Reaction Medium Research Articles

In situ detection of miR-93/VEGFR2 by nanosensor and inhibition of trophoblast apoptosis

We investigated the pathogenesis of recurrent spontaneous abortion (RSA) and evaluated the therapeutic effect of Pill Nourishing Kidney and Fetus (PNKF). A sensitive DNA sensor was used to detect miR-93 expression and vascular endothelial growth factor receptor 2 (VEGFR2). We testing the penetration capacity and physicochemical properties of the DNA sensor and found that the sensor had higher penetration and good stability and effectively detected miR-93 and VEGFR2 at different reaction temperatures and mediums with similar fluorescence signals. The sensor detected higher miR-93 expression, increased apoptosis, and negative regulation of VEGFR2 in patients with RSA. Treatment with PNKF of cultured trophoblast cells collected from patients with RSA were treated with PNKF significantly inhibited trophoblast cell apoptosis and promoted trophoblast cell proliferation by reducing miR-93 expression and promoting VEGFR2 expression. In conclusion, PNKF can improve the proliferation and inhibit apoptosis of trophoblast cells by suppressing miR-93 and promoting VEGFR2. Furthermore, the miR-93/VEGFR2 sensor demonstrated high sensitivity that has potential applications in clinical practice.

Flavonoid-metal ion Complexes as Potent Anticancer metallodrugs: A comprehensive Review.

Flavonoids and their analogous are mainly found in pink lady apples, green and black tea (catechins), celery and red peppers, onions, broccoli and spinach, berries, cherries, soybean, citrus fruits, and fungi. The different derivatives of flavonoids belonging to polyphenolic compounds such as 3,4',5,7-Tetrahydroxyflavylium (pelargonidin), 2-(3,4-Dihydroxyphenyl)chromenylium-3,5,7-triol (cyanidin), 3,3',4',5,5',7-Hexahydroxyflavylium (delphinidin), 3,3',4',5,7-Pentahydroxy-5'-methoxyflavylium (petunidin), and 3,4',5,7-Tetrahydroxy-3',5'-dimethoxyflavylium (malvidin) can act as good chelating agents for metal-chelate complex formation. These flavonoid-metal complexes have been reported to have various biomedical and pharmacological activities. Flavonoid-metal ion complexes display a broad spectrum of biological properties such as antioxidant, anti-inflammatory, anti-allergic, antiviral, anticarcinogenic, and cytotoxic activity. The literature survey showed that flavonoid metal complexes have potential therapeutic properties against various cancerous cells. The objective is to gain insight into the current perspective and development of novel anticancer metallodrug drugs. The flavonoid-metal ion complexes can be prepared by reacting flavonoid ligand with appropriate metal salt in aqueous or alcoholic reaction medium under stirring or refluxing conditions. In this review article, the various reported methods for the synthesis of flavonoid-metal complexes have been included. The utility of synthetic methods for flavonoid-metal complexes will support the discovery of novel therapeutic drugs. In this review study, short libraries of flavonoid-metal ion complexes were studied as potential anticancer agents against various human cancer cell lines. The review report reveals that metal ions such as Fe, Co, Ni, Cu, Zn, Rh, Ru, Ga, Ba, Sn etc., when binding to flavonoid ligands, enhance the anticancer activity compared to free ligands. This review study covered some important literature surveys for the last two decades. It has been concluded that flavonoid metal complexes have been associated with a wide range of biological properties that could be noteworthy in the medicinal field. Therefore, to develop a new anticancer drug, it is essential to determine the primordial interaction drug with DNA under physiological or anatomical conditions. The study of numerous flavonoid metal complexes mentioned in this paper could be the future treatment against various cancerous diseases.

