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Li R, Liu J, Zhu T, Zhou F, Zhang H. Cascade Rearrangement: Nitro Group-Participating Syntheses of 1,2,5-Thiadiazoles and 1,2,4-Thiadiazolones. J Org Chem 2024; 89:4467-4473. [PMID: 38502932 DOI: 10.1021/acs.joc.3c02623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
A trifluoroacetic anhydride-mediated cascade process for the synthesis of thiadiazole derivatives is described. 1,2,5-Thiadiazoles and 1,2,4-thiadiazolones could be obtained by variation of the reaction conditions. A group of functionalized thiadiazole derivatives were synthesized in moderate to good yields from nitro-group-containing N-tert-butanesulfinamides. The reactions involved in this tandem process are a Pummerer-like rearrangement of the tert-butanesulfinamide unit, a nitrile oxide formation via nitro group rearrangement, addition of oxygenated nucleophiles, and an N-S bond forming cyclization followed by concomitant elimination.
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Affiliation(s)
- Rui Li
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan Key Laboratory of Research and Development for Natural Products, Yunnan Characteristic Plant Extraction Laboratory, School of Pharmacy, Yunnan University, Kunming, Yunnan 650091, P. R. China
| | - Jie Liu
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan Key Laboratory of Research and Development for Natural Products, Yunnan Characteristic Plant Extraction Laboratory, School of Pharmacy, Yunnan University, Kunming, Yunnan 650091, P. R. China
| | - Tuo Zhu
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan Key Laboratory of Research and Development for Natural Products, Yunnan Characteristic Plant Extraction Laboratory, School of Pharmacy, Yunnan University, Kunming, Yunnan 650091, P. R. China
| | - Feng Zhou
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan Key Laboratory of Research and Development for Natural Products, Yunnan Characteristic Plant Extraction Laboratory, School of Pharmacy, Yunnan University, Kunming, Yunnan 650091, P. R. China
| | - Hongbin Zhang
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan Key Laboratory of Research and Development for Natural Products, Yunnan Characteristic Plant Extraction Laboratory, School of Pharmacy, Yunnan University, Kunming, Yunnan 650091, P. R. China
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Chmovzh TN, Kudryashev TA, Alekhina DA, Rakitin OA. Palladium-Catalyzed Direct (Het)arylation Reactions of Benzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole and 4,8-Dibromobenzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole). Molecules 2023; 28:molecules28093977. [PMID: 37175386 PMCID: PMC10180130 DOI: 10.3390/molecules28093977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 04/26/2023] [Accepted: 05/06/2023] [Indexed: 05/15/2023] Open
Abstract
Palladium-catalyzed direct (het)arylation reactions of strongly electron-withdrawing tricyclic benzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole) and its 4,8-dibromo derivative were studied; the conditions for the selective formation of mono- and bis-aryl derivatives were found. The reaction of 4,8-dibromobenzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole) with thiophenes in the presence of palladium acetate as a catalyst and potassium pivalate as a base, depending on the conditions used, selectively gave both mono- and bis-thienylated benzo-bis-thiadiazoles in low to moderate yields; arenes were found to be inactive in these reactions. It was discovered that direct C-H arylation of benzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole with bromo(iodo)arenes and -thiophenes in the presence of Pd(OAc)2 and di-tert-butyl(methyl)phosphonium tetrafluoroborate salt is a powerful tool for the selective formation of 4-mono- and 4,8-di(het)arylated benzo-bis-thiadiazoles. Oxidative double C-H hetarylation of benzo[1,2-d:4,5-d']bis([1,2,3]thiadiazole with thiophenes in the presence of Pd(OAc)2 and silver (I) oxide in DMSO was successfully employed to prepare bis-thienylbenzo-bis-thiadiazoles in moderate yields.
