1
|
Steffenfauseweh H, Vishnevskiy YV, Neumann B, Stammler HG, de Bruin B, Ghadwal RS. N-Heterocyclic Carbene Analogues of Wittig Hydrocarbon. Chemistry 2024; 30:e202400879. [PMID: 38437163 DOI: 10.1002/chem.202400879] [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: 03/03/2024] [Accepted: 03/04/2024] [Indexed: 03/06/2024]
Abstract
N-Heterocyclic carbene (NHC) analogues of Wittig hydrocarbon, [(NHC)(Stil)(NHC)] (3a-c) (NHC = SIPr (1a) = C[N(Dipp)CH2]2, Dipp = 2,6-iPr2C6H3; IPr (1b) = C[N(Dipp)CH]2; Me-IPr (1c) = C[N(Dipp)CMe]2 and Stil = C6H4CHCHC6H4) have been reported as crystalline solids. 3a-c are prepared by two-electron reductions of the corresponding bis-1,3-imidazoli(ni)um bromides [(NHC)(Stil)NHC)](Br)2 (2a-c) with KC8 in >94 % yields. 2a-c are accessible by the nickel catalyzed direct C-C coupling of NHCs (1a-c) with (E)-4,4'-dibromostilbene. One-electron oxidation of 3a,b yields the corresponding radical cations [(NHC)(Stil)NHC)]B(C6F5)4 4a,b. All compounds have been characterized by UV-Vis/NMR/EPR spectroscopy as well as 2a, 3a, and 3b by single crystal X-ray diffraction. The electronic structures of representative systems have been analyzed by quantum chemical calculations.
Collapse
Affiliation(s)
- Henric Steffenfauseweh
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Yury V Vishnevskiy
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Beate Neumann
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Hans-Georg Stammler
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Bas de Bruin
- University of Amsterdam (UvA), Faculty of Science, Van 't Hoff Institute for Molecular Sciences (HIMS), Homogeneous and Supramolecular Catalysis Group, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Rajendra S Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| |
Collapse
|
2
|
Hou P, Peschtrich S, Feuerstein W, Schoch R, Hohloch S, Breher F, Paradies J. Imidazolyl-Substituted Benzo- and Naphthodithiophenes as Precursors for the Synthesis of Transient Open-Shell Quinoids. ChemistryOpen 2023; 12:e202300003. [PMID: 36703547 PMCID: PMC10661821 DOI: 10.1002/open.202300003] [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: 01/04/2023] [Revised: 01/09/2023] [Indexed: 01/28/2023] Open
Abstract
The synthesis of three novel imidazolyl-substituted sulfur-containing heteroacenes is reported. These heteroacenes consisting of annelated benzo- and naphthothiophenes serve as precursors for the generation of open-shell quinoid heteroacenes by oxidation with alkaline ferric cyanide. Spectroscopic and computational experiments support the formation of reactive open-shell quinoids, which, however, quickly produce paramagnetic polymeric material.
Collapse
Affiliation(s)
- Peng Hou
- Chemistry DepartmentPaderborn UniversityWarburger Strasse 10033098PaderbornGermany
| | - Sebastian Peschtrich
- Chemistry DepartmentPaderborn UniversityWarburger Strasse 10033098PaderbornGermany
| | - Wolfram Feuerstein
- Institute of Inorganic ChemistryKarlsruhe Institute of Technology (KIT)Engesserstraße 1576131KarlsruheGermany
| | - Roland Schoch
- Chemistry DepartmentPaderborn UniversityWarburger Strasse 10033098PaderbornGermany
| | - Stephan Hohloch
- Department of General, Inorganic and Theoretical ChemistryUniversity of InnsbruckInnrain 80–826020InnsbruckAustria
| | - Frank Breher
- Institute of Inorganic ChemistryKarlsruhe Institute of Technology (KIT)Engesserstraße 1576131KarlsruheGermany
| | - Jan Paradies
- Chemistry DepartmentPaderborn UniversityWarburger Strasse 10033098PaderbornGermany
| |
Collapse
|
3
|
Ghadwal RS. 1,3-Imidazole-Based Mesoionic Carbenes and Anionic Dicarbenes: Pushing the Limit of Classical N-Heterocyclic Carbenes. Angew Chem Int Ed Engl 2023; 62:e202304665. [PMID: 37132480 DOI: 10.1002/anie.202304665] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 05/02/2023] [Accepted: 05/03/2023] [Indexed: 05/04/2023]
Abstract
Classical N-heterocyclic carbenes (NHCs) featuring the carbene center at the C2-position of 1,3-imidazole framework (i.e. C2-carbenes) are well acknowledged as very versatile neutral ligands in molecular as well as in materials sciences. The efficiency and success of NHCs in diverse areas is essentially attributed to their persuasive stereoelectronics, in particular the potent σ-donor property. The NHCs with the carbene center at the unusual C4 (or C5) position, the so-called abnormal NHCs (aNHCs) or mesoionic carbenes (iMICs), are however superior σ-donors than C2-carbenes. Hence, iMICs have substantial potential in sustainable synthesis and catalysis. The main obstacle in this direction is rather demanding synthetic accessibility of iMICs. The aim of this review article is to highlight recent advances, particularly by the author's research group, in accessing stable iMICs, quantifying their properties, and exploring their applications in synthesis and catalysis. In addition, the synthetic viability and use of vicinal C4,C5-anionic dicarbenes (ADCs), also based on an 1,3-imidazole framework, are presented. As will be apparent on following pages, iMICs and ADCs hold potentials in pushing the limit of classical NHCs by enabling access to conceptually new main-group heterocycles, radicals, molecular catalysts, ligands sets, and more.
