トランス1,4-シクロヘキサンジカルボン酸銅 (II) についてSPring-8での放射光粉末X線構造解析とヘリウム温度から室温に至る温度領域での精密熱容量測定を行った。160 Kに1次相転移を持ち,結晶構造が変化した。これにトルエンを吸蔵させると,吸蔵量の増加とともに転移温度が高温側にシフトしながら相転移が消失した。一方,四塩化炭素を吸蔵させると転移温度は低温側にシフトしながら吸蔵量の増加とともに熱異常が消失し,構造相転移を起さなくなった。トルエンの場合は吸蔵により格子が収縮するが,四塩化炭素の場合は吸蔵により格子が膨張した。1次元細孔に吸蔵されたこれらの分子鎖は融解現象を示さないことなどが明らかになった。
Large amount of toluene and carbon tetrachloride can be absorbed into 1-dimensional tunnels in copper(II) trans-1,4-cyclohexanedicarboxylate Cu2(OOC-C6H10-COO) under the saturated vapor pressure at room temperature. The absorbed toluene and carbon tetrachloride can be desorbed easily by evacuation above room temperature, and the absorption/desorption is completely reversible. The absorption/desorption phenomena were studied for the empty, partly and fully toluene and carbon tetrachloride absorbed samples by adiabatic calorimetry between 13 K and 300 K and by powder X-ray diffractiometry with high-energy synchrotron radiation at SPring-8 of JASRI. The first-order phase transition was observed in the empty sample. The partly toluene-absorbed samples showed smaller heat capacity anomaly at higher temperatures than the empty sample. On the other hand, the partly carbon tetrachloride-absorbed samples showed smaller heat capacity anomaly at lower temperatures than the empty sample. The difference in the two cases was discussed on the basis of structural and thermal data.
Keywords:copper(II)-trans-1,4-cyclohexanedicarboxylate(Cu2(OOC-C6H10-COO)); heat capacity; phase transition; absorption/desorption, crystal structure