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Palion-Gazda J, Kwiecień A, Choroba K, Penkala M, Kryczka A, Machura B. The Role of Intraligand Charge Transfer Processes in Iridium(III) Complexes with Morpholine-Decorated 4'-Phenyl-2,2':6',2″-terpyridine. Molecules 2024; 29:3074. [PMID: 38999026 PMCID: PMC11243112 DOI: 10.3390/molecules29133074] [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: 06/03/2024] [Revised: 06/24/2024] [Accepted: 06/25/2024] [Indexed: 07/14/2024] Open
Abstract
To investigate the impact of the electron-donating morpholinyl (morph) group on the ground- and excited-state properties of two different types of Ir(III) complexes, [IrCl3(R-C6H4-terpy-κ3N)] and [Ir(R-C6H4-terpy-κ3N)2](PF6)3, the compounds [IrCl3(morph-C6H4-terpy-κ3N)] (1A), 4[Ir(morph-C6H4-terpy-κ3N)2](PF6)3 (2A), [IrCl3(Ph-terpy-κ3N)] (1B) and [Ir(Ph-terpy-κ3N)2](PF6)3 (2B) were obtained. Their photophysical properties were comprehensively investigated with the aid of static and time-resolved spectroscopic methods accompanied by theoretical DFT/TD-DFT calculations. In the case of bis-terpyridyl iridium(III) complexes, the attachment of the morpholinyl group induced dramatic changes in the absorption and emission characteristics, manifested by the appearance of a new, very strong visible absorption tailing up to 600 nm, and a significant bathochromic shift in the emission of 2A relative to the model chromophore. The emission features of 2A and 2B were found to originate from the triplet excited states of different natures: intraligand charge transfer (3ILCT) for 2A and intraligand with a small admixture of metal-to-ligand charge transfer (3IL-3MLCT) for 2B. The optical properties of the mono-terpyridyl iridium(III) complexes were less significantly impacted by the morpholinyl substituent. Based on UV-Vis absorption spectra, emission wavelengths and lifetimes in different environments, transient absorption studies, and theoretical calculations, it was demonstrated that the visible absorption and emission features of 1A are governed by singlet and triplet excited states of a mixed MLLCT-ILCT nature, with a dominant contribution of the first component, that is, metal-ligand-to-ligand charge transfer (MLLCT). The involvement of ILCT transitions was reflected by an enhancement of the molar extinction coefficients of the absorption bands of 1A in the range of 350-550 nm, and a small red shift in its emission relative to the model chromophore.
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Affiliation(s)
- Joanna Palion-Gazda
- Institute of Chemistry, University of Silesia, 9 Szkolna Str., 40-006 Katowice, Poland
| | - Aleksandra Kwiecień
- Institute of Chemistry, University of Silesia, 9 Szkolna Str., 40-006 Katowice, Poland
| | - Katarzyna Choroba
- Institute of Chemistry, University of Silesia, 9 Szkolna Str., 40-006 Katowice, Poland
| | - Mateusz Penkala
- Institute of Chemistry, University of Silesia, 9 Szkolna Str., 40-006 Katowice, Poland
| | - Anna Kryczka
- Institute of Chemistry, University of Silesia, 9 Szkolna Str., 40-006 Katowice, Poland
| | - Barbara Machura
- Institute of Chemistry, University of Silesia, 9 Szkolna Str., 40-006 Katowice, Poland
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Esteruelas MA, Moreno-Blázquez S, Oliván M, Oñate E. Competition between N, C, N-Pincer and N, N-Chelate Ligands in Platinum(II). Inorg Chem 2023; 62:10152-10170. [PMID: 37343120 PMCID: PMC11003652 DOI: 10.1021/acs.inorgchem.3c00694] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Indexed: 06/23/2023]
Abstract
Replacement of the chloride ligand of PtCl{κ3-N,C,N-[py-C6HR2-py]} (R = H (1), Me (2)) and PtCl{κ3-N,C,N-[py-O-C6H3-O-py]} (3) by hydroxido gives Pt(OH){κ3-N,C,N-[py-C6HR2-py]} (R = H (4), Me (5)) and Pt(OH){κ3-N,C,N-[py-O-C6H3-O-py]} (6). These compounds promote deprotonation of 3-(2-pyridyl)pyrazole, 3-(2-pyridyl)-5-methylpyrazole, 3-(2-pyridyl)-5-trifluoromethylpyrazole, and 2-(2-pyridyl)-3,5-bis(trifluoromethyl)pyrrole. The coordination of the anions generates square-planar derivatives, which in solution exist as a unique species or equilibria between isomers. Reactions of 4 and 5 with 3-(2-pyridyl)pyrazole and 3-(2-pyridyl)-5-methylpyrazole provide Pt{κ3-N,C,N-[py-C6HR2-py]}{κ1-N1-[R'pz-py]} (R = H; R' = H (7), Me (8). R = Me; R' = H (9), Me (10)), displaying κ1-N1-pyridylpyrazolate coordination. A 5-trifluoromethyl substituent causes N1-to-N2 slide. Thus, 3-(2-pyridyl)-5-trifluoromethylpyrazole affords equilibria between Pt{κ3-N,C,N-[py-C6HR2-py]}{κ1-N1-[CF3pz-py]} (R = H (11a), Me (12a)) and Pt{κ3-N,C,N-[py-C6HR2-py]}{κ1-N2-[CF3pz-py]} (R = H (11b), Me (12b)). 