1
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Yuhara K, Tanaka K. The Photosalient Effect and Thermochromic Luminescence Based on o-Carborane-Assisted π-Stacking in the Crystalline State. Angew Chem Int Ed Engl 2024; 63:e202319712. [PMID: 38339862 DOI: 10.1002/anie.202319712] [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: 12/20/2023] [Revised: 02/08/2024] [Accepted: 02/09/2024] [Indexed: 02/12/2024]
Abstract
Herein, we report the unique multiple-stimuli responsiveness of anthracene-tethered o-carborane derivatives. We designed and synthesized anthracene derivatives with different substitution positions and numbers of the o-carborane units. Two compounds had characteristic crystal structures involving the columnar π-stacking structures of the anthracene units. From the analysis of crystalline-state structure-property relationships, it was revealed that the crystals exhibited the photosalient effect accompanied by photochemical [4+4] cycloaddition reactions and temperature-dependent photophysical dual-emission properties including excimer emission of anthracene. Those properties were considered as non-radiative and radiative deactivation pathways through the excimer formation in the excited state and the formation of excimer species was facilitated by the π-stacking structure of anthracene units. Moreover, we found unusual temperature dependency on the occurrence of the photosalient effect. According to the data from variable temperature X-ray crystallography, a strong correlation between lattice shrinkage and strain accumulation is suggested.
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Affiliation(s)
- Kazuhiro Yuhara
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan
| | - Kazuo Tanaka
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan
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2
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You DK, Kim M, Kim D, Kim N, Lee KM. Improvement in Radiative Efficiency Via Intramolecular Charge Transfer in ortho-Carboranyl Luminophores Modified with Functionalized Biphenyls. Inorg Chem 2023. [PMID: 37311712 DOI: 10.1021/acs.inorgchem.3c01242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In this study, we found that the electronic effects of the functional groups on aromatic units attached to o-carboranyl species can enhance the efficiency of intramolecular charge transfer (ICT)-based radiative decay processes. Six o-carboranyl-based luminophores having attached functionalized biphenyl groups with CF3, F, H, CH3, C(CH3)3, and OCH3 substituents were prepared and fully characterized by multinuclear magnetic resonance spectroscopy. In addition, their molecular structures were determined by single-crystal X-ray diffractometry, which revealed that the distortion of the biphenyl rings and the geometries around the o-carborane cages were similar. All compounds exhibited ICT-based emissions in the rigid state (solution at 77 K and film). Intriguingly, the quantum efficiencies (Φem) of five compounds (that of the group with CF3 could not be measured because of its extremely weak emissions) in the film state increased gradually as the electron-donating power of the terminal functional group modifying the biphenyl moiety increased. Furthermore, the nonradiative decay constants (knr) for the group with OCH3 were estimated to be one-tenth of those for the group with F, whereas the radiative decay constants (kr) for the five compounds were similar. The dipole moments (μ) calculated for the optimized first excited state (S1) structures gradually increased, from that of the group with CF3 to that of the group with OCH3, implying that the inhomogeneity of the molecular charge distribution was enhanced by electron donation. The electron-rich environment formed as a result of electron donation led to efficient charge transfer to the excited state. Both experimental and theoretical findings revealed that the electronic environment of the aromatic moiety in o-carboranyl luminophores can be controlled to accelerate or interrupt the ICT process in the radiative decay of excited states.
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Affiliation(s)
- Dong Kyun You
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Mingi Kim
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Dongwook Kim
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Namkyun Kim
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Kang Mun Lee
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
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3
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Ochi J, Yanagihara T, Tanaka K, Chujo Y. Tuning of the height of energy barrier between locally-excited and charge transfer states by altering the fusing position of o-carborane in phenylnaphthalene. Phys Chem Chem Phys 2023; 25:11839-11844. [PMID: 37067862 DOI: 10.1039/d3cp00334e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
We synthesized two types of the regioisomers fused by a phenylnaphthalene ring with variable connection points to the o-carborane scaffold. In this paper, we describe their photoluminescence (PL) properties and detailed photochemical mechanisms. According to the series of optical measurements, interestingly, they showed different PL characters in terms of wavelength and the dual-emission character despite that they have the common aromatic unit. Variable-temperature PL measurements and quantum chemical calculations suggested that the substitution position of aryl groups to o-carborane plays an important role in determining the energy barrier to the intramolecular charge-transfer (ICT) state at the S1 state. Finally, it is revealed that the relative position of the C-C bond of o-carborane and the aryl center should be responsible for the photophysical events of aryl-o-carboranes.
