The mechanical adaptability
of a family of six one-dimensional
crystalline coordination polymers (CPs) of cadmium ([CdX2(3-X′py)2]
n
; 1: X = Br, X′ = Cl, 2: X = I, X′
= Cl, 3: X = I, X′ = Br, 4: X = Cl,
X′ = I, 5: X = Br, X′ = I, and 6: X, X′ = I) to applied external force was examined, and a
plethora of flexible responses was noticed. While two of the six CPs
(4 and 6) were slightly elastic, the remaining
four CPs (1–3 and 5)
presented variable plastic deformation; three of these (1–3) displayed exceptional crystal flow, and one
(2) demonstrated unprecedented ductility of crystalline
metal–organic material. The feature was examined by theory
and custom-designed experiments, and it was shown that specific and
directional intermolecular interactions are not only the most influential
structural feature in determining the type of mechanical responses
(i.e., elastic vs plastic), with interlocking of adjacent molecules
playing only a supportive role, but also an unavoidable tool for dialing-in
a diversity of plastic responses in Cd(II) coordination polymers.