1
|
Mishra S, Vilas-Varela M, Fatayer S, Albrecht F, Peña D, Gross L. Observation of SOMO-HOMO Inversion in a Neutral Polycyclic Conjugated Hydrocarbon. ACS NANO 2024; 18:15898-15904. [PMID: 38833667 PMCID: PMC11191738 DOI: 10.1021/acsnano.4c03257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 05/17/2024] [Accepted: 05/24/2024] [Indexed: 06/06/2024]
Abstract
We report the generation of a nonbenzenoid polycyclic conjugated hydrocarbon, which consists of a biphenyl moiety substituted by indenyl units at the 4,4' positions, on ultrathin sodium chloride films by tip-induced chemistry. Single-molecule characterization by scanning tunneling and atomic force microscopy reveals an open-shell biradical ground state with a peculiar electronic configuration wherein the singly occupied molecular orbitals (SOMOs) are lower in energy than the highest occupied molecular orbital (HOMO).
Collapse
Affiliation(s)
| | - Manuel Vilas-Varela
- Center
for Research in Biological Chemistry and Molecular Materials (CiQUS)
and Department of Organic Chemistry, University
of Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Shadi Fatayer
- Applied
Physics Program, Physical Science and Engineering Division, King Abdullah University of Science and Technology
(KAUST), Thuwal 23955-6900, Kingdom
of Saudi Arabia
| | | | - Diego Peña
- Center
for Research in Biological Chemistry and Molecular Materials (CiQUS)
and Department of Organic Chemistry, University
of Santiago de Compostela, Santiago de Compostela 15782, Spain
- Oportunius, Galician
Innovation Agency (GAIN), Santiago
de Compostela 15702, Spain
| | - Leo Gross
- IBM
Research Europe − Zurich, Rüschlikon 8803, Switzerland
| |
Collapse
|
2
|
Sakamaki T, Zhang Y, Fukuma S, Cruz CM, Valdivia AC, Campaña AG, Casado J, Shang R, Nakamura E. Doubly Spiro-Conjugated Chiral Carbocycles Exhibiting SOMO-HOMO Inversion in Persistent Radical Cations. J Am Chem Soc 2024; 146:12712-12722. [PMID: 38655573 DOI: 10.1021/jacs.4c02404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Persistent chiral organic open-shell systems have captured growing interest due to their potential applications in organic spintronic and optoelectronic devices. Nevertheless, the integration of configurationally stable chirality into an organic open-shell system continues to pose challenges in molecular design. The π-extended skeleton incorporated in spiro-conjugated carbocycles can provide robust chiroptical properties and a significant stabilization of the excited and ionic radical states. However, this approach has been relatively less explored in the design of persistent organic open-shell systems. We report here the (S,S)-, (R,R)-, and meso-isomers of doubly spiro-conjugated carbocycles featuring flat and rigid carbon-bridged para-phenylenevinylene (CPV) of different conjugation lengths connected by two spiro-carbon centers, which we denote D-spiro-CPV for its quasi-dimeric structure. Our synthetic method based on a double lithiation cyclization approach enables facile production of D-spiro-CPV. D-spiro-CPVs exhibit circularly polarized luminescence (CPL) with high fluorescence quantum yields (ΦFL) resulting in a high CPL brightness of 21 M-1 cm-1 and also exhibit high thermal and photostability. The monoradical cation of D-spiro-CPV absorbing near-infrared light is notably persistent, exhibiting a half-life of 570 h under ambient conditions due to doubly spiro-conjugative stabilization. Theoretical and electrochemical studies indicate the radical cation of D-spiro-CPVs presents a non-Aufbau electron filling, exhibiting inversion of the energy level of the singly occupied molecular orbital (SOMO) and the highest (doubly) occupied molecular orbitals with the SOMO level even below the HOMO-1 level (double SHI effect). Our discoveries provide valuable insights into non-Aufbau molecules and the development of configurationally stable, optically active persistent radicals.
