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Rana SS, Choudhury J. Orchestrated Octuple C-H Activation: A Bottom-Up Topology Engineering Approach toward Stimuli-Responsive Double-Heptagon-Embedded Wavy Polycyclic Heteroaromatics. Angew Chem Int Ed Engl 2024; 63:e202406514. [PMID: 38758986 DOI: 10.1002/anie.202406514] [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: 04/06/2024] [Revised: 05/09/2024] [Accepted: 05/15/2024] [Indexed: 05/19/2024]
Abstract
Curiosity-driven innovations on the design and synthesis of nonplanar polycyclic aromatic/heteroaromatic compounds with new molecular topologies unfold exciting opportunities for harnessing their intriguing supramolecular properties and thereby the development of novel functional organic materials. This work presents such an innovative synthetic concept of a bottom-up molecular topology engineering through a unique orchestrated octuple C-H activation reaction, toward the rapid synthesis of a novel class of double heptagon-incorporated nitrogen-doped laterally-fused polycyclic compounds with rarely reported wavy structural configuration. The profound impact of the molecular wavy structures of these compounds on their properties is manifested by weak and tunable solid-state intermolecular interactions controlling the electronic properties of the materials, leading to reversibly switchable fluorochromism in the solid state and thin films with mechanical force and solvent vapors as external stimuli, thereby indicating their potential applicability in rewritable fluorescent optical recording media, security papers, mechanosensors, volatile organic compound (VOC) sensors etc.
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Affiliation(s)
- Samim Sohel Rana
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, 462 066, India
| | - Joyanta Choudhury
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, 462 066, India
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2
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Fukuda H, Tsurumaki E, Wakamatsu K, Toyota S. Unusually Short H⋅⋅⋅H Contacts in Intramolecularly Cyclized Helically Fused Anthracenes. Chemistry 2024; 30:e202401627. [PMID: 38751350 DOI: 10.1002/chem.202401627] [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: 04/24/2024] [Indexed: 06/27/2024]
Abstract
The intramolecular coupling of dichloro-substituted helically fused anthracenes using the Yamamoto coupling yielded cyclized products with sterically congested molecular structures. The X-ray analysis and DFT calculations showed that the aromatic framework adopted a nonplanar structure with a twisted conformation about the newly formed single bond, which acts as a chiral axis. Interestingly, the X-ray structure obtained through the Hirshfeld atom refinement revealed short interatomic distances between the inner hydrogen atoms (1.648-1.692 Å), much shorter than the sum of their van der Waals radii. Owing to these unusually short contacts, the 1H NMR spectrum exhibited a significant deshielding (12.5 ppm) and a large nuclear Overhauser effect (44 %). Additionally, the IR spectrum displayed a high-frequency shift of the C-H stretching vibration. These observations, along with the noncovalent interaction plot indicative of a characteristic steric environment, strongly support the presence of steric hindrance. Moreover, dynamic NMR measurement of the mesityl-substituted derivative yielded a barrier to helical inversion of 84 kJ mol-1. The optical properties and crystal packing of the cyclized products are also reported.
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Affiliation(s)
- Hiroki Fukuda
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Eiji Tsurumaki
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Kan Wakamatsu
- Department of Chemistry, Faculty of Science, Okayama University of Science, 1-1 Ridaicho, Kita-ku, Okayama, 700-0005, Japan
| | - Shinji Toyota
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551, Japan
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3
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Matsuo Y, Gon M, Tanaka K, Seki S, Tanaka T. Synthesis of Aza[ n]helicenes up to n = 19: Hydrogen-Bond-Assisted Solubility and Benzannulation Strategy. J Am Chem Soc 2024; 146:17428-17437. [PMID: 38866732 DOI: 10.1021/jacs.4c05156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
Synthetic challenges toward anomalous structures and electronic states often involve handling problems such as insolubility in common organic solvents and oxidative degradation under aerobic conditions. We designed benzo-annulated aza[n]helicenes, which benefit from both the suppressed elevation of highest occupied molecular orbital (HOMO) energies and high solubility due to hydrogen bonding with solvent molecules to overcome these challenges. This strategy enabled the synthesis of six new aza[n]helicenes ([n]AHs) of different lengths (n = 9-19) from acyclic precursors via one-pot intramolecular oxidative fusion reactions. The structures of all of the synthesized aza[n]helicenes were determined by X-ray diffraction (XRD) analysis, and their electrochemical potentials were measured by cyclic voltammetry. Among the synthesized aza[n]helicenes, [17]AH and [19]AH are the first heterohelicenes with a triple-layered helix. The noncovalent interaction (NCI) plots confirm the existence of an effective π-π interaction between the layers. The absorption and fluorescence spectra red-shifted as the helical lengths increased, without any distinct saturation points. The optical resolutions of N-butylated [9]AH, [11]AH, [13]AH, and [15]AH were accomplished, and their circular dichroism (CD) and circularly polarized luminescence (CPL) were measured. Thus, the structural, (chir)optical, and electrochemical properties of the aza[n]helicenes were comprehensively analyzed.
