A spin-crossover complex based on a 2,6-bis(pyrazol-1-yl)pyridine (1-bpp) ligand functionalized with a carboxylate group

摘要

Spin crossover (SCO) complexes are one of the most spectacular examples of molecular bistability. In these systems low-spin (LS) to high-spin (HS) transitions can be triggered through a variety of external stimuli (e.g. temperature, pressure or electromagnetic radiation). In addition to the interesting fundamental aspects of this phenomenon, these systems are of growing interest in the area of functional materials due to their possible applications as sensors, memories or switching devices.~1 The most studied SCO systems are based on iron(II) complexes that undergo spin crossover between their diamagnetic LS (S = 0) and paramagnetic HS (S = 2) configurations.~2 The change of electronic configuration is accompanied by drastic changes in the optical and magnetic properties of these compounds.~3 Thus, under given experimental conditions, the same material can be found in two states exhibiting different optical and magnetic behaviours. Abrupt transformations with hysteretic behaviour are expected for systems with strong intermolecular interactions.