Collapse
Affiliation(s)
- Takumi Sakamaki
- Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Yan Zhang
- Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Shota Fukuma
- Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Carlos M Cruz
- Departamento de Química Orgánica, Facultad de Ciencias, Unidad de Excelencia de Química Aplicada a Biomedicina y Medioambiente (UEQ), Universidad de Granada (UGR), Avenida Fuente Nueva s/n, 18071 Granada, Spain
| | - Abel Cárdenas Valdivia
- Department of Physical Chemistry, Faculty of Science, University of Málaga, Campus de Teatinos, s/n, 29071 Málaga, Spain
| | - Araceli G Campaña
- Departamento de Química Orgánica, Facultad de Ciencias, Unidad de Excelencia de Química Aplicada a Biomedicina y Medioambiente (UEQ), Universidad de Granada (UGR), Avenida Fuente Nueva s/n, 18071 Granada, Spain
| | - Juan Casado
- Department of Physical Chemistry, Faculty of Science, University of Málaga, Campus de Teatinos, s/n, 29071 Málaga, Spain
| | - Rui Shang
- Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Eiichi Nakamura
- Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| |
Collapse
|
3
|
Matsuda K, Xiaotian R, Nakamura K, Furukori M, Hosokai T, Anraku K, Nakao K, Albrecht K. Photostability of luminescent tris(2,4,6-trichlorophenyl)methyl radical enhanced by terminal modification of carbazole donor. Chem Commun (Camb) 2022; 58:13443-13446. [PMID: 36373670 DOI: 10.1039/d2cc04481a] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Stable organic luminescent radicals have attracted much attention, but their stability under light irradiation is not yet satisfactory. New luminescent radicals (TTMs) based on terminal benzene ring modified carbazole donors were synthesized and evaluated. Their photostability (half-life under continuous laser irradiation) has improved by 1 order of magnitude compared to simple carbazole donors. This is a new molecular design strategy to improve the photostability of luminescent radicals without reducing other photophysical properties.
Collapse
Affiliation(s)
- Kenshiro Matsuda
- Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580, Japan
| | - Rui Xiaotian
- Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580, Japan
| | - Kazuhiro Nakamura
- Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580, Japan
| | - Minori Furukori
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
- Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Takuya Hosokai
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
- Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Kosuke Anraku
- Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580, Japan
| | - Kohei Nakao
- Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580, Japan.
| | - Ken Albrecht
- Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580, Japan.
- JST-PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| |
Collapse
|
4
|
Sabuj MA, Muoh O, Huda MM, Rai N. Non-Aufbau orbital ordering and spin density modulation in high-spin donor-acceptor conjugated polymers. Phys Chem Chem Phys 2022; 24:23699-23711. [PMID: 36148814 DOI: 10.1039/d2cp02355e] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High-spin ground-state organic materials with unique spin topology can significantly impact molecular magnetism, spintronics, and quantum computing devices. However, strategies to control the spin topology and alignment of the unpaired spins in different molecular orbitals are not well understood. Here, we report modulating spin distribution along the molecular backbone in high-spin ground-state donor-acceptor (D-A) conjugated polymers. Density functional theory calculations indicate that substitution of different heteroatoms (such as C, Si, N, and Se) alters the aromatic character in the thiadiazole unit of the benzobisthiadiazole (BBT) acceptor and modulates the oligomer length to result in high-spin triplet ground-state, orbital and spin topology. The C, Si, and Se atom substituted polymers show a localized spin density at the two opposite ends of the polymers. However, a delocalized spin distribution is observed in the N substituted polymer. We find that the hybridization (sp3vs. sp2) of the substituent atom plays an important role in controlling the electronic structure of these materials. This study shows that atomistic engineering is an efficient technique to tune the spin topologies and electronic configurations in the high-spin ground-state donor-acceptor conjugated polymers, compelling synthetic targets for room-temperature magnetic materials.
Collapse
Affiliation(s)
- Md Abdus Sabuj
- Dave C Swalm School of Chemical Engineering, and Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, Mississippi, 39762, USA.
| | - Obinna Muoh
- Dave C Swalm School of Chemical Engineering, and Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, Mississippi, 39762, USA.
| | - Md Masrul Huda
- Dave C Swalm School of Chemical Engineering, and Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, Mississippi, 39762, USA.
| | - Neeraj Rai
- Dave C Swalm School of Chemical Engineering, and Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, Mississippi, 39762, USA.
