Russian Chemical Bulletin最新文献

Environmentally friendly processes for recycling synthetic polymers have recently gained popularity, and living organisms and their enzymes are playing a key role in these processes. Herein we evaluated the degradation of a polyethylene terephthalate matrix by various ascomycete species. Within 30 days, polyethylene terephthalate was the only source of carbon for Lecanicillum aphanocladii, Fusarium oxysporum, Talaromyces sayulitensis, and Trichoderma harzianum. All the considered micromycetes were capable of utilizing polyethylene terephthalate, but the greatest weight loss (22%) was observed upon growing Fusarium oxysporum. DSC analysis revealed an increase in melting points by 2.5 °C and in the glass transition temperatures by 1–3 °C for all the treated samples of polyethylene terephthalate. Changes in chemical structure were estimated using IR spectroscopy, demonstrating various effects of the ascomycetes on the degradation of polymer matrix.

To assess the factors influencing the catalytic action of the Pluronic F127 and Synperonic F68 triblock copolymers in the alkaline hydrolysis of O-alkyl-O-p-nitrophenyl chloromethyl phosphonates, the self-organization in polymer solutions was studied. The critical micelle concentration and size of the aggregates were determined. The kinetic dependencies of the reaction in micellar solutions of the polymers were obtained under pseudo-first-order conditions and analyzed within the framework of a pseudophase model of micellar catalysis. In the system based on Pluronic F127, hydrolysis is inhibited by up to 6.5 times. In the case of Synperonic F68, the micellar effect is temperature-dependent: at 25 °C, the reaction rate remains unchanged, while at 40 °C, a slight inhibition to 1.5 times is observed. This difference is likely attributed to the distinction in the aggregation behavior of the polymers under these conditions.

Uracil-1-acetic acid hydrazides were synthesized according to the standard procedures. The derivatives of this series containing 5-positioned chlorine, bromine, and iodine atoms are new compounds.

10-(Chloroacetyl)phenothiazine reacted with 2-thioxo-1,2-dihydronicotinonitriles in the presence of KOH to form 2-{[2-oxo-2-(10H-phenothiazin-10-yl)ethyl]thio}nicotinonitriles or (3-aminothieno[2,3-b]pyridin-2-yl)(10H-phenothiazin-10-yl)methanones. Some of the synthesized compounds manifested herbicide safening effects against 2,4-D herbicide under conditions of laboratory experiments on sunflower seedlings. According to the results of molecular docking, the nicotinonitrile—phenothiazine heterodimers were found to be promising modulators of the PI3K/AKT/mTOR signaling pathway and of interest as potential antitumor agents.

Calcium carbonate crystallization was investigated under dynamic conditions at elevated temperature in the presence of magnesium ions and organic additives. The crystallization at dynamic conditions was simulated at temperatures above 80 °C in a mildly alkaline medium, at varied Mg²⁺ concentrations, in the presence of dicarboxylic, polycarboxylic, and phosphonic acids. Scanning electron microscopy and X-ray diffraction were used to analyze the obtained sediments. Thermodynamic and kinetic parameters of calcium carbonate crystallization were calculated. It is shown that the presence of Mg²⁺ ions increases the fraction of metastable aragonite and vaterite phases by a factor of 1.2–1.3. The introduction of dicarboxylic acids increases the fraction of aragonite and calcite, whereas polycarboxylic acids inhibit the transformation of metastable vaterite into calcite. In the presence of poly(acrylic) acid, poly(aspartic) acid, and aminotris(methylene)phosphonic acid, the induction period of crystallization is 1.3–1.5 times higher indicating an effect of these acids on the nucleation and growth of calcium carbonate crystals.

The synthesis of 5-([1,1′-diphenyl]-4-yl)thiophene-2-substituted 1,3,4-oxadiazole, 1,3,4-thiadiazole, benzo[1,2-d:4,3-d′]bis(thiazole), 1,2,4-triazole, and 1,3,4-selenadiazole is reported. The optical, electrochemical, and electronic properties of these compounds and 2,5-bis(3-decyl-5′-phenyl-[2,2′-dithiophen]-5-yl)-1,3,4-oxadiazole were studied. The influence of the nature of the central acceptor heterocycle and side donor blocks on the band gap, position of the frontier orbitals, and photophysical properties was established. It is shown that successive replacement of phenyl units of the conjugated chain by thiophene rings leads to a narrowing of the band gap and to a decrease in the fluorescence quantum yield.