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Affiliation(s)
- Yusuke Matsuo
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Masayuki Gon
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kazuo Tanaka
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Shu Seki
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Takayuki Tanaka
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
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Mori T. Significance of Vibronic Coupling that Shapes Circularly Polarized Luminescence of Double Helicenes. Angew Chem Int Ed Engl 2024; 63:e202319702. [PMID: 38317539 DOI: 10.1002/anie.202319702] [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: 12/19/2023] [Revised: 01/31/2024] [Accepted: 02/05/2024] [Indexed: 02/07/2024]
Abstract
The circularly polarized luminescence (CPL) spectra of S- and X-shaped double helicenes exhibit distinct vibrational structures and overall shape variations. In this study, we conducted an in-depth investigation into the vibronic effects influencing the CPL spectra of two double helicenes, namely DPC and DNH. Employing state-of-the-art computations utilizing the FC-HT1|VH model at the CAM-B3LYP/def2-TZVP level, we unveiled the paramount impact of Franck-Condon (FC), Herzberg-Teller (HT), and Duschinsky effects on their chiroptical responses. Our research underscores the pivotal role of structural deformations associated with the S1-to-S0 electronic transition in molding CPL spectra and wavelength-dependent dissymmetry (g) factor values, as well as the significance of HT effects in shaping and enhancing CPL responses. This extensive investigation not only advances our comprehension of the vibronic characteristics in configurationally distinct double helicenes but also offers valuable insights for the design of chiral molecules featuring controllable or finely-tunable CPL responses.
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Affiliation(s)
- Tadashi Mori
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871, Japan
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Rana SS, Choudhury J. Unveiling N-Fused Nitreniums as Potent Catalytic Photooxidants. J Am Chem Soc 2024; 146:3603-3608. [PMID: 38293737 DOI: 10.1021/jacs.3c12606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
The first example of a hitherto-unknown facet of catalytic photooxidant capability of nitrenium cations is reported herein. The fundamental limitation of inability of the traditional and reported nitreniums to achieve the excited-state redox potential beyond +2.0 V (vs Ag/AgCl), the primary requirement for a powerful photooxidant, is addressed in this work by developing a structurally unique class of N-fused nitrenium cations, with the required structural engineering involving extensive π-conjugation through ring fusion at the nitrenium site, which enabled significant lowering of the LUMO energy and easy reduction at the excited state (excited-state redox potential up to +2.5 V vs Ag/AgCl), facilitated by effective delocalization/stabilization of the generated radical. This finding opens a new way to discover novel and useful (photo)catalytic properties of nitrenium cations beyond just Lewis acidity.
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Affiliation(s)
- Samim Sohel Rana
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal 462 066, India
| | - Joyanta Choudhury
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal 462 066, India
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Agrawal AR, Shiouki I, Deree Y, Bogoslavsky B, Gidron O. Controlling helicene's pitch by molecular tethering. Org Biomol Chem 2024; 22:1365-1368. [PMID: 38258458 DOI: 10.1039/d3ob02075d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
We applied post-cyclization annulation to introduce a series of tethered S-shaped double [4]helicenes in which the intramolecular tether imposes a specific helical handedness. Introducing a tether and then shortening the tether length incrementally increase the pitch angle of [4]helicene, thus enabling a quantitative study of the effects of helicene's pitch on its electronic and (chiro)optical properties.