An efficient synthesis, structural analysis, and computational studies of benzothiazole derivatives activated by formic acid under solvent-free conditions

In the present work, formic acid was used as a low-cost and eco-friendly catalyst to synthesize 2-(2-hydroxyphenyl)benzothiazole (HB) through a cycloaddition process in a solvent-free reaction medium. Imine molecule was synthesized with the help of acetic acid (B). The ring closure and formation of the thiazole moiety give acetic acid distinctiveness as a catalyst. The cyclization of fused HB failed without an acid catalyst. The chemical structures were characterized using microanalysis techniques such as IR, 1H-NMR, and 13C-NMR. The obtained FT-IR spectra were compared to theoretical data using the B3LYP/6-31G* level of theory. The electronic characteristics of molecules can be predicted utilizing wave function-dependent features, such as Average localized ionization energy (ALIE), Localized orbital locator (LOL), Electron localized function (ELF), Reduced density gradient (RDG), and Noncovalent interactions NCI studies, which have provided a wealth of knowledge. The molecular docking study was investigated to explore binding energy and interaction type. Docking analysis displayed binding energies (kcal/mol) of HB with values of -8.29, -6.80, -6.68, -7.43, and -6.69 of acetylcholinesterase (AChE) and butylcholinesterase (BuChE)), SARS-CoV-2 main protease (Mpro), human immunodeficiency virus reverse transcription (HIV RT)) and cytochrome (P450), respectively, which was the most active compound against all receptors. The dramatic improvement of the proposed approach over the existing methods can be used to derive an efficient and successful route for the synthesis of HB. This process provides a fresh and high-yield method for the synthesis of benzimidazoles.

A complete and sustained organic/inorganic reaction mechanism of Baeyer’s test

The Baeyer’s test for unsaturation has been used in Qualitative Organic Analysis for a long time. However, if an alkaline reagent is used, compounds having an active hydrogen (carbon acids) also give a positive test with potassium permanganate, detracting the test for unsaturation. The first steps of the reaction sequence have been described but the next stages are missing. These are very important because they involve the formation mode of the observed end product, brown manganese dioxide. In this communication, a complete and sustained reaction mechanism is provided for both reaction mediums, neutral and alkaline. It is in accordance with observed experimental facts. The missing steps are a redox reaction between hypomanganate and permanganate ions, and a second cyclic intermediate now formed with manganate ion. The instability of this intermediate leads directly to manganese dioxide and alkalinization of the neutral medium, as observed experimentally.

Photocatalytic degradation of methylene blue dye under solar light irradiation by zinc oxide nanoparticles using aqueous extract of Cleome gynandra

A simple green synthetic technique is proposed for the synthesis of zinc oxide nanoparticles (ZnONPs) using the plant extract Cleome gynandra as a bio-template. The morphological, functional and structural characterization of synthesized ZnONPs was investigated using several techniques, such as energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-visible spectroscopy. The synthesized ZnONPs have a wurtzite hexagonal nanostructure with an average size of 15.20 nm. Furthermore, the photocatalytic degradation of methylene blue (MB) in an aqueous solution was carried out using the synthesized ZnONPs. The photocatalytic activity of ZnONPs was investigated by adjusting physicochemical variables as reaction time, medium pH, precursor concentration, and photocatalyst dosage. All results indicate that ZnONPs produced by the green approach exhibits significant photocatalytic activity against dye molecules.

Pt-Decorated bimetallic PdRu nanocubes with tailorable surface electronic structures for highly efficient acidic hydrogen evolution reaction

Efficient and stable catalysts are crucial for green hydrogen production from acidic water splitting. Herein, using interface engineering, the surface electronic structures of bimetallic PdRu nanocubes have been significantly regulated by Pt atoms (PdRu@Pt). Interestingly, Pt atoms are located on the corners and facets of PdRu nanocubes, resulting in lattice tension and fast electron transfer. As a result, the obtained trimetallic PdRu@Pt nanocubes with an average size of 13 nm have exhibited highly enhanced catalytic activity and stability for hydrogen evolution reaction (HER) in acidic media, delivering 18 mV lower overpotential to reach a current density of 10 mA cm−2, and maintaining a remarkable long-term stability for up to 24 h. In particular, the lower overpotential of 489 mV at 500 mA cm−2 for PdRu0.04@Pt0.12 nanocubes indicates its potential for future industrial application in the future. Such enhancements in HER performance can be attributed to the highly facet-edge-exposed Pt atoms and the significant strain effects resulting from the introducing Pt atomic layers to PdRu surfaces.

