceso en línea:	https://doaj.org/article/a6ae09408e3c45f9b7d13cd8b82d34c1
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spelling	oai:doaj.org-article:a6ae09408e3c45f9b7d13cd8b82d34c12021-11-25T18:28:29ZLight-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation10.3390/molecules262269251420-3049https://doaj.org/article/a6ae09408e3c45f9b7d13cd8b82d34c12021-11-01T00:00:00Zhttps://www.mdpi.com/1420-3049/26/22/6925https://doaj.org/toc/1420-3049Cyclic 6-membered aromatic compounds such as benzene and azabenzenes (pyridine, pyridazine, and pyrazine) are known to be light-sensitive, affording, in particular, the Dewar benzene type of intermediates. Pyridine is known to provide the only Dewar pyridine intermediate that undergoes reversible ring-opening. We found that irradiation of photosensitive gels prepared from poly(4-vinyl pyridine) and pyridine at 254 or 312 nm leads to pyridine ring-opening and subsequent formation of 5-amino-2,4-pentadienals. We show that this light-induced process is only partially reversible, and that the photogenerated aminoaldehyde and aminoaldehyde-pending groups undergo self-condensation to produce cross-linked, conjugated oligomers that absorb light in the visible spectrum up to the near-infrared range. Such a sequence of chemical reactions results in the formation of gel with two distinct morphologies: spheres and fiber-like matrices. To gain deeper insight into this process, we prepared poly(4-vinyl pyridine) with low molecular weight (about 2000 g/mol) and monitored the respective changes in absorption, fluorescence, <sup>1</sup>H-NMR spectra, and electrical conductivity. The conductivity of the polymer gel upon irradiation changes from ionic to electronic, indicative of a conjugated molecular wire behavior. Quantum mechanical calculations confirmed the feasibility of the proposed polycondensation process. This new polyacetylene analog has potential in thermal energy-harvesting and sensor applications.Evgenia VaganovaDror EliazUlyana ShimanovichGregory LeitusEmad AqadVladimir LokshinVladimir KhodorkovskyMDPI AGarticlephotochemistryaromatic heterocyclepyridineelectroconducting polymerOrganic chemistryQD241-441ENMolecules, Vol 26, Iss 6925, p 6925 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	photochemistry aromatic heterocycle pyridine electroconducting polymer Organic chemistry QD241-441
spellingShingle	photochemistry aromatic heterocycle pyridine electroconducting polymer Organic chemistry QD241-441 Evgenia Vaganova Dror Eliaz Ulyana Shimanovich Gregory Leitus Emad Aqad Vladimir Lokshin Vladimir Khodorkovsky Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation
description	Cyclic 6-membered aromatic compounds such as benzene and azabenzenes (pyridine, pyridazine, and pyrazine) are known to be light-sensitive, affording, in particular, the Dewar benzene type of intermediates. Pyridine is known to provide the only Dewar pyridine intermediate that undergoes reversible ring-opening. We found that irradiation of photosensitive gels prepared from poly(4-vinyl pyridine) and pyridine at 254 or 312 nm leads to pyridine ring-opening and subsequent formation of 5-amino-2,4-pentadienals. We show that this light-induced process is only partially reversible, and that the photogenerated aminoaldehyde and aminoaldehyde-pending groups undergo self-condensation to produce cross-linked, conjugated oligomers that absorb light in the visible spectrum up to the near-infrared range. Such a sequence of chemical reactions results in the formation of gel with two distinct morphologies: spheres and fiber-like matrices. To gain deeper insight into this process, we prepared poly(4-vinyl pyridine) with low molecular weight (about 2000 g/mol) and monitored the respective changes in absorption, fluorescence, <sup>1</sup>H-NMR spectra, and electrical conductivity. The conductivity of the polymer gel upon irradiation changes from ionic to electronic, indicative of a conjugated molecular wire behavior. Quantum mechanical calculations confirmed the feasibility of the proposed polycondensation process. This new polyacetylene analog has potential in thermal energy-harvesting and sensor applications.
format	article
author	Evgenia Vaganova Dror Eliaz Ulyana Shimanovich Gregory Leitus Emad Aqad Vladimir Lokshin Vladimir Khodorkovsky
author_facet	Evgenia Vaganova Dror Eliaz Ulyana Shimanovich Gregory Leitus Emad Aqad Vladimir Lokshin Vladimir Khodorkovsky
author_sort	Evgenia Vaganova
title	Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation
title_short	Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation
title_full	Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation
title_fullStr	Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation
title_full_unstemmed	Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation
title_sort	light-induced reactions within poly(4-vinyl pyridine)/pyridine gels: the 1,6-polyazaacetylene oligomers formation
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/a6ae09408e3c45f9b7d13cd8b82d34c1
work_keys_str_mv	AT evgeniavaganova lightinducedreactionswithinpoly4vinylpyridinepyridinegelsthe16polyazaacetyleneoligomersformation AT droreliaz lightinducedreactionswithinpoly4vinylpyridinepyridinegelsthe16polyazaacetyleneoligomersformation AT ulyanashimanovich lightinducedreactionswithinpoly4vinylpyridinepyridinegelsthe16polyazaacetyleneoligomersformation AT gregoryleitus lightinducedreactionswithinpoly4vinylpyridinepyridinegelsthe16polyazaacetyleneoligomersformation AT emadaqad lightinducedreactionswithinpoly4vinylpyridinepyridinegelsthe16polyazaacetyleneoligomersformation AT vladimirlokshin lightinducedreactionswithinpoly4vinylpyridinepyridinegelsthe16polyazaacetyleneoligomersformation AT vladimirkhodorkovsky lightinducedreactionswithinpoly4vinylpyridinepyridinegelsthe16polyazaacetyleneoligomersformation
_version_	1718411096798265344

Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation

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