1,3-Bis(2-pyridyloxy)phenyl allows the chelating coordination of the incoming anions. Deprotonations of 3-(2-pyridyl)pyrazole and its substituted 5-methyl counterpart promoted by 6 lead to equilibria between Pt{κ3-N,C,N-[pyO-C6H3-Opy]}{κ1-N1-[R'pz-py]} (R' = H (13a), Me (14a)) with a κ-N1-pyridylpyrazolate anion, keeping the pincer coordination of the di(pyridyloxy)aryl ligand, and Pt{κ2-N,C-[pyO-C6H3(Opy)]}{κ2-N,N-[R'pz-py]} (R' = H (13c), Me (14c)) with two chelates. Under the same conditions, 3-(2-pyridyl)-5-trifluoromethylpyrazole generates the three possible isomers: Pt{κ3-N,C,N-[pyO-C6H3-Opy]}{κ1-N1-[CF3pz-py]} (15a), Pt{κ3-N,C,N-[pyO-C6H3-Opy]}{κ1-N2-[CF3pz-py]} (15b), and Pt{κ2-N,C-[pyO-C6H3(Opy)]}{κ2-N,N-[CF3pz-py]} (15c). The N1-pyrazolate atom produces a remote stabilizing effect on the chelating form, pyridylpyrazolates being better chelate ligands than pyridylpyrrolates. Accordingly, reactions of 4-6 with 2-(2-pyridyl)-3,5-bis(trifluoromethyl)pyrrole yield Pt{κ3-N,C,N-[py-C6HR2-py]}{κ1-N1-[(CF3)2C4(py)HN]} (R = H (16), Me (17)) or Pt{κ3-N,C,N-[pyO-C6H3-Opy]}{κ1-N1-[(CF3)2C4(py)HN]} (18), displaying κ1-N1-pyrrolate coordination. Complexes 7-10 are efficient green phosphorescent emitters (488-576 nm). In poly(methyl methacrylate) (PMMA) films and in dichloromethane, they experience self-quenching, due to molecular stacking. Aggregation occurs through aromatic π-π interactions, reinforced by weak platinum-platinum interactions.
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Affiliation(s)
- Miguel A. Esteruelas
- Departamento de Química
Inorgánica, Instituto de Síntesis Química y Catálisis
Homogénea (ISQCH), Centro de Innovación en Química
Avanzada (ORFEO-CINQA), Universidad de Zaragoza—CSIC, 50009 Zaragoza, Spain
| | - Sonia Moreno-Blázquez
- Departamento de Química
Inorgánica, Instituto de Síntesis Química y Catálisis
Homogénea (ISQCH), Centro de Innovación en Química
Avanzada (ORFEO-CINQA), Universidad de Zaragoza—CSIC, 50009 Zaragoza, Spain
| | - Montserrat Oliván
- Departamento de Química
Inorgánica, Instituto de Síntesis Química y Catálisis
Homogénea (ISQCH), Centro de Innovación en Química
Avanzada (ORFEO-CINQA), Universidad de Zaragoza—CSIC, 50009 Zaragoza, Spain
| | - Enrique Oñate
- Departamento de Química
Inorgánica, Instituto de Síntesis Química y Catálisis
Homogénea (ISQCH), Centro de Innovación en Química
Avanzada (ORFEO-CINQA), Universidad de Zaragoza—CSIC, 50009 Zaragoza, Spain
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Li G, Jiang Z, Tang M, Jiang X, Tu H, Zhu S, Liu R, Zhu H. Synthesis, Photophysics and Tunable Reverse Saturable Absorption of Bis-Tridentate Iridium(III) Complexes via Modification on Diimine Ligand. Molecules 2023; 28:molecules28020566. [PMID: 36677626 PMCID: PMC9864372 DOI: 10.3390/molecules28020566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 12/25/2022] [Accepted: 01/02/2023] [Indexed: 01/09/2023] Open
Abstract
Five novel bis-tridentate Ir(III) complexes (Ir-1−Ir-5) incorporating versatile N^N^C ligands and a N^C^N ligand (1,3-di(2-pyridyl)-4,6-dimethylbenzene) were synthesized. With the combination of experimental and theoretical methods, their steady and transient state characteristics were researched scientifically. The UV-visible absorption spectra show that the broadband charge transfer absorbance of those bis-tridentate Ir(III) complexes can reach 550 nm, all of these complexes reveal the long-lasting phosphorescent emission. Because the excited-state absorption is more powerful than the ground-state absorption, a sturdy reverse saturable absorption (RSA) process can ensue in the visible and near-infrared regions when the complexes are exposed to a 532 nm laser. Therefore, the optical power limiting (OPL) effect follows the trend: Ir-5 > Ir-4 ≈ Ir-3 > Ir-2 > Ir-1. Generally speaking, the expansion of π-conjugation and the introduction of electron donating/withdrawing groups on the N^N^C ligand could effectively elevate the OPL effect. Therefore, these octahedral bis-tridentate Ir(III) complexes might be exploited as potential OPL materials.