Recent progress and perspective on electrocatalysis in neutral media: Mechanisms, materials, and advanced characterizations

AbstractElectrocatalysis, which involves oxidation and reduction reactions with direct electron transfer, is essential for a variety of clean energy conversion devices. Currently, the vast majority of studies regarding electrocatalysis reactions focus on strong acidic or alkaline media because of the higher catalytic activity. Nevertheless, some inherent drawbacks, including the corrosive environment, expensive proton exchange membranes, and side effects, are still hard to break through. A sustainably promising way to overcome these shortcomings is to deploy neutral/near‐neutral electrolytes for electrocatalysis reactions. Unfortunately, insufficient research in this area due to the lack of attention to related issues has slowed down the development process. In this review, we systematically review the catalytic reaction mechanisms, neutral electrolytes, electrocatalysts, and modification strategies carried out in neutral media on the three most common electrocatalytic reactions, that is, hydrogen evolution reaction, oxygen reduction reaction, and oxygen evolution reaction. Furthermore, the advanced characterization tools for guiding catalyst synthesis and mechanistic studies are also summarized. Eventually, we propose some challenges and perspectives on electrocatalysis reactions in neutral media and hope it will attract more research interest and provide guidance in neutral electrocatalysis.

2D Co-N-C catalysts derived by 1D CoxZn1-xO hexagonal microrods for oxygen reduction reaction

A novel and feasible strategy to construct 2D Co-N-C catalyst from one-dimensional (1D) CoxZn1-xO microrod is reported. In the strategy, 1D CoxZn1-xO microrods are firstly transformed into CoxZn1-xO@CoZn-ZIF hexagonal core-shell microrods by regulating the reaction conditions of high-pressure vapor-solid transformation, and subsequently pyrolyzed at high temperature to form Co-N-C hexagonal microtubes, which are finally fractured along its edges under the action of thermal stress, evolving gradually to Co-N-C nanosheets. Besides, by investigating the effects of Co doping contents, a catalyst with optimal chemical and structural properties and more highly accessible Co-N4 active sites has achieved respectable activity and stability for the oxygen reduction reaction (ORR) in alkaline media. Among them, Co0.3-N-C NS exhibits superior ORR performance (Eon=1.01 V, E1/2 = 0.87 V), durability and tolerance to methanol than those of commercial Pt/C catalysts (Eon=0.99 V, E1/2 = 0.85 V) in alkaline media.

In-situ activation of three-dimensional porous NiFe alloy: Synergistic NiFe hydroxide/alloy as composite active sites for efficiently catalyzing alkaline water splitting

The strategic engineering of bifunctional catalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media is critical for water-splitting technologies. This study presented a catalyst consisting of in situ grown nickel iron (NiFe) hydroxide/porous alloy composite catalytic sites on a nickel foam (NF) substrate. Initially, a porous NiFe alloy was electrodeposited onto NF, employing hydrogen (H2) bubbles as dynamic templates to induce a three-dimensional (3D) architecture. Subsequently, ultrathin layers of NiFe hydroxide nanosheets were synthesized in situ via electrochemical activation. The distinctive porous structure, coupled with the in-situ activated nanosheets, augmented the exposure of active sites, optimized electrolyte interaction, and expedited the expulsion of gaseous byproducts, collectively enhancing the kinetics of water electrolysis. The resultant a-Ni2Fe/NF demonstrated superior OER/HER activities, achieving overpotentials of merely 240mV for OER and 183mV for HER at a current density of 100mAcm-2 in alkaline solution. Moreover, a voltage of just 1.53V was requisite to attain a current density of 10mAcm-2 for overall water splitting. Operando Raman spectroscopy revealed the formation of NiOOH and FeOOH active phases during HER, indicating the hydroxide’s role in adsorbing hydroxyl groups and shielding NiFe alloy’s H⁎ adsorption sites from oxidation. The presence of the more reactive β-NiOOH phase was discerned during OER process, acting as an intermediate. This straightforward yet efficacious strategy heralded a new paradigm in the design of NiFe-based bifunctional catalysts, significantly bolstering the efficiency of water electrolysis catalysis.

