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 hightemperature 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.

Rare-earth complexes of mesomorphic SchiOE's bases, 4-[ (alkylimino)methyl ]-3-hydroxyphenyl 4-alkyloxybenzoates, were synthesized. Whereas the ligands LH display a nematic and/or a smectic C phase, the metal complexes show a viscous smectic A phase and decompose at the clearing point. The mesophase was investigated by hot-stage polarizing optical microscopy, by diOE erential scanning calorimetry and by high temperature X-ray diOE raction. Two types of complex were found, [Ln (LH)], depending on the ligand or the central metal ion. The rst coordination sphere of the rare-earth ion in these metallomesogens is comparable to that in the structure of complexes with 4-alkoxy-N-alkyl-2-hydroxybenzaldimine ligands.

The Schiff base LH 3 obtained by condensation of 3-formyl-4-hydroxyphenyl-3,4,5-tris(tetradecyloxy)benzoate with 1,3-diamino-2-propanol reacts with lanthanide(III) acetate salts to form dinuclear complexes of the type Ln 2 L 2 with the trivalent ions from the first half of the lanthanide series (Ln =

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