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Affiliation(s)
- Junki Ochi
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
| | - Takumi Yanagihara
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
| | - Kazuo Tanaka
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
| | - Yoshiki Chujo
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
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4
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Relationship between the Molecular Geometry and the Radiative Efficiency in Naphthyl-Based Bis-Ortho-Carboranyl Luminophores. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27196565. [PMID: 36235102 PMCID: PMC9572229 DOI: 10.3390/molecules27196565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 09/26/2022] [Accepted: 09/28/2022] [Indexed: 11/05/2022]
Abstract
The efficiency of intramolecular charge transfer (ICT)-based emission on π-aromatic-group-appended closo-ortho-carboranyl luminophores is known to be affected by structural fluctuations and molecular geometry, but investigation of this relationship has been in progress to date. In this study, four naphthyl-based bis-o-carboranyl compounds, in which hydrogen (15CH and 26CH) or trimethysilyl groups (15CS and 26CS) were appended at the o-carborane cage, were synthesized and fully characterized. All the compounds barely displayed an emissive trace in solution at 298 K; however, 15CH and 26CH distinctly exhibited a dual emissive pattern in rigid states (in solution at 77 K and in films), attributed to locally excited (LE) and ICT-based emission, while 15CS and 26CS showed strong ICT-based greenish emission. Intriguingly, the molecular structures of the four compounds, analyzed by single X-ray crystallography, showed that the C-C bond axis of the o-carborane cage in the trimethysilyl group-appended compounds 15CS and 26CS were more orthogonal to the plane of the appended naphthyl group than those in 15CH and 26CH. These features indicate that 15CS and 26CS present an efficient ICT transition based on strong exo-π-interaction, resulting in a higher quantum efficiency (Φem) for ICT-based radiative decay than those of 15CH and 26CH. Moreover, the 26CS structure revealed most orthogonal geometry, resulting in the highest Φem and lowest knr values for the ICT-based emission. Consequently, all the findings verified that efficient ICT-based radiative decay of aromatic group-appended o-carboranyl luminophores could be achieved by the formation of a specific geometry between the o-carborane cage and the aromatic plane.
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5
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Kim M, Ryu CH, You DK, Hong JH, Lee KM. Crucial Factors Regulating Intramolecular Charge-Transfer-Based Radiative Efficiency in ortho-Carboranyl Luminophores: Planarity between Substituted Biphenyl Rings. ACS OMEGA 2022; 7:24027-24039. [PMID: 35847313 PMCID: PMC9281304 DOI: 10.1021/acsomega.2c03344] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
o-Carboranyl compounds contain specific geometries, ranging from planar to orthogonally distorted biphenyl rings. Herein, 13 o-carboranyl compounds, 1HF-13PP, were synthesized and fully characterized to determine the impact of structural formation of the aromatic group appended with the o-carborane to estimate the efficiency of their radiative decay process. All the compounds exhibited significant intramolecular charge transfer (ICT)-based emission in the crystalline state at 298 K. Remarkably, increasing the distorted dihedral angles between biphenyl rings gradually decreased the emission efficiencies. Furthermore, their radiative decay constants decreased linearly with increasing dihedral angles, which demonstrated the inversely proportional relationship between these two factors. These findings distinctly suggest that the planar or distorted geometry of substituted aryl groups can strongly affect the efficiency of the ICT-based radiative process in o-carboranyl luminophores.
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6
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Tahaoğlu D, Usta H, Alkan F. Revisiting the Role of Charge Transfer in the Emission Properties of Carborane-Fluorophore Systems: A TDDFT Investigation. J Phys Chem A 2022; 126:4199-4210. [PMID: 35658432 PMCID: PMC9272399 DOI: 10.1021/acs.jpca.2c02435] [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] [Indexed: 12/03/2022]
Abstract
In this study, we performed a detailed investigation of the S1 potential energy surface (PES) of o-carborane-anthracene (o-CB-Ant) with respect to the C-C bond length on o-CB and the dihedral angle between o-CB and Ant moieties. The effects of different substituents (F, Cl, CN, and OH) on carbon- or boron-substituted o-CB, along with a π-extended acene-based fluorophore, pentacene, on the nature and energetics of S1 → S0 transitions are evaluated. Our results show the presence of a non-emissive S1 state with an almost pure charge transfer (CT) character for all systems as a result of significant C-C bond elongation (C-C = 2.50-2.56 Å) on o-CB. In the case of unsubstituted o-CB-Ant, the adiabatic energy of this CT state corresponds to the global minimum on the S1 PES, which suggests that the CT state could be involved in emission quenching. Despite large deformations on the o-CB geometry, predicted energy barriers are quite reasonable (0.3-0.4 eV), and the C-C bond elongation can even occur without a noticeable energy penalty for certain conformations. With substitution, it is shown that the dark CT state becomes even more energetically favorable when the substituent shows -M effects (e.g., -CN), whereas substituents showing +M effects (e.g., -OH) can result in an energy increase for the CT state, especially for partially stretched C-C bond lengths. It is also shown that the relative energy of the CT state on the PES depends strongly on the LUMO level of the fluorophore as this state is found to be energetically less favorable compared to other conformations when anthracene is replaced with π-extended pentacene. To our knowledge, this study shows a unique example of a detailed theoretical analysis on the PES of the S1 state in o-CB-fluorophore systems with respect to substituents or fluorophore energy levels. Our findings could guide future experimental work in emissive o-CB-fluorophore systems and their sensing/optoelectronic applications.
