N,N′‐Ethylenebis(pyridoxylideneiminato) and N,N′‐Ethylenebis(pyridoxylaminato): Synthesis, Characterization, Potentiometric, Spectroscopic, and DFT Studies of Their Vanadium(IV) and Vanadium(V) Complexes

Abstract

The Schiff base N,N'-ethylenebis(pyridoxylideneiminato) (H 2 pyr 2 en, 1) was synthesized by reaction of pyridoxal with ethylenediamine; reduction of H 2 pyr 2 en with NaBH 4 yielded the reduced Schiff base N,N'-ethylenebis-(pyridoxylaminato) (H 2 Rpyr 2 en, 2); their crystal structures were determined by X-ray diffraction. The totally protonated forms of 1 and 2 correspond to H 6 L 4 + , and all protonation constants were determined by pH-potentiometric and Supporting information for this article is available on the WWW under http://www.chemeurj.org/ or from the author. Some additional X-ray data for 1, 2, 4, and 9 (SI-1); further discussion of IR spectra (

Vanadium (IV and V) Complexes of Reduced Schiff Bases Derived from the Reaction of Aromatic o‐Hydroxyaldehydes and Diamines Containing Carboxyl Groups

“…However, as salLys (3) is not soluble in water or in ethanol/water at least up to 10 % ethanol, this compound was characterised in the solid state but was not further studied. Studies of moderately water-soluble Schiff bases and their hydrolytically more stable salan derivatives were previously reported, [15,17] [18] and in this work we also find that it is an effective ligand for V IV O 2+ and V V O 2 + . Moreover, the pendant carboxylate group may help with the coupling of the salan moiety to other molecules that may target the compound to specific biological sites, thereby anticipating the possibility of minimising its toxicity and increasing its efficacy.…”

“…-565 ppm. [15] However, as this complex corresponds to a relatively intense CD signal (see below), structures involving the coordination of the COO -group instead of one O phen or one NH amine cannot be ruled out.…”

“…Several vanadium complexes of the dianionic tetradentate Schiff base salen (N,NЈ-disalicylideneethylenediamine)-type ligands have been pro posed for use as insulin-enhancing agents, and for treatment of obesity and hypertension. [13][14][15] Durai and Saminathan [13] reported the ability of V IV O(salen) to reverse the hyperglycemic condition of alloxan-induced diabetic rats to near normal, thereby exerting insulin-like action. However, rats tended to become hypoglycemic, and withdrawal of treatment brought about an immediate return of the hyperglycemia.…”

“…Moreover, some of the V complexes with salan ligands have been shown to be several orders of magnitude more stable than the corresponding salen compounds. [15,17] We report the preparation of salan compounds derived from the condensation of salicylaldehyde [in one case also of o-vanillin (o-van)] with ,-and -diaminopropionic acid (DPA), -2,4-diaminopentanoic acid (-ornithine) and -2,5-diamino-hexanoic acid (-lysine), which are designated by salDPA (1), salOrn (2) and salLys (3), respectively, and the preparation of V IV O-and V V O 2 -salDPA complexes. The compounds were characterised in the solid state and in solution.…”

Crystal structure of (N,N′-bis(2-(((2,6-diisopropylphenyl)imino)methyl)phenyl)benzene-1,2-diamido-κ4 O,O′,O′′,O′′′)oxidovanadium(IV), C44H48N4OV

“…The title compound is a very important organic intermediate in the applications of medicines [7]. The title structure VL crystallized with one V(IV) atom, one oxygen atom and a L ligand molecule in the asymmetric unit.…”