Absorption effects of carbon tetrachloride on the structural and thermodynamic properties of copper(II) trans-1,4-cyclohexanedicarboxylate

Large amount of carbon tetrachloride can be absorbed into 1-dimensional tunnels in copper(II) trans-1,4-cyclohexane dicarboxylate (Cu(trans-1,4-OOCC6H10COO)) under the saturated vapor pressure at room temperature, and the desorption can be performed easily by evacuation above room temperature. It has been confirmed that the absorption/desorption is reversible. The thermodynamic and structural properties were studied for the empty (non-absorbed) sample, and 10, 22 and 31% of full carbon tetrachloride-absorbed samples by adiabatic calorimetry between 13 and 300 K and by powder X-ray diffractometry with high-energy synchrotron radiation at SPring-8 of JASRI. The heat capacity anomaly due to the first-order phase transition observed in the empty sample was not observed in the full carbon tetrachloride-absorbed sample. However, the partially absorbed samples showed smaller heat capacity anomaly at lower temperatures than the empty sample. Such phenomena were compared with the previous results of toluene-absorbed sample, and the difference between the two cases was discussed.