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Affiliation(s)
- Duygu Tahaoğlu
- Department of Nanotechnology Engineering, Abdullah Gül University, Kayseri 38080, Turkey
| | - Hakan Usta
- Department of Nanotechnology Engineering, Abdullah Gül University, Kayseri 38080, Turkey
| | - Fahri Alkan
- Department of Nanotechnology Engineering, Abdullah Gül University, Kayseri 38080, Turkey
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7
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Ryu CH, Lee SH, Kim M, Lee KM. Geometric structural insights for enhanced radiative efficiency: Spiro[fluorene–carbazole]‐based
ortho
‐carboranyl
luminophores. B KOREAN CHEM SOC 2022. [DOI: 10.1002/bkcs.12540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Chan Hee Ryu
- Department of Chemistry, Institute for Molecular Science and Fusion Technology Kangwon National University Chuncheon Gangwon Republic of Korea
| | - Seok Ho Lee
- Department of Chemistry, Institute for Molecular Science and Fusion Technology Kangwon National University Chuncheon Gangwon Republic of Korea
| | - Mingi Kim
- Department of Chemistry, Institute for Molecular Science and Fusion Technology Kangwon National University Chuncheon Gangwon Republic of Korea
| | - Kang Mun Lee
- Department of Chemistry, Institute for Molecular Science and Fusion Technology Kangwon National University Chuncheon Gangwon Republic of Korea
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8
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Im S, Ryu CH, Kim M, You DK, Yi S, Lee W, Lee KM. Effects of molecular geometry on the efficiency of intramolecular charge transfer-based luminescence in o-carboranyl-substituted 1H-phenanthro[9,10-d]imidazoles. Inorg Chem Front 2022. [DOI: 10.1039/d1qi01405f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The distinct difference in solid-state emission efficiency between 1H-phenanthro[9,10-d]imidazole–o-carboranyl luminophores showed that the geometric orientation is a key factor for controlling intramolecular charge transfer-based radiative decay.
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Affiliation(s)
- Sehee Im
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Chan Hee Ryu
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Mingi Kim
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Dong Kyun You
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Sanghee Yi
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Wonchul Lee
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Kang Mun Lee
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
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9
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Ryu CH, Lee SH, Yi S, Hong JH, Im S, Lee KM. Naphthyl‐ and Quinoline‐Appended
o
‐Carboranyl Luminophores: Intramolecular Charge Transfer‐Based Radiative Decay Controlled by Structural Geometry around C−C Bond Axis. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100768] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Chan Hee Ryu
- Department of Chemistry Institute for Molecular Science and Fusion Technology Kangwon National University Chuncheon, Gangwon 24341 Republic of Korea
| | - Seok Ho Lee
- Department of Chemistry Institute for Molecular Science and Fusion Technology Kangwon National University Chuncheon, Gangwon 24341 Republic of Korea
| | - Sanghee Yi
- Department of Chemistry Institute for Molecular Science and Fusion Technology Kangwon National University Chuncheon, Gangwon 24341 Republic of Korea
| | - Ju Hyun Hong
- Department of Chemistry Institute for Molecular Science and Fusion Technology Kangwon National University Chuncheon, Gangwon 24341 Republic of Korea
| | - Sehee Im
- Department of Chemistry Institute for Molecular Science and Fusion Technology Kangwon National University Chuncheon, Gangwon 24341 Republic of Korea
| | - Kang Mun Lee
- Department of Chemistry Institute for Molecular Science and Fusion Technology Kangwon National University Chuncheon, Gangwon 24341 Republic of Korea
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10
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Lee SH, Mun MS, Kim M, Lee JH, Hwang H, Lee W, Lee KM. Alteration of intramolecular electronic transition via deboronation of carbazole-based o-carboranyl compound and intriguing 'turn-on' emissive variation. RSC Adv 2021; 11:24057-24064. [PMID: 35479040 PMCID: PMC9036662 DOI: 10.1039/d1ra03716a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 07/05/2021] [Indexed: 01/10/2023] Open
Abstract
