Luminescent Gold(I) Complexes with Tetrathia[7]helicene diphosphanes: photophysical and chiroptical properties

Gold(I) phosphine complexes exhibit significant biological activities that can be used for the development of novel therapeutic agents.1 In particular, a number of new gold(I) phosphine complexes displays a wide spectrum of anticancer activity, especially in some cisplatin-resistant cell lines,2 and their cytotoxicity was found to be mediated by targeting mitochondria and inducing apoptosis.3 In this context, innovative gold(I) complexes based on tetrathia[7]helicene phosphanes could represent a promising and interesting class of anticancer gold-based drugs. Tetrathia[7]helicenes (7-TH) are polyconjugated -systems, in which four thiophene rings alternate with three benzene rings, to form a non planar, chiral, stable helix which allows the existence of M and P antipodes.4 In the course of our studies on the applications of 7-TH derivatives in the field of the organometallic chemistry,5 we have synthesized and fully characterized the dinuclear gold(I) complex 1.6 The luminescence properties of Au(I) complex ()-1 at room and low temperature in diluted solution and in solid state, as well as the chiroptical properties of its antipodes have been investigated. In collaboration with the Fondazione IRCCS Istituto Nazionale dei Tumori of Milan, biological experiments to evaluate the cytotoxicity of enantiopure ()-1 and ()-1 against a panel of human cancer cell lines are in progress.