Complex formation between Pd(H(2)O)(4)(2+) and maleic acid (H(2)A) has been studied at 25 degrees C and 2.00 M ionic strength in acidic aqueous solution. Reaction takes place with 1:1 stoichiometry. The kinetics has been followed by use of stopped-flow spectrophotometry under pseudo-first-order conditions with maleic acid in excess. In the concentration ranges 0.01 C where, in addition, both steps contain contributions from parallel reactions. The amplitude of the first phase increases with increasing [H(2)A](tot) and with decreasing [H(+)]. Multiwavelength global analysis of the kinetic traces and the UV-vis spectral changes suggest that a monodentate oxygen-bonded hydrogen maleate complex, [Pd(H(2)O)(3)OOCCH=CHCOOH](+), B, with stability constant K(2) = 205 +/- 40 M(-)(1) is formed as an intermediate in this first step via two parallel reversible reactions in which Pd(H(2)O)(4)(2+) reacts with maleic acid and hydrogen maleate, respectively. In the following step, B --> C, slow intramolecular ring closure with a rate constant of 0.8 +/- 0.1 s(-)(1) at 25 degrees C gives the reaction product C, which is concluded to be a 4.5-membered olefin-carboxylato chelate complex on the basis of stoichiometry and UV-vis/NMR spectra. Parallel and irreversible attack by maleic acid and hydrogen maleate acting as olefins on the intermediate B also leads to formation of C. C is stable for at least 20 h for concentrations of
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/ic980072f | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Comparison of lipid dynamics and permeability in styrene-maleic acid and diisobutylene-maleic acid copolymer lipid nanodiscs by electron paramagnetic resonance spectroscopy.
J Biol Inorg Chem
January 2025
Department of Chemistry and Biochemistry, Miami University, Oxford, OH, USA.
Lipid nanoparticles formed with copolymers are a new and increasingly powerful tool for studying membrane proteins, but the extent to which these systems affect the physical properties of the membrane is not completely understood. This is critical to understanding the caveats of these new systems and screening for structural and functional artifacts that might be caused in the membrane proteins they are used to study. To better understand these potential effects, the fluid properties of dipalmitoylphosphatidylcholine lipid bilayers were examined by electron paramagnetic resonance (EPR) spectroscopy with spin-labeled reporter lipids in either liposomes or incorporated into nanoparticles with the copolymers diisobutylene-maleic acid or styrene maleic acid.
View Article and Find Full Text PDFUltra-stretchable, self-recoverable, notch-insensitive, self-healable and adhesive hydrogel enabled by synergetic hydrogen and dipole-dipole crosslinking.
Mater Horiz
January 2025
College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, 610068, China.
Hydrogels are promising materials for wearable electronics, artificial skins and biomedical engineering, but their limited stretchability, self-recovery and crack resistance restrict their performance in demanding applications. Despite efforts to enhance these properties using micelle cross-links, nanofillers and dynamic interactions, it remains a challenge to fabricate hydrogels that combine high stretchability, self-healing and strong adhesion. Herein, we report a novel hydrogel synthesized the copolymerization of acrylamide (AM), maleic acid (MA) and acrylonitrile (AN), designed to address these limitations.
View Article and Find Full Text PDFThermally Solvent-Free Cross-Linked pH/Thermosensitive Hydrogels as Smart Drug Delivery Systems.
Gels
December 2024
"Petru Poni" Institute of Macromolecular Chemistry, Grigore Ghica Voda Alley 41A, 700487 Iasi, Romania.
An imbalance in the body's pH or temperature may modify the immune response and result in ailments such as autoimmune disorders, infectious diseases, cancer, or diabetes. Dual pH- and thermo-responsive carriers are being evaluated as advanced drug delivery microdevices designed to release pharmaceuticals in response to external or internal stimuli. A novel drug delivery system formulated as hydrogel was developed by combining a pH-sensitive polymer (the "biosensor") with a thermosensitive polymer (the delivery component).
View Article and Find Full Text PDFTunable Terpolymer Series for the Systematic Investigation of Membrane Proteins.
Biomacromolecules
December 2024
Department of Chemistry and Polymer Science, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa.
Membrane proteins (MPs) are critical to cellular processes and serve as essential therapeutic targets. However, their isolation and characterization are often impeded by traditional detergent-based methods, which can compromise their native states, and retention of their native lipid environment. Amphiphilic polymers have emerged as effective alternatives, enabling the formation of nanoscale discs that preserve MPs' structural and functional integrity.
View Article and Find Full Text PDFEnhanced abatement of phenolic compounds by chlorine in the presence of CuO: Absence of electrophilic aromatic substitution.
Water Res
December 2024
Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address:
It has been demonstrated that chlorine predominately reacts with phenolic compounds through an electrophilic aromatic substitution, yielding chlorinated phenols. Previous studies showed that copper oxide (CuO), a water pipe corrosion product, can catalytically enhance the reactivity of chlorine and its disproportionation. In this study, kinetics and mechanisms for the reactions of chlorine with phenolic compounds in the presence of CuO were investigated.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!