A Cd(II) Luminescent Coordination Grid as a Multiresponsive Fluorescence Sensor for Cr(VI) Oxyanions and Cr(III), Fe(III), and Al(III) in Aqueous Medium

Hydro(solvo)thermal reactions of Cd(NO3)2, N-(pyridin-3-ylmethyl)-4-(pyridin-4-yl)-1,8-naphthalimide (NI-mbpy-34), and 5-bromobenzene-1,3-dicarboxylic acid (Br-1,3-H2bdc) afforded a luminescent coordination polymer, {[Cd(Br-1,3-bdc)(NI-mbpy-34)(H2O)]∙2H2O}n (1). Single-crystal X-ray diffraction analysis showed that 1 features a two-dimensional (2-D) gridlike sql layer with the point symbol of (44·62), where the Cd(II) center adopts a {CdO5N2} pentagonal bipyramidal geometry. Thermogravimetric (TG) analysis confirmed the thermal stability of 1 up to about 340 °C, whereas XRPD patterns proved the maintenance of crystallinity and framework integrity of 1 in CH2Cl2, H2O, CH3OH, and toluene. Photoluminescence studies indicated that 1 displayed intense blue fluorescence emissions in both solid-state and H2O suspension-phase. Owing to the good fluorescent properties, 1 could serve as an excellent turn-off fluorescence sensor for selective and sensitive Cr(VI) detection in water, with LOD = 15.15 μM for CrO42− and 14.91 μM for Cr2O72−, through energy competition absorption mechanism. In addition, 1 could also sensitively detect Cr3+, Fe3+, and Al3+ ions in aqueous medium via fluorescence-enhancement responses, with LOD = 2.81 μM for Cr3+, 3.82 μM for Fe3+, and 3.37 μM for Al3+, mainly through an absorbance-caused enhancement (ACE) mechanism.

Approaches to increasing the heat stability of whey proteins

В работе обобщаются новейшие теоретические подходы к регулированию термических реакций денатурации и агрегации сывороточных белков, включая физические, химические, ферментативные, а также комбинации различных методов. Описывается поведение модифицированных сывороточных белков во время термической обработки. Среди физических способов модификации приведены существующие технологии обработки сывороточных белков с использованием ультразвука, а также обработки белка под высоким давлением в сочетании с предварительным нагревом. В обзоре подчеркивается, что любая химическая модификация сывороточных белков осуществляется посредством нарушения структуры белка за счет блокирования свободных сульфгидрильных групп. Приводятся такие способы повышения термостойкости, как создание белково-полисахаридных комплексов, которые при pH, близких к изоэлектрической точке, проявляют характеристики псевдопластических жидкостей. В обзоре отмечается способность реакции гликирования также повышать термическую стойкость сывороточных белков. Подчеркивается перспективность ферментативной модификации сывороточных белков в пищевой промышленности, способствующей повышению как термостабильности, так и растворимости белков в кислых значениях pH из-за потери вторичной структуры. Отмечается возможность применения продуктов гидролиза, обладающих растворимостью вблизи изоэлектрической точки, в технологии напитков. Представляет интерес повышение эффективности ферментативного гидролиза сывороточных белков за счет фракционирования гидролизатов молочной сыворотки с использованием ультрафильтрации. Как следствие продукты фракционирования, а именно пермеат с низкомолекулярными пептидными фракциями, прогнозируемо являются потенциальными ингредиентами в технологии напитков. Практический интерес представляет производство термостойких напитков, содержащих высокий уровень сывороточных белков. The article summarizes the latest theoretical approaches to the regulation of thermal reactions of denaturation and aggregation of whey proteins, including physical, chemical, enzymatic, as well as combinations of various methods. Describes the behavior of modified whey proteins during heat treatment. Among the methods of physical modification, the existing technologies for processing whey proteins using ultrasound, as well as processing proteins under high pressure in combination with preheating are given. The review emphasizes that any chemical modification of whey proteins is carried out by disrupting the protein structure by blocking free sulfhydryl groups. Methods for increasing thermal stability are presented, such as the creation of protein-polysaccharide complexes that exhibit the characteristics of pseudoplastic fluids at a pH close to the isoelectric point. The review notes the ability of the glycation reaction to also increase the thermal stability of whey proteins. The prospects for enzymatic modification of whey proteins in the food industry are emphasized, which contribute to an increase in both thermal stability and solubility of proteins at acidic pH values due to the loss of secondary structure. The possibility of using hydrolysis products with a solubility close to the isoelectric point in the technology of beverage production is noted. It is of interest to increase the efficiency of enzymatic hydrolysis of whey proteins due to fractionation of whey hydrolysates using ultrafiltration. Fractionation products, namely permeate with low molecular weight peptide fractions, are predictable potential ingredients in beverage technology. Of practical interest is the production of heat-resistant drinks with a high content of whey proteins.

Evaluated kinetic and photochemical data for atmospheric chemistry: volume VIII – gas-phase reactions of organic species with four, or more, carbon atoms ( ≥ C₄)

This article, the eighth in the series, presents kinetic and photochemical data sheets evaluated by the IUPAC Task Group on Atmospheric Chemical Kinetic Data Evaluation. It covers the gas-phase thermal and photochemical reactions of organic species with four, or more, carbon atoms (≥ C4) available on the IUPAC website in 2021, including thermal reactions of closed-shell organic species with HO and NO3 radicals and their photolysis. The present work is a continuation of volume II (Atkinson et al., 2006), with new reactions and updated data sheets for reactions of HO (77 reactions) and NO3 (36 reactions) with ≥ C4 organics, including alkanes, alkenes, dienes, aromatics, oxygenated, organic nitrates and nitro compounds in addition to photochemical processes for nine species. The article consists of a summary table (Table 1), containing the recommended kinetic parameters for the evaluated reactions, and a supplement containing the data sheets, which provide information upon which recommendations are made.

A highly stable Zn coordination polymer exhibiting pH-dependent fluorescence and as a visually ratiometric and on−off fluorescence sensor

Hydro(solvo)thermal reactions of Zn(NO3)2∙6H2O, naphthalene-1,4-dicarboxylic acid (1,4-H2ndc), and 3,6-bis(pyridin-4-yl)-9H-carbazole (Cz-3,6-bpy) afforded a coordination polymer [Zn2(OH)(1,4-ndc)1.5(Cz-3,6-bpy)]∙2H2O (1), which has a complicated two-dimensional layer structure that can be simplified as a topological...

Impact of tensile and compressive forces on hydrolysis of cellulose and chitin

Mechanochemistry enables unique reaction pathways in comparison to conventional thermal reactions. Notably, it can achieve selective hydrolysis of cellulose and chitin, a set of abundant and recalcitrant biomass, by solvent-free...