Asymmetric seven-/eight-step spin-crossover in a three-dimensional Hofmann-type metal–organic framework

Abstract

Spin-crossover (SCO) materials with multiple spin states have attracted special interest for their potential applications in multi-switches and high-order data storage. Herein, an unprecedented asymmetric seven-/eight-step SCO behavior is revealed in a three-dimensional Hofmann-type metal–organic framework [Fe(4-abpt){Au(CN)₂}₂]·2DMF·EtOH (4-abpt = 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole), which represents the highest step in the SCO field. Moreover, the formation of a molecular alloy by mixing [Au(CN)₂]⁻ and [Ag(CN)₂]⁻ units is explored as a strategy towards multi-step SCO materials for the first time.