Vapochromic Soft Crystals Constructed with Metal Complexes

Abstract

AbstractVapochromism, a phenomenon in which the color or luminescence color of a substance changes in response to gaseous molecules, has potential for developing sensor materials to detect harmful substances in the environment. In addition, vapochromism is scientifically interesting for the direct visualization of interactions between gases and solids. The crystals of metal complexes involve diverse and flexible electronic interactions, such as metal–metal and metal–ligand interactions. It is expected that slight structural changes in such crystals will lead to distinct color or emission color changes, thus achieving highly sensitive and selective vapochromic responses. Consequently, highly ordered and flexible response systems (i.e., soft crystals) can be constructed. This chapter introduces the interesting and attractive features of vapor-responsive soft crystals by discussing platinum complexes that show color and luminescence changes in dilute vapor atmospheres while maintaining an ordered structure, nickel(II) complexes that change magnetic properties in conjunction with a color change, and copper(I) complexes that change luminescence color in response to N-heteroaromatic vapors.