The conversion of closo-o-carborane–containing compounds to the nido-o-species via deboronation causes photophysical changes that could be used for sensing applications. 9-Methyl-9H-carbazole–based closo- (closo-Cz) and nido-o-carboranyl (nido-Cz) compounds were prepared and fully characterised by multinuclear NMR spectroscopy and elemental analysis, and the solid-state molecular structure of closo-Cz was analysed by X-ray crystallography. Although the closo-compound exhibited an emissive pattern centred at λem = ca. 530 nm in the rigid state only (in THF at 77 K and as a film), nido-Cz demonstrated intense emission in the near-UV region (λem = ca. 380 nm) in both solution and film states at 298 K. The positive solvatochromic effect of nido-Cz and the results of theoretical calculations for both the o-carboranyl compounds supported that these emissive features originate from intramolecular charge transfer (ICT) corresponding to the o-carborane. Furthermore, the calculations verified that the electronic role of the o-carboranyl unit changed from acceptor to donor upon deboronation from closo-Cz to nido-Cz. Investigations of the radiative decay mechanisms of closo-Cz and nido-Cz according to their quantum efficiencies (Φem) and decay lifetimes (τobs) suggested that the ICT-based radiative decays of closo-Cz and nido-Cz readily occur in the film (solid) and solution state, respectively. These observations implied that the emission of closo-Cz in the solution state could be drastically enhanced by deboronation to nido-Cz upon exposure to an increasing concentration of fluoride anions. Indeed, turn-on emissive features in an aqueous solution were observed upon deboronation, strongly suggesting the potential of closo-Cz as a turn-on and visually detectable chemodosimeter for fluoride ion sensing. Deboronation of a 9-methyl-9H-carbazole–based closo-o-carboranyl compound to the nido-o-carborane in an aqueous solution results in a ratiometric turn-on response in the deep-blue emission region with moderate reactivity.![]()
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Affiliation(s)
- Seok Ho Lee
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University Chuncheon Gangwon 24341 Republic of Korea
| | - Min Sik Mun
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University Chuncheon Gangwon 24341 Republic of Korea
| | - Mingi Kim
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University Chuncheon Gangwon 24341 Republic of Korea
| | - Ji Hye Lee
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University Chuncheon Gangwon 24341 Republic of Korea
| | - Hyonseok Hwang
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University Chuncheon Gangwon 24341 Republic of Korea
| | - Wonchul Lee
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University Chuncheon Gangwon 24341 Republic of Korea
| | - Kang Mun Lee
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University Chuncheon Gangwon 24341 Republic of Korea
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11
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You DK, So H, Ryu CH, Kim M, Lee KM. Strategic molecular design of closo-ortho-carboranyl luminophores to manifest thermally activated delayed fluorescence. Chem Sci 2021; 12:8411-8423. [PMID: 34221322 PMCID: PMC8221186 DOI: 10.1039/d1sc00791b] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 05/11/2021] [Indexed: 11/22/2022] Open
Abstract
In this paper, we propose a strategic molecular design of closo-o-carborane-based donor-acceptor dyad system that exhibits thermally activated delayed fluorescence (TADF) in the solution state at ambient temperature. Planar 9,9-dimethyl-9H-fluorene-based compounds with closo- and nido-o-carborane cages appended at the C2-, C3-, and C4-positions of each fluorene moiety (closo-type: 2FC, 3FC, 4FC, and 4FCH, and nido-type: nido-4FC = [nido-form of 4FC]·[NBu4]) were prepared and characterized. The solid-state molecular structure of 4FC exhibited a significantly distorted fluorene plane, which suggests the existence of severe intramolecular steric hindrance. In photoluminescence measurements, 4FC exhibits a noticeable intramolecular charge transition (ICT)-based emission in all states (solution at 298 K and 77 K, and solid states); however, emissions by other closo-compounds were observed in only the rigid state (solution at 77 K and film). Furthermore, nido-4FC did not exhibit emissive traces in any state. These observations verify that all radiative decay processes correspond to ICT transitions triggered by closo-o-carborane, which acts as an electron acceptor. Relative energy barriers calculated by TD-DFT as dihedral angles around o-carborane cages change in closo-compounds, which indicates that the structural formation of 4FC is nearly fixed around its S0-optimized structure. This differs from that for other closo-compounds, wherein the free rotation of their o-carborane cages occurs easily at ambient temperature. Such rigidity in the structural geometry of 4FC results in ICT-based emission in solution at 298 K and enhancement of quantum efficiency and radiative decay constants compared to those for other closo-compounds. Furthermore, 4FC displays short-lived (∼0.5 ns) and long-lived (∼30 ns) PL decay components in solution at 298 K and in the film state, respectively, which can be attributed to prompt fluorescence and TADF, respectively. The calculated energy difference (ΔE ST) between the first excited singlet and triplet states of the closo-compounds demonstrate that the TADF characteristic of 4FC originates from a significantly small ΔE ST maintained by the rigid structural fixation around its S0-optimized structure. Furthermore, the strategic molecular design of the o-carborane-appended π-conjugated (D-A) system, which forms a rigid geometry due to severe intramolecular steric hindrance, can enhance the radiative efficiency for ICT-based emission and trigger the TADF nature.
