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Vaganova E, Eliaz D, Shimanovich U, Leitus G, Aqad E, Lokshin V, Khodorkovsky V. Light-Induced Reactions within Poly(4-vinyl pyridine)/Pyridine Gels: The 1,6-Polyazaacetylene Oligomers Formation. Molecules 2021; 26:6925. [PMID: 34834017 PMCID: PMC8621047 DOI: 10.3390/molecules26226925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 11/14/2021] [Accepted: 11/15/2021] [Indexed: 11/16/2022] Open
Abstract
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, 1H-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.
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Affiliation(s)
- Evgenia Vaganova
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel; (E.V.); (D.E.)
| | - Dror Eliaz
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel; (E.V.); (D.E.)
| | - Ulyana Shimanovich
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel; (E.V.); (D.E.)
| | - Gregory Leitus
- Chemical Research Support Department, Weizmann Institute of Science, Rehovot 7610001, Israel;
| | - Emad Aqad
- DuPont Electronics & Industrial, Marlborough, MA 01752, USA
| | - Vladimir Lokshin
- Aix Marseille Univ, CNRS UMR 7325, Centre Interdisciplinaire de Nanoscience de Marseille (CINaM) Campus de Luminy, CEDEX 09, 13288 Marseille, France;
| | - Vladimir Khodorkovsky
- Aix Marseille Univ, CNRS UMR 7325, Centre Interdisciplinaire de Nanoscience de Marseille (CINaM) Campus de Luminy, CEDEX 09, 13288 Marseille, France;
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Wieszczycka K, Zembrzuska J. Photodegradation of Hydrophobic Pyridineketoximes in Toluene and Heptane. Photochem Photobiol 2015; 91:786-96. [PMID: 25763903 DOI: 10.1111/php.12453] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 03/08/2015] [Indexed: 11/28/2022]
Abstract
The goal of the research was to study the reactivity of the hydrophobic 2- and 3-pyridineketoximes under exposure to UV-VIS light. The photodegradation was conducted in both toluene and heptane for 10 h under atmosphere of argon. Ten-hour irradiation experiments demonstrated that the pyridineketoximes underwent the facile E-Z photoisomerization, photo-Beckmann rearrangement, and to a lesser extent, the photosubstitution to the pyridine ring. From LC-MS and NMR analysis of the irradiated solutions, it was found that the photosubstitution proceeded to give the corresponding 6-substituted 2- or 3-pyridylketoxime via the replacement of the ring hydrogen by the benzyl or heptyl group. The photo-Beckmann rearrangement led to the formation of the corresponding amides, but also other products formed in the photo-decomposition reaction.
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Affiliation(s)
- Karolina Wieszczycka
- Poznan University of Technology, Institute of Chemical Technology and Engineering, Poznan, Poland
| | - Joanna Zembrzuska
- Poznan University of Technology, Institute of Chemistry and Technical Electrochemistry, Poznan, Poland
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Hamouda AK, Jin X, Sanghvi M, Srivastava S, Pandhare A, Duddempudi PK, Steinbach JH, Blanton MP. Photoaffinity labeling the agonist binding domain of alpha4beta4 and alpha4beta2 neuronal nicotinic acetylcholine receptors with [(125)I]epibatidine and 5[(125)I]A-85380. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1987-95. [PMID: 19545536 DOI: 10.1016/j.bbamem.2009.06.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2009] [Revised: 06/15/2009] [Accepted: 06/16/2009] [Indexed: 11/26/2022]
Abstract
The development of nicotinic acetylcholine receptor (nAChR) agonists, particularly those that discriminate between neuronal nAChR subtypes, holds promise as potential therapeutic agents for many neurological diseases and disorders. To this end, we photoaffinity labeled human alpha4beta2 and rat alpha4beta4 nAChRs affinity-purified from stably transfected HEK-293 cells, with the agonists [(125)I]epibatidine and 5[(125)I]A-85380. Our results show that both agonists photoincorporated into the beta4 subunit with little or no labeling of the beta2 and alpha4 subunits respectively. [(125)I]epibatidine labeling in the beta4 subunit was mapped to two overlapping proteolytic fragments that begin at beta4V102 and contain Loop E (beta4I109-P120) of the agonist binding site. We were unable to identify labeled amino acid(s) in Loop E by protein sequencing, but we were able to demonstrate that beta4Q117 in Loop E is the principal site of [(125)I]epibatidine labeling. This was accomplished by substituting residues in the beta2 subunit with the beta4 homologs and finding [(125)I]epibatidine labeling in beta4 and beta2F119Q subunits with little, if any, labeling in alpha4, beta2, or beta2S113R subunits. Finally, functional studies established that the beta2F119/beta4Q117 position is an important determinant of the receptor subtype-selectivity of the agonist 5I-A-85380, affecting both binding affinity and channel activation.
