Theoretical studies on cyclometalated platinum(II) complexes based on isoquinolinyl azolate: ππ-stacking interaction and photophysical properties |
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| Affiliation: | 1. Division of Hematology, Takasago-Seibu Hospital, 1-10-41 Nakasuji, Takasago 676-0812, Japan;2. Children’s Center for Cancer and Blood Disorders, Department of Child Health, Phoenix Children’s Hospital, University of Arizona College of Medicine, 445 North 5th Street, Suite 322, Phoenix, AZ 85004, USA;1. State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China;2. State Key Laboratory of Organic–Inorganic Composites, Department of Polymer Engineering, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China;3. Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China;1. Materials & Engineering Research Institute, Sheffield Hallam University, City Campus, Howard Street, Sheffield S1 1WB, UK;2. Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK;1. State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China;2. Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, The Chinese Academy of Sciences, Beijing 100190, China;1. College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang 421002, People’s Republic of China;2. Department of Applied Physics, School of Physics and Electronics, Hunan University, Changsha 410082, People’s Republic of China;3. School of Physics and Electronics, Central South University, Changsha 410083, People’s Republic of China |
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| Abstract: | The photophysical properties of four Pt(II) complexes Pt(Lx)2], x = 1–4, (1–4), where Lx are 6-t-butyl-1-(3-trifluoro-methyl-1H-pyrazol-5-yl) isoquinoline (1), 3,5-di-t-butyl-1-(3-trifluoromethyl-1H-pyrazol-5-yl) isoquinoline (2), 6-(2,6-diisopropylphenyl)-1-(3-trifluoro-methyl-1H-pyrazol-5-yl) isoquinoline (3), and 4-(2,6-diisopropylphenyl)-1-(3-trifluoro-methyl-1H-pyrazol-5-yl) isoquinoline (4), are investigated by the density functional theory (DFT) and time-dependent density functional theory (TD-DFT). Furthermore, the binding interaction in Ptn stack is studied to discover the influence of different cyclometalated ligand. The calculated results rationalize that the complex 1 exhibits a stack of three molecules rather than the infinite aligned stack. Complexes 1 and 3 present the stronger tendency to form the aligned ππ-stacking interaction as compared with complexes 2 and 4. The dimers of other four complexes, 3a (Pt(L3)(Ma), Ma = 5-(2-pyridyl)-3-trifluoromethylpyrazole), 3b (Pt(L3)(Mb), Mb = 5-(4-phenyl-2-pyridyl)-3-trifluoromethylpyrazole), 3c (Pt(L3)(Mc), Mc = 5-(4-tert-butyl-2-pyridyl)-3-trifluoromethylpyrazole), and 5 (Pt(fppz)2 fppz = 5-(2-pyridyl)-3-trifluoromethylpyrazole), are also studied to investigate the effect of different aromatic ligand or substituents on the ππ-stacking interaction. The emissions of complexes 1–4 originate from various charge transfer states including the intraligand charge transfer (ILCT) and ligand-to-ligand charge transfer (LLCT) together with the metal-to-ligand charge transfer (MLCT). Finally, the items related with the radiative and nonradiative rate constants are examined. Besides the potential energy profile between the lowest triplet state (3MLCT) and metal centered state (3MC), the deactivation process of the 3MC state via the minimum energy crossing point (MECP) between the 3MC and the ground state (1S0) potential surfaces is also explored. |
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| Keywords: | Stack Pt(II) complex Minimum energy crossing point Quantum yield Isoquinolinyl azolate |
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