Interface Engineering of Mo‐doped Ni2P/FexP‐V Multiheterostructure for Efficient Dual‐pH Hydrogen Evolution and Overall Water Splitting

AbstractDeveloping highly effective transition metal‐based bifunctional electrocatalysts remains a tremendously challenging task for large‐scale overall water splitting. Herein, a multiheterostructured Mo‐doped Ni2P/FexP electrocatalyst on NiFe foam with P vacancy (denoted as Mo─Ni2P/FexP‐V/NFF) is developed to serve as an efficient dual‐pH electrocatalyst. Due to the synergistic effect of multiple strategies (heteroatom doping, heterointerface, and P vacancy), the Mo─Ni2P/FexP‐V/NFF possesses remarkable hydrogen evolution reaction (HER) catalytic activity in alkaline/acidic and excellent oxygen evolution reaction (OER) in alkaline media, along with encouraging durability. The mechanisms of improved electrocatalytic activity combining multicharacterizations and density functional theory (DFT) calculations are elucidated. Specifically, X‐ray absorption fine structure experimental analysis confirms that the Mo doping can optimize the electronic structure of electrocatalyst. In situ Raman spectroscopy demonstrates that the evolved oxyhydroxides are the real active substances for the OER. DFT calculations reveal that the conductivity of as‐prepared samples can be enhanced through multiple strategy synergy. Moreover, in the HER process, multiple strategies can not only reduce the hydrogen binding energy to near zero but also enhance the H2O dissociation and *OH desorption. In the OER process, DFT calculations also verify that Mo doping and interface engineering can optimize the adsorption of the rate‐determining step, achieving the lowest theoretical overpotential.

Friedel Crafts Reactions Revisited: Some Applications in Heterogeneous Catalysis

Abstract: Important organic reactions require the use of catalysts. The Friedel-Crafts reactions were discovered by Charles Friedel and James Mason Crafts in 1887. They are an essential catalytic process since they are widely applied in different areas such as fuels, cleaning, and pharmacological products. The reaction is usually carried out in the presence of Lewis acids or Brønsted acids in a homogeneous medium, with the nucleophilic aromatic substrate in excess. Although there is still work in the literature on the Friedel-Crafts reaction in a homogeneous medium using metal halides, the tendency is to replace these catalysts, which generate effluents that are harmful to the environment. Heterogeneous catalysts using solid acids show advantages over homogeneous catalysts, especially concerning separating products from the reaction medium, recycling, and reusing. This paper presents a mini-review focusing on the use of solid acids in Friedel-Crafts reactions.

Efficient Neutral H2O2 Electrosynthesis from Favorable Reaction Microenvironments via Porous Carbon Carrier Engineering

The efficient electrosynthesis of hydrogen peroxide (H2O2) via two‐electron oxygen reduction reaction (2e‐ ORR) in neutral media is undoubtedly a practical route, but the limited comprehension of electrocatalysts has hindered the system advancement. Herein, we present the design of model catalysts comprising mesoporous carbon spheres‐supported Pd nanoparticles for H2O2 electrosynthesis at near‐zero overpotential with approximately 95% selectivity in a neutral electrolyte. Impressively, the optimized Pd/MCS‐8 electrocatalyst in a flow cell device achieves an exceptional H2O2 yield of 15.77 mol gcatalyst‐1 h‐1, generating a neutral H2O2 solution with an accumulated concentration of 6.43 wt.%, a level sufficiently high for medical disinfection. Finite element simulation and experimental results suggest that mesoporous carbon carriers promote O2 enrichment and localized pH elevation, establishing a favorable microenvironment for 2e‐ ORR in neutral media. Density functional theory calculations reveal that the robust interaction between Pd nanoparticles and the carbon carriers optimized the adsorption of OOH* at the carbon edge, ensuring high active 2e‐ process. These findings offer new insights into carbon‐loaded electrocatalysts for efficient 2e‐ ORR in neutral media, emphasizing the role of carrier engineering in constructing favorable microenvironments and synergizing active sites.