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Affiliation(s)
| | | | | | | | | | | | - Rui Liu
- Correspondence: (S.Z.); (R.L.)
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Shen Y, Kong X, Yang F, Bian HD, Cheng G, Cook TR, Zhang Y. Deep Blue Phosphorescence from Platinum Complexes Featuring Cyclometalated N-Pyridyl Carbazole Ligands with Monocarborane Clusters (CB 11H 12-). Inorg Chem 2022; 61:16707-16717. [PMID: 36205461 DOI: 10.1021/acs.inorgchem.2c02467] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The utilization of deep blue phosphorescent materials in high-performance displays and solid-state lighting requires high quantum efficiencies and color purities. Here, we describe the preparation and luminescent properties of novel platinum triplet emitters featuring cyclometalated N-pyridyl-carbazole ligands functionalized with closo-monocarborane clusters [CB11H12]-. All reported complexes were fully characterized by using standard small molecule techniques (UV-vis, cyclic voltammetry, nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HRMS)), and their solid-state structures were elucidated by X-ray diffraction. These platinum phosphors emit in the blue region of the visible wavelength spectrum in both the solid and solution states. Complex 4a exhibits the highest luminous efficiency at λem = 439 nm with a photoluminescent quantum yield (PLQY) of 60% by dispersing in a PMMA matrix. Electrochemical and computational studies of complexes 4a and 4b revealed that the blue phosphorescence originates mainly from intraligand 3π → π* (3ILCT) transitions with relatively small 3MLCT mixing. A deep-blue OLED containing 4a as the light-emitting dopant was successfully fabricated using a solution-processed method, and the device exhibited blue photoluminescence with CIE coordinates of (0.17, 0.15) and a maximum external quantum efficiency (EQEmax) value of 6.2%. This article represents the pioneering study of a deep blue PhOLED using a Pt complex bearing a closo-monocarborane anion substituent, providing a new avenue into the preparation of novel triplet emitters based on boron-rich cluster anions.
