Uniaxial Negative Thermal Expansion and Mechanical Properties of a Zinc-Formate Framework.The thermal expansion behavior of a metal-formate framework, Zn(HCOO)₂·2(H₂O) (1), has been systematically studied via variable temperature single-crystal X-ray diffraction.  Our results demonstrate that this formate exhibits significant negative thermal expansion (NTE, -26(2) MK-1) along its c-axis.  The stiffness and hardness anisotropy can be correlated well with the underlying framework structure, like its thermoelastic behavior.
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