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Lanthanide(III) Dodecanoates: Structure, Thermal Behaviour, and Ion‐Size Effects on the Mesomorphism
Author(s) -
Binnemans Koen,
Jongen Liesbet,
GörllerWalrand Christiane,
D’Olieslager Willem,
Hinz Dirk,
Meyer Gerd
Publication year - 2000
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200007)2000:7<1429::aid-ejic1429>3.0.co;2-9
Subject(s) - lanthanide , chemistry , mesophase , crystallography , differential scanning calorimetry , thermogravimetry , ionic radius , lutetium , alkyl , bilayer , lamellar structure , phase (matter) , inorganic chemistry , ion , organic chemistry , yttrium , biochemistry , physics , membrane , thermodynamics , oxide
Rare‐earth salts of dodecanoic acid (lauric acid) have been prepared and characterized. The compounds have the stoichiometry Ln(C 11 H 23 COO) 3 , where Ln = Y, La, Ce−Lu (except Pm). The thermal behaviour of these rare‐earth dodecanoates has been investigated by hot‐stage polarized optical microscopy, differential scanning calorimetry (DSC), thermogravimetry (TG), and high‐temperature X‐ray diffraction analysis. The compounds have a lamellar bilayer structure in the solid state, with the alkyl chains in an all ‐ trans conformation normal to the ionic sublayer. The size of the trivalent lanthanide ion has proved to be a critical factor with regard to the existence of mesophases of this type of metallomesogens bearing carboxylate ligands. Thus, it was found that a mesophase can only be formed with the light lanthanide ions having large ionic radii. The mesophase stability range decreases rapidly on traversing the lanthanide series. Whereas a smectic A phase has been observed for the La III , Ce III , Pr III , and Nd III dodecanoates, no mesomorphism is apparent for the other lanthanide complexes.