| |
Collapse
|
5
|
Kasemthaveechok S, Abella L, Crassous J, Autschbach J, Favereau L. Organic radicals with inversion of SOMO and HOMO energies and potential applications in optoelectronics. Chem Sci 2022; 13:9833-9847. [PMID: 36128246 PMCID: PMC9430691 DOI: 10.1039/d2sc02480b] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 07/06/2022] [Indexed: 11/21/2022] Open
Abstract
Organic radicals possessing an electronic configuration in which the energy of the singly occupied molecular orbital (SOMO) is below the highest doubly occupied molecular orbital (HOMO) level have recently attracted significant interest, both theoretically and experimentally. The peculiar orbital energetics of these SOMO-HOMO inversion (SHI) organic radicals set their electronic properties apart from the more common situation where the SOMO is the highest occupied orbital of the system. This review gives a general perspective on SHI, with key fundamental aspects regarding the electronic and structural factors that govern this particular electronic configuration in organic radicals. Selected examples of reported compounds with SHI are highlighted to establish molecular guidelines for designing this type of radical, and to showcase the potential of SHI radicals in organic spintronics as well as for the development of more stable luminescent radicals for OLED applications.
Collapse
Affiliation(s)
| | - Laura Abella
- Department of Chemistry, University at Buffalo, State University of New York Buffalo New York 14260 USA
| | | | - Jochen Autschbach
- Department of Chemistry, University at Buffalo, State University of New York Buffalo New York 14260 USA
| | | |
Collapse
|
6
|
Kasemthaveechok S, Abella L, Jean M, Cordier M, Vanthuyne N, Guizouarn T, Cador O, Autschbach J, Crassous J, Favereau L. Carbazole Isomerism in Helical Radical Cations: Spin Delocalization and SOMO-HOMO Level Inversion in the Diradical State. J Am Chem Soc 2022; 144:7253-7263. [PMID: 35413200 DOI: 10.1021/jacs.2c00331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report a new molecular design to afford persistent chiral organic open-shell systems with configurational stability and an inversion in energy of the singly occupied molecular orbital (SOMO) and the highest doubly occupied molecular orbital (HOMO) for both mono- and diradical states. The unpaired electron delocalization within the designed extended helical π-conjugated systems is a crucial factor to reach chemical stabilities, which is not obtained using the classical steric protection approach. The unique features of the obtained helical monoradicals allow an exploration of the chiral intramolecular electron transfer (IET) process in solvents of different polarity by means of optical and chiroptical spectroscopies, resulting in an unprecedented electronic circular dichroism (ECD) sign inversion for the radical transitions. We also characterized the corresponding helical diradicals, which show near-infrared electronic circular dichroism at wavelengths up to 1100 nm and an antiferromagnetic coupling between the spins, with an estimated singlet-triplet gap (ΔEST) of about -1.2 kcal mol-1. The study also revealed an intriguing double SOMO-HOMO inversion (SHI) electronic configuration for these diradicals, providing new insight regarding the peculiar energetic ordering of radical orbitals and the impact on the corresponding (chiral) optoelectronic properties.
Collapse
Affiliation(s)
| | - Laura Abella
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - Marion Jean
- Aix Marseille University, CNRS Centrale Marseille, iSm2, 13284 Marseille, France
| | - Marie Cordier
- Univ Rennes, CNRS, ISCR - UMR 6226, F-35000 Rennes, France
| | - Nicolas Vanthuyne
- Aix Marseille University, CNRS Centrale Marseille, iSm2, 13284 Marseille, France
| | | | - Olivier Cador
- Univ Rennes, CNRS, ISCR - UMR 6226, F-35000 Rennes, France
| | - Jochen Autschbach
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | | | | |
Collapse
|
7
|
Murata R, Wang Z, Abe M. Singly Occupied Molecular Orbital−Highest Occupied Molecular Orbital (SOMO−HOMO) Conversion. Aust J Chem 2021. [DOI: 10.1071/ch21186] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Singly occupied molecular orbital−highest occupied molecular orbital (SOMO−HOMO) conversion (inversion), SHC, is a phenomenon in which the SOMO is lower in energy than the doubly occupied molecular orbitals (DOMO, HOMO). A non-Aufbau electronic structure leads to unique properties such as a switch in bond dissociation energy and the generation of high-spin species on one-electron oxidation. In addition, the pronounced photostability of these species has been reported recently for application in organic light-emitting devices. In this review article, we summarise the chemistry of SOMO−HOMO converted (inverted) species reported to date.
Collapse
|