Hydrogen-bond engineering induced ferroelastic phase transition in copper-based organic–inorganic hybrid thermochromic materials

Abstract

We report two organic–inorganic hybrid thermochromic crystals, [(2A5MP)₂CuCl₄] (2A5MP = 2-amino-5-methylpyridine) (1) and [(2A4MP)₂CuCl₄] (2A4MP = 2-amino-4-methylpyridine) (2). Through hydrogen bond engineering optimization, the ferroelastic material 2 undergoes an isomorphic phase transition with a large thermal hysteresis of 36 K at 397 K/361 K.