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Affiliation(s)
- Dong Kyun You
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University Chuncheon Gangwon 24341 Republic of Korea
| | - Hyunhee So
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University Chuncheon Gangwon 24341 Republic of Korea
| | - Chan Hee Ryu
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University Chuncheon Gangwon 24341 Republic of Korea
| | - Mingi Kim
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University Chuncheon Gangwon 24341 Republic of Korea
| | - Kang Mun Lee
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University Chuncheon Gangwon 24341 Republic of Korea
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12
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Liu K, Wang G, Ding N, Zhang J, Kong J, Liu T, Fang Y. High-Performance Trichloroacetic Acid Sensor Based on the Intramolecular Hydrogen Bond Formation and Disruption of a Specially Designed Fluorescent o-Carborane Derivative in the Film State. ACS APPLIED MATERIALS & INTERFACES 2021; 13:19342-19350. [PMID: 33848121 DOI: 10.1021/acsami.1c03331] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Discriminative and sensitive detection of environmentally important and health-related trichloroacetic acid (TCA) suffers from various problems such as bulky instruments and time-consuming operation as well as complex sample processing. Herein, we present a rapid, sensitive, and specific method for the detection of gaseous TCA using a fluorescent single-molecule array. An o-carborane-based benzothiazole derivative (CB-BT-OCH3) with specific fluorescence properties was specifically designed and utilized to fabricate a film-based single-molecule array. It was revealed that the fluorescent film is photochemically stable and extremely sensitive to TCA vapor, depicting an observable fluorescence color change from green to blue. The experimental detection limit is 0.2 ppm, which is lower than the safety limit (1 ppm) required by the threshold limit values and biological exposure indices. In addition, the film could show detectable intensity change within 0.2 s. On the basis of multiple signal responses, a conceptual two-channel-based fluorescent TCA sensor was developed. Importantly, the proposed conceptual sensor paves a new route to the development of specific fluorescent film-based sensor arrays with a single fluorophore as sensing units.
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Affiliation(s)
- Ke Liu
- Key Laboratory of Applied Surface and Colloid Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, P. R. China
| | - Gang Wang
- Key Laboratory of Applied Surface and Colloid Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, P. R. China
| | - Nannan Ding
- Key Laboratory of Applied Surface and Colloid Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, P. R. China
| | - Jing Zhang
- Key Laboratory of Applied Surface and Colloid Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, P. R. China
| | - Jinglin Kong
- State Key Laboratory of NBC Protection for Civilian, Beijing 102205, P. R. China
| | - Taihong Liu
- Key Laboratory of Applied Surface and Colloid Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, P. R. China
| | - Yu Fang
- Key Laboratory of Applied Surface and Colloid Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, P. R. China
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13
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Lee SH, Mun MS, Lee JH, Im S, Lee W, Hwang H, Lee KM. Impact of the Electronic Environment in Carbazole-Appended o-Carboranyl Compounds on the Intramolecular-Charge-Transfer-Based Radiative Decay Efficiency. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00060] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Seok Ho Lee
- Department of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Min Sik Mun
- Department of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Ji Hye Lee
- Department of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Sehee Im
- Department of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Wonchul Lee
- Department of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Hyonseok Hwang
- Department of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
| | - Kang Mun Lee
- Department of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea
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14
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Lee SH, Lee JH, Mun MS, Yi S, Yoo E, Hwang H, Lee KM. Influence of Electronic Environment on the Radiative Efficiency of 9-Phenyl-9 H-carbazole-Based ortho-Carboranyl Luminophores. Molecules 2021; 26:molecules26061763. [PMID: 33801078 PMCID: PMC8003977 DOI: 10.3390/molecules26061763] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/19/2021] [Accepted: 03/19/2021] [Indexed: 11/16/2022] Open
Abstract
The photophysical properties of closo-ortho-carboranyl-based donor–acceptor dyads are known to be affected by the electronic environment of the carborane cage but the influence of the electronic environment of the donor moiety remains unclear. Herein, four 9-phenyl-9H-carbazole-based closo-ortho-carboranyl compounds (1F, 2P, 3M, and 4T), in which an o-carborane cage was appended at the C3-position of a 9-phenyl-9H-carbazole moiety bearing various functional groups, were synthesized and fully characterized using multinuclear nuclear magnetic resonance spectroscopy and elemental analysis. Furthermore, the solid-state molecular structures of 1F and 4T were determined by X-ray diffraction crystallography. For all the compounds, the lowest-energy absorption band exhibited a tail extending to 350 nm, attributable to the spin-allowed π–π* transition of the 9-phenyl-9H-carbazole moiety and weak intramolecular charge transfer (ICT) between the o-carborane and the carbazole group. These compounds showed intense yellowish emission (λem = ~540 nm) in rigid states (in tetrahydrofuran (THF) at 77 K and in films), whereas considerably weak emission was observed in THF at 298 K. Theoretical calculations on the first excited states (S1) of the compounds suggested that the strong emission bands can be assigned to the ICT transition involving the o-carborane. Furthermore, photoluminescence experiments in THF‒water mixtures demonstrated that aggregation-induced emission was responsible for the emission in rigid states. Intriguingly, the quantum yields and radiative decay constants in the film state were gradually enhanced with the increasing electron-donating ability of the substituent on the 9-phenyl group (‒F for 1F < ‒H for 2P < ‒CH3 for 3M < ‒C(CH3)3 for 4T). These features indicate that the ICT-based radiative decay process in rigid states is affected by the electronic environment of the 9-phenyl-9H-carbazole group. Consequently, the efficient ICT-based radiative decay of o-carboranyl compounds can be achieved by appending the o-carborane cage with electron-rich aromatic systems.
