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Shoji T, Yamazaki A, Ariga Y, Uda M, Ando D, Sasahara N, Kai N, Ito S. Azulene-Substituted Donor-Acceptor Polymethines and 1,6'-Bi-, 1,6';3,6''-Ter-, and Quinqueazulenes via Zincke Salts: Synthesis, and Structural, Optical, and Electrochemical Properties. Chempluschem 2021; 86:946-966. [PMID: 33973729 DOI: 10.1002/cplu.202100174] [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: 04/15/2021] [Revised: 04/26/2021] [Indexed: 11/06/2022]
Abstract
Azulene-substituted donor-acceptor polymethines, bi-, ter-, and quinqueazulenes composed of the 1,6'-biazulene unit have been successfully prepared from corresponding Zincke salts. The synthesis of polymethines through the reaction of Zincke salts with several amines, followed by a Knoevenagel reaction with malononitrile, was accomplished in moderate to high yields (40-92 %). Meanwhile, the reaction of Zincke salts with secondary amines and the subsequent sequential condensation-cyclization with cyclopentadienide ions, so-called Ziegler-Hafner method, produced the corresponding 1,6'-biazulenes, 1,6';3,6''-terazulenes, and quinqueazulene, respectively. The structural, optical, and electrochemical properties of the azulene-substituted donor-acceptor polymethines, bi-, ter-, and quinqueazulenes were revealed by single-crystal X-ray structure analysis, UV/vis spectroscopy, voltammetry analysis, spectroelectrochemistry, and theoretical calculations. These results suggested that the substituents on the azulene ring and their substitution positions directly affect their reactivities, optical and electrochemical properties.
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Affiliation(s)
- Taku Shoji
- Department of Material Science, Graduate School of Science and Technology, Shinshu University, Matsumoto, 390-8621, Nagano, Japan
- Department of Chemistry, Faculty of Science, Shinshu University, Matsumoto, 390-8621, Nagano, Japan
| | - Akari Yamazaki
- Department of Material Science, Graduate School of Science and Technology, Shinshu University, Matsumoto, 390-8621, Nagano, Japan
| | - Yukino Ariga
- Department of Material Science, Graduate School of Science and Technology, Shinshu University, Matsumoto, 390-8621, Nagano, Japan
| | - Mayumi Uda
- Department of Material Science, Graduate School of Science and Technology, Shinshu University, Matsumoto, 390-8621, Nagano, Japan
| | - Daichi Ando
- Department of Chemistry, Faculty of Science, Shinshu University, Matsumoto, 390-8621, Nagano, Japan
| | - Nichika Sasahara
- Department of Chemistry, Faculty of Science, Shinshu University, Matsumoto, 390-8621, Nagano, Japan
| | - Naohito Kai
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, 036-8561, Aomori, Japan
| | - Shunji Ito
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, 036-8561, Aomori, Japan
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Reissig HU. A Homage to Siegfried Hünig and His Research. Angew Chem Int Ed Engl 2021; 60:9180-9191. [PMID: 33738963 DOI: 10.1002/anie.202101550] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Indexed: 11/07/2022]
Abstract
Examples from different research areas of Siegfried Hünig are displayed to remind us that organic chemistry owes much more than Hünig's base to this exceptionally versatile and creative chemist. The main research lines dealing with the synthesis and physical characterization of new dyes, multistage redox systems, and organic metals will be presented as well as his contributions to enamine chemistry, the discovery of diimine as a hydrogenation agent, and nucleophilic acylation with trimethylsilyl cyanide, which are less well-known nowadays. In addition, exotic compounds with parallel C=C and N=N bonds were systematically studied in Hünig's group. Reflecting on the development of his research demonstrates both the importance of a systematic approach and how fruitful entirely unexpected results are if they meet a "well-prepared mind". During Hünig's academic career, teaching played an indisputable role. His efforts in modernizing the chemistry institute at Würzburg and his support of young researchers in the academic system in Germany are also highlighted.
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Affiliation(s)
- Hans-Ulrich Reissig
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195, Berlin, Germany
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Arjona-Esteban A, Stolte M, Würthner F. Conformational Switching of π-Conjugated Junctions from Merocyanine to Cyanine States by Solvent Polarity. Angew Chem Int Ed Engl 2016; 55:2470-3. [PMID: 26797795 DOI: 10.1002/anie.201510620] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Indexed: 12/21/2022]
Abstract
Directed by the solvent polarity, the prevalent conformation of a polymethine dye bearing a branched π-conjugated junction can be switched from a heptamethine donor-acceptor (DA) merocyanine-type π-conjugated system to a nonamethine DAD cyanine-type π-conjugated scaffold. Concomitantly the absorption maximum shifts from 585 nm in dichloromethane to 748 nm in methanol solution.
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Affiliation(s)
- Alhama Arjona-Esteban
- Universität Würzburg, Institut für Organische Chemie and Center for Nanosystems Chemistry, Am Hubland, 97074, Würzburg, Germany
| | - Matthias Stolte
- Universität Würzburg, Institut für Organische Chemie and Center for Nanosystems Chemistry, Am Hubland, 97074, Würzburg, Germany
| | - Frank Würthner
- Universität Würzburg, Institut für Organische Chemie and Center for Nanosystems Chemistry, Am Hubland, 97074, Würzburg, Germany.
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Arjona-Esteban A, Stolte M, Würthner F. Conformational Switching of π-Conjugated Junctions from Merocyanine to Cyanine States by Solvent Polarity. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201510620] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Alhama Arjona-Esteban
- Universität Würzburg; Institut für Organische Chemie and Center for Nanosystems Chemistry; Am Hubland 97074 Würzburg Germany
| | - Matthias Stolte
- Universität Würzburg; Institut für Organische Chemie and Center for Nanosystems Chemistry; Am Hubland 97074 Würzburg Germany
| | - Frank Würthner
- Universität Würzburg; Institut für Organische Chemie and Center for Nanosystems Chemistry; Am Hubland 97074 Würzburg Germany
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