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Affiliation(s)
- Ayman K Hamouda
- Department of Pharmacology and Neuroscience and the Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, 3601 4th Street, Lubbock, TX 79430, USA
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Shibamoto TY. Photochemistry of Fragrance Materials. II. Aromatic Compounds and Phototoxicity. ACTA ACUST UNITED AC 2008. [DOI: 10.3109/15569528309036266] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Borowiak-Resterna A, Klonowska K, Olszanowski A, Tomaszewska M. Photostability of hydrophobic amides of pyridinecarboxylic acid as copper extractants from chloride media. J Photochem Photobiol A Chem 2007. [DOI: 10.1016/j.jphotochem.2006.06.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Affiliation(s)
- M. Rama Devi
- a Regional Research Laboratory , Hyderabad , 500 007 , India
| | | | - V. R. Srinivasan
- b Department of Chemistry , Osmania University , Hyderabad , 500 007 , India
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Rollet F, Richard C, Aguer JP. Laser flash photolysis study of nicotinic acid in water. J Photochem Photobiol A Chem 2002. [DOI: 10.1016/s1010-6030(02)00238-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Abstract
The monoazaaromatics, pyridine (1), hexyl nicotinate (2), and quinoline (3) and diazaaromatics, pyrimidine (4) and purine (5), readily act as photo-initiators for the peroxidation of methyl linoleate in 0.50 M SDS at 37 degrees C giving free radical chain oxidations of linoleate. Quantitative kinetic runs on the order in substate, RH, and in the rate of chain initiation, Ri, showed that the classical rate law for autoxidation, -d[O2]/dt = (kp/(2 kt 1/2))[RH] x Ri 1/2, is applicable to these photo-initiated oxidations. The oxidizability of methyl linoleate under these conditions is 2.92 x 10(-2) M-1/2 s-1/2. These peroxidations were inhibited by chromanol phenolic antioxidants of the vitamin E class, such as lipid-soluble 2,2,5,7,8-pentamethyl-6-hydroxychroman (PMHC) and water-soluble 2-carboxy- 2,5,7,8-tetramethyl-6-hydroxychroman (Trolox) and derived rate constants for inhibition of peroxidation were kinh (PMHC) = 4.35 x 10(4) M-1 s-1 and k(inh) (Trolox) = 2.81 x 10(4) M-1 s-1 during inhibited oxidation of methyl linoleate photo-initiated by 4. The products from photo-initiated peroxidation of methyl linoleate by 1 through 5 were determined by reduction and high-performance liquid chromatography analyses to be the 9- and 13-positional hydroperoxides of the four geometrical isomers: cis-9, trans-11 (6), trans-10, cis-12 (7), trans-9, trans-11 (8), and trans-10, trans-12 (9)-octadecadienoates typical of the free radical chain mechanism of lipid peroxidation. Products from dye-sensitized oxidation by Methylene Blue or Rose Bengal of methyl linoleate gave a product distribution of six hydroperoxides typical of oxidation by singlet oxygen. Thermal or photo-initiated peroxidation of methyl linoleate in SDS gave some selectivity of oxidation at the 13-position of the linoleate chain. The ratio of 13- to 9-oxidation varied in the range 1.23 to 1.14 as the cis/trans to trans/trans ratio of geometrical isomers varied from 0.44 to 1.25 during photooxidation of increased amounts of linoleate in SDS. This selectivity is attributed to loss of the pseudo symmetry around the pentadienyl system in the lipid chain in the SDS system during the peroxidation.
