Synthesis and kinetic studies in aqueous solution on chromium(III) complexes with isocinchomeronic acid—potential new biochromium sources

Abstract

The chromium(III) complexes with a new potential chromium transporting ligand-2,5-pyridinedicarboxylic acid (isocinchomeronic acid, icaH 2 ):[Cr(icaH) 3 ] 0 , [Cr(icaH) 2 (H 2 O) 2 ] + and [Cr(icaH)(H 2 O) 4 ] 2+ (where icaH = N,O-bonded isocinchomeronic acid anion), have been obtained and characterized in solution. The [Cr(icaH) 3 ] 0 complex undergoes aquation in acidic media to the diaquaproduct. Kinetics of this process was studied spectrophotometrically in the 0.1-1.0 M HClO 4 range, at I = 1.0 M. The first aquation stage, the chelate-ring opening at the Cr-N bond, is a much faster than the second one. The rate laws are of the form: k obs = k 1 + k -1 /Q 1 [H + ] and k obs = k 2 Q 2 [H + ]/ (1 + Q 2 [H + ]), where k 1 and k 2 are the rate constants for the chelate-ring opening and the ligand liberation, respectively, k -1 is the rate constant of the chelate-ring closure, Q 1 and Q 2 are the protonation constants of the pyridine nitrogen and 5-carboxylate group in the one-end bonded intermediate, respectively. The results are discussed in terms of potential pharmaceutical application of the complex.

Chromium(III)-isocinchomeronato and quinolinato complexes: kinetic studies in NaOH solutions and effect on 3T3 fibroblast proliferation

“…They appeared to have increased solubility and reactivity in comparison to analogous picolinic acid derivatives, including the most popular chromium(III) complex, mer-[Cr(pic) 3 ] 0 . Our studies on acid-catalysed aquation of the [Cr(quinH) 3 ] 0 and [Cr(icaH) 3 ] 0 compounds [18,19] revealed that introduction of a second carboxylic group to the pyridine ring of the ligand increases the rate of ligand dissociation. Both complexes could potentially serve as biochromium sources and for that reason should be extensively examined.…”

“…Recently, chromium(III) complexes with quinolinic and isocinchomeronic acids were obtained and characterized in acidic media [18,19]. They appeared to have increased solubility and reactivity in comparison to analogous picolinic acid derivatives, including the most popular chromium(III) complex, mer-[Cr(pic) 3 ] 0 .…”

“…[Cr(quinH) 3 ] 0 , [Cr(icaH) 3 ] 0 and their di-and tetra-aqua derivatives were obtained as described in [18] and [19], respectively. Solutions of complexes used in biological studies were prepared in NaCl medium.…”

Thermal and spectroscopic properties of light lanthanides (III) and sodium complexes of 2,5-pyridinedicarboxylic acid

“…Like Lewis base, it can also act as chelating or multidentate bridging ligand [7]. There were many compounds reported in which M-O and M-N coordination was observed [8][9][10].…”

“…It also accelerates the redox reactions between alcohols and chromic acid [26]. Pyridinedicarboxylic acids also act as chelating agents of chromium, zinc, manganese, copper, iron and molybdenum [7].…”