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Kim M, Im S, Ryu CH, Lee SH, Hong JH, Lee KM. Impact of deboronation on the electronic characteristics of closo-o-carborane: intriguing photophysical changes in triazole-appended carboranyl luminophores. Dalton Trans 2021; 50:3207-3215. [PMID: 33576753 DOI: 10.1039/d0dt04038j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
5-Phenyl-1,2,4-triazole-appended closo- (CB1 and CB2) and nido-o-carboranyl (nido-CB1 and nido-CB2) compounds were prepared and fully characterized using multinuclear NMR spectroscopy and elemental analysis. The solid-state molecular structures of both closo-compounds were analyzed by X-ray crystallography. Although the closo-compounds exhibited dual emissive patterns in the rigid state (in THF at 77 K), which were assignable to a π-π* local excitation (LE)-based emission (λem = ca. 380 nm) on the triazole moieties and to an intramolecular charge transfer (ICT)-based emission (ca. 460 nm) in which the o-carborane units acted as the acceptor (A), at 298 K in THF, the LE-based emission dominated. In contrast, the nido-compounds exhibited an intensive emission originating from ICT transitions in which the o-carborane units reversibly acted as the donor (D). In particular, the positive solvatochromic effects of both nido-compounds and the results of theoretical calculations for the o-carboranyl compounds supported the electronic role of the o-carboranyl unit in each compound. Investigation of the radiative decay mechanism of the closo- and nido-compounds using their quantum efficiency (Φem) and decay lifetime (τobs) suggested that the ICT-based radiative decay of nido-compounds occurred more efficiently than the LE-based decay of closo-compounds. These results implied that emission from the closo-compounds was drastically enhanced by the deboronation reaction upon exposure to an increasing concentration of fluoride anions, and finally became similar to the emission color (sky-blue) of the nido-compounds.
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Affiliation(s)
- Mingi Kim
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon, Gangwon 24341, Republic of Korea.
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Deboronation-Induced Ratiometric Emission Variations of Terphenyl-Based Closo- o-Carboranyl Compounds: Applications to Fluoride-Sensing. Molecules 2020; 25:molecules25102413. [PMID: 32455846 PMCID: PMC7287808 DOI: 10.3390/molecules25102413] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 05/20/2020] [Accepted: 05/21/2020] [Indexed: 01/02/2023] Open
Abstract
Closo-o-carboranyl compounds bearing the ortho-type perfectly distorted or planar terphenyl rings (closo-DT and closo-PT, respectively) and their nido-derivatives (nido-DT and nido-PT, respectively) were synthesized and fully characterized using multinuclear NMR spectroscopy and elemental analysis. Although the emission spectra of both closo-compounds exhibited intriguing emission patterns in solution at 298 and 77 K, in the film state, closo-DT mainly exhibited a π-π* local excitation (LE)-based emission in the high-energy region, whereas closo-PT produced an intense emission in the low-energy region corresponding to an intramolecular charge transfer (ICT) transition. In particular, the positive solvatochromic effect of closo-PT and theoretical calculation results at the first excited (S1) optimized structure of both closo-compounds strongly suggest that these dual-emissive bands at the high- and low-energy can be assigned to each π-π* LE and ICT transition. Interestingly, both the nido-compounds, nido-DT and nido-PT, exhibited the only LE-based emission in solution at 298 K due to the anionic character of the nido-o-carborane cages, which cannot cause the ICT transitions. The specific emissive features of nido-compounds indicate that the emissive color of closo-PT in solution at 298 K is completely different from that of nido-PT. As a result, the deboronation of closo-PT upon exposure to increasing concentrations of fluoride anion exhibits a dramatic ratiometric color change from orange to deep blue via turn-off of the ICT-based emission. Consequently, the color change response of the luminescence by the alternation of the intrinsic electronic transitions via deboronation as well as the structural feature of terphenyl rings indicates the potential of the developed closo-o-carboranyl compounds that exhibit the intense ICT-based emission, as naked-eye-detectable chemodosimeters for fluoride ion sensing.
