Deformable Mn( iii )–Schiff-base dimer for anomalously large positive and negative anisotropic thermal expansions

A new molecular crystal with supramolecular layers assembled by a Mn(iii)-Schiff-base dimer and fumaric acid was investigated by means of variable-temperature single-crystal structural analyses. The Mn(iii)-Schiff-base dimer reveals remarkable thermally-induced deformation and hence causes anomalously large positive and negative anisotropic thermal expansions in the supramolecular layers, providing a new type of promising weak supramolecular synthon for designing sensitive thermomechanical actuators.