Collapse
Affiliation(s)
- Rajendra S Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, 33615, Bielefeld, Germany
| |
Collapse
|
4
|
Abstract
Heteroatom-centered diradical(oid)s have been in the focus of molecular main group chemistry for nearly 30 years. During this time, the diradical concept has evolved and the focus has shifted to the rational design of diradical(oid)s for specific applications. This review article begins with some important theoretical considerations of the diradical and tetraradical concept. Based on these theoretical considerations, the design of diradical(oid)s in terms of ligand choice, steric, symmetry, electronic situation, element choice, and reactivity is highlighted with examples. In particular, heteroatom-centered diradical reactions are discussed and compared with closed-shell reactions such as pericyclic additions. The comparison between closed-shell reactivity, which proceeds in a concerted manner, and open-shell reactivity, which proceeds in a stepwise fashion, along with considerations of diradical(oid) design, provides a rational understanding of this interesting and unusual class of compounds. The application of diradical(oid)s, for example in small molecule activation or as molecular switches, is also highlighted. The final part of this review begins with application-related details of the spectroscopy of diradical(oid)s, followed by an update of the heteroatom-centered diradical(oid)s and tetraradical(oid)s published in the last 10 years since 2013.
Collapse
Affiliation(s)
- Alexander Hinz
- Institut für Anorganische Chemie (AOC), Karlsruher Institut für Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
| | - Jonas Bresien
- Institut für Chemie, Universität Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
| | - Frank Breher
- Institut für Anorganische Chemie (AOC), Karlsruher Institut für Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
| | - Axel Schulz
- Institut für Chemie, Universität Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
| |
Collapse
|
5
|
Kundu G, Dash SR, Kumar R, Vanka K, Ghosh A, Sen SS. Enhancing Diradical Character of Chichibabin's Hydrocarbon through Fluoride Substitution. Chempluschem 2023; 88:e202300273. [PMID: 37409641 DOI: 10.1002/cplu.202300273] [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: 06/07/2023] [Revised: 07/04/2023] [Accepted: 07/06/2023] [Indexed: 07/07/2023]
Abstract
In this work, 5-SIDipp [SIDipp=1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene] (1) derived Chichibabin's hydrocarbon with an octafluorobiphenylene spacer (3) has been reported. The addition of two equivalents of 5-SIDipp with decafluorobiphenyl in presence of BF3 gives the double C-F bond activated imidazolium salt with two tetrafluoroborate anions, 2. Further reduction of 2 gives the fluorine substituted 5-SIDipp based Chichibabin's hydrocarbon, 3. Quantum chemical calculations suggested a singlet state of 3 with a singlet-triplet energy gap (ΔES-T ) of 3.7 kcal mol-1 , which is substantially lower with respect to the hydrogen substituted NHC-based Chichibabin's hydrocarbons (10.7 kcal mol-1 , B3LYP). As a result, the diradical character (y) of 3 (y=0.62) is also noticeably higher than the hydrogen substituted CHs (y=0.41-0.43). The ▵ES-T was found to be higher in CASSCF (22.24 kcal mol-1 ) and CASPT2 (11.17 kcal mol-1 ) for 3 and the diradical character (d) is 44.6 %.
Collapse
Affiliation(s)
- Gargi Kundu
- Inorganic Chemistry and Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road Pashan, Pune, 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Soumya Ranjan Dash
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road Pashan, Pune, 411008, India
| | - Ravi Kumar
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road Pashan, Pune, 411008, India
| | - Kumar Vanka
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road Pashan, Pune, 411008, India
| | - Aryya Ghosh
- Department of Chemistry, Ashoka University, Sonipat, Haryana, 131029, India
| | - Sakya S Sen
- Inorganic Chemistry and Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road Pashan, Pune, 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| |
Collapse
|
6
|
Song H, Lee E. Revisiting the Reaction of IPr with Tritylium: An Alternative Mechanistic Pathway. Chemistry 2023; 29:e202203364. [PMID: 36445754 DOI: 10.1002/chem.202203364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 11/29/2022] [Accepted: 11/29/2022] [Indexed: 11/30/2022]
Abstract
Despite a recent proposal on the mechanism of a single-electron transfer (SET) process between tritylium and 2,6-bis(diisopropylphenyl)imidazol-2-ylidene (IPr) based on evidence of transient IPr radical cation intermediate ([IPr]⋅+ ) formation, such oxidation is still contentious because of the high oxidation potential of N-heterocyclic carbenes. Our experimental analysis indicates that the appearance of deep purple color, previously considered to be from transient [IPr]⋅+ , originates from a zwitterionic intermediate (3 a), not a radical cation. Here, we propose an alternative mechanism for the reaction involving tritylium and IPr. This mechanism is noteworthy for explaining how [NHC-H]+ can be generated without the formation of transient [NHC]⋅+ , which has been frequently proposed as an intermediate for the reaction between NHC and oxidants. These results also show that a transient strong single-electron donor (3 a) could be generated by the alternative mechanism for oxidants using NHCs, which is a more feasible explanation for the reactivity of NHCs with oxidants.
