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Autori: Tachita Vlad-Bubulakc Jens Buchs, Alexandra Kohlmeier, Maria Bruma, Dietmar Janietz
Editorial: Chemistry of Materials, 19, p.4460-4466, 2007.
Two 2,4-diamino-6-biphenyl-4-yl-1,3,5-triazines carrying either one semiperfluorinated or two lipophilic
alkoxy chains at the terminal position of the biphenyl moiety have been investigated in binary mixtures
with two-chain and three-chain partially fluorinated benzoic acids by means of polarizing microscopy,
differential scanning calorimetry, and X-ray diffraction. Equimolar compositions of the triazines with
the complementary two-chain benzoic acid form descrete hydrogen-bonded heterodimers. The dimeric
supermolecules organize to rectangular columnar phases in the c2mm plane group. The Colr phases are
composed of infinite ribbons of parallel aligned H-bonded rigid polar cores which are separated by aliphatic/
fluorinated regions. H-bonded associates of the fluorinated triazine with three equivalents of the twochain
acid form a rectangular columnar phase (p2m symmetry). Replacing the one fluorinated chain of
the triazine by two alkoxy groups leads to a columnar phase on a two-dimensional square lattice (p4mm)
in a 1:3 mixture with the two-chain benzoic acid. The 1:3 mixed systems of the triazines with the threechain
aromatic acid display micellar cubic phases.
Cuvinte cheie: cristale lichide, auto-asamblare, recunoastere moleculara // Liquid crystals, self-assembly, molecular recognition