Guest-tuned spin crossover in flexible supramolecular assemblies templated by a halide (Cl−, Br− or I−)

Abstract

Ligand 1,3-bis(3-(pyridin-2-yl)-1H-pyrazol-5-yl)benzene, L, forms mononuclear spin crossover complexes [FeL₃]²⁺ with pendant arms that cause them to dimerize through numerous intermolecular interactions forming supramolecular (X@[FeL₃]₂)³⁺ cations. They have the flexibility to encapsulate Cl⁻, Br⁻ or I⁻, which allow tuning the magnetic properties, in the solid state and in solution.