Collapse
Affiliation(s)
- Hayoung Song
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Eunsung Lee
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea.,Division of Advanced Materials Science, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| |
Collapse
|
7
|
Hou P, Peschtrich S, Huber N, Feuerstein W, Bihlmeier A, Krummenacher I, Schoch R, Klopper W, Breher F, Paradies J. Impact of Heterocycle Annulation on NIR Absorbance in Quinoid Thioacene Derivatives. Chemistry 2022; 28:e202200478. [PMID: 35254693 PMCID: PMC9314731 DOI: 10.1002/chem.202200478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Indexed: 11/30/2022]
Abstract
The synthesis and characterisation of a homologous series of quinoid sulfur‐containing imidazolyl‐substituted heteroacenes is described. The optoelectronic and magnetic properties were investigated by UV/vis, fluorescence and EPR spectroscopy as well as quantum‐chemical calculations, and were compared to those of the corresponding benzo congener. The room‐temperature and atmospherically stable quinoids display strong absorption in the NIR region between 678 and 819 nm. The dithieno[3,2‐b:2′,3′‐d]thiophene and the thieno[2′,3′:4,5]thieno[3,2‐b]thieno[2,3‐d]thiophene derivatives were EPR active at room temperature. For the latter, variable‐temperature EPR spectroscopy revealed the presence of a thermally accessible triplet state, with a singlet‐triplet separation of 14.1 kJ mol−1.
Collapse
Affiliation(s)
- Peng Hou
- Chemistry Department Paderborn University Warburger Straße 100 33098 Paderborn Germany
| | - Sebastian Peschtrich
- Chemistry Department Paderborn University Warburger Straße 100 33098 Paderborn Germany
| | - Nils Huber
- Institute of Physical Chemistry Karlsruhe Institute of Technology (KIT) Kaiserstraße 12 76131 Karlsruhe Germany
| | - Wolfram Feuerstein
- Institute of Inorganic Chemistry Karlsruhe Institute of Technology (KIT) Engesserstraße 15 76131 Karlsruhe Germany
| | - Angela Bihlmeier
- Institute of Physical Chemistry Karlsruhe Institute of Technology (KIT) Kaiserstraße 12 76131 Karlsruhe Germany
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry University of Würzburg Am Hubland 97074 Würzburg Germany
| | - Roland Schoch
- Chemistry Department Paderborn University Warburger Straße 100 33098 Paderborn Germany
| | - Wim Klopper
- Institute of Physical Chemistry Karlsruhe Institute of Technology (KIT) Kaiserstraße 12 76131 Karlsruhe Germany
| | - Frank Breher
- Institute of Inorganic Chemistry Karlsruhe Institute of Technology (KIT) Engesserstraße 15 76131 Karlsruhe Germany
| | - Jan Paradies
- Chemistry Department Paderborn University Warburger Straße 100 33098 Paderborn Germany
| |
Collapse
|
8
|
Khurana R, Bajaj A, Ali ME. Tuning the magnetic properties of a diamagnetic di-Blatter's zwitterion to antiferro- and ferromagnetically coupled diradicals. Phys Chem Chem Phys 2022; 24:2543-2553. [PMID: 35024707 DOI: 10.1039/d1cp04807d] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the quest of obtaining organic molecular magnets based on stable diradicals, we have tuned the inherent zwitterionic ground state of tetraphenylhexaazaanthracene (TPHA), a molecule containing two Blatter's moieties, by adopting two different strategies. In the first strategy, we have increased the length of the coupler between the two radical moieties and observed a transition from the zwitterionic ground state to the diradicalized state. With a larger coupler, ferromagnetic interactions are realized based on density functional theory (DFT) and wave-function theory (WFT) based complete active space self-consistent field (CASSCF)-N-electron valence state perturbation theory (NEVPT2) methods. An analysis based on the extent of spin contamination, diradical character, CASSCF orbital occupation number, Head-Gordon's index, HOMO-LUMO and SOMOs energy gaps is demonstrated that marks the transition of the ground state in these systems. In another approach, we systematically explore the effect of push-pull substitution on the way to obtain molecules based on a TPHA skeleton with diradicaloid state and, in some cases, even a triplet ground state.
Collapse
Affiliation(s)
- Rishu Khurana
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, 140306, India.
| | - Ashima Bajaj
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, 140306, India.
| | - Md Ehesan Ali
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab, 140306, India.
| |
Collapse
|
9
|
Maiti A, Sobottka S, Chandra S, Jana D, Ravat P, Sarkar B, Jana A. Diamidocarbene-Based Thiele and Tschitschibabin Hydrocarbons: Carbonyl Functionalized Kekulé Diradicaloids. J Org Chem 2021; 86:16464-16472. [PMID: 34780693 DOI: 10.1021/acs.joc.1c01827] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Herein, we report diamidocarbene (DAC)-based Thiele and Tschitschibabin hydrocarbons, diradicaloids that contain four carbonyl/amido functional groups. The impact of two different π-conjugated spacers, p-phenylene vs p,p'-biphenylene, has been realized. The quantum chemical calculations suggest diamidocarbene (DAC)-based Thiele hydrocarbon (p-phenylene bridged) closed-shell singlet is the ground state, whereas for the diamidocarbene (DAC)-based Tschitschibabin hydrocarbon (p,p'-biphenylene bridged), open-shell singlet is the ground state. The influence of two different π-conjugated spacers also has been reflected in their UV-vis spectra. To gain more information on the diamidocarbene (DAC)-based Thiele and Tschitschibabin hydrocarbons, we have also carried out cyclic voltammetry investigations along with UV-vis-NIR-spectroelectrochemical studies of their corresponding 2-e oxidized product.
