ABSTRACT
The thermotropic polymorphism of a series of guanidinium alkanesulfonates (6 < or = n < or = 18) was investigated by optical microscopy and differential scanning calorimetry. Hydrogen bonding was analyzed by infrared spectroscopy. Molecular volumes were measured by dilatometry. The structure of the crystal, smectic A, and ordered smectic phases observed were studied by X-ray diffraction and utilized to prove that the supramolecular arrangement of the molecules in the crystal survives in the smectic phases at high temperature.
Subject(s)
Alkanesulfonates/chemistry , Guanidine/chemistry , Alkanesulfonates/chemical synthesis , Calorimetry, Differential Scanning , Crystallization , Guanidine/chemical synthesis , Spectrophotometry, Infrared , Temperature , X-Ray DiffractionABSTRACT
A set of optically active and racemic n-alkylammonium pyroglutamates from dodecyl to octadecyl were synthesized and characterised. Their thermotropic polymorphism was investigated by polarizing optical microscopy, differential scanning calorimetry and dilatometry. Their structure in the crystalline and smectic state was analysed by X-ray diffraction. The hydrogen bonding of the molecules in the crystalline and smectic layers was examined by infrared spectroscopy. The chirality control over the supramolecular self-assembly of the molecules along with the homochiral and heterochiral architecture of the self-assembled dimers are briefly discussed.
Subject(s)
Pyrrolidonecarboxylic Acid/analogs & derivatives , Pyrrolidonecarboxylic Acid/chemistry , Quaternary Ammonium Compounds/chemistry , Crystallization , Crystallography, X-Ray , Dimerization , Drug Stability , Heating , Hydrogen Bonding , Models, Molecular , Molecular Structure , Pyrrolidonecarboxylic Acid/chemical synthesis , Quaternary Ammonium Compounds/chemical synthesis , Stereoisomerism , Structure-Activity RelationshipABSTRACT
A homologous series of guanidinium alkylbenzenesulfonates from ethyl to tetradecyl were synthesized and characterised. Their thermotropic polymorphism was investigated by polarizing optical microscopy, differential scanning calorimetry, and dilatometry. The structure of the smectic liquid crystal phases obtained at high temperature with the compounds from octyl to tetradecyl was analysed by X-ray diffraction. The supramolecular assembling of the ionic species inside the smectic layers was investigated by infrared spectroscopy.
ABSTRACT
Carboxylate-bridged chain complexes of Co(II) (the diaquacobalt(II) mono- and ,-dialkanoates) form two homologous series of layered compounds which have been fully characterised both structurally and magnetically. The crystal structures of two selected members, [Co[CH3(CH2)10COO]2(H2O)2] and [Co[CH3(CH2)18COO]2(H2O)2], have been solved by X-ray powder diffraction and selected-area electron diffraction methods, and refined by the Rietveld technique. Crystal data: monoclinic, P 2(1)/a; a=9.688(1), b=7.5495(9), c=37.281(5) A, =96.70(3) primary, Z=4; and monoclinic, P 2(1)/a; a=9.7260(7), b=7.5477(7), c=57.53(1) A, =94.66(4) primary, Z=4, respectively. Their isomorphous structures contain layers of octahedral diaquacobalt(II) ions bonded to two chemically inequivalent alkanoates, one chelating and one bridging two Co atoms about 6.3 A apart, thus confirming the rare anti-anti conformation mode of the -RCOO groups recently proposed for diaquacobalt(II) ,-dodecanedioate. Extensive magnetic characterisation allowed estimation of the feeble antiferromagnetic coupling, which is weaker in the mono- than in the dialkanoate series.
ABSTRACT
The subtle balance between organized and chaotic domains in the nondiscoidal ligand in the helicate 1, which displays liquid crystalline properties, represents the key element which enables the local molecular architecture to be integrated into an organized macroscopic ensemble.
ABSTRACT
A columnar structure with lamellar morphology in the liquid crystalline state is displayed by the palladium complex salt 1, which is synthesized from nonmesogenic ligands.