Protecting-Group-FreeSynthesis of ADP-Ribose and Dinucleoside Di-/Triphosphate DerivativesviaP(V)-P(V) Coupling Reaction.

Biomolecules containing adenosine di- or triphosphate (ADP or ATP) are crucial for diverse biological processes. Synthesis of these biomolecules and development of their chemical probes are important to elucidate their functions. Enabling reproducible and high-yielding access to these ADP- and ATP-containing molecules via conventional P(III)-P(V) and P(V)-P(V) coupling reactions is challenging owing to water content in highly polar phosphate-containing substrates. Herein, we report an efficient and reliable method for protecting-group-free P(V)-P(V) coupling reaction through in situ activation of phosphates using hydrolysis-stable 2-[N-(2-methylimidazoyl)]-1,3-dimethylimidazolinium chloride (2-MeImIm-Cl), providing the corresponding electrophilic P(V) intermediates for subsequent nucleophilic attack using their coupling partners. This P(V)-P(V) coupling reaction proceeded even in a wet reaction medium and showed a broad substrate scope, accommodating protecting-group-free synthesis of ADP-riboseand nicotinamide adenine diphosphateanalogs, ATP-containing biomolecules, and ADP-ribosyl peptides.

Polycations as Aptamer-Binding Modulators for Sensitive Fluorescence Anisotropy Assay of Aflatoxin B1.

Fluorescence induced by the excitation of a fluorophore with plane-polarized light has a different polarization depending on the size of the fluorophore-containing reagent and the rate of its rotation. Based on this effect, many analytical systems have been implemented in which an analyte contained in a sample and labeled with a fluorophore (usually fluorescein) competes to bind to antibodies. Replacing antibodies in such assays with aptamers, low-cost and stable oligonucleotide receptors, is complicated because binding a fluorophore to them causes a less significant change in the polarization of emissions. This work proposes and characterizes the compounds of the reaction medium that improve analyte binding and reduce the mobility of the aptamer-fluorophore complex, providing a higher analytical signal and a lower detection limit. This study was conducted on aflatoxin B1 (AFB1), a ubiquitous toxicant contaminating foods of plant origins. Eight aptamers specific to AFB1 with the same binding site and different regions stabilizing their structures were compared for affinity, based on which the aptamer with 38 nucleotides in length was selected. The polymers that interact reversibly with oligonucleotides, such as poly-L-lysine and polyethylene glycol, were tested. It was found that they provide the desired reduction in the depolarization of emitted light as well as high concentrations of magnesium cations. In the selected optimal medium, AFB1 detection reached a limit of 1 ng/mL, which was 12 times lower than in the tris buffer commonly used for anti-AFB1 aptamers. The assay time was 30 min. This method is suitable for controlling almond samples according to the maximum permissible levels of their contamination by AFB1. The proposed approach could be applied to improve other aptamer-based analytical systems.