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Affiliation(s)
- Timofey N Chmovzh
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia
- Nanotechnology Education and Research Center, South Ural State University, 454080 Chelyabinsk, Russia
| | - Timofey A Kudryashev
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia
- Department of Chemistry, Moscow State University, 119899 Moscow, Russia
| | - Daria A Alekhina
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia
- Higher Chemical College, Mendeleev University of Chemical Technology of Russia, 125047 Moscow, Russia
| | - Oleg A Rakitin
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia
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Synthesis and nucleophilic dearomatization of highly electrophilic [1,2,5]selenadiazolo[3,4-b]pyridines. Russ Chem Bull 2022. [DOI: 10.1007/s11172-022-3596-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Chmovzh TN, Rakitin OA. Benzobischalcogenadiazoles: synthesis and applications (microreview). Chem Heterocycl Compd (N Y) 2022. [DOI: 10.1007/s10593-022-03088-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Yu W, Wang L, Zhang N, Yan J, Zheng K. Wavelength-tunable fluorophores based on quinoline fused α-cyanovinyl derivatives: Synthesis, photophysics properties and imaging. Tetrahedron Lett 2022. [DOI: 10.1016/j.tetlet.2022.153996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Novel D-A-π-A1 Type Organic Sensitizers from 4,7-Dibromobenzo[d][1,2,3]thiadiazole and Indoline Donors for Dye-Sensitized Solar Cells. Molecules 2022; 27:molecules27134197. [PMID: 35807443 PMCID: PMC9267993 DOI: 10.3390/molecules27134197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 06/15/2022] [Accepted: 06/27/2022] [Indexed: 02/01/2023] Open
Abstract
Two novel D-A-π-A1 metal-free organic dyes of the KEA series containing benzo[d][1,2,3]thiadiazole (isoBT) internal acceptor, indoline donors fused with cyclopentane or cyclohexane rings (D), a thiophene as a π-spacer, and a cyanoacrylate as an anchor part were synthesized. Monoarylation of 4,7-dibromobenzo[d][1,2,3]thiadiazole by Suzuki-Miyamura cross-coupling reaction showed that in the case of indoline and carbazole donors, the reaction was non-selective, i.e., two monosubstituted derivatives were isolated in each case, whereas only one mono-isomer was formed with phenyl- and 2-thienylboronic acids. This was explained by the fact that heterocyclic indoline and carbazole fragments are much stronger donor groups compared to thiophene and benzene, as confirmed by cyclic voltammetry measurements and calculation of HOMO energies of indoline, carbazole, thiophene and benzene molecules. The structure of monoaryl(hetaryl) derivatives was strictly proven by NMR spectroscopy and X-ray diffraction. The optical and photovoltaic properties observed for the KEA dyes showed that these compounds are promising for the creation of solar cells. A comparison with symmetrical benzo[c][1,2,3]thiadiazole dyes WS-2 and MAX114 showed that the asymmetric nature of benzo[d][1,2,3]thiadiazole KEA dyes leads to a hypsochromic shift of the ICT band in comparison with the corresponding benzo[c][1,2,5]thiadiazole isomers. KEA dyes have a narrow HOMO-LUMO gap of 1.5–1.6 eV. Amongst these dyes, KEA321 recorded the best power efficiency (PCE), i.e., 5.17%, which is superior to the corresponding symmetrical benzo[c][1,2,3]thiadiazole dyes WS-2 and MAX114 (5.07 and 4.90%).
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3,4-Diaminopyridine-2,5-dicarbonitrile. MOLBANK 2022. [DOI: 10.3390/m1386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Pyridines fused with heterocyclic rings are of great interest as both photovoltaic materials and biologically active compounds. The most convenient precursors for these compounds are pyridine-2,3-diamines. In this communication, 3,4-diaminopyridine-2,5-dicarbonitrile was synthesized by the reaction of 2,5-dibromo-3,4-diaminopyridine with copper cyanide; the best yield of the target compound was achieved by heating the reaction mixture in N,N-dimethylformamide at 120 °C for 6 h. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR, IR, UV spectroscopy and mass-spectrometry.
