Analytical Determination of Cephalosporin Antibiotics Using Coordination Polymer Based on Cobalt Terephthalate as a Sorbent.

In this work, a coordination polymer based on cobalt terephthalate was obtained and characterized by elemental analysis, infrared spectroscopy, X-ray diffraction analysis, and scanning electron microscopy. The coordination polymer was tested as a sorbent for the solid-phase extraction of cephalosporin antibiotics, including ceftriaxone, cefotaxime, and cefazolin, from aqueous solutions. The coordination polymer had a high adsorption capacity (520.0 mg/g). Antibiotics adsorption followed pseudo-second order kinetic model and the Freundlich isotherm model. The calculated thermodynamic parameters indicate a spontaneous process. The resulting coordination polymer has good stability and reusability. The possibility of separating the studied cephalosporins on a chromatographic column filled with a coordination polymer was shown. This work opens great prospects for the development and application of a coordination polymer based on cobalt terephthalate for the removal of cephalosporins from ambient water.

Determination of Tetracycline Antibiotics in Milk by Solid-Phase Extraction Using a Coordination Polymer Based on Cobalt Trimesinate as a Sorbent.

The coordination polymer was obtained based on cobalt trimesinate. It was characterized by elemental analysis, IR spectroscopy, X-ray diffraction analysis and scanning electron microscopy. The polymer was studied as a sorbent for solid-phase extraction of tetracycline antibiotics. Cobalt trimesinate had a high adsorption capacity (400 mg/g). Antibiotic adsorption followed the pseudo-second-order kinetic model and the Freundlich isotherm model. The process proceeded spontaneously, as indicated by the calculated thermodynamic parameters. The resulting coordination polymer has good stability and recyclability. The possibility of using cobalt trimesinate for the determination of tetracycline in various milk samples was investigated. This work holds great promise for the development and application of a cobalt trimesinate-based coordination polymer for use in sample preparation to replace the time-consuming vacuum evaporation procedure with a relatively simple solid-phase extraction procedure.

Preparation of Reactive Indicator Papers Based on Silver-Containing Nanocomposites for the Analysis of Chloride Ions.

In recent decades, metal-containing nanocomposites have attracted considerable attention from researchers. In this work, for the first time, a detailed analysis of the preparation of reactive indicator papers (RIPs) based on silver-containing nanocomposites derived from silver fumarate was carried out. Thermolysis products are silver-containing nanocomposites containing silver nanoparticles uniformly distributed in a stabilizing carbon matrix. The study of the optical properties of silver-containing nanocomposites made it possible to outline the prospects for their application in chemical analysis. RIPs were made by impregnating a cellulose carrier with synthesized silver fumarate-derived nanocomposites, which change their color when interacting with chlorine vapor. This made it possible to propose a method for the determination of chloride ions with preliminary oxidation to molecular chlorine, which is then separated from the solution by gas extraction. The subsequent detection of the active zone of RIPs using colorimetry makes it possible to identify mathematical dependences of color coordinates on the concentration of chloride ions. The red (R) color coordinate in the RGB (red-green-blue) system was chosen as the most sensitive and promising analytical signal. Calibration plots of exponential and linear form and their equations are presented. The limit of detection is 0.036 mg/L, the limits of quantification are 0.15-2.4 mg/L, and the time of a single determination is 25 min. The prospects of the developed technique have been successfully shown in the example of the analysis of the natural waters of the Don River, pharmaceuticals, and food products.

Silver Itaconate as Single-Source Precursor of Nanocomposites for the Analysis of Chloride Ions.

At present, conjugated thermolysis of metal-containing monomers is widely used as single-source precursors to obtain new metal- and metal oxide-containing nanocomposites. In this study, a detailed analysis of the main stages of conjugated thermolysis of silver itaconate was carried out. The obtained nanocomposites containing silver nanoparticles are evenly distributed in a stabilizing carbon matrix. The structural characteristics and properties of the resulting nanomaterials were studied using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). We have developed a method of test analysis of chlorides using paper modified with the obtained silver-containing nanocomposites. The analysis technique is based on the in situ conversion of chlorides to molecular chlorine, its dynamic release, and colorimetric detection using NP-modified paper test strips. A simple installation device is described that allows this combination to be realized. The proposed approach seems promising for nanoparticle-based determinations of other analytes that can be converted into volatile derivatives.

Novel Self-Healing Metallocopolymers with Pendent 4-Phenyl-2,2':6',2″-terpyridine Ligand: Kinetic Studies and Mechanical Properties.

We report here our successful attempt to obtain self-healing supramolecular hydrogels with new metal-containing monomers (MCMs) with pendent 4-phenyl-2,2':6',2″-terpyridine metal complexes as reversible moieties by free radical copolymerization of MCMs with vinyl monomers, such as acrylic acid and acrylamide. The resulting metal-polymer hydrogels demonstrate a developed system of hydrogen, coordination and electron-complementary π-π stacking interactions, which play a critical role in achieving self-healing. Kinetic data show that the addition of a third metal-containing comonomer to the system decreases the initial polymerization rate, which is due to the specific effect of the metal group located in close proximity of the active center on the growth of radicals.

Synthesis of Copper(II) Trimesinate Coordination Polymer and Its Use as a Sorbent for Organic Dyes and a Precursor for Nanostructured Material.

Several important synthesis pathways for metal-organic frameworks (MOFs) were applied to determine how the synthesis methods and conditions affect the structure and adsorption capacity of the resulting samples. In the present work, three different synthesis routes were used to obtain copper trimesinate coordination polymer: Slow evaporation (A), solvothermal synthesis using a polyethylene glycol (PEG-1500) modulator (B), and green synthesis in water (C). This MOF was characterized by elemental analysis, infrared spectrometry, X-ray diffraction, scanning electron microscopy, thermogravimetry and volumetric nitrogen adsorption/desorption. The samples have permanent porosity and a microporous structure with a large surface area corresponding to the adsorption type I. The obtained MOF was tested as a sorbent to remove organic dyes methylene blue (МВ), Congo red (CR) and methyl violet (MV) as examples. Dye adsorption followed pseudo-first-order kinetics. The equilibrium data were fitted to the Langmuir and Freundlich isotherm models, and the isotherm constants were determined. Thermodynamic parameters, such as changes in the free energy of adsorption (ΔG0), enthalpy (ΔH0), and entropy (ΔS0), were calculated. Thermolysis of copper trimesinate leads to the formation of carbon materials Cu@C with a high purity.