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Recent Progress in the Development of Solid‐State Luminescent
o
‐Carboranes with Stimuli Responsivity. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201916666] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Ochi J, Tanaka K, Chujo Y. Recent Progress in the Development of Solid-State Luminescent o-Carboranes with Stimuli Responsivity. Angew Chem Int Ed Engl 2020; 59:9841-9855. [PMID: 32009291 DOI: 10.1002/anie.201916666] [Citation(s) in RCA: 120] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Indexed: 12/20/2022]
Abstract
o-Carborane, a cluster compound containing boron and adjacent carbon atoms, displays intriguing luminescent properties. Recently, compounds containing o-carborane units were found to show suppressed aggregation-induced quenching and intense solid-state emission; they also show potential for the development of stimuli-responsive luminochromic materials. In this Minireview, we introduce three kinds of fundamental photochemical properties: aggregation-induced emission, twisted intramolecular charge transfer in crystals, and environment-sensitive excimer formation in solids. Based on these properties, several types of luminochromism, such as thermos-, vapo-, and mechanochromism, have been discovered. Based mainly on results from recent studies, we illustrate these mechanisms as well as unique luminescent behaviors of o-carborane derivatives.
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Affiliation(s)
- Junki Ochi
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan
| | - Kazuo Tanaka
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan
| | - Yoshiki Chujo
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan
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Li J, Hou C, Huang C, Xu S, Peng X, Qi Q, Lai WY, Huang W. Boosting Circularly Polarized Luminescence of Organic Conjugated Systems via Twisted Intramolecular Charge Transfer. RESEARCH (WASHINGTON, D.C.) 2020; 2020:3839160. [PMID: 32395717 PMCID: PMC7193308 DOI: 10.34133/2020/3839160] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 03/22/2020] [Indexed: 04/11/2023]
Abstract
Realizing a high luminescence dissymmetry factor (g lum) is a paramount yet challenging issue in the research field of circularly polarized luminescence (CPL). Here, we reported a novel set of organic conjugated systems with twisted intramolecular charge transfer (TICT) characteristics based on conjugated o-carborane-binaphthyl dyads composing of binaphthyl units as chiral electron donors and o-carborane units as achiral electron acceptors, demonstrating intense CPL with large g lum values. Interestingly, single-crystalline o-1 exhibited a high-level brightness and a large g lum factor as high as +0.13, whereas single-crystalline o-2 processed a relatively low brightness with a decreased g lum value to -0.04. The significant diversity of CPL-active properties was triggered by the selective introduction of o-carborane units onto the binaphthyl units. Benefiting from the large magnetic dipole transition moments in TICT states, the CPL activity of TICT o-carborane-based materials exhibited amplified circular polarization. This study provides an efficient molecular engineering strategy for the rational design and development of highly efficient CPL-active materials.
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Affiliation(s)
- Junfeng Li
- Key Laboratory for Organic Electronics and Information Displays, Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210023, China
| | - Chenxi Hou
- Key Laboratory for Organic Electronics and Information Displays, Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210023, China
| | - Chao Huang
- Key Laboratory for Organic Electronics and Information Displays, Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210023, China
| | - Shanqi Xu
- Key Laboratory for Organic Electronics and Information Displays, Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210023, China
| | - Xuelei Peng
- Key Laboratory for Organic Electronics and Information Displays, Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210023, China
| | - Qi Qi
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China
| | - Wen-Yong Lai
- Key Laboratory for Organic Electronics and Information Displays, Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210023, China
- Shaanxi Institute of Flexible Electronics (SIFE), Northwestern Polytechnical University (NPU), 127 West Youyi Road, Xi'an, 710072 Shaanxi, China
| | - Wei Huang
- Key Laboratory for Organic Electronics and Information Displays, Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210023, China
- Shaanxi Institute of Flexible Electronics (SIFE), Northwestern Polytechnical University (NPU), 127 West Youyi Road, Xi'an, 710072 Shaanxi, China
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Kim M, Ryu CH, Hong JH, Lee JH, Hwang H, Lee KM. Planarity of N-aryl in appended 1,2,4-triazole-based o-carboranyl luminophores: a key factor to control intramolecular charge transfer. Inorg Chem Front 2020. [DOI: 10.1039/d0qi00915f] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The distinct difference in the photophysical characteristics between two triazole-based o-carboranes revealed that the planarity of aryl groups strongly influences intramolecular-charge-transfer-based emission.