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(E)-7-(4-(Diphenylamino)styryl)benzo[c][1,2,5]thiadiazole-4-carbonitrile. MOLBANK 2022. [DOI: 10.3390/m1385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Donor-acceptor-donor (D-A-A) structures with 2,1,3-benzothiadiazole as an internal acceptor and the 4(7)-cyanogroup as anchor acceptor have been investigated for various photovoltaic applications such as dye-sensitized solar cells (DSSCs) and organic light emitting diodes (OLEDs). They are usually obtained by cyanation of 4(7)-bromo-2,1,3-benzothiadiazoles. In this communication, the reaction of (E)-4-(2-(7-bromobenzo[c][1,2,5]thiadiazol-4-yl)vinyl)-N,N-diphenylaniline with cyanating agents was studied and it was shown that the best yield of (E)-7-(4-(diphenylamino)styryl)benzo[c][1,2,5]thiadiazole-4-carbonitrile was achieved by heating with zinc cyanide in NMP at 120 °C in the presence of tetrakis(triphenylphosphine)palladium (0). The structure of newly synthesized compound was established by means of an elemental analysis, high resolution mass-spectrometry, 1H, 13C-NMR, IR, UV spectroscopy and mass-spectrometry.
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Abstract
(Diphenylamino)phenylethenyl group-containing chromophores are widely employed to design effective materials with useful electronic properties. In this communication, (E)-4-(2-(7-Bromo-[1,2,5]thiadiazolo[3,4-c]pyridin-4-yl)vinyl)-N,N-diphenylaniline was regioselectively obtained by the Heck reaction of 4,7-dibromo-[1,2,5]thiadiazolo[3,4-c]pyridine with N,N-diphenyl-4-vinylaniline. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C, NOESY NMR, IR and UV spectroscopy and mass-spectrometry.
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Abstract
Bromoderivatives of benzofused 1,2,5-thiadiazoles are important precursors for the synthesis of dyes, which are widely used to design effective photovoltaic materials. In this study, 4-bromobenzo[1,2-d:4,5-d′]bis([1,2,3]thiadiazole was selectively obtained from the bromination of benzo[1,2-d:4,5-d′]bis([1,2,3]thiadiazole. The structure of the newly synthesized compound was established by means of elemental analysis, high-resolution mass spectrometry, 1H-, 13C-NMR, IR and UV spectroscopy and mass spectrometry.
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Korshunov VM, Chmovzh TN, Chkhetiani GR, Taydakov IV, Rakitin OA. New D–A–D luminophores of the [1,2,5]thiadiazolo[3,4-d]pyridazine series. MENDELEEV COMMUNICATIONS 2022. [DOI: 10.1016/j.mencom.2022.05.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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4,7-Bis(5-(9-hexyl-9H-carbazol-3-yl)thiophen-2-yl)-[1,2,5]thiadiazolo[3,4-d]pyridazine. MOLBANK 2022. [DOI: 10.3390/m1332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Donor molecules of the D-π-A-π-D type structure are often used for applications in organic photovoltaics. In this communication, bromination of 4,7-di(thiophen-2-yl)-[1,2,5]thiadiazolo[3,4-d]pyridazine followed by Suzuki cross-coupling with carbazoleboronic acid gave 4,7-bis( 5-(9-hexyl-9H-carbazol-3-yl)thiophen-2-yl)-[1,2,5]thiadiazolo[3,4-d]pyridazine. The structure of the newly synthesized compounds was established by high resolution mass-spectrometry, 1H, 13C NMR, IR, and UV spectroscopy and mass-spectrometry. A study of the luminescent properties of the dye showed that it exhibits fluorescence in the near infrared region of the spectrum, which makes it a promising compound for use as an active emitting layer in NIR OLED as well as for other possible applications as an IR luminophore.
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Makarov AY, Volkova YM, Zikirin SB, Irtegova IG, Bagryanskaya IY, Gatilov YV, Nefedov AA, Zibarev AV. New 3,1,2,4-benzothiaselenadiazines, related π-heterocycles including Herz cations, radicals and molecular complexes, and Bunte salts. NEW J CHEM 2022. [DOI: 10.1039/d1nj05979c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
3,1,2,4-Benzothiaselenadiazines, 1,3,2,4-benzodithiadiazines and 1,2,4,3,5-benzotrithiadiazepines are synthesized from Ar–NSN–SiMe3 and chalcogen chlorides, and converted into Herz salts, radicals and molecular complexes, and S- and Se-Bunte salts.
