Speciation and structure of copper(II) complexes with (S)-phenylalanine- and (S)-tryptophanhydroxamic acids in methanol/water solution: a combined potentiometric, spectrophotometric, CD and ESI-MS study

Electrospray mass spectrometry (ESI‐MS) in the study of metal–ligand solution equilibria

“…This happened in above-cited studies (Caudle, Stevens, & Crumbliss, 1994a,b;Deery et al, 1998;Dallavalle & Tegoni, 2001;Schmitt et al, 2002;Careri et al, 2003b). As well, Bond et al (1993) detected some new Fe(III), Co(III), Ni(II), and Cu(II) dithiocarbamates in dichloromethane/methanol 1:10 solutions, and a new cationic Au(I)-phosphine derivative in dichloromethane/methanol solution (Colton et al, 1995a ) with ferrocene-derivatised calix[4]arene ligands, possessing ester amide and acid amide coordination groups.…”

“…For example, since the solvent is lacking in the gasphase, it may happen that a species, which is stable and exists in solution, is not stable in the gas-phase, and vice versa. For this reason, the quite popular postulate that if a species requires a high energy to fragment in MS/MS spectra, it already exists in solution and has not been formed in the gas-phase (Dallavalle & Tegoni, 2001;Moder et al, 2001;Careri et al, 2003b), may be false in several cases.…”

“…ESI-MS was used together with potentiometry and spectrophotometry for the determination of the number and stoichiometry of the species in solution. Dallavalle & Tegoni (2001) studied the complexation equilibria of (S)-phenylalaninehydroxamic and (S)-tryptophanhydroxamic acids with Cu(II) by potentiometry, UV-Vis, CD, and ESI-MS. The latter data were obtained in both positive and negative ion modes, in methanol/ water 9:1 solutions, at two metal-to-ligand ratios, and at different pH values.…”

Succinylhydroxamic derivatives of α-amino acids as MMP inhibitors. Study of complex-formation equilibria with Cu2+, Ni2+ and Zn2+

“…Metallacrowns structurally resemble crown ethers with a transition metal ion and a nitrogen atom replacing the methylene groups [19]. Copper(II) metallacrowns of a-and b-aminohydroxamic acids (HL) have been extensively investigated both in solution [20][21][22] and in the solid state [19]. In solution, a-and b-aminohydroxamic acids can form a network of twelve 5-or (5-and 6-) membered chelate rings, respectively (Scheme 3(a) and (b)).…”

Synthesis, Solution Thermodynamics, and X‐ray Study of CuII [12]Metallacrown‐4 with GABA Hydroxamic Acid: An Unprecedented Crystal Structure of a [12]MC‐4 with a γ‐Aminohydroxamate

“…[1] However, since 2001 it has been established that also aaminohydroxamates can form Cu II [12]MC-4 complexes in solution and a tensioned-cup structure has been proposed. [11,12] More recently, solid pentacopper complexes of (S)-a-phenylalanine-and 2-picoline-hydroxamic acids were isolated and characterized, [13] and metallahelicates containing 28 copper(II) atoms were synthesized with d-and l-norvalinehydroxamic acids and characterized by X-ray diffraction. [5] Moreover, we have demonstrated that also the (S)-glutamic-g-monohydroxamic acid, which gives rise to sevenmembered (NH 2 ,N À ) chelate rings, can form a Cu II [12]metallacrown-4 in solution.…”