Potentiometric, Spectroscopic and DFT Study of the V^IVO Complexes Formed by Di(pyridin‐2‐yl) Ligands

Abstract

The coordinating properties of a series of di(pyridin-2-yl) derivatives towards the V IV O 2+ ion have been studied through the combined application of potentiometric and spectroscopic (electronic absorption and EPR spectroscopies) methods. In particular, di(pyridin-2-yl)amine (DPA), di(pyridin-2-yl)methane (DPM), di(pyridin-2-yl) ketone (DPK), di(pyridin-2-yl)methanol (DPMO), 2-acetylpyridine (2-AP) and 2-hydroxymethylpyridine (2-HMP), and two amino acid derivatives of di(pyridin-2-yl)methylamine (DPMA), namely N-glycyl-DPMA and N-histidyl-DPMA, have been examined. The stability constants of proton and V IV O complexes (logβ) were measured at 25°C and at a constant ionic strength of 0.2 M (KCl). The results show that the simple di(pyridin-2-yl) derivatives having only pyridine nitrogen atoms form mono-chelated species with the (N pyr , N pyr ) donor set, whereas those

The Equilibrium Between the Octahedral and Square Pyramidal Form and the Influence of an Axial Ligand on the Molecular Properties of VIVO Complexes: A Spectroscopic and DFT Study

“…Very recently, we proposed the same explanation for the species with stoichiometry [VO(dpmoH −1 ) 2 ] formed by dipyridin‐2‐ylmethanol in the pH range 5–10 with a ligand‐to‐metal molar ratio of 2 32. The square‐pyramidal and trans octahedral species are characterised by | A z | values of 151×10 −4 and 144×10 −4 cm −1 , respectively 32. Whereas the | A z | value for [VO(dpmoH −1 ) 2 ] is comparable to that expected on the basis of the “additivity rule” (| A z | expct ∼152×10 −4 cm −1 for the coordination mode 2(N pyr , O − )), that for trans ‐[VO(dpmoH −1 ) 2 (H 2 O)] is sensibly lower.…”

“…After these observations for the 6‐methylpicolinic and 6‐methyl‐2,3‐pyridinedicarboxylic acids, we wondered whether this type of behaviour for V IV O complexes could be more frequent than what is currently believed. Very recently, we proposed the same explanation for the species with stoichiometry [VO(dpmoH −1 ) 2 ] formed by dipyridin‐2‐ylmethanol in the pH range 5–10 with a ligand‐to‐metal molar ratio of 2 32. The square‐pyramidal and trans octahedral species are characterised by | A z | values of 151×10 −4 and 144×10 −4 cm −1 , respectively 32.…”

Application of DFT Methods in the Study of VIVO2+–Peptide Interactions

“…Oligopeptides can interact with V IV O 2+ ions through the terminal amino and carboxylate groups, intermediate peptide bonds and side‐chain donors, which can play the role of “anchoring groups” and promote the deprotonation of the amide bond and its coordination in the N – form 16. Many examples of V IV O 2+ complexes containing a V–N – amide bond, both in solution and in the solid state, have been characterised over the last years in the literature 16–28…”

“…In this work the potential of DFT methods to characterise V IV O 2+ –oligopeptides will be illustrated. Three important tripeptides, histidylglycylglycine (HisGlyGlyH), glycylglycylhistidine (GlyGlyHisH) and glycylglycylcysteine (GlyGlyCysH 2 ), were examined and the results were compared with those observed for N ‐glycyl‐bis(imidazol‐2‐yl)methylamine (Gly–BIMA),27 N ‐glycyl‐bis(pyridin‐2‐yl)methylamine (Gly–BPMA),28 salicylglycyl‐ L ‐Alanine (SalGly‐ L ‐AlaH)24 and 1,2‐bis(2‐hydroxybenzamido)benzene (H 2 hybeb) 17,18. They are shown in Scheme .…”

The “periodic table” of di-2-pyridyl ketone: vanadium complexes

“…depending on the pH. 13 The reaction of VOSO 4 •4H 2 O and ( py) 2 CO in a 1 : 1 molar ratio in MeOH under reflux gave a green solution that upon slow evaporation at room temperature produced blue prisms of…”