Collapse
Affiliation(s)
- Avijit Maiti
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, Telangana, India
| | - Sebastian Sobottka
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195 Berlin, Germany
| | - Shubhadeep Chandra
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195 Berlin, Germany.,Universität Stuttgart, Fakultät Chemie, Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Debayan Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, Telangana, India
| | - Prince Ravat
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Biprajit Sarkar
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195 Berlin, Germany.,Universität Stuttgart, Fakultät Chemie, Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, Telangana, India
| |
Collapse
|
10
|
Zhao J, Li X, Han YF. Air-/Heat-Stable Crystalline Carbon-Centered Radicals Derived from an Annelated N-Heterocyclic Carbene. J Am Chem Soc 2021; 143:14428-14432. [PMID: 34469133 DOI: 10.1021/jacs.1c06464] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Organic radicals are open-shell species and have been extensively applied to functional materials due to their unique physicochemical properties with unpaired electrons; however, most of them are highly reactive and short-lived. Herein, a series of stable radicals were readily accessed in two steps from a bis(imino)acenaphthene-supported N-heterocyclic carbene (IPr(BIAN)) through enhancing the delocalization of spin density. The IPr(BIAN)-based radicals 3a-c, obtained by reduction of the corresponding iminium salts 2a-c with KC8, have been spectroscopically and crystallographically (3a,c) characterized. DFT calculations indicate that increasing the electron-withdrawing properties of the para substituent on the carbene carbon atom results in the spin density evolving from the acenaphthene ring to the phenyl ring. The IPr(BIAN)-based radicals 3a-c show excellent stability: they have half-lives of 1 week in well-aerated solutions and feature a high thermal decomposition temperature up to 200 °C.
Collapse
Affiliation(s)
- Jing Zhao
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, People's Republic of China
| | - Xin Li
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, People's Republic of China
| | - Ying-Feng Han
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, People's Republic of China
| |
Collapse
|
11
|
Merschel A, Glodde T, Neumann B, Stammler H, Ghadwal RS. Nickel-Catalyzed Intramolecular 1,2-Aryl Migration of Mesoionic Carbenes (iMICs). Angew Chem Int Ed Engl 2021; 60:2969-2973. [PMID: 33155756 PMCID: PMC7898293 DOI: 10.1002/anie.202014328] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Indexed: 12/26/2022]
Abstract
Intramolecular 1,2-Dipp migration of seven mesoionic carbenes (iMICAr ) 2 a-g (iMICAr =ArC{N(Dipp)}2 CHC; Ar=aryl; Dipp=2,6-iPr2 C6 H3 ) under nickel catalysis to give 1,3-imidazoles (IMDAr ) 3 a-g (IMDAr =ArC{N(Dipp)CHC(Dipp)N}) has been reported. The formation of 3 indicates the cleavage of an N-CDipp bond and the subsequent formation of a C-CDipp bond in 2, which is unprecedented in NHC chemistry. The use of 3 in accessing super-iMICs (5) (S-iMIC=ArC{N(Dipp)N(Me)C(Dipp)}C) has been shown with selenium (6), gold (7), and palladium (8) compounds. The quantification of the stereoelectronic properties reveals the superior σ-donor strength of 5 compared to that of classical NHCs. Remarkably, the percentage buried volume of 5 (%Vbur =45) is the largest known amongst thus far reported iMICs. Catalytic studies show a remarkable activity of 5, which is consistent with their auspicious stereoelectronic features.
Collapse
Affiliation(s)
- Arne Merschel
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Timo Glodde
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Beate Neumann
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Hans‐Georg Stammler
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Rajendra S. Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| |
Collapse
|
12
|
Abstract
Singlet fission (SF) is a photophysical downconversion pathway, in which a singlet excitation transforms into two triplet excited states. As such, it constitutes an exciton multiplication generation process, which is currently at the focal point for future integration into solar energy conversion devices. Beyond this, various other exciting applications were proposed, including quantum cryptography or organic light emitting diodes. Also, the mechanistic understanding evolved rapidly during the last year. Unfortunately, the number of suitable SF-chromophores is still limited. This is per se problematic, considering the wide range of envisaged applicability. With that in mind, we emphasize uncommon SF-scaffolds and outline requirements as well as strategies to expand the chromophore pool of SF-materials.
Collapse
Affiliation(s)
- Tobias Ullrich
- Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Department für Chemie und Pharmazie, Egerlandstr. 1-3, 91058 Erlangen, Germany.
| | | | | |
Collapse
|
13
|
Das A, Ahmed J, Rajendran NM, Adhikari D, Mandal SK. A Bottleable Imidazole-Based Radical as a Single Electron Transfer Reagent. J Org Chem 2021; 86:1246-1252. [PMID: 33280378 DOI: 10.1021/acs.joc.0c02465] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Reduction of 1,3-bis(2,6-diisopropylphenyl)-2,4-diphenyl-1H-imidazol-3-ium chloride (1) resulted in the formation of the first structurally characterized imidazole-based radical 2. 2 was established as a single electron transfer reagent by treating it with an acceptor molecule tetracyanoethylene. Moreover, radical 2 was utilized as an organic electron donor in a number of organic transformations such as in activation of an aryl-halide bond, alkene hydrosilylation, and in catalytic reduction of CO2 to methoxyborane, all under ambient temperature and pressure.
