Copper-catalyzed ortho-thiocyanation of aromatic amines.

A copper-catalyzed direct ortho-Csp2-H thiocyanation of free anilines has been developed. This method employs stable and non-toxic ammonium thiocyanate as a thiocyanation source, and tert-butyl hydroperoxide as the oxidant, enabling the synthesis of ortho-thiocyanated anilines with good yields and broad substrate tolerance. Hitherto, no reports have been found in the literature for the ortho-thiocyanation of aromatic amines, making this reaction an important breakthrough in synthetic organic chemistry.

Preparation of sodium alginate/Cur-PLA hydrogel beads for curcumin encapsulation.

The low bioavailability of hydrophobic compounds, however, limits their medicinal use. Hydrogel beads made of biopolymers can be employed as controlled delivery systems and as a carrier to carry curcumin molecules. In this study, encapsulation of curcumin is done within the hydrogel by using Polylactic acid. The prepared SA/Cur-PLA and SA/Cur beads were examined using FTIR, SEM, TGA, NMR, and, XRD to study the interaction between drug and polymer. The developed bead's curcumin encapsulation efficiency was found to be 81.47 % in SA/Cur-PLA. Curcumin's release kinetics have been studied in systems (SGF, pH 1.2, and SCF, pH 7.4) that simulate oral consumption, which possess good pH sensitivity. The in vitro drug release studies of SA/Cur-PLA beads suggest that the curcumin release was significantly increased in a controlled manner and within 12 h, the cumulative release of curcumin was accomplished. In vitro hemolysis study shows a 7.93 % hemolysis rate which suggests that the produced bead is hemocompatible. For SA/Cur-PLA and SA/Cur, cytotoxicity evaluation and antimicrobial study was performed. Results show that both hydrogels are cytocompatible and antimicrobial in nature. It was found that biopolymer-based hydrogel beads enhanced the bioavailability of curcumin, antioxidant, biodegradable, and considered an effective carrier for the oral delivery of several hydrophobic nutraceuticals.

Covalent Organic Framework Impregnated with Silver and Copper Nanoparticles: An Advanced Approach for Catalytic Degradation of Organic Pollutants in Wastewater.

In this study, we introduce an economically viable and scalable process for developing a novel covalent organic framework (COF), which is a cross-linked polymer. The resulting material, TzTFB-COF, is successfully functionalized with silver and copper nanoparticles, which show high adequacy in the degradation of nitroaromatic compounds (NACs). For the synthesis of TzTFB-COF, s-tetrazine diamine (Tz) and 1,3,5-triformylbenzene (TFB) are chosen as building blocks, which exhibit a high density of nitrogen-containing sites. TzTFB-COF shows good chemical and thermal stability (>300 °C). For functionalization of TzTFB-COF with silver and copper nanoparticles, a solution infiltration technique is used. The composite materials, i.e., Ag@TzTFB-COF and Cu@TzTFB-COF, have been characterized using various spectroscopic and analytical techniques, which show high activity, high selectivity, and excellent chemical and thermal stability up to 350 °C. The silver and copper contents of Ag@TzTFB-COF and Cu@TzTFB-COF are determined to be 9.6 and 12.4 wt % by inductively coupled plasma optical emission spectrometer (ICP-OES). The catalytic efficiency of the synthesized Ag@TzTFB-COF and Cu@TzTFB-COF materials is assessed in the context of catalyzing the hydrogenation of NACs. Experimental results reveal a remarkable catalytic performance when conducted in an aqueous medium, and notably, the materials demonstrate substantial potential for reusability across multiple catalytic cycles. The determined parameters for the catalytic hydrogenation reaction, i.e., the rate constants and Gibbs free energies, are found to be 0.0185 s-1 and 9.878 kJ/mol for Ag@TzTFB-COF and 0.0219 s-1 and 9.615 kJ/mol for Cu@TzTFB-COF. Thus, the catalytic reaction exhibits characteristics of endothermic, endergonic, and nonspontaneous nature.

Preparation and characterization of slow-release fertilizers loaded guar gum-g-poly methylmethacrylate-cl-polylactic acid (Gg-g-PMMA-cl-PLA) hydrogel and its effect on wheat growth.

