Photophysical Property of catena-Bis(thiocyanato)aurate(I) Complexes in Ionic Liquids

• Published in: Crystal growth & design Vol. 15; no. 3; pp. 1422 - 1429
• Main Authors: Aoyagi, Noboru, Shinha, Yusuke, Ikeda-Ohno, Atsushi, Haga, Yoshinori, Shimojo, Kojiro, Brooks, Neil R, Izuoka, Akira, Naganawa, Hirochika, Kimura, Takaumi, Binnemans, Koen
• Format: Journal Article
• Language: English
• Published: American Chemical Society 04.03.2015
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/cg501792m

The photochemistry of a gold(I) thiocyanate complex has been investigated to determine the coordination structure in both the solid and liquid states. The coordination geometries of the supramolecular [Au(SCN)2] n complex and the concomitant exciplex have mainly been analyzed by crystallographic analysis and X-ray absorption spectroscopy. The Au–S bond distance and Au···Au separation of the compound in the S0 ground state and in the T1 phosphorescent excited state (λex = 340 nm) were compared. Upon irradiation with UV light, the excimeric interactions were enhanced, resulting in a contraction of the AuI···AuI aurophilic distance by 0.0113(4) Å. A broad luminescence spectrum was observed for the one-dimensional chain suprastructure. The time-resolved luminescence spectra indicated the entity of several oligomeric species in the crude liquid without neutral solvent molecules. In addition, extended X-ray absorption fine structure spectroscopy exhibited a slight change in the nearest Au–S distance due to the photoswitched transformation. The deformation of the (Au---Au)* exciplexes was not apparently promoted in the liquid state with the asymmetrical imidazoium cations having a nonlocal charge distribution in the present observation. This is plausibly due to a flexible molecular structure and a property in the liquid state. In conclusion, the photoexcited nature of the pseudo-one-dimensional complexes has emerged in controlling bond distances among the supramolecular networks.