Collapse
Affiliation(s)
- Arpan Das
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Jasimuddin Ahmed
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - N M Rajendran
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Debashis Adhikari
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, SAS Nagar, 140306, India
| | - Swadhin K Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| |
Collapse
|
14
|
Merschel A, Glodde T, Neumann B, Stammler H, Ghadwal RS. Nickel‐katalysierte intramolekulare 1,2‐Aryl‐Wanderung von mesoionischen Carbenen (iMICs). Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202014328] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Arne Merschel
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Centrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Timo Glodde
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Centrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Beate Neumann
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Centrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Hans‐Georg Stammler
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Centrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Rajendra S. Ghadwal
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Centrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
| |
Collapse
|
15
|
Jiménez VG, Mayorga-Burrezo P, Blanco V, Lloveras V, Gómez-García CJ, Šolomek T, Cuerva JM, Veciana J, Campaña AG. Dibenzocycloheptatriene as end-group of Thiele and tetrabenzo-Chichibabin hydrocarbons. Chem Commun (Camb) 2020; 56:12813-12816. [PMID: 32966400 DOI: 10.1039/d0cc04489j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Thiele (Th) and tetrabenzo-Chichibabin (TBC) derivatives with terminal dibenzocycloheptatriene (DBHept) units were prepared. A clear correlation between their electronic and molecular structures was stablished. Insights into their closed- or open-shell ground states were gained, where particular contribution of the heptagonal carbocycles as end-groups was proved. Remarkably, a thermally accessible triplet diradical configuration was confirmed for the DBHept-TBC compound.
Collapse
Affiliation(s)
- Vicente G Jiménez
- Department of Organic Chemistry, Unidad de Excelencia de Química aplicada a Biomedicina y Medio Ambiente, University of Granada (UGR), C. U. Fuentenueva, Granada 18071, Spain.
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Maiti A, Chandra S, Sarkar B, Jana A. Acyclic diaminocarbene-based Thiele, Chichibabin, and Müller hydrocarbons. Chem Sci 2020; 11:11827-11833. [PMID: 34123209 PMCID: PMC8162802 DOI: 10.1039/d0sc03622f] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Thiele, Chichibabin and Müller hydrocarbons are considered as classical Kekulé diradicaloids. Herein we report the synthesis and characterization of acyclic diaminocarbene (ADC)-based Thiele, Chichibabin, and Müller hydrocarbons. The calculated singlet–triplet energy gaps are ΔES–T = −27.96, −3.70, −0.37 kcal mol−1, respectively, and gradually decrease with the increasing length of the π-conjugated spacer (p-phenylene vs. p,p′-biphenylene vs. p,p′′-terphenylene) between the two ADC-scaffolds. In agreement with the calculations, we also experimentally observed the enhancement of paramagnetic diradical character as a function of the length of the π-conjugated spacer. ADC-based Thiele's hydrocarbon is EPR silent and exhibits very well resolved NMR spectra, whereas ADC-based Müller's hydrocarbon displays EPR signals and featureless NMR spectra at room temperature. The spacer also has a strong influence on the UV-Vis-NIR spectra of these compounds. Considering that our methodology is modular, these results provide a convenient platform for the synthesis of an electronically modified new class of carbon-centered Kekulé diradicaloids. We report the synthesis of acyclic diaminocarbene (ADC)-scaffold based Thiele, Chichibabin, and Müller hydrocarbons. Studies support that the singlet-triplet energy gap depends on the π-conjugated spacer between the ADC scaffolds.![]()
Collapse
Affiliation(s)
- Avijit Maiti
- Tata Institute of Fundamental Research Hyderabad Gopanpally Hyderabad-500046 Telangana India
| | - Shubhadeep Chandra
- Universität Stuttgart, Fakultät Chemie, Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie Pfaffenwaldring 55 D-70569 Stuttgart Germany
| | - Biprajit Sarkar
- Universität Stuttgart, Fakultät Chemie, Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie Pfaffenwaldring 55 D-70569 Stuttgart Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad Gopanpally Hyderabad-500046 Telangana India
| |
Collapse
|
17
|
Rottschäfer D, Fuhs DE, Neumann B, Stammler H, Ghadwal RS. Saturated NHC Derived Dichalcogen Dications. Z Anorg Allg Chem 2020. [DOI: 10.1002/zaac.202000189] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Dennis Rottschäfer
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
| | - Désirée E. Fuhs
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
| | - Beate Neumann
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
| | - Hans‐Georg Stammler
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
| | - Rajendra S. Ghadwal
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
| |
Collapse
|
18
|
Rottschäfer D, Glodde T, Neumann B, Stammler HG, Ghadwal RS. A crystalline C5-protonated 1,3-imidazol-4-ylidene. Chem Commun (Camb) 2020; 56:2027-2030. [DOI: 10.1039/c9cc09428h] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The first C5-protonated 1,3-imidazole-based mesoionic carbene (iMICBp) has been isolated and characterized by single-crystal X-ray diffraction.