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Affiliation(s)
- Abhijeet R Agrawal
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, Israel.
| | - Israa Shiouki
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, Israel.
| | - Yinon Deree
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, Israel.
| | - Benny Bogoslavsky
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, Israel.
| | - Ori Gidron
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, Israel.
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Matsuo Y, Maeda C, Tsutsui Y, Tanaka T, Seki S. Synthesis of Closed-Heterohelicenes Interconvertible between Their Monomeric and Dimeric Forms. Angew Chem Int Ed Engl 2023; 62:e202314968. [PMID: 37883214 DOI: 10.1002/anie.202314968] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 10/25/2023] [Accepted: 10/26/2023] [Indexed: 10/28/2023]
Abstract
Oxidative fusion reaction of cyclic heteroaromatic pentads consisting of pyrrole and thiophene gave closed-heterohelicene monomers and dimers depending on the oxidation conditions. Specifically, oxidation with [bis(trifluoroacetoxy)iodo]benzene (PIFA) gave closed-[7]helicene dimers connected at the β-position of one of the pyrrole units with remarkably elongated C-C bonds of about 1.60 Å. Although this bond was intact against thermal and physical activations, homolytic bond dissociation took place in DMSO upon irradiation with UV light to give the corresponding monomers. Thus, interconversion between the closed-helicene monomer and dimer was achieved. The optically pure dimer was photo-dissociated into the monomers associated with a turn-on of circularly polarized luminescence (CPL).
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Affiliation(s)
- Yusuke Matsuo
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Chihiro Maeda
- Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Okayama 700-8530, Japan
| | - Yusuke Tsutsui
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
- JST-PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Takayuki Tanaka
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Shu Seki
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
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Li R, Ma B, Li S, Lu C, An P. Chalcogen-doped, ( seco)-hexabenzocoronene-based nanographenes: synthesis, properties, and chalcogen extrusion conversion. Chem Sci 2023; 14:8905-8913. [PMID: 37621425 PMCID: PMC10445433 DOI: 10.1039/d3sc02595k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 07/16/2023] [Indexed: 08/26/2023] Open
Abstract
A series of chalcogen-doped nanographenes (NGs) and their oxides are described. Their molecular design is conceptually based on the insertion of different chalcogens into the hexa-peri-hexabenzocoronene (HBC) backbone. All the NGs adopt nonplanar conformations, which would show better solubility compared to planar HBC. Except for the oxygen-doped, saddle-shaped NG, the insertion of large chalcogens like sulfur and selenium leads to a seco-HBC-based, helical geometry. All the three-dimensional structures are unambiguously confirmed by single-crystal X-ray diffractometry. Their photophysical properties including UV-vis absorption, fluorescence, chiroptical, charge distribution, and orbital gaps are investigated experimentally or theoretically. The properties of each structure are significantly affected by the doped chalcogen and its related oxidative state. Notably, upon heating or adding an acid, the selenium-doped NG or its oxide undergoes a selenium extrusion reaction to afford seco-HBC or HBC quantitatively, which can be treated as precursors of hydrocarbon HBCs.
