Optically Multiresponsive Heteroleptic Platinum Dithiolene Complex with Proton-Switchable Properties

Both linear- and nonlinear-optical properties of Bu₄N[Pt(L1)(L2)] (1; L1 = [4′,5′:5,6][1,4]dithiino[2,3-b]quinoxaline-1′,3′dithiolato; L2 = (R)-α-MBAdto dithiooxamidate, where (R)-α-MBA = (R)-(+)-α-methylbenzyl) upon HCl addition at room temperature change dramatically: the color turns from deep blue to green; the luminescence switches from deep red to green; the nonlinear-optical response (first hyperpolarizability) increases by a factor of 12. Thus, 1 behaves as a unique multiresponsive optical switch whose properties can be followed by the naked eye.