The polymerization of methyl methacrylate in the presence of 3-amino-7-dimethyl-amino-2-methylphenazine as a phenazine photocatalyst and tert-butyl bromide as an initiator was studied. It was shown that this dye, in both neutral and protonated forms, is capable of initiating radical polymerization when exposed to visible light, both under anaerobic conditions and in the presence of atmospheric oxygen. The effect of the solvent on the processes under study was assessed and it was established that polymerization occurs according to the metal-free atom transfer radical polymerization (ATRP) scheme of the oxidative type only in polar solvents. Under the reductive type metal-free ATRP conditions, both the protonated and neutral forms of 3-amino-7-dimethylamino-2-methyl-phenazine acted as catalysts regardless of the solvent nature, with the efficiency of the catalytic system increasing as the polarity of the medium, in which the polymerization process takes place, increased.

A procedure was developed for the synthesis of sodium poly-α-d-galactopyranosyluronate (PGNa) complexes with silver. The proposed approach involves the saponification of citrus pectin with a NaOH solution and the subsequent partial replacement of sodium ions in PGNa with silver(i) ions. Biogenic aldehydes, such as glucose, reduce silver(i) ions during the preparation of metal complexes to form silver nanoparticles (AgNPs) 38–70 nm in size. The size of AgNPs and the efficiency of silver(i) reduction in AgNPs depend on the conditions for the preparation of the complexes and the nature of the silver(i) salt used. The best results (the fraction of AgNPs of the total silver content in the complexes was >88%) were obtained using [Ag(NH₃)₂]OH as a silver source. The powder X-ray diffraction analysis showed that an increase in the fraction of silver in the complexes disrupts the ordering of PGNa regions, resulting in the almost complete amorphization of the complexes in the case of the replacement of about 30 mol of sodium with silver(i). The cytotoxic effects of the complexes were evaluated in comparison to silver nitrate.

A series of hybrid compounds were synthesized based on 5-nitrofurfural acetylhydrazone and 3,5-dichlorosalicylanilides, the structural fragments of which are linked to each other via the oxygen atom in the aniline moiety of salicylanilide. The synthesis of the target compounds included three steps: esterification of the carboxymethyl groups of salicylanilides with methanol, hydrazinolysis of the resulting methyl esters followed by the reaction with 5-nitrofurfural. The obtained hybrid compounds exhibited pronounced antimicrobial activity against Staphylococcus aureus with a minimum inhibitory concentration of 0.24–3.91 µg mL⁻¹. The efficacy was found to depend on the position in the aniline fragment of salicylanilide through which the structural fragments are linked.

Heterocyclization reactions of unsubstituted 2-alkenylsulfanyl derivatives of 1,3,4-thiadiazole with bromine and iodine were studied for the first time in inert solvents (acetonitrile and dichloromethane) under mild conditions. The annulation pathways of the thiazole and thiazine rings were analyzed. The structures of all synthesized compounds were determined by ¹H and ¹³C NMR spectroscopy and GC-MS. The structures of 6-iodo-5-phenyl-6,7-dihydro-5H-[1,3,4]thiadiazolo[2,3-b][1,3]thiazinium triiodide and 5-bromomethyl-5-methyl-5,6-dihydrothiazolo[2,3-b][1,3,4]thiadiazolium tribromide were studied by X-ray diffraction. For the tribromide, the polarized vibrational spectra and the tensor of elastic moduli were calculated to evaluate the response of the system to external mechanical stimuli and investigate the directionality of the main structural moieties in the crystal. 6-Iodo-5-phenyl-6,7-dihydro-5H-[1,3,4]thiadiazolo[2,3-b][1,3]thiazinium triiodide was shown to exhibit moderate fungicidal activity against Botrytis cinerea, the causative agent of gray mold, and the phytopathogen Sclerotinia sclerotiorum.