In order to reduce the harmful effects of synthetic non-biodegradable hydrogel, biopolymers have attracted attention, particularly for use in slow-release fertilizers. The current attempt intends to develop a hydrogel from biopolymers for sustainable release of water and nutrients in soil. Here, guar gum is used as a polysaccharide, MMA as a monomer, KPS as an initiator, and Polylactic acid as a cross-linker. Further investigation is done to study synthesized hydrogel in the development of wheat crop. Biodegradation study shows that it's environmentally favorable and degradable, contributing nutrients to the soil as it decomposes. Fertilizer release studies in soil and water show that the timing of the nutrient release is delayed, improving soil water holding capacity and retention studies. The agronomic parameters show that fertilizers-loaded hydrogel has a positive effect on physiological, morphological characteristics like shoot length, root length, number of shoots and roots, shoot weight and root weight, chlorophyll content, and most notably, fruiting efficiency is enhanced as compared with commercially available hydrogel. ATR-FTIR, SEM-EDX, TGA-DTA, and XRD analysis used to confirm successful loading of fertilizers and biodegradation of hydrogel. The encouraging findings suggested that this hydrogel could be used as a multifunctional, fertilizers-loaded hydrogel in crop production.

Microbial Synthesis of Lactic Acid from Cotton Stalk for Polylactic Acid Production.

Cotton stalk, a waste product in agriculture, serves as a beneficial, low-cost material as a medium for microbial synthesis of lactic acid as desired for polylactic acid synthesis. Cotton stalk was used as a substrate for microbial lactic acid synthesis, and a novel strain of Lactococcus cremoris was reported to synthesize 51.4 g/L lactic acid using cellulose recovered from the cotton stalk. In total, 18 Lactobacillus isolates were isolated from kitchen waste, soil, sugarcane waste, and raw milk samples screened for maximum lactic acid production. It was found that one of the Lactococcus cremoris isolates was found to synthesize maximum lactic acid at a concentration of 51.4 g/L lactic acid in the hydrolysate prepared from cotton stalk. The upstream process parameters included 10% inoculum size, hydrolysate containing reducing sugars 74.23 g/L, temperature 37 °C, agitation 220 rpm, production age 24 h. Only the racemic (50:50) mixture of D-LA and L-LA (i.e., D/L-LA) is produced during the chemical synthesis of lactic acid, which is undesirable for the food, beverage, pharmaceutical, and biomedical industries because only the L-form is digestible and is not suitable for biopolymer, i.e., PLA-based industry where high optically purified lactic acid is required. Furthermore, polylactic acid was synthesized through direct polycondensation methods using various catalysts such as chitosan, YSZ, and Sb2O3. PLA is biocompatible and biodegradable in nature (its blends and biocomposites), supporting a low-carbon and circular bioeconomy.

The recent advances in cobalt-catalyzed C(sp3)-H functionalization reactions.

Over the past decades, reactions involving C-H functionalization have become a hot theme in organic transformations because they have a lot of potential for the streamlined synthesis of complex molecules. C(sp3)-H bonds are present in most organic species. Since organic molecules have massive significance in various aspects of life, the exploitation and functionalization of C(sp3)-H bonds hold enormous importance. In recent years, the first-row transition metal-catalyzed direct and selective functionalization of C-H bonds has emerged as a simple and environmentally friendly synthetic method due to its low cost, unique reactivity profiles and easy availability. Therefore, research advancements are being made to conceive catalytic systems that foster direct C(sp3)-H functionalization under benign reaction conditions. Cobalt-based catalysts offer mild and convenient reaction conditions at a reasonable expense compared to conventional 2nd and 3rd-row transition metal catalysts. Consequently, the probing of Co-based catalysts for C(sp3)-H functionalization is one of the hot topics from the outlook of an organic chemist. This review primarily focuses on the literature from 2018 to 2022 and sheds light on the substrate scope, selectivity, benefits and limitations of cobalt catalysts for organic transformations.

Optimization of biodegradable cross-linked guar-gum-PLA superabsorbent hydrogel formation employing response surface methodology.

