Four Anderson- and isopolymolybdate-viologen photochromic materials for UV detection, inkless erasable printing, and ammonia detection

In this work, four POMs-based compounds are devised and synthesized by employing viologen organic ligand under hydrothermal and solvothermal conditions, namely [M2(H2O)6(Cpmbpy)2(TeMo6O24)] M = Ni (1); Co (2)), {[M(Cpmbpy)2(DMF)2(beta-Mo8O26)][H4(beta-Mo8O26)]}& sdot;4C2H7N (M = Cu (3); Co (4)), (Cpmbpy = 1-Cyclopropylmethyl-[4,4 ']bipyridinyl-1-ium & sdot;chloride). Compound 1 or 2 exhibits one-dimensional (1D) POMs-Ni chain constructed from the [TeMo6O24]6- POMs and Ni metal ions. For compound 3 or 4, two 4,4 '-bipyridine groups and two DMF molecules coordinate with a CuII ion to form a {Cu(Cpmbpy)2(DMF)2}4subunit. And the two [beta-Mo8O26]4- are directly connected the {Cu(Cpmbpy)2(DMF)2}4+ subunit to form a 1D chain structure. Compounds 1-4 exhibits photochromic properties under irradiation with a filtered Xe lamp (300-400 nm), showing rapid light response and varying degrees of color change. Four compounds can also be utilized as visible UV detectors and inkless erasable printing materials. In addition, compounds 1 and 2 exhibits a significant NH3 response.