The exceptionally rich coordination chemistry generated by Schiff-base ligands derived from o-vanillin

Abstract

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.

Pentanuclear Spirocyclic Ni4Ln Derivatives: Field Induced Slow Magnetic Relaxation in the Dysprosium and Erbium Analogues

“…It is well known that multi‐compartmental Schiff base ligands are an excellent host to assemble 3d‐4f hybrid molecules , . The multisite coordinating Schiff base ligand LH 3 was synthesized by condensation reaction in methanol of 2‐(hydroxymethyl)‐6‐carbaldehyde‐4‐methylphenol, with 2‐aminophenol.…”

The Effect of Guest Metal Ions on the Reduction Potentials of Uranium(VI) Complexes: Experimental and Theoretical Investigations

“…[42,43] Such U VI compounds usually show ar eversible redox cycle at ap otential around À1.6 V( vs. Fc + /Fc;F c + = ferrocenium, Fc = ferrocene), whichiss usceptible to the donor atoms of the coordinated ligandsa nd the solvent environment. [44,45] The inner compartment of such al igand hosts a3 dm etal ion through the coordination of aN 2 O 2 donor set of atoms, whereas the open O 2 O' 2 compartment accommodates variouso xophilic cations including lanthanides. [44,45] The inner compartment of such al igand hosts a3 dm etal ion through the coordination of aN 2 O 2 donor set of atoms, whereas the open O 2 O' 2 compartment accommodates variouso xophilic cations including lanthanides.…”

“…[43] Diamines such as 1,2-ethanediamine or 1,3-propanediamine readily undergo 1:2c ondensation with o-vanillin to produce a group of bicompartmental ligandst hat have been used extensively for the synthesis of phenoxido-bridged heterometallic complexes. [44][45][46][47] Such ligandsa re known to coordinate to the uranyli on through the N 2 O 2 donor set but do not behave as ac ompartmental ligand presumably due to the bigger size and preference for pentacoordination around the basal plane of uranium.O n the other hand, the Schiff basef ormed by the 1:2 condensation of diethylenetriamine and o-vanillin is expectedt ob ew ell-suited to host au ranyl ion in its inner N 3 O 2 donorc ompartment, [41] and the outer O 2 O' 2 donor set remains suitably positioned to coordinate to asecond metal ion. [44][45][46][47] Such ligandsa re known to coordinate to the uranyli on through the N 2 O 2 donor set but do not behave as ac ompartmental ligand presumably due to the bigger size and preference for pentacoordination around the basal plane of uranium.O n the other hand, the Schiff basef ormed by the 1:2 condensation of diethylenetriamine and o-vanillin is expectedt ob ew ell-suited to host au ranyl ion in its inner N 3 O 2 donorc ompartment, [41] and the outer O 2 O' 2 donor set remains suitably positioned to coordinate to asecond metal ion.…”

Syntheses, Structures, and Magnetic Properties of Symmetric and Dissymmetric Ester‐Functionalized 3d‐4f Schiff Base Complexes

“…Salen belongs to the Schiff base ligands, which are easily prepared by condensation between an aldehyde derivative and a primary diamine, and present facile access to a large panel of chelating molecules in coordination chemistry . An important family is derived from o ‐vanillin (2‐hydroxy‐3‐methoxybenzaldehyde) yielding bicompartmental ligands with two dissimilar binding cavities able to selectively accommodate the 3d ion (through the N2O2 set of chelating atoms) and the rare‐earth ion (through the O2O2 set) . Such a ligand is ideally suited for the preparation of strictly dimetallic 3d‐4f complexes, and since the first use of o ‐vanillin as a precursor for the preparation of a bicompartmental ligand, numerous examples of dinuclear 3d‐4f complexes have been employed to assess fundamental knowledge on the magnetic behavior of Ln III ions in molecular complexes.…”