Cross-linked polymer networks with three-dimensional structures known as hydrogels absorb and retain a large amount of water. Because of their properties, hydrogel materials have been considered a boon in agriculture science. In the present investigation, guar gum cross-linked polylactic acid hydrogel is synthesized using MMA as monomer and optimized using a central composite design of response surface methodology for better swelling. The studied input variables are monomer concentration, initiator concentration, and cross-linker concentration at constant pH and temperature. The constructed response model has been tested using the analysis of variance (ANOVA), where the model F-value of 4.64 indicates that the model is significant. The R2 value (0.806) (multiple correlation coefficient) and the standard deviation for the quadratic model were both found to be 4.27. A separate validation experiment is conducted to ensure the quadratic model is sufficient. The hydrogel synthesis was confirmed by characterization techniques like FTIR spectroscopy, SEM, TGA, XRD, and water absorption studies. Synthesized hydrogels swell maximum in water and least in 0.9 % NaCl solution. The present work highlights the development of guar gum-based super-absorbent hydrogels, which are biodegradable and lead to potential application in agriculture, especially in drought regions.

Recent advances in visible-light-mediated functionalization of olefins and alkynes using copper catalysts.

Over the past decade, visible-light photoredox catalysis has blossomed as a powerful strategy and offers a discrete activation mode complementary to thermal controlled reactions. Visible-light-mediated photoredox catalysis also offers exciting opportunities to achieve challenging carbon-carbon and carbon-heteroatom bond formations with excellent chemo-, regio-, or stereoselectivity under mild and ecologically benign conditions. The greater part of photoredox reactions depends on heavy metals like ruthenium(II) or iridium(III) based complexes as photoredox catalysts owing to their strong absorption, long-lived excited-state lifetimes and high oxidation or redox potentials. However, these transition metal complexes are expensive and pose severe drawbacks with respect to large scale application and sustainability. Organic dyes are also commonly used as a low-cost alternative to Ru- or Ir-based complexes. However, they have inferior photostability. Thus, further development of alternative photocatalysts based on copper salts or copper complexes is widely investigated because of their economic and environmental benefits. In recent years, visible-light-mediated direct functionalization of olefins or alkynes to afford a diverse range of organic compounds has received extensive interest from synthetic chemists due to their easy availability and reactivity towards a large number of reactants. In this review, we have highlighted the most recent significant advances that have been made in the use of copper-based photocatalysts for the functionalization of olefins and alkynes with an emphasis on substrate scope, limitations, mechanistic understanding and applications of these reactions. This review covers the literature from 2015 to 2021.

Recent advances in directed sp2 C-H functionalization towards the synthesis of N-heterocycles and O-heterocycles.

Heterocyclic compounds are widely present in the core structures of several natural products, pharmaceuticals and agrochemicals, and thus great efforts have been devoted to their synthesis in a mild and simpler way. In the past decade, remarkable progress has been made in the field of heterocycle synthesis by employing C-H functionalization as an emerging synthetic strategy. As a complement to previous protocols, transition metal catalyzed C-H functionalization of arenes using various directing groups has recently emerged as a powerful tool to create different classes of heterocycles. This review is mainly focussed on the recent key progress made in the field of the synthesis of N,O-heterocycles from olefins and allenes by using nitrogen based and oxidizing directing groups.

Nucleobase-based barbiturates: their protective effect against DNA damage induced by bleomycin-iron, antioxidant, and lymphocyte transformation assay.

A number of nucleobase-based barbiturates have been synthesized by combination of nucleic acid bases and heterocyclic amines and barbituric acid derivatives through green and efficient multicomponent route and one pot reaction. This approach was accomplished efficiently using aqueous medium to give the corresponding products in high yield. The newly synthesized compounds were characterized by spectral analysis (FT-IR, (1)H NMR, (13)C NMR, HMBC, and UV spectroscopy) and elemental analysis. Representative of all synthesized compounds was tested and evaluated for antioxidant, bleomycin-dependent DNA damage, and Lymphocyte Transformation studies. Compounds TBC > TBA > TBG showed highest lymphocyte transformation assay, TBC > TBA > BG showed inhibitory antioxidant activity using ABTS methods, and TBC > BPA > BAMT > TBA > 1, 3 -TBA manifested the best protective effect against DNA damage induced by bleomycin.