Lattice Water Controlled Photo- and Thermochromism of N-Protonated Carbomethoxypyridinium Iodoargentate Hybrids

Two iodoargentate hybrids, {[HNOM][AgI2]·H2O} (1) and {[HINOM][AgI2]·H2O} (2) (HNOM+ = N-protonated 3-carbomethoxypyridinium; HINOM+ = N-protonated 4-carbomethoxypyridinium), have been designed and prepared, which were constructed from typical [AgI2]- inorganic chains and cationic hydrogen-bonding supramolecular networks (one-dimensional for 1 and three-dimensional for 2) of lattice water and positional isomeric N-protonated carbomethoxypyridinium. Two hybrids exhibit sensitive photochromism based on intermolecular electron transfer (ET) and thermochromism due to reversible hydration and dehydration and the consequent variation of intermolecular charge transfer (CT). Furthermore, loss of lattice water gives rise to improved photochromic dehydrated form 1T and optically inert dehydrated form 2T, suggesting a delicate modulating effect of lattice contraction on the intermolecular CT and ET as well as consequently photoresponsive behaviors.