Theoretical studies on the structural and optical properties of a series of Os(II) diimine complexes [Os(NN)(CO)2I2] (NN = 2,2′-bipyridine(bpy), 4,4′-di-tert-butyl-2,2′-bipyridine(dbubpy), 4,4′-dichlorine-2,2′-bipyridine(dclbpy)) |
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Authors: | Yu-Hui Wu Qing-Jiang Pan Xin Zhou Bao-Hui Xia Tao Liu Hong-Xing Zhang |
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Affiliation: | aState Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, People’s Republic of China;bSchool of Chemistry and Materials Science, Heilongjiang University, Haerbin 150080, People’s Republic of China;cCollege of Chemistry, Jilin University, Changchun 130023, People’s Republic of China |
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Abstract: | The ground- and excited-state structures for a series of Os(II) diimine complexes [Os(N N)(CO)2I2] (N N = 2,2′-bipyridine (bpy) (1), 4,4′-di-tert-butyl-2,2′-bipyridine (dbubpy) (2), and 4,4′-dichlorine-2,2′-bipyridine (dclbpy) (3)) were optimized by the MP2 and CIS methods, respectively. The spectroscopic properties in dichloromethane solution were predicted at the time-dependent density functional theory (TD-DFT, B3LYP) level associated with the PCM solvent effect model. It was shown that the lowest-energy absorptions at 488, 469 and 539 nm for 1–3, respectively, were attributed to the admixture of the [dxy (Os) → π*(bpy)] (metal-to-ligand charge transfer, MLCT) and [p(I) → π*(bpy)] (interligand charge transfer, LLCT) transitions; their lowest-energy phosphorescent emissions at 610, 537 and 687 nm also have the 3MLCT/3LLCT transition characters. These results agree well with the experimental reports. The present investigation revealed that the variation of the substituents from H → t-Bu → Cl on the bipyridine ligand changes the emission energies by altering the energy level of HOMO and LUMO but does not change the transition natures. |
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Keywords: | Excited-state Luminescence Os complexes |
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