Collapse
Affiliation(s)
- Dennis Rottschäfer
- Molecular Inorganic Chemistry and Catalysis
- Inorganic and Structural Chemistry
- Center for Molecular Materials
- Faculty of Chemistry
- Universität Bielefeld
| | - Timo Glodde
- Molecular Inorganic Chemistry and Catalysis
- Inorganic and Structural Chemistry
- Center for Molecular Materials
- Faculty of Chemistry
- Universität Bielefeld
| | - Beate Neumann
- Molecular Inorganic Chemistry and Catalysis
- Inorganic and Structural Chemistry
- Center for Molecular Materials
- Faculty of Chemistry
- Universität Bielefeld
| | - Hans-Georg Stammler
- Molecular Inorganic Chemistry and Catalysis
- Inorganic and Structural Chemistry
- Center for Molecular Materials
- Faculty of Chemistry
- Universität Bielefeld
| | - Rajendra S. Ghadwal
- Molecular Inorganic Chemistry and Catalysis
- Inorganic and Structural Chemistry
- Center for Molecular Materials
- Faculty of Chemistry
- Universität Bielefeld
| |
Collapse
|
19
|
Sharma MK, Blomeyer S, Neumann B, Stammler HG, Hinz A, van Gastel M, Ghadwal RS. Isolation of singlet carbene derived 2-arsa-1,3-butadiene radical cations and dications. Chem Commun (Camb) 2020; 56:3575-3578. [PMID: 32104835 DOI: 10.1039/d0cc00624f] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
2-Arsa-1,3-butadienes (L)As(cAACR) (L = PhC[double bond, length as m-dash]C{(NDipp)CH}2, Dipp = 2,6-iPr2C6H3; cAACR = C{(NDipp)CMe2CH2C(R)}, R = Me22a, R = cyclohexyl (Cy) 2b) and the corresponding radical cations [(L)As(cAACR)]GaCl4 (R = Me23a, Cy 3b) and dications [(L)As(cAACR)](GaCl4)2 (R = Me 4a, Cy 4b) featuring a C[double bond, length as m-dash]C-As[double bond, length as m-dash]C π-conjugated framework are reported.
Collapse
Affiliation(s)
- Mahendra K Sharma
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
| | - Sebastian Blomeyer
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
| | - Beate Neumann
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
| | - Hans-Georg Stammler
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
| | - Alexander Hinz
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstr. 15, 76131 Karlsruhe, Germany
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung, Molecular Theory and Spectroscopy, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr, D-45470, Germany
| | - Rajendra S Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
| |
Collapse
|
20
|
Kundu G, De S, Tothadi S, Das A, Koley D, Sen SS. Saturated N-Heterocyclic Carbene Based Thiele's Hydrocarbon with a Tetrafluorophenylene Linker. Chemistry 2019; 25:16533-16537. [PMID: 31609519 DOI: 10.1002/chem.201904421] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/06/2019] [Indexed: 01/24/2023]
Abstract
The synthesis of a SIPr [1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene] derived Kekulé diradicaloid with a tetrafluorophenylene spacer (3) has been described. Two synthetic routes have been reported to access 3. The cleavage of C-F bond of C6 F6 by SIPr in the presence of BF3 led to double C-F activated compound with two tetrafluoro borate counter anions (2), which upon reduction by lithium metal afforded 3. Alternatively, 3 can be directly accessed in one step by reacting SIPr with C6 F6 in presence of Mg metal. Compounds 2 and 3 were well characterized spectroscopically and by single-crystal X-ray diffraction studies. Experimental and computational studies support the cumulenic closed-shell singlet state of 3 with a singlet-triplet energy gap (ΔES-T ) of 23.7 kcal mol-1 .
Collapse
Affiliation(s)
- Gargi Kundu
- Inorganic Chemistry and Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India.,Academy of Scientific and Innovative Research (AcSIR), New Ghaziabad, 201002, India
| | - Sriman De
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, 741246, India
| | - Srinu Tothadi
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India
| | - Abhishek Das
- Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata, 700032, India
| | - Debasis Koley
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, 741246, India
| | - Sakya S Sen
- Inorganic Chemistry and Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India.,Academy of Scientific and Innovative Research (AcSIR), New Ghaziabad, 201002, India
| |
Collapse
|
21
|
Werr M, Kaifer E, Wadepohl H, Himmel HJ. Tuneable Redox Chemistry and Electrochromism of Persistent Symmetric and Asymmetric Azine Radical Cations. Chemistry 2019; 25:12981-12990. [PMID: 31306523 DOI: 10.1002/chem.201902216] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/21/2019] [Indexed: 12/16/2022]
Abstract
Molecular organic radicals have been intensively studied in the last decades, due to their interesting optical, magnetic and redox properties. Here we report the synthesis and characterisation of persistent organic radicals from one-electron oxidation of redox-active azines (RAAs), composed of two guanidinyl or related groups. By connecting two different groups together, asymmetric compounds result. In this way a series of compounds with varying redox potential is obtained that could be oxidised reversibly to the mono- and the dicationic charge states. The accessible redox states were fully determined by chemical redox reactions. The standard Gibbs free energy change for disproportionation of the radical monocation into the dication and the neutral molecule in solution, estimated from cyclovoltammetric measurements, varies between 43 and 71 kJ mol-1 . While the neutral RAAs absorb predominately UV light, the radical monocations display strong absorptions covering almost the entire visible region and extending for some compounds into the NIR region. A detailed analysis of this highly reversible electrochromism is presented, and the fast switching characteristics are demonstrated in an electrochromic test device.
