Choline-based deep eutectic solvents mediated Aza-Michael addition reaction using environmentally benign methodology

The copper benzene-1, 3, 5-tricarboxylate metal–organic framework (CuBTC) was found to be an effective heterogeneous catalyst for the aza-Michael addition reaction of the four types of amines to electron deficient alkenes at room temperature. The catalytic protocol showed high product yields and outstanding chemo selectivity. The cyclic amines (piperidine and pyrrolidine) and aliphatic amines (n-dibutylamine) provided aza-Michael addition with a high yield of product (⁓98%) within shorter reaction period (2 h) at room temperature under mild reaction conditions using CuBTC. However, it was observed that the aza-Michael reaction proceeded more slowly, giving 62% yield of product after 24 h in the case of aromatic amine (aniline) with n-butyl acrylate in the presence of CuBTC under identical reaction conditions. The catalyst could be reused four recycles without losing its initial catalytic activity and selectivity. XRD and SEM analysis further confirmed that the crystallinity of catalyst was retained during the reaction. A reaction mechanism is proposed for the aza-Michael addition reaction over heterogeneous CuBTC catalyst.

Chitosan films plasticized with choline-based deep eutectic solvents: UV shielding, antioxidant, and antibacterial properties

The aza-Michael reaction is a fundamental transformation for carbon-nitrogen bond formation, providing efficient access to β-amino carbonyl compounds, nitriles, and related nitrogen-containing building blocks of broad importance in medicinal chemistry and organic synthesis. Over the past two decades, ionic liquids (ILs) have attracted considerable attention as alternative reaction media, promoters, and catalysts for aza-Michael reactions, owing to their distinctive physicochemical properties and tunable structures. This review presents a comprehensive and critical overview of ionic-liquid-mediated aza-Michael reactions, emphasizing the evolution of IL design from early imidazolium-based systems to modern task-specific, supported, and bio-derived ionic liquids. Conventional room-temperature ionic liquids are discussed as non-innocent solvents capable of stabilizing charged intermediates and enhancing electrophilicity, thereby enabling catalyst-free or metal-assisted aza-Michael additions. Subsequent sections focus on task-specific ionic liquids incorporating Brønsted acidic, basic, hydrogen-bond-donating, or bifunctional motifs, highlighting how rational structural design translates into improved activity, selectivity, and substrate scope. Particular attention is devoted to guanidine-, DABCO-, and DBU-based ionic liquids, where mechanistic studies reveal cooperative activation modes rather than simple acid-base catalysis. Recent advances in supported and polymeric ionic liquids are also reviewed, demonstrating effective strategies to combine IL-like reactivity with enhanced recyclability and operational simplicity. Overall, this review clarifies the diverse roles of ionic liquids in aza-Michael chemistry and outlines current challenges and future perspectives toward more sustainable and efficient C-N bond-forming methodologies.

Solubility enhancement and intermolecular interactions of salicylic acid in aqueous solutions of choline chloride based deep eutectic solvents

Background: Deep eutectic solvents (DESs) exist a wide variety of potential and existing applications. Based on the fact that the choline chloride (ChCl) is a complex B vitamin and widely used as food additive, the choline-based DESs are generically regarded as being harmless and non-toxic. In this regard, the low aqueous solubility of celecoxib (CLX) have been increased by use of DESs as neoteric class of solvents at T = (298.15 to 313.15) K. Methods: DESs were prepared by combination of the ChCl/EG, U and G with the molar ratios: 1:2 and ChCl/MA with 1:1. The shake flask method was used to measure the solubility of CLX in the aqueous DESs solutions at different temperatures. Results: The solubility of the CLX increased with increasing the weight fraction of DESs. The observed solubility data was subjected to evaluate the relative performance of a number of models including Apelblat, Yalkowsky and Jouyban–Acree models for their correlation efficacy. Moreover, the apparent dissolution enthalpy, entropy and Gibbs free energy were obtained from the experimental solubility values. Conclusion: It was found that the solubility data was satisfactorily fitted using the mentioned models at different temperatures. The dissolution process of CLX in the studied solvent mixtures within investigated temperature range was endothermic, and the driving mechanism is the positive entropy.

The novel efficient complex catalyst containing a Lewis acid and a Bronsted acid have been prepared by the reaction of proline ion liquid and cuprous iodide. The catalyst was characterized by FT-IR techniques using pyridine as probe molecule. A fast, mild, and quantitative procedure for aza-Michael addition reactions between various amines and α,β-unsaturated carbonyl compounds and nitriles has been developed using the novel complex catalyst. The results showed that the novel catalyst owned high activities for the reactions with excellent yields within 1 min.

The chemical response of liquid crystal elastomers (LCEs) offers substantial potential for applications in propulsion systems, micromechanical systems, and active smart surfaces. However, the shape-changing behaviors of LCEs in response to organic (isotropic) solvents remain scarcely explored, with most research focusing on liquid crystal (anisotropic) solvents. Herein, we prepared a series of aligned LCEs with varying crosslink densities using a surface alignment technique combined with an aza-Michael addition reaction, aiming to investigate their swelling behaviors in different isotropic solvents. We found that the rates of shape and volume variation modes, the elastic modulus of the LCEs, and the polarity of the solvent all significantly influence the swelling behavior. Specifically, when LCEs swell in acetone, dimethylformamide (DMF), and ethyl acetate, contraction occurs along the alignment direction. Conversely, extension along the alignment direction is observed when LCEs swell in toluene, anisole, and acrylic acid. Meanwhile, extension in the perpendicular direction is noted when LCEs swell in nearly all solvents. These shape changes can be attributed to the phase transitions of the LCEs. This research not only provides valuable insights into the swelling mechanisms of LCEs but also holds great promise for the development of solvent sensors and gas sensing applications.