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Affiliation(s)
- Ranran Li
- School of Chemical Science and Technology, Yunnan University Kunming 650091 P. R. China
| | - Bin Ma
- School of Chemical Science and Technology, Yunnan University Kunming 650091 P. R. China
| | - Shengtao Li
- School of Chemical Science and Technology, Yunnan University Kunming 650091 P. R. China
| | - Chongdao Lu
- School of Chemical Science and Technology, Yunnan University Kunming 650091 P. R. China
| | - Peng An
- School of Chemical Science and Technology, Yunnan University Kunming 650091 P. R. China
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan University Kunming 650091 P. R. China
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Karak P, Mandal SK, Choudhury J. Exploiting the NADP +/NADPH-like Hydride-Transfer Redox Cycle with Bis-Imidazolium-Embedded Heterohelicene for Electrocatalytic Hydrogen Evolution Reaction. J Am Chem Soc 2023; 145:17321-17328. [PMID: 37499097 DOI: 10.1021/jacs.3c04737] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Generation of clean energy in a viable manner demands efficient and sustainable catalysts. One prospective method of clean energy generation is the electrochemical hydrogen evolution reaction (HER). Over the years, various transition metal-based complexes/polymeric organic materials were utilized in HER. However, the use of a redox-active small organic molecule as a catalyst for HER has not been explored well. The requirements of a strongly acidic solution, very high overpotential, and stability under acidic conditions pose several challenges for applying organic electrocatalysts for HER. Considering these challenges, herein, we demonstrated an NADP+-like organic system (NADP+ = nicotinamide adenine dinucleotide phosphate), a bis-imidazolium-fused heterohelicene, which acts as a catalyst for HER with mild acid (acetic acid) as a proton source at moderate overpotential. The unique structural backbone of this dicationic heterohelicene allowed to exploit the NADP+/NADPH-type (NADPH = reduced nicotinamide adenine dinucleotide phosphate) hydride transfer-based redox cycle efficiently under the applied conditions, where the NADPH-like hydride intermediate transfers the hydride to the proton of the mild acid to generate H2. The Faradaic efficiency and turnover number for the present HER were achieved up to 85 ± 5% and 50 ± 3, respectively. In addition, the maximum turnover frequency, TOFmax, value of 410 s-1 was observed, which is around 400 times that obtained for the existing reported NADP+-like organic compounds used as catalysts for HER. Thorough mechanistic studies were conducted experimentally and computationally to establish a plausible catalytic cycle. This advancement could help in designing efficient organic electrocatalysts for HER from a mild proton source.
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Affiliation(s)
- Pirudhan Karak
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, Madhya Pradesh 462 066, India
| | - Sanajit Kumar Mandal
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, Madhya Pradesh 462 066, India
| | - Joyanta Choudhury
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, Madhya Pradesh 462 066, India
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Karak P, Mandal SK, Choudhury J. Bis-Imidazolium-Embedded Heterohelicene: A Regenerable NADP + Cofactor Analogue for Electrocatalytic CO 2 Reduction. J Am Chem Soc 2023; 145:7230-7241. [PMID: 36944228 DOI: 10.1021/jacs.2c12883] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
Biomimetic NAD(P)H-type organic hydride donors have recently been advocated as potential candidates to act as metal-free catalysts for fuel-forming reactions such as the reduction of CO2 to formic acid and methanol, similar to the natural photosynthesis process of fixing CO2 into carbohydrates. Although these artificial synthetic organic hydrides are extensively used in organic reduction chemistry in a stoichiometric manner, translating them into catalysts has been challenging due to problems associated with the regeneration of these hydride species under applied reaction conditions. A recent discovery of the possibility of their regeneration under electrochemical conditions via a proton-coupled electron-transfer pathway triggered intense research to accomplish their catalytic use in electrochemical CO2 reduction reactions (eCO2RR). However, success is yet to be realized to term them as "true" catalysts, as the typical turnover numbers (TONs) of the eCO2RR processes on inert electrodes for the production of formic acid and/or methanol reported so far are still in the order of 10-3-10-2; thus, sub-stoichiometric only! Herein, we report a novel class of structurally engineered heterohelicene-based organic hydride donor with a proof-of-principle demonstration of catalytic electrochemical CO2 reduction reaction showing a significantly improved activity with more than stoichiometric turnover featuring a 100-1000-fold enhancement of the existing TON values. Mechanistic investigations suggested the critical role of the two cationic imidazolium motifs along with the extensive π-conjugation present in the backbone of the heterohelicene molecules in accessing and stabilizing various radical species involved in the generation and transfer of hydride, via multielectron-transfer steps in the electrochemical process.
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Affiliation(s)
- Pirudhan Karak
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal 462 066, India
| | - Sanajit Kumar Mandal
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal 462 066, India
| | - Joyanta Choudhury
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal 462 066, India
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