A new series of N-heterocyclic carbene (NHC) ligand precursors (1 and 2) with their [Ag(I)(NHC) 2 ]PF 6 complexes (3 and 4) and [ClAu(I)(NHC)] complexes (5 and 6) are reported. Complexes 5 and 6 were synthesized via transmetalation reaction using either 3 or 4 and AuCl(SMe 2 ) as reactants, respectively. All the synthesized compounds were fully characterized using elemental analyses and Fourier transform infrared, 1 H NMR and 13 C NMR spectroscopies. In the crystal structures of 3, 5 and 6, the Ag(I) and Au(I) ions are in a linear geometry. The entire structure of 3 is stabilized by significant π-π interactions, while the structures of 5 and 6 are stabilized with the presence of aurophilic interactions between the adjacent Au(I) ions as well as CH-π or π-π interactions. From photoluminescence studies, complexes 5 and 6 show dual-emission characteristics. The higher-energy fluorescence originates from 1 XLCT mixed with 1 MLCT, while the lower-energy phosphorescence is ascribed to 3 XLCT and 3 MLCT with small contribution of 3 ILCT, as evidenced by density functional theory (DFT) and time-dependent DFT calculations of the modelled molecules.

Electroactive self-assembled monolayers (SAMs) containing viologen group are formed through the adeorption of thiol-functionalized viologen compound CHJ(CHZ)QV~+(CHZ)~SH, where p+ i N,N'-dialkylbipyridum (i.e. a viologen p u p ) , onto gold electrodes h m methanol/water solution and its electrochemical behavior is investigated by Ac voltammetry and square wave voltammetry, which have the high sensitivity against beckground charging. The viologen S A M formed is a sub-monolayer and the normal potentials corresponding to the two successive oneelectron transfer processes of the active centers (viologen) are -360 mV and -750 mV (us. Ag/AgCl) in 0.1 mol/L phosphate b d e r solutions (pH 6.96) respectively, and the standard electron transfer rate coastant L 9.0 s-' . The electrochemicd behavior of this SAM in various solUtiOM has been preliminarily discussed. KeywordsSelf-assembled monolayers, viologen, Ac voltammetry, q u a r e wave voltammetry