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Affiliation(s)
- Yunjun Shen
- Key Laboratory of Chemistry and Engineering of Forest Products, State Ethnic Affairs Commission, Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, Guangxi Collaborative Innovation Center for Chemistry and Engineering of Forest Products, School of Chemistry and Chemical Engineering, Guangxi Minzu University, No. 158, Daxue West Road, Nanning, Guangxi 530006, China
| | - Xiangjun Kong
- Key Laboratory of Chemistry and Engineering of Forest Products, State Ethnic Affairs Commission, Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, Guangxi Collaborative Innovation Center for Chemistry and Engineering of Forest Products, School of Chemistry and Chemical Engineering, Guangxi Minzu University, No. 158, Daxue West Road, Nanning, Guangxi 530006, China
| | - Fengjie Yang
- Key Laboratory of Chemistry and Engineering of Forest Products, State Ethnic Affairs Commission, Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, Guangxi Collaborative Innovation Center for Chemistry and Engineering of Forest Products, School of Chemistry and Chemical Engineering, Guangxi Minzu University, No. 158, Daxue West Road, Nanning, Guangxi 530006, China
| | - He-Dong Bian
- Key Laboratory of Chemistry and Engineering of Forest Products, State Ethnic Affairs Commission, Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, Guangxi Collaborative Innovation Center for Chemistry and Engineering of Forest Products, School of Chemistry and Chemical Engineering, Guangxi Minzu University, No. 158, Daxue West Road, Nanning, Guangxi 530006, China
| | - Gang Cheng
- State Key Laboratory of Synthetic Chemistry, HKU-CAS Joint Laboratory on New Materials, Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Timothy R Cook
- Department of Chemistry, University at Buffalo, The State University of New York, 856 Natural Sciences Complex, Buffalo, New York 14260, United States
| | - Yuzhen Zhang
- Key Laboratory of Chemistry and Engineering of Forest Products, State Ethnic Affairs Commission, Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, Guangxi Collaborative Innovation Center for Chemistry and Engineering of Forest Products, School of Chemistry and Chemical Engineering, Guangxi Minzu University, No. 158, Daxue West Road, Nanning, Guangxi 530006, China
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Su H, Hu L, Zhu S, Lu J, Hu J, Liu R, Zhu H. Transition metal complexes with strong and long-lived excited state absorption: from molecular design to optical power limiting behavior. REV INORG CHEM 2022. [DOI: 10.1515/revic-2022-0013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Transition metal complexes (TMCs) with strong and long-lived excited state absorption (ESA) usually exhibit high-performance optical power limiting (OPL) response. Several techniques, such as transmission vs. incident fluence curves and Z-scan have been widely used to assess the OPL performance of typical TMCs. The OPL performance of TMCs is highly molecular structure-dependent. Special emphasis is placed on the structure-OPL response relationships of Pt(II), Ir(III), Ru(II), and other metal complexes. This review concludes with perspectives on the current status of OPL field, as well as opportunities that lie just beyond its frontier.
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Affiliation(s)
- Huan Su
- School of Chemistry and Molecular Engineering, Nanjing Tech University , Nanjing , China
| | - Lai Hu
- School of Chemistry and Molecular Engineering, Nanjing Tech University , Nanjing , China
| | - Senqiang Zhu
- School of Chemistry and Molecular Engineering, Nanjing Tech University , Nanjing , China
| | - Jiapeng Lu
- School of Chemistry and Molecular Engineering, Nanjing Tech University , Nanjing , China
| | - Jinyang Hu
- School of Chemistry and Molecular Engineering, Nanjing Tech University , Nanjing , China
| | - Rui Liu
- School of Chemistry and Molecular Engineering, Nanjing Tech University , Nanjing , China
| | - Hongjun Zhu
- School of Chemistry and Molecular Engineering, Nanjing Tech University , Nanjing , China
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Zhu S, Pan Q, Li Y, Liu W, Liu R, Zhu H. Fluorene-decorated Ir(III) complexes: synthesis, photophysics and tunable triplet excited state properties in aggregation. Dalton Trans 2022; 51:13322-13330. [PMID: 35983911 DOI: 10.1039/d2dt01592g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two new heteroleptic cationic Ir(III) complexes bearing benzothiazole and pyridine motifs on fluorene groups were synthesized and characterized. Complexes Ir1 and Ir2 exhibit 1π,π* transitions below 430 nm, with broad but weak metal-to-ligand and ligand-to-ligand charge transfer absorption bands above 430 nm. Both complexes possess long-lived emissions (τem = 0.37 μs for Ir1, τem = 5.41 μs for Ir2) and triplet excited states (τTA = 0.14 μs for Ir1, τTA = 6.06 μs for Ir2). Their optical properties in solution and aggregated states were also investigated. Both Ir(III) complexes exhibit aggregation-induced phosphorescence emission behavior in an acetonitrile-water mixture. As the water content increased to 90%, the emission intensities of complexes Ir1 and Ir2 increased nearly 3 times and 2.8 times, respectively. Moreover, nonlinear transmittance experiments were performed in CH3CN and a CH3CN-H2O mixture (fw = 90%), and the strength of the reverse saturable absorption (RSA) at 532 nm followed the trend: Ir2 (CH3CN) ≥ Ir1 (CH3CN) > Ir2 (CH3CN-H2O) > Ir1 (CH3CN-H2O). Abundant triplet state excitons participated in the radiative transition progress, which inhibited the RSA process. These results indicate that the fluorene-decorated Ir(III) complexes are suitable for aggregation emission and optical power limiting applications.
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Affiliation(s)
- Senqiang Zhu
- School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China.
| | - Qianqian Pan
- School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China.
| | - Yuhao Li
- Institute of Bismuth and Rhenium, School of Materials and Chemistry, University of Shanghai for Science and Technology, Shanghai 200093, China.
| | - Wenqing Liu
- Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China
| | - Rui Liu
- School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China.
| | - Hongjun Zhu
- School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China.
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