Shape‐Memory Platinum(II) Complexes: Intelligent Vapor‐History Sensor with ON–OFF Switching Function

A novel platinum(II)–diimine complex, [Pt(CN) 2 (H 2 dcphen)] ( 1 ; H 2 dcphen=4,7‐dicarboxy‐1,10‐ phenanthroline), was synthesized and its vapochromic shape‐memory behavior was evaluated. The as‐synthesized amorphous purple solid, [Pt(CN) 2 (H 2 dcphen)]⋅2 H 2 O ( 1 P ), exhibited vapochromic behavior in the presence of alcoholic vapors through transformation to a red, crystalline, porous, vapor‐adsorbed form, 1 R⊃vapor . The obtained 1 R⊃vapor complex released the adsorbed vapors upon heating without collapse of the porous structure. The vaporfree, porous 1 R⊃open could detect water or n ‐hexane vapor, although these vapors could not induce 1 P ‐to‐ 1 R⊃vapor transformation, and 1 R⊃open could easily be converted to the initial 1 P by manual grinding. These results indicate that 1 is a new shape‐memory material that functions through formation and collapse of the porous framework with an emission change upon vapor‐adsorption and grinding; this enables it to exhibit vapor history and ON–OFF switching sensing functions.