Chromium-complexed collagen is generated as waste during processing of skin into leather. Here, we report a simple heat treatment process to convert this hazardous industrial waste into core–shell chromium–carbon nanomaterials having a chromium-based nanoparticle core encapsulated by partially graphitized nanocarbon layers that are self-doped with oxygen and nitrogen functionalities. We demonstrate that these core–shell nanomaterials can be potentially utilized in electromagnetic interference (EMI) shielding application or as a catalyst in aza-Michael addition reaction. The results show the ability to convert industrial bio-waste into useful nanomaterials, suggesting new scalable and simple approaches to improve environmental sustainability in industrial processes.

The title compound was prepared by an aza-Michael addition reaction between 1-[1-(4-chlorobenzenesulfonyl)-1H-indole-3-yl]prop-2-en-1-one and 2-piridylpiperazine catalyzed by SiO2. The structural identity of the title compound was proven by elemental analysis and spectroscopic methods (IR, NMR). The compound was assayed in a binding assay at the 5-HT6 receptor, showing poor affinity.

The first total synthesis of kukoamine B bimesylate was completed from 1,4-diaminobutane dihydrochloride in 12 steps with a 11.4% overall yield, and all the steps could be carried out at a kilogram scale. The cyano groups were used as the precursor of amino groups to avoid the competitive reaction delicately. The aza-Michael addition reaction, amidation and hydrogenation of the cyano group sequence was streamlined as a general approach towards the synthesis of polyamine structures.

To enhance cell survival and engraftment for cell therapy, cell encapsulated injectable biomaterials have been widely used. However, the challenges were hypoxia and nutrient shortage in the core, inflammatory cell infiltration and limited distribution of cells from injection sites. Encapsulation of single cells in sub-100-micron microgels with higher surface to volume ratios provides more efficient oxygen and mass exchange. However, typical production of single-cell-laden microgels by microfluidics devices results in cell damage and compromised biological properties. We hypothesized that stimuli responsive amphiphilic copolymer bearing RGD peptides may self-assemble around single cells induced by cell adhesion moieties would result in single cell microvesicles (MV). A stimuli responsive amphiphilic copolymer GPM (Gelatin Poly glycerol sebacate Methacrylate) was synthesized by grafting hydrophobic synthetic polymer PGS into hydrophilic natural polymer gelatin via methacrylation followed by aza-Michael addition reaction. Single cell microvesicles of endothelial cells (EC-MVs) were fabricated by self-assembly of GPM at room temperature. For in vivo studies, sub-50-micron EC-MVs made of reprogrammed endothelial cells (rECs) were clustered into 200 micron spheres (mGPM) using sodium alginate and injected into a hindlimb ischemia model to investigate cell survival and biological function. The mGPM microspheres functioned as a barrier from immune cell infiltration and also enhanced cellular distribution. The encapsulated rECs were released over 2-4 wks in vivo and were shown robust engraftment, migration, and survival in limb tissues, promoting blood flow recovery and sustained vascular regeneration over 6 months. Interestingly, in in vitro culture, rEC-MVs secreted sheet like extra cellular matrix (ECM) which appeared to make an important role for vessel formation (neovascularization) in vivo (Figure 1). The current study clearly demonstrated the favorable biological applicability of GPM single cell MVs toward vascular regeneration by reprogrammed ECs.

Catalyst and base free aza-Michael addition reaction: Synthesis of poly-substituted 4-pyrazole based benzopyrans

Local and cooperative structural transitions of double-stranded DNA in choline-based deep eutectic solvents

A nanostructure-based catalytic system has the advantages of both homogeneous and heterogeneous catalysis. It is of great significance to develop the sustainable and green process of homogeneous catalytic reaction. We report a novel, efficient and recyclable magnetic Fe3O4 nanoparticles-catalyzed aza-Michael addition reaction of acryl amides, and the magnetic nanoparticles catalysts can be recovered by external magnetic field. Both primary amine and secondary amine can react with various acryl amides providing a good output to target products successfully at room temperature. Further experiments reveal that the magnetic Fe3O4 nanoparticles-based catalyst shows excellent yields, which can be recycled 10 times, and, at the same time, it maintains a high catalytically activity. In this catalytic system, the tedious separation procedures are replaced by external magnetic field, which gives us a different direction for choosing a catalyst in a nanostructure-based catalytic system.

The recovery of platinum group metals (PGMs) from secondary raw materials has become a topic of critical importance mainly due to the gradual depletion of their natural resources and their continuously increasing demand. However, the insufficient recovery of PGMs coupled with the negative environmental impact of the state-of-the-art recycling procedures mandate the investigation and development of alternative recovery processes that will assist in minimizing or even eliminating these drawbacks. Herein, we present a process for the extraction of platinum group metals from spent car catalysts relying on benign deep eutectic solvents (DESs). It is demonstrated that with addition of small amounts of an oxidizing agent, deep eutectic solvents can act as excellent leaching media for the quantitative extraction of platinum group metals. Despite its inertness towards acidic and oxidizing agents, Rh can be leached in a considerable amount which can be further increased by physical pre-treatment of the spent car catalyst material.