The Reactivity of Multidentate Schiff Base Ligands Derived from Bi‐ and Terphenyl Polyamines towards M(II) (M=Ni, Cu, Zn, Cd) and M(III) (M=Co, Y, Lu)

Abstract

Multidentate Schiff base ligands derived from a selection of biphenyl-and terphenyl polyamines were synthesized, and their reactivity towards divalent (Ni, Cu, Zn, Cd) and trivalent (Co, Y, Lu) metals was studied by single-crystal X-ray diffraction analysis, NMR spectroscopy, and UV/Vis spectroscopy for the Cu(II) complexes. Large variations in the resulting complexes were observed based on the relative position of the amine substituents in the parent triamines, as well as the electronic properties of the Schiff base ligand itself. Most notably, Schiff base ligands derived from a m-terphenyl-2,2',2''-triamine were found to coordinate in a tetradentate, pentadentate or hexadentate fashion, depending on the size and the valency of the corresponding metal center.

Ferrocene functionalized enantiomerically pure Schiff bases and their Zn(ii) and Pd(ii) complexes: a spectroscopic, crystallographic, electrochemical and computational investigation

“…[23][24][25] Schiff bases, characterized by an imine (4CQN-) or an azomethine (-CHQN-) group, 26,27 form an outstanding class of proligands that play a key role in the development of coordination chemistry due to their facile synthesis, structural flexibility, easily tunable electronic properties, selectivity and sensitivity towards the coordinated metal ion and their ability to form stable complexes under various coordination geometries and oxidation states. 22,[28][29][30] Transition-metal complexes of Schiff base ligands have been widely investigated because of their applications in various branches of science such as in catalysis, [31][32][33] sensing, [34][35][36] as NLO molecular materials, 23,[37][38][39] and in biochemistry, [40][41][42] among others. Ferrocene substituted asymmetric N 2 O 2 -tetradentate Schiff bases are generally obtained upon condensation of salicylaldehyde or its derivatives with a preformed tridentate organometallic precursor bearing a free amino group.…”

Structural Elucidation, Aggregation, and Dynamic Behaviour of N,N,N,N‐Copper(I) Schiff Base Complexes in Solid and in Solution: A Combined NMR, X‐ray Spectroscopic and Crystallographic Investigation

“…Typical processes that induce ligation changes in copper(I) and other d 10 species are solvent coordination, intermolecular ligand exchange and/or aggregation. [ 42 , 45 , 56 , 57 , 58 , 59 , 60 , 61 ] For reference purposes, the ligand of each complex was synthesized by adapting previously reported procedures for Schiff base ligands. [62] …”

“…Typical processes that induce ligation changes in copper(I) and other d 10 species are solvent coordination, intermolecular ligand exchange and/or aggregation. [42,45,[56][57][58][59][60][61] For reference purposes, the ligand of each complex was synthesized by adapting previously reported procedures for Schiff base ligands. [62] Based on literature reports for similar ML 2 -type complexes, [60,63,64] it seems likely that complexes 2, 4 and 6 are in equilibrium with an ML complex and the free ligand.…”

Strategies for Improving Selectivity and Sensitivity of Schiff Base Fluorescent Chemosensors for Toxic and Heavy Metals

“…They can undergo chemical transformations such as hydrolysis, reduction, oxidation, and nucleophilic addition reactions. The reactivity of Schiff bases makes them valuable intermediates for the synthesis of diverse organic compounds and coordination complexes [34]. (6) Biological Activity: Schiff bases have shown a range of biological activities and applications.…”