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Affiliation(s)
- Alexander Yu. Makarov
- N. N. Vorozhtsov Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation
| | - Yulia M. Volkova
- N. N. Vorozhtsov Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation
| | - Samat B. Zikirin
- V. V. Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation
| | - Irina G. Irtegova
- N. N. Vorozhtsov Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation
| | - Irina Yu. Bagryanskaya
- N. N. Vorozhtsov Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation
| | - Yuri V. Gatilov
- N. N. Vorozhtsov Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation
| | - Andrey A. Nefedov
- N. N. Vorozhtsov Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation
| | - Andrey V. Zibarev
- N. N. Vorozhtsov Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation
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4,7-Bis(1,2,3,4,4a,9a-Hexahydro-9H-carbazol-9-yl)-[1,2,5]oxadiazolo[3,4-d]pyridazine. MOLBANK 2021. [DOI: 10.3390/m1295] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
New donor-acceptor-donor (D-A-D)-type structures are widely used to design effective organic light-emitting diodes (OLEDs). In this communication, 4,7-bis(1,2,3,4,4a,9a-hexahydro-9H-carbazol-9-yl)-[1,2,5]oxadiazolo[3,4-d]pyridazine was obtained in a 65% yield by the treatment of 4,7-dichloro[1,2,5]oxadiazolo[3,4-d]pyridazine 1-oxide with 2,3,4,4a,9,9a-hexahydro-1H-carbazole. The structure of the newly synthesized compounds was established by means of an elemental analysis, 1H, 13C NMR, IR and UV spectroscopy, and HRMS and LR mass-spectrometry.
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Benzothiadiazole vs. iso-Benzothiadiazole: Synthesis, Electrochemical and Optical Properties of D-A-D Conjugated Molecules Based on Them. Molecules 2021; 26:molecules26164931. [PMID: 34443520 PMCID: PMC8399333 DOI: 10.3390/molecules26164931] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/10/2021] [Accepted: 08/11/2021] [Indexed: 11/24/2022] Open
Abstract
This paper presents an improved synthesis of 4,7-dibromobenzo[d][1,2,3]thiadiazole from commercially available reagents. According to quantum-mechanical calculations, benzo[d][1,2,3]thiadiazole (isoBTD) has higher values of ELUMO and energy band gap (Eg), which indicates high electron conductivity, occurring due to the high stability of the molecule in the excited state. We studied the cross-coupling reactions of this dibromide and found that the highest yields of π-spacer–acceptor–π-spacer type compounds were obtained by means of the Stille reaction. Therefore, 6 new structures of this type have been synthesized. A detailed study of the optical and electrochemical properties of the obtained π-spacer–acceptor–π-spacer type compounds in comparison with isomeric structures based on benzo[c][1,2,5]thiadiazole (BTD) showed a red shift of absorption maxima with lower absorptive and luminescent capacity. However, the addition of the 2,2′-bithiophene fragment as a π-spacer resulted in an unexpected increase of the extinction coefficient in the UV/vis spectra along with a blue shift of both absorption maxima for the isoBTD-based compound as compared to the BTD-based compound. Thus, a thorough selection of components in the designing of appropriate compounds with benzo[d][1,2,3]thiadiazole as an internal acceptor can lead to promising photovoltaic materials.
