Mechanically induced polyamorphism in a one-dimensional coordination polymer

Abstract

We created different amorphous structures of a coordination polymer by applying mechanical shear forces. One-dimensional Cu(Tf₂N)₂(bip)₂ (1, Tf₂N⁻ = bis(trifluoromethanesulfonyl)imide, bip = 1,3-bis(1-imidazolyl)propane) melted at 245 °C and underwent a glass transition at −10 °C by a static cooling process. 1 formed another amorphous state with a distinct glass transition point of 70 °C under oscillatory shear stress. The difference of orientation in their structures was studied by X-ray absorption fine structure and small-angle X-ray scattering. The reversible transition between the two amorphous states was observed by dynamic mechanical analyses.