Phase and Glass Transitions Observed by Adiabatic Calorimetry of Host p-tert-Butylcalix[4]arene and Guest Toluene Inclusion Crystal, Suggesting the Progress of the Combined Order-Disorder Process of the Host-Guest Molecules

作者：Ueda Kouhei^*; Oguni Masaharu

来源：Journal of Physical Chemistry B, 2013, 117(39): 11836-11842.

DOI：10.1021/jp404561b

Heat capacities of crystalline p-tert-butylcalix[4]arene toluene host-guest compound were measured in a temperature range between 3 K and 345 K by adiabatic calorimetry. The crystal showed one second order phase transition at 256.4 K accompanied by wide heat-capacity tails on both the high and low temperature sides and two first-order phase transitions with heat-capacity peaks at 127 K and 139 K. The total entropy of a sequence of the phase transitions was assessed experimentally to be 47 J K-1 mol(-1), indicating that the number of allowed distinguishable molecular configurations is over 100 in the high temperature disordered state. Many such distinguishable configurations are understood to be produced by a special intermolecular interaction of C-H center dot center dot center dot(pi-electron) bonds formed between p-tert-butylcalix[4]arene and toluene molecules, and the transitions were interpreted as originating from orientational order-disorder of both the guest toluene molecule and the tert-butyl groups of host arene in their combination.

• 出版日期2013-10-3