| Abstract: | High resolution calorimetric studies have been carried out on the chiral compound methylheptyloxydifluorooctyloxybenzoyloxytolane (8BTF2O1M7). The tilt tendency is greater in this compound than in several other structurally similar fluorinated tolane liquid crystals, and it exhibits tilted chiral smectic C(SmC*) and tilted twist-grain-boundary (TGBC) phases but not the untilted SmA or TGBA phases. The data confirm the presence of two tilted TGBC phases denoted TGB1 and TGB2. The TGB1-TGB2 first-order transition exhibits considerable hysteresis and a very small latent heat. There is no rounded excess heat capacity peak in the cholesteric N* phase associated with the non-transitional evolution of a chiral line liquid N*L, although such a feature has been observed in other fluorinated tolanes with a smaller tilt tendency. |
