Gold(III) Complexes of Asymmetrically Aryl-Substituted 1,2-Dithiolene Ligands Featuring Potential-Controlled Spectroscopic Properties: An Insight into the Electronic Properties of bis(Pyren-1-yl-ethylene-1,2- dithiolato)Gold (III)

ARAGONI, MARIA CARLA;ARCA, MASSIMILIANO;Devillanova F. A;ISAIA, FRANCESCO;LIPPOLIS, VITO;PINTUS, ANNA

2011-01-01

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Abstract

The electrochemical, UV/Vis–NIR absorption, and emission-spectroscopic features of (TBA+)(1−) and the corresponding neutral complex 1 were investigated (TBA+=tetrabutylammonium; 1−=[AuIII(Pyr,H-edt)2]−; Pyr,H-edt2−=pyren-1-yl-ethylene-1,2-dithiolato). The intense electrochromic NIR absorption (λmax=1432 nm; ε=13000 m−1 cm−1 in CH2Cl2) and the potential-controlled visible emission in the range 400–500 nm, the energy of which depends on the charge of the complex, were interpreted on the grounds of time-dependent DFT calculations carried out on the cis and trans isomers of 1, 1−, and 12−. In addition, to evaluate the nonlinear optical properties of 1x− (x=0, 1), first static hyperpolarizability values βtot were calculated (βtot=78×10−30 and 212×10−30 esu for the cis isomer of 1− and 1, respectively) and compared to those of differently substituted [Au(Ar,H-edt)2]x− gold dithiolenes [Ar=naphth-2-yl (2), phenyl (3); x=0, 1].