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Affiliation(s)
- L R Barclay
- Chemistry Department, Mount Allison University, Sackville N.B, Canada
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Middleton RE, Cohen JB. Mapping of the acetylcholine binding site of the nicotinic acetylcholine receptor: [3H]nicotine as an agonist photoaffinity label. Biochemistry 1991; 30:6987-97. [PMID: 2069955 DOI: 10.1021/bi00242a026] [Citation(s) in RCA: 164] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The agonist [3H]nicotine was used as a photoaffinity label for the acetylcholine binding sites on the Torpedo nicotinic acetylcholine receptor (AChR). [3H]nicotine binds at equilibrium with Keq = 0.6 microM to the agonist binding sites. Irradiation with 254-nm light of AChR-rich membranes equilibrated with [3H]nicotine resulted in covalent incorporation into the alpha- and gamma-subunits, which was inhibited by agonists and competitive antagonists but not by noncompetitive antagonists. Inhibition of labeling by d-tubocurarine demonstrated that the alpha-subunit was labeled via both agonist sites but the gamma-subunit was labeled only via the site that binds d-tubocurarine with high affinity. Within the alpha-subunit, 93% of the labeling was contained within a 20-kDa Staphylococcus aureus V8 proteolytic fragment beginning at Ser-173. Sequence analysis of this peptide indicated that approximately 80% of the incorporation was into Tyr-198, approximately 13% was into Cys-192, and approximately 7% was into Tyr-190. Chymotryptic digestion of the alpha-subunit confirmed that Tyr-198 was the principal amino acid labeled by [3H]nicotine. This confirmation required a novel radio-sequencing strategy employing omicron-phthalaldehyde, since the efficiency of photolabeling was low (approximately 1.0%) and the labeled chymotryptic peptide was not isolated in sufficient quantity to be identified by mass. [3H]Nicotine, which is the first photoaffinity agonist used, labels primarily Tyr-198 in contrast to competitive antagonist affinity labels, which label primarily Tyr-190 and Cys-192/Cys-193.
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Affiliation(s)
- R E Middleton
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110
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Cossy J, Pete JP. Photodehydrogenation of substituted pyrrolidines hydrogen transfer induced by benzophenone. Tetrahedron Lett 1978. [DOI: 10.1016/s0040-4039(01)85776-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Castellano A, Catteau J, Lablache-Combier A. Mechanism of the photochemical substitution of 6-membered ring monoazaaromatic compounds by methanol in neutral and HCl acidified medium. Tetrahedron 1975. [DOI: 10.1016/0040-4020(75)80224-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Mechanism of the photochemical addition-substitution reactions of six-membered aza aromatic compounds in hydrogen-containing solvents (review). Chem Heterocycl Compd (N Y) 1974. [DOI: 10.1007/bf00471348] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Castellano A, Catteau JP, Lablache-Combier A, Allan G. FORMATION OF SEMIQUINONE RADICALS BY ULTRAVIOLET IRRADIATION OF PYRIMIDINES IN METHANOL. Photochem Photobiol 1974. [DOI: 10.1111/j.1751-1097.1974.tb06543.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Hata N, Saito T. The Photochemistry of 2-Quinolinecarbonitriles. II. A Mechanism of the Photoinduced Substitution Reaction. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1974. [DOI: 10.1246/bcsj.47.942] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Minisci F, Porta O. Advances in Homolytic Substitution of Heteroaromatic Compounds. ADVANCES IN HETEROCYCLIC CHEMISTRY 1974. [DOI: 10.1016/s0065-2725(08)60461-4] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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