A three-dimensional Mn(ii) coordination polymer with ferroelasticity obtained by introducing coligands to form novel networks

Abstract

Ferroelastic materials have rich properties, which have important applications in memory devices, multifunctional devices and novel controllable devices, but few ferroelastic crystals based on metal coordination complexes have been reported. Herein, we have introduced coligands in the structure to obtain a ferroelastic complex {Mn[(i-Pr)₃PO](dca)₂} (1), [dca = N(CN)₂⁻, (i-Pr₃PO) = triisopropylphosphine oxide], with a new topology (3,5)-connected binodal network. The dca ligands of 1 show two different bonding modes, μ-1,5- and μ-1,3,5-bridging, to form a 3D structure. Stimulation by high temperature leads to more intense molecular motion and greater symmetry changes, thus producing a high-temperature (390 K) ferroelastic phase transition with the Aizu symbol mmmF2/m. The full elastic constants of 1 were calculated using density functional theory to describe the Young's modulus, shear modulus and Poisson's ratio, and the results indicate that 1 is a ductile material. In addition, 1 emits blue light under excitation at 380 nm. This provides new ideas for the exploration and design of molecular ferroelastic materials with elaborate structures and excellent properties.