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Pakulski P, Pinkowicz D. 1,2,5-Thiadiazole 1,1-dioxides and Their Radical Anions: Structure, Properties, Reactivity, and Potential Use in the Construction of Functional Molecular Materials. Molecules 2021; 26:4873. [PMID: 34443461 PMCID: PMC8400987 DOI: 10.3390/molecules26164873] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/07/2021] [Accepted: 08/09/2021] [Indexed: 11/19/2022] Open
Abstract
This work provides a summary of the preparation, structure, reactivity, physicochemical properties, and main uses of 1,2,5-thiadiazole 1,1-dioxides in chemistry and material sciences. An overview of all currently known structures containing the 1,2,5-thiadiazole 1,1-dioxide motif (including the anions radical species) is provided according to the Cambridge Structural Database search. The analysis of the bond lengths typical for neutral and anion radical species is performed, providing a useful tool for unambiguous assessment of the valence state of the dioxothiadiazole-based compounds based solely on the structural data. Theoretical methodologies used in the literature to describe the dioxothiadiazoles are also shortly discussed, together with the typical 'fingerprint' of the dioxothiadiazole ring reported by means of various spectroscopic techniques (NMR, IR, UV-Vis). The second part describes the synthetic strategies leading to 1,2,5-thiadiazole 1,1-dioxides followed by the discussion of their electrochemistry and reactivity including mainly the chemical methods for the successful reduction of dioxothiadiazoles to their anion radical forms and the ability to form coordination compounds. Finally, the magnetic properties of dioxothiadiazole radical anions and the metal complexes involving dioxothiadiazoles as ligands are discussed, including simple alkali metal salts and d-block coordination compounds. The last section is a prospect of other uses of dioxothiadiazole-containing molecules reported in the literature followed by the perspectives and possible future research directions involving these compounds.
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Affiliation(s)
- Paweł Pakulski
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
| | - Dawid Pinkowicz
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
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Konstantinova LS, Rakitin OA. Chalcogen exchange in chalcogen–nitrogen π-heterocycles. MENDELEEV COMMUNICATIONS 2021. [DOI: 10.1016/j.mencom.2021.07.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
New heterocyclic systems containing 1,2,5-chalcogenadiazoles are of great interest for the creation of organic photovoltaic materials and biologically active compounds. In this communication, 3,6-dibromopyridazine-4,5-diamine was investigated in reaction with selenium dioxide in order to obtain 4,7-dibromo-[1,2,5]selenadiazolo[3,4-d]pyridazine. We found that 7-bromo-[1,2,5]selenadiazolo[3,4-d]pyridazin-4(5H)-one, the first representative of the new heterocyclic system, was isolated as a hydrolysis product of the corresponding 4,7-dibromoderivative. The structure of the newly synthesized compound was established by means of elemental analysis, high-resolution mass spectrometry, 1H, 13C NMR, IR and UV spectroscopy, and mass spectrometry.
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Abstract
Dibromoderivatives of benzofused chalcogen-nitrogen heterocycles are important precursors in the synthesis of various photovoltaic materials. 4,7-Dibromobenzo[d][1,2,3]thiadiazole is a practically unexplored compound in this series. In this communication, it was shown that the nucleophilic substitution of 4,7-dibromobenzo[d][1,2,3]thiadiazole with morpholine gave selectively 4-substituted product—4-(7-bromobenzo[d][1,2,3]thiadiazol-4-yl)morpholine. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR, and IR spectroscopy, mass-spectrometry, and X-ray analysis.
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Sukhikh TS, Khisamov RM, Konchenko SN. Unexpectedly Long Lifetime of the Excited State of Benzothiadiazole Derivative and Its Adducts with Lewis Acids. Molecules 2021; 26:molecules26072030. [PMID: 33918327 PMCID: PMC8038179 DOI: 10.3390/molecules26072030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 03/26/2021] [Accepted: 03/30/2021] [Indexed: 11/29/2022] Open
Abstract
We report a study of photoluminescent properties of 4-bromo-7-(3-pyridylamino)-2,1,3-benzothiadiazole (Py-btd) and its novel Lewis adducts: (PyH-btd)2(ZnCl4) and [Cu2Cl2(Py-btd)2{PPO}2]·2C7H8 (PPO = tetraphenyldiphosphine monoxide), whose crystal structure was determined by X-ray diffraction analysis. Py-btd exhibits a lifetime of 9 microseconds indicating its phosphorescent nature, which is rare for purely organic compounds. This phenomenon arises from the heavy atom effect: the presence of a bromine atom in Py-btd promotes mixing of the singlet and triplet states to allow efficient singlet-to-triplet intersystem crossing. The Lewis adducts also feature a microsecond lifetime while emitting in a higher energy range than free Py-btd, which opens up the possibility to color-tune luminescence of benzothiadiazole derivatives.
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