Further Theoretical Studies of the Aquation of Chromium(III) Chloride Nutritional Supplement: Effect of pH and Solvation

Uddin, Kabir M.; Henry, David J.

doi:10.1002/slct.201601305

Cited by 4 publications

(3 citation statements)

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“…A key finding in these studies was the importance of outer-sphere solvation on the reaction mechanism. We have also studied [29] the aquation of conjugate-base systems of chromium(III), which is favourable under physiological conditions (pH ~ 7.4), where once again outer sphere solvation is involved in the reaction mechanism. Therefore, the study of these systems leads to a better understanding of the stability and speciation under physiological conditions, prior to binding to enzymes or peptides.…”

Section: Introductionmentioning

confidence: 99%

Investigation of mono-, bis- and tris-glycinatochromium(III): Comparisons of computational and experimental results

2017

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The synthesis and characterization of mono-, bis-and tris-glycinatochromium(III) complexes by UV-Vis, electron paramagnetic resonance (EPR), ATR-FTIR and Raman spectroscopy has been performed in this work. IR stretching bands obtained from DFT calculations of the mono-, bisand tris-glycinatochromium(III) complexes are in good agreement with experimental data. Different mechanistic pathways were explored for the water exchange reactions of [Cr(+ NH 3 CH 2 COO-)(H 2 O) 5 ] 3+ and its conjugate base species including, associative interchange (I a), and dissociative (D) mechanisms. The lowest activation enthalpies for the mono-and biscomplexes are obtained for the I a pathways with explicit outer sphere solvation (88 and 76 kJ mol −1), which are in good agreement with the experimental values (87 and 75 kJ mol −1). In comparison, tris-glycinatochromium(III) undergoes aquation via the dissociative (D) mechanism. Investigation of these systems in the pH range ~3.0 to ~8.5 by UV-Vis monitoring, helps identify the speciation of these complexes in physiological environments.

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Section: Introductionmentioning

confidence: 99%

Investigation of mono-, bis- and tris-glycinatochromium(III): Comparisons of computational and experimental results

2017

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“…Our previous results,− indicate that PBE0/cc‐pVDZ is a suitable theory for determining the structural parameters of chromium(III) complexes. The calculated structural parameters for the neutral ( fac ‐[Cr(gly) 3 ]) and reduced form ( fac ‐[Cr(gly) 3 ] −1 ) are reported in Table (Figure ) and compared to the X‐ray data of fac ‐[Cr(gly) 3 ].…”

Section: Resultsmentioning

confidence: 97%

Investigation of the Spectroscopic, Thermal and Electrochemical Properties of Tris-(glycinato)chromium(III)

2017

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The tris‐glycinatochromium(III) complex ([Cr(gly)3]) has been proposed as a nutritional supplement and treatment for Type 2 diabetes. The exact mode of action of this and other Cr(III) supplements is not known but may involve redox reactions with biomolecules. In this study fac‐[Cr(gly)3] was synthesized and the electrochemical properties investigated by cyclic voltammetry. The complex undergoes a reversible one electron reduction with E1/2=−0.66 to −0.69 V that is essentially independent of scan rate. Thermal decomposition was explored by differential scanning calorimetry under nonisothermal conditions from 30−1000 °C. Structural parameters obtained from DFT calculations are in good agreement with crystallographic data. The reduced form of the complex has a high‐spin quintet electronic configuration due to the small crystal field splitting from the weak π‐donor ligands. Both the theoretical calculations and the electrochemical measurements demonstrate that the complex is stable in the anionic form. These results indicate that [Cr(gly)3] can undergo reversible electron transfer, which may play a role in it's biological activity.

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“…In the present study, chromium salt (CrCl3.6H2O) was employed, which is found as (trans-[Cr(H2O)4Cl2]Cl.2H2O) naturally [47]. This salt is easily hydrolyzable in water.…”

Section: Proposed Mechanism Of Cr (Iii) Transport In Slmmentioning

confidence: 99%

Chromium (III) Ions Were Extracted from Wastewater Effluent Using a Synergistic Green Membrane with a BinaryCombination of D2EHPA and Kerosene

et al. 2022

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This study used a supported liquid membrane system (SLM) using Celgard 2400 polypropylene as the support, di(2-ethylhexyl) phosphoric acid (D2EHPA) as the carrier, and kerosene as the diluent. To obtain the best carrier concentration, D2EHPA concentrations between 0.04 and 0.6 M were used. The Cr (III) solutions used in the feed phase had various ionic strengths and were adjusted with NaCl at concentrations ranging from 0.25 to 1.75 M. To maintain a constant pH (4) in the feed phase, a 0.2 M acetic acid–sodium acetate buffer was utilized. Because the rate of Cr (III)-carrier complex formation at the interface of the feed solution and membrane increased up to 20 × 10−4 mol/L, it was discovered that transport of Cr (III) rose with an increase in chromium content in the feeding phase. For the optimization of the various stripping agents, HCl concentration was employed, from 0.25 M to 1.75 M. It was observed that Cr (III) transport increased with the increase in HCl concentration because the transport was at a pH gradient, which was the main driving force. Because of the fact that at the feed phase-membrane contact, D2EHPA combined with chromium ions to form the Cr (III)-carrier complex and released H+ protons, in the feed phase, the Cr (III)-carrier complex was diffused into a stripping phase, wherein Cr (III) ions were stripped and the carrier was reversibly protonated again.

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Further Theoretical Studies of the Aquation of Chromium(III) Chloride Nutritional Supplement: Effect of pH and Solvation

Cited by 4 publications

References 50 publications

Investigation of mono-, bis- and tris-glycinatochromium(III): Comparisons of computational and experimental results

Investigation of mono-, bis- and tris-glycinatochromium(III): Comparisons of computational and experimental results

Investigation of the Spectroscopic, Thermal and Electrochemical Properties of Tris-(glycinato)chromium(III)

Chromium (III) Ions Were Extracted from Wastewater Effluent Using a Synergistic Green Membrane with a BinaryCombination of D2EHPA and Kerosene

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