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

Abstract

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 S 0 ground state and in the T 1 phosphorescent excited state (λ ex = 340 nm) were compared. Upon irradiation with UV light, the excimeric interactions were enhanced, resulting in a contraction of the Au I ···Au I 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.

Synthesis, Crystal Structure and Selected Properties of Mono(dithiocarbamato)‐gold(I), AuS2CNH2

“…Similar luminescence behavior of gold compounds has been previously reported in the literature, for instance, for the compounds as [Au(epdtc)] 2 , [Au(mpdtc)] 2 , [C 2 mim][Au(SCN) 2 ], Au 2 (NHC–(CH 2 ) n –NHC) 2 Br 2 [epdtc = ethyl(pyridine‐4‐ylmethyl)dithiocarbamate, mpdtc = methyl(2‐(pyridin‐2‐yl)ethyl)dithiocarbamate, C 2 mim = 1‐alkyl‐3‐methylimidazolium], and was assigned to aurophilic interactions in these compounds , . Although the aurophilic interaction is involved as a source of the emission process, the luminescence energy cannot be correlated a priori with the Au I –Au I separations, because the (resultant) luminescence additionally depends on structural features (e.g.…”

Re‐investigation of Barium‐Gold(I)‐Tetra‐Thiostannate(IV), Ba[Au2SnS4], with Short AuI···AuI Separation Showing Luminescence Properties

“…This luminescent behavior can be assigned to aurophilic interactions. Similar luminescence behavior for Au I compounds was already reported in the literature, for instance, for the compounds [Au(epdtc)] 2 , [56] [ [56] [C2mim][Au(SCN) 2 ], [76] Au 2 (NHC-(CH 2 ) 3 -NHC) 2 (PF 6 ) 2 [77] (Au•••Au: 3.189 Å; λ em,max = 21187 cm -1 ) Au 2 (NHC-(CH 2 ) 3 -NHC) 2 Br 2 [77] (Au•••Au: 3.132 Å; λ em,max = 22728 cm -1 ) [epdtc = ethyl(pyridine-4-ylmethyl)dithiocarbamate, mpdtc = methyl(2-(pyridin-2-yl)ethyl)dithiocarbamate, C 2 mim = 1alkyl-3-methylimidazolium]. As already mentioned in the in-troduction, it seems likely that with increasing Au-Au distances the emission energy declines and vice versa.…”

α‐ and β‐[Bmim][BiCl4(2,2′‐bpy)]: Two Polymorphic Bismuth‐Containing Ionic Liquids with Crystallization‐Induced Phosphorescence

“…In particular, in the past decade, researchers have made headway in fabricating luminescent metal‐containing ILs by choosing appropriate metal centers for the [ MX n ] y − anions. To date, the most commonly used M centers have been f ‐block (lanthanides) and transition metal elements (e.g., Mn 2+ , Ru 2+ , Cu + , Ag + , Au + , and Pt 2+[12] ). In contrast, luminescent ILs containing main‐group metal ions have scarcely been reported.…”