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Scholz AS, Massoth JG, Stoess L, Bolte M, Braun M, Lerner HW, Mewes JM, Wagner M, Froitzheim T. NBN- and BNB-Phenalenyls: the Yin and Yang of Heteroatom-doped π Systems. Chemistry 2024; 30:e202400320. [PMID: 38426580 DOI: 10.1002/chem.202400320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 02/29/2024] [Accepted: 03/01/2024] [Indexed: 03/02/2024]
Abstract
NBN- and BNB-doped phenalenyls are isoelectronic to phenalenyl anions and cations, respectively. They represent a pair of complementary molecules that have essentially identical structures but opposite properties as electron donors and acceptors. The NBN-phenalenyls 1-4 considered here were prepared from N,N'-dimethyl-1,8-diaminonaphthalene and readily available boron-containing building blocks (i. e., BH3⋅SMe2 (1), p-CF3-C6H4B(OH)2 (2), C6H5B(OH)2 (3), or MesBCl2/iPr2NEt (4)). Treatment of 1 with 4-Me2N-2,6-Me2-C6H2Li gave the corresponding NBN derivative 5. The BNB-phenalenyl 6 was synthesized from 1,8-naphthalenediyl-bridged diborane(6), PhNH2, and MesMgBr. A computational study reveals that the photoemission of 1, 4, and 5 originates from locally excited (LE) states at the NBN-phenalenyl fragments, while that of 2 is dominated by charge transfer (CT) from the NBN-phenalenyl to the p-CF3-C6H4 fragment. Depending on the dihedral angle θ between its Ph and NBN planes, compound 3 emits mainly from a less polar LE (θ >55°) or more polar CT state (θ <55°). In turn, the energetic preference for either state is governed by the polarity of the solvent used. An equimolar aggregate of the NBN- and BNB-phenalenyls 3 and 6 (in THF/H2O) shows a distinct red-shifted emission compared to that of the individual components, which originates from an intermolecular CT state.
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Affiliation(s)
- Alexander S Scholz
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt am Main, Max-von-Laue-Straße 7, 60438, Frankfurt am Main, Germany
| | - Julian G Massoth
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt am Main, Max-von-Laue-Straße 7, 60438, Frankfurt am Main, Germany
| | - Lennart Stoess
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt am Main, Max-von-Laue-Straße 7, 60438, Frankfurt am Main, Germany
| | - Michael Bolte
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt am Main, Max-von-Laue-Straße 7, 60438, Frankfurt am Main, Germany
| | - Markus Braun
- Institut für Physikalische und Theoretische Chemie, Goethe-Universität Frankfurt am Main, Max-von-Laue-Straße 7, 60438, Frankfurt am Main, Germany
| | - Hans-Wolfram Lerner
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt am Main, Max-von-Laue-Straße 7, 60438, Frankfurt am Main, Germany
| | - Jan-M Mewes
- Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich Wilhelms-Universität Bonn, Beringstr. 4, 53115, Bonn, Germany
| | - Matthias Wagner
- Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt am Main, Max-von-Laue-Straße 7, 60438, Frankfurt am Main, Germany
| | - Thomas Froitzheim
- Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich Wilhelms-Universität Bonn, Beringstr. 4, 53115, Bonn, Germany
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