The binuclear complexes (3d–3d, 3d–3d′, 3d–4f) with compartmental ligands can efficiently act as tectons in crystal engineering. Various high nuclearity clusters and coordination polymers can be easily obtained by choosing the appropriate spacers. The main interest in such systems arises from their magnetic and photophysical properties. Moreover, 3d–3d′ and 3d–4f complexes are useful precursors in designing heterotrimetallic systems with relevance in molecular magnetism.

Ortho-vanillin became very popular in coordination chemistry because of its Schiff bases, which generate a rich variety of complexes, ranging from oligonuclear species to coordination polymers. Some of these organic molecules are particularly useful in metallosupramolecular chemistry for assembling homo- and heterometallic helicates. The Schiff bases obtained using aminoalcohols open the door to the synthesis of homo- and heterometallic clusters with various nuclearities and surprising topologies of the metal centers. Several relevant structural types are reviewed. The heterobinuclear 3d–3d′ and 3d–4f complexes are valuable building-blocks for the synthesis of heterotrimetallic systems. Beyond the richness of this chemistry, the complexes obtained from o-vanillin-based Schiff ligands show interesting properties: magnetism, luminescence, chirality, catalysis, cytotoxicity, and ferroelectricity. This paper reviews recent data that illustrate a very fertile and dynamic research field in coordination chemistry and materials science.

This article focuses on the employment of bi- and trinuclear complexes as building blocks in designing novel heterometallic systems. A large variety of polynuclear complexes, ranging from high-nuclearity clusters to high-dimensionality coordination polymers, can be constructed by taking advantage of the high flexibility of the multimetallic nodes. The following oligonuclear complexes are currently used as tectons in our laboratory: (a) bis(alkoxo)-bridged copper(II) species; (b) homobinuclear species with metal ions held together by end-off, or macrocyclic compartmental ligands; (c) heterometallic complexes with dissymmetric compartmental ligands. The 3d–4f nodes are particularly interesting since the metal ions interact selectively with various spacers. The intra-node exchange interactions, as well as those between the resulting spins, generate interesting magnetic properties.