Mixed copper-lanthanide metallomesogens.
This paper describes the first examples of heteropolynuclear metallomesogens that contain both a transition metal ion and a trivalent lanthanide ion. Adducts were formed between a mesomorphic [Cu(salen)] complex (salen=2,2'-N,N'-bis(salicylidene)ethylenediamine) with six terminal tetradecyloxy chains and a lanthanide nitrate (Ln=La, Gd). Different stoichiometries were found, depending on the lanthanide ion: a trinuclear copper-lanthanum-copper complex [La(NO(3))(3)(Cu(salen))(2)] and a binuclear copper-gadolinium complex [Gd(NO(3))(3)Cu(salen)]. The compounds exhibit a hexagonal columnar mesophase (Col(H)) over a wide temperature-range with rather low melting temperatures. Although the clearing point could be observed for the parent [Cu(salen)] complex, the mixed f-d complexes decomposed in the high-temperature part of the mesomorphic domain before clearing. On the basis of X-ray diffraction measurements and molecular modelling, a structural model for the mesophase of the metal complexes is proposed.
Binnemans
Koen
K
Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium. koen.binnemans@chem.kuleuven.ac.be
Lodewyckx
Katleen
K
Donnio
Bertrand
B
Guillon
Daniel
D