Cyclometalated heteronuclear Pt/Ag and Pt/Tl complexes: A structural and photophysical study
- Jamali, S. 2
- Ghazfar, R. 2
- Lalinde, E. 3
- Jamshidi, Z. 1
- Samouei, H. 5
- Shahsavari, Hamid Reza. 3
- Moreno, M.T. 3
- Escudero-Adán, E. 5
- Benet-Buchholz, J. 5
- Milic, D. 4
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1
Chemistry and Chemical Engineering Research Center of Iran
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Chemistry and Chemical Engineering Research Center of Iran
Teherán, Irán
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2
Sharif University of Technology
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3
Universidad de La Rioja
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4
University of Zagreb
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5
Instituto Catalán de Investigación Química
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ISSN: 1477-9226
Year of publication: 2014
Volume: 43
Issue: 3
Pages: 1105-1116
Type: Article
beta Ver similares en nube de resultadosMore publications in: Dalton Transactions
Abstract
To investigate the factors influencing the luminescent properties of polymetallic cycloplatinated complexes a detailed study of the photophysical and structural properties of the heteronuclear complexes [Pt2Me 2(bhq)2(μ-dppy)2Ag2(μ-acetone) ](BF4)2, 2, [PtMe(bhq)(dppy)Tl]PF6, 3, and [Pt2Me2(bhq)2(dppy)2Tl]PF 6, 4, [bhq = benzo[h]quinoline, dppy = 2-(diphenylphosphino)pyridine] was conducted. Complexes 3 and 4 synthesized by the reaction of [PtMe(bhq)(dppy)], 1, with TlPF6 (1 or 1/2 equiv.) and stabilized by unsupported Pt-Tl bonds as revealed by multinuclear NMR spectroscopy and confirmed by X-ray crystallography for 3. DFT calculations for the previously reported butterfly Pt2Ag2 cluster 2 reveal that in the optimized geometry the bridging acetone molecule is removed and the metal core displays a planar-shaped geometry in which according to a QTAIM calculation and natural bond orbital (NBO) analysis the Ag⋯Ag metallophilic interaction is strengthened. In contrast to the precursor 1, which is only emissive in glassy solutions (3MLCT 485 nm), all 2-4 heteropolynuclear complexes display intense emissions in the solid state and in glassy solutions. Time-dependent density functional theory (TD-DFT) is used to elucidate the origin of the electronic transitions in the heteronuclear complexes 2 and 3. The low energy absorption and intense orange emission for cluster 2 (solid 77 K and glass) are attributed to metal-metal to ligand charge transfer (MM′LCT) with a minor L′LCT contribution. For 3 and 4 two different bands are developed: the high energy band (602-630 nm) observed for 4 at 77 K (solid, glass) and in diluted glasses for 3 is ascribed to emission from discrete Pt2Tl units of mixed 3L′LCT/3LM′CT origin. However, the low energy band (670-690 nm) observed at room temperature (solid) for both complexes and also in concentrated glasses for 3 is assigned to 3ππ excited states arising from intermolecular interactions. © The Royal Society of Chemistry 2014.