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Affiliation(s)
- Mingi Kim
- Department of Chemistry
- Institute for Molecular Science and Fusion Technology
- Kangwon National University
- Chuncheon
- Republic of Korea
| | - Chan Hee Ryu
- Department of Chemistry
- Institute for Molecular Science and Fusion Technology
- Kangwon National University
- Chuncheon
- Republic of Korea
| | - Ju Hyun Hong
- Department of Chemistry
- Institute for Molecular Science and Fusion Technology
- Kangwon National University
- Chuncheon
- Republic of Korea
| | - Ji Hye Lee
- Department of Chemistry
- Institute for Molecular Science and Fusion Technology
- Kangwon National University
- Chuncheon
- Republic of Korea
| | - Hyonseok Hwang
- Department of Chemistry
- Institute for Molecular Science and Fusion Technology
- Kangwon National University
- Chuncheon
- Republic of Korea
| | - Kang Mun Lee
- Department of Chemistry
- Institute for Molecular Science and Fusion Technology
- Kangwon National University
- Chuncheon
- Republic of Korea
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Yan JF, Zhu GG, Yuan Y, Lin CX, Huang SP, Yuan YF. Carborane bridged ferrocenyl conjugated molecules: synthesis, structure, electrochemistry and photophysical properties. NEW J CHEM 2020. [DOI: 10.1039/d0nj00826e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
mono- and bis-carborane bridged ferrocenyl conjugated molecules 8–11 have been synthesized and systematically analyzed.
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Affiliation(s)
- Jian-Feng Yan
- Key Laboratory of Molecule Synthesis and Function Discovery (Fujian Province University)
- Department of Chemistry
- Fuzhou University
- Fuzhou 350108
- People's Republic of China
| | - Gai-Ge Zhu
- Key Laboratory of Molecule Synthesis and Function Discovery (Fujian Province University)
- Department of Chemistry
- Fuzhou University
- Fuzhou 350108
- People's Republic of China
| | - Ye Yuan
- Key Laboratory of Molecule Synthesis and Function Discovery (Fujian Province University)
- Department of Chemistry
- Fuzhou University
- Fuzhou 350108
- People's Republic of China
| | - Cai-Xia Lin
- Key Laboratory of Molecule Synthesis and Function Discovery (Fujian Province University)
- Department of Chemistry
- Fuzhou University
- Fuzhou 350108
- People's Republic of China
| | - Shu-Ping Huang
- Key Laboratory of Molecule Synthesis and Function Discovery (Fujian Province University)
- Department of Chemistry
- Fuzhou University
- Fuzhou 350108
- People's Republic of China
| | - Yao-Feng Yuan
- Key Laboratory of Molecule Synthesis and Function Discovery (Fujian Province University)
- Department of Chemistry
- Fuzhou University
- Fuzhou 350108
- People's Republic of China
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22
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Kim S, Lee JH, So H, Kim M, Mun MS, Hwang H, Park MH, Lee KM. Insights into the effects of substitution position on the photophysics of mono-o-carborane-substituted pyrenes. Inorg Chem Front 2020. [DOI: 10.1039/d0qi00563k] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mono-o-carborane-substituted pyrenes were prepared and apparently showed the effects of substitution position on their photophysical property.
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Affiliation(s)
- Seonah Kim
- Department of Chemistry
- Institute for Molecular Science and Fusion Technology
- Kangwon National University
- Chuncheon
- Republic of Korea
| | - Ji Hye Lee
- Department of Chemistry
- Institute for Molecular Science and Fusion Technology
- Kangwon National University
- Chuncheon
- Republic of Korea
| | - Hyunhee So
- Department of Chemistry
- Institute for Molecular Science and Fusion Technology
- Kangwon National University
- Chuncheon
- Republic of Korea
| | - Mingi Kim
- Department of Chemistry
- Institute for Molecular Science and Fusion Technology
- Kangwon National University
- Chuncheon
- Republic of Korea
| | - Min Sik Mun
- Department of Chemistry
- Institute for Molecular Science and Fusion Technology
- Kangwon National University
- Chuncheon
- Republic of Korea
| | - Hyonseok Hwang
- Department of Chemistry
- Institute for Molecular Science and Fusion Technology
- Kangwon National University
- Chuncheon
- Republic of Korea
| | - Myung Hwan Park
- Department of Chemistry Education
- Chungbuk National University
- Cheongju
- Republic of Korea
| | - Kang Mun Lee
- Department of Chemistry
- Institute for Molecular Science and Fusion Technology
- Kangwon National University
- Chuncheon
- Republic of Korea
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