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Abstract
The polymorphism of the di(4-alkylphenyl) and di(4-alkoxyphenyl) tetrathiafulvalene (TTF) is investigated by optical, crystallographic and calorimetric methods. All the studied derivatives are mesomorphic. The first mesophase is always a smectic G phase; the second one is a nematic N phase for short chains and a smectic C phase for long chains.
The entropies corresponding to the passage high-temperature crystalline phase C1 → SG and to the “melting” (C1 → mesophases → isotropic phase I) increase with the length of the chain and with the presence of the oxygen atom in the radical.
