A novel Pt(II)-diimine complex, [Pt(CN)2(H2dcphen)] (1; H2dcphen = 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(H2dcphen)]·2H2O (1P), exhibited vapochromic behavior in the presence of alcoholic vapors via a transformation to the red, crystalline, porous vaporadsorbed form, 1R ⊃ vapor. The obtained 1R ⊃ vapor complex released the adsorbed vapors upon heating without collapse of the porous structure. The vapor-free, porous 1R⊃ open could detect water or n-hexane vapor, although these vapors could not induce 1P to 1R ⊃ vapor transformation, and 1R ⊃ open could be easily converted to the initial 1P by manual grinding. These results indicate that 1 is a new shape-memory material that functions via formation and collapse of the porous framework with emission change upon vapor-adsorption and grinding; this enables it to exhibit vapor history and ON-OFF switching sensing functions.

A highly methanol-selective vapochromic response has been realized in a Ni -quinonoid complex, [Ni(HL ) ] (H L =4-methylamino-6-methyliminio-3-oxocyclohexa-1,4-dien-1-olate) which exhibits a reversible structural transformation including a coordination geometrical change between the square-planar and octahedral structure by the selective uptake of methanol vapor. This was accompanied by a remarkable color change between purple and orange, as well as temperature-robust spin-state switching in the solid state under ambient conditions. It is remarkable that the properties are derived by the fine structural modification of the quinonoid ligand such as methyl or ethyl analogues. Such a system has high potential for applications in memory devices as well as chemical sensors and smart responsive materials.

A highly methanol‐selective vapochromic response has been realized in a NiII‐quinonoid complex, [Ni(HLMe)2] (H2LMe=4‐methylamino‐6‐methyliminio‐3‐oxocyclohexa‐1,4‐dien‐1‐olate) which exhibits a reversible structural transformation including a coordination geometrical change between the square‐planar and octahedral structure by the selective uptake of methanol vapor. This was accompanied by a remarkable color change between purple and orange, as well as temperature‐robust spin‐state switching in the solid state under ambient conditions. It is remarkable that the properties are derived by the fine structural modification of the quinonoid ligand such as methyl or ethyl analogues. Such a system has high potential for applications in memory devices as well as chemical sensors and smart responsive materials.

We synthesized a carboxy-functionalized Pt(ii)–terpyridine complex that exhibits vapochromic behavior that is switchable via protonation/deprotonation of the carboxy group.

A luminescent Pt(ii) complex with potassium ions was successfully synthesized and its coordination-based vapochromic behavior was investigated.