Effect of Varieties and Dates of Sowing on Seed Yield of Sunhemp

A field experiment was conducted at Agricultural Research Stattion, Amadalavalasa to identify a suitable sunhemp variety and sowing window during Khariff or obtaining higher yields in North Coastal Andhra Pradesh. The soil of experimental site was sandy loam in texture, medium in alkaline reaction (pH: 8.24), non-saline (EC: 0.22 dS m-1), low in organic carbon (0.5%), low in available nitrogen (219.3 kg ha-1), low in available phosphorus (22.18 kg P2O5 ha-1) and medium in available potassium (268.3 kg K2O ha-1). The experiment was laid out in a split plot design with four main plot treatments, three subplot treatments and with three replications. The main treatments comprised of four dates of sowing viz., D1: 1st may,D2:15th may,D3:1st june and D4: 15th june. The sub plot treatments comprised of three varieties viz., V1: K12 yellow, V2: K12 black and V3: SH 4. All the cultural practices were adopted as per the recommendations of University. The results of the experiment indicated that growth and yield of sunhemp was significantly influenced by variety as well as date of sowing. It was evident that sowing of sunhemp in North Coastal AndhraPradesh on 15th June was optimum as it recorded shorter plant height (224.8 cm), early flowering i.e flower initiation at 80 days, 50% flowering in 91 days, higher plant population and significantly higher seed yield (2.35 q/ha) was recorded. Among the varieties tested SH 4 produced taller plants exhibited early flowering and finally recorded significantly higher seed yield (2.16 q/ha). However, plant population did not vary significantly among the varieties. Interaction between dates of sowing and varieties indicated that for seed crop K12 black and SH 4 of sunhemp can be sown between 1st june to 15th June in North Coastal Andhra Pradesh for getting higher seed yield of sunhemp as the seed yield of the above two varieties and dates of sowing were atpar.

Oxy-hydrogen, solar and wind assisted hydrogen ([formula omitted]) recovery from municipal plastic waste (MPW) and saltwater electrolysis for better environmental systems and ocean cleanup

The pyrolysis of plastic waste and the electrolysis of saltwater is a promising route to carbon neutrality in ocean cleanup and plastic waste management. Therefore, a solar and wind assisted H2-fuelled fast pyrolysis of MPW (municipal plastic waste) and electrolysis of desalinated saline were developed. The combined system uses an oxy-hydrogen furnace for thermal decomposition of MPW feed, CO2 as an inert reaction medium and both solar and wind energy systems to operate the electrical units. The deionised H2O feed to the electrolyser cell was produced from saltwater using the recovered heat from the fast pyrolyser unit. The process CO2 was captured and reused for soil improvement as current waste-to-energy routes of MPW recycling emit 695,850 tonnes of CO2. 2.65 kg/hrH2 fuel in an O2 environment was utilised to meet the decomposer operating temperature and heat duty which is approximately 29 % of the produced H2. Instability associated with bio-oil was prevented by using fast pyrolysis which release more volatiles. Compared to the related studies, this investigated work achieved the highest gas and carbon yields. Thermal NO < 0.1 ppm was recorded. The developed system is expected to reach ≥70 % energy efficiency and a sales price of < $3.89/kgH2.

Catalytic activity of Ni–Cr–Fe–Mo porous materials for hydrogen evolution reaction in alkaline media

The hydrogen evolution reaction (HER) based on water electrolysis represents an ideal approach for hydrogen production. The advancement of highly active non-precious metal catalysts holds paramount importance. This research employed powder metallurgy sintering to prepare Ni–Cr–Fe and Ni–Cr–Fe–Mo porous materials. It investigated the impact of Mo doping and sintering temperature on the catalytic activity and microstructural influence of hydrogen evolution materials. Furthermore, the materials' electrochemical performance and long-term stability in 6 mol/L KOH were examined. In complicated systems, the current work provides a feasible method for producing hydrogen from Ni–Cr–Fe–Mo porous materials in a strong alkali environment. The results exhibited that when Mo content is 5% and the sintering temperature is 800 °C, the porosity of Ni–Cr–Fe–Mo porous materials is up to 39.9% and the catalytic activity is up to 97%. At the same time, the current density decays to 7.1% after 1000 cycles of electrolysis and shows good HER stability after 48 h. The enhanced catalytic activity for hydrogen evolution emanated from the positive synergy among the transition metal elements.

Enhancing the Activity of a Carbon Nitride Photocatalyst by Constructing a Triazine-Heptazine Homojunction.

Establishing homojunctions at the molecular level between different but physicochemically similar phases belonging to the same family of materials is an effective approach to promoting the photocatalytic activity of polymeric carbon nitride (CN) materials. Here, we prepared a CN material with a uniform distribution of homojunctions by combining