Mechanical and Thermal ON-OFF Switching of the Vapochromic Behavior of a Luminescent Polymorphic Pt(II) Complex.

Vapochromic materials that exhibit color/luminescence changes induced by vapor exposure have attracted considerable attention. Herein, we report the grinding- and heating-induced ON-OFF switching of the vapochromic behavior of [Pt(ppyCl 2 )(Clacac)] ( 1 ; ppyCl 2 = 2-(3-chlorophenyl)-4-chloropyridinato, Clacac = 3-chloroacetylacetonato). 1 formed yellow and orange polymorphs ( 1-Y and 1-O ), and 1-Y could be converted to 1-Og , which showed a very similar crystal structure but with a broadened X-ray diffraction pattern compared with that of 1-O . Moreover, 1-Og can be reversibly transformed into 1-O via heating and grinding. Notably, 1-Og underwent a N , N -dimethylacetamide vapor-induced transformation to 1-Y , whereas 1-O did not undergo such a transformation. These results indicate the ON-OFF switching of vapochromic behavior induced via grinding and heating. This finding will be beneficial for developing intelligent molecular devices.