Collapse
Affiliation(s)
- Marco Werr
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Elisabeth Kaifer
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Hubert Wadepohl
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Hans-Jörg Himmel
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| |
Collapse
|
22
|
Chen D, Bu Y. Rational magnetic modification of N,N-dioxidized pyrazine ring expanded adenine and thymine: a diradical character induced by base pairing and double protonation. Phys Chem Chem Phys 2019; 21:20095-20106. [PMID: 31482894 DOI: 10.1039/c9cp03234g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Rational modification of biomolecules especially DNA base pairs for the theoretical design of molecular magnets has attracted extensive interest. In this work, we report a modification strategy for adenine/thymine-based magnets through introducing a N,N-dioxidized pyrazine ring to either adenine or thymine to form ring-expanded bases (noA/noT) based on their experimentally synthesized derivatives. Further functionalization is conducted by double protonation and pairing with a normal complementary base (nohA-T/nohT-A), respectively. The diversity of protonation sites in noA generates totally six nohA-Ts, together with nohT-A forming seven two-step modified topic base pairs. DFT calculations are performed to characterize the magnetic properties and the diradical character, which indicate three diamagnetic (DM) nohA-Ts and three antiferromagnetic (AFM) nohA-Ts with extremely large magnetic coupling constants J ranging from -1279.7 to -2807.4 cm-1, while a relatively mild AFM nohT-A with a J of -194.6 cm-1. The electron separation effect induced by attraction of positive charges originating from protonation is proposed to explain the diradicalization, which is different from the traditional radical-coupler-radical coupling mode. In addition, atomic natural charges and spin densities, and H-bond and molecular orbital analyses are further discussed for verification and deep understanding of the observed unique phenomena. It should be noted that our designed seven topic base pairs have excellent characters including a good synthetic basis, a large scope of the |J| values, and the AFM-DM magnetic conversion or AFM strength modulation controlled by protonation/deprotonation, prototropic tautomerization, base pairing/dissociation, single proton transfer, and even the applied electric field. All these indicate the promising applications in the field of magnetic information storage or switch control. This work highlights the magnetic modification schemes and possible modulation methods of double positive charge doped DNA base pairs by utilizing their potential spin coupling modes.
Collapse
Affiliation(s)
- Dongxiao Chen
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, People's Republic of China.
| | | |
Collapse
|
23
|
Escayola S, Callís M, Poater A, Solà M. Effect of Exocyclic Substituents and π-System Length on the Electronic Structure of Chichibabin Diradical(oid)s. ACS OMEGA 2019; 4:10845-10853. [PMID: 31460182 PMCID: PMC6648453 DOI: 10.1021/acsomega.9b00916] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 06/03/2019] [Indexed: 06/10/2023]
Abstract
The ground state (GS) of Chichibabin's polycyclic hydrocarbons (CPHs) can be singlet [open- or closed-shell (OSS or CS)] or triplet (T), depending on the elongation of the π-system and the exocyclic substituents. CPHs with either a small singlet-triplet energy gap (ΔE ST) or even a triplet GS have potential applications in optoelectronics. To analyze the effect of the size and exocyclic substituents on the nature of the GS of CPHs, we have selected a number of them with different substituents in the exocyclic carbon atoms and different ring chain lengths. The OPBE/cc-pVTZ level of theory was used for the optimization of the systems. The aromaticity of the resulting electronic structures was evaluated with HOMA, NICS, FLU, PDI, Iring, and MCI aromaticity indices. Our results show that the shortest π-systems (one or two rings) have a singlet GS. However, systems with three to five rings favor OSS GSs. Electron-withdrawing groups (EWGs) and aromatic substituents in the exocyclic carbons tend to stabilize the OSS and T states, whereas electron-donating groups slightly destabilize them. For CS, OSS, and T states, aromaticity measures indicate a gain of aromaticity of the 6-membered rings of the CPHs with the increase in their size and when CPHs incorporate EWGs or aromatic substituents. In general, the CPHs analyzed present small singlet-triplet energy gaps, and in particular, the ones containing EWGs or aromatic substituents present the smallest singlet-triplet energy gaps.
Collapse
Affiliation(s)
- Sílvia Escayola
- Institut de Química
Computacional i Catàlisi and Departament de Química, Universitat de Girona, C/Maria Aurèlia Capmany, 69, 17003 Girona, Catalonia, Spain
| | - Marc Callís
- Institut de Química
Computacional i Catàlisi and Departament de Química, Universitat de Girona, C/Maria Aurèlia Capmany, 69, 17003 Girona, Catalonia, Spain
| | - Albert Poater
- Institut de Química
Computacional i Catàlisi and Departament de Química, Universitat de Girona, C/Maria Aurèlia Capmany, 69, 17003 Girona, Catalonia, Spain
| | - Miquel Solà
- Institut de Química
Computacional i Catàlisi and Departament de Química, Universitat de Girona, C/Maria Aurèlia Capmany, 69, 17003 Girona, Catalonia, Spain
| |
Collapse
|
24
|
Rottschäfer D, Neumann B, Stammler H, Kishi R, Nakano M, Ghadwal RS. A Phosphorus Analogue ofp‐Quinodimethane with a Planar P4Ring: A Metal‐Free Diphosphorus Source. Chemistry 2019; 25:3244-3247. [PMID: 30716177 DOI: 10.1002/chem.201805932] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/03/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Dennis Rottschäfer
- Anorganische Molekülchemie und Katalyse, Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für ChemieUniversität Bielefeld Universitätsstrasse 25 33615 Bielefeld Germany
| | - Beate Neumann
- Anorganische Molekülchemie und Katalyse, Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für ChemieUniversität Bielefeld Universitätsstrasse 25 33615 Bielefeld Germany
| | - Hans‐Georg Stammler
- Anorganische Molekülchemie und Katalyse, Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für ChemieUniversität Bielefeld Universitätsstrasse 25 33615 Bielefeld Germany
| | - Ryohei Kishi
- Department of Materials Engineering Science, Graduate School of, Engineering ScienceOsaka University Toyonaka Osaka 560-8531 Japan
| | - Masayoshi Nakano
- Department of Materials Engineering Science, Graduate School of, Engineering ScienceOsaka University Toyonaka Osaka 560-8531 Japan
- Institute for Molecular Science 38 Nishigo-Naka, Myodaiji Okazaki 444-8585 Japan
| | - Rajendra S. Ghadwal
- Anorganische Molekülchemie und Katalyse, Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für ChemieUniversität Bielefeld Universitätsstrasse 25 33615 Bielefeld Germany
| |
Collapse
|
25
|
Sharma MK, Rottschäfer D, Blomeyer S, Neumann B, Stammler HG, van Gastel M, Hinz A, Ghadwal RS. Diphosphene radical cations and dications with a π-conjugated C 2P 2C 2-framework. Chem Commun (Camb) 2019; 55:10408-10411. [PMID: 31403648 DOI: 10.1039/c9cc04701h] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis and characterization of the crystalline diphosphene radical cations [{(NHC)C(Ph)}P]2(GaCl4) (NHC = IPr = C{(NDipp)CH}23, SIPr = C{(NDipp)CH2}24; Dipp = 2,6-iPr2C6H3) and dications [{(NHC)C(Ph)}P]2(GaCl4)2 (NHC = IPr 5, SIPr 6) featuring a π-conjugated C2P2C2-framework has been reported.
Collapse
Affiliation(s)
- Mahendra K Sharma
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
26
|
Hu X, Chen H, Zhao L, Miao M, Han J, Wang J, Guo J, Hu Y, Zheng Y. Nitrogen analogues of Chichibabin's and Müller's hydrocarbons with small singlet-triplet energy gaps. Chem Commun (Camb) 2019; 55:7812-7815. [PMID: 31215565 DOI: 10.1039/c9cc02725d] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Nitrogen analogues of Chichibabin's and Müller's hydrocarbons, DPh-D and TPh-D, based on 1,2,4-benzotriazinyl (Blatter) were studied. The two diradicaloids with good chemical and thermal stability exhibit smaller singlet-triplet energy gaps (ΔES-T from -1.05 to -1.27 kcal mol-1) than the hydrocarbon diradicaloids with the same bridges.
Collapse
Affiliation(s)
- Xiaoguang Hu
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu 610054, People's Republic of China.
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Stuyver T, Zeng T, Tsuji Y, Geerlings P, De Proft F. Diradical Character as a Guiding Principle for the Insightful Design of Molecular Nanowires with an Increasing Conductance with Length. NANO LETTERS 2018; 18:7298-7304. [PMID: 30346793 DOI: 10.1021/acs.nanolett.8b03503] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In recent years, a considerable interest has grown in the design of molecular nanowires with an increasing conductance with length. The development of such nanowires is highly desirable because they could play an important role in future molecular-scale circuitry. Whereas the first experimental observation of this nonclassical behavior still has to be realized, a growing number of candidate wires have been proposed theoretically. In this Letter, we point out that all the wires with an anti-Ohmic increasing conductance with length proposed so far share a common characteristic: their diradical character increases with length. The conceptual connection between diradical character and conductance enables a systematic design of such anti-Ohmic wires and explains the difficulty in their syntheses. A strategy is proposed to balance the stability and conductance so that this nonclassical phenomenon can be observed.
Collapse
Affiliation(s)
- Thijs Stuyver
- Algemene Chemie , Vrije Universiteit Brussel , Pleinlaan 2 , 1050 Brussels , Belgium
| | - Tao Zeng
- Department of Chemistry , Carleton University , Ottawa , Ontario K1S5B6 , Canada
| | - Yuta Tsuji
- Institute for Materials Chemistry and Engineering and IRCCS , Kyushu University , Nishi-ku, Fukuoka 819-0395 , Japan
| | - Paul Geerlings
- Algemene Chemie , Vrije Universiteit Brussel , Pleinlaan 2 , 1050 Brussels , Belgium
| | - Frank De Proft
- Algemene Chemie , Vrije Universiteit Brussel , Pleinlaan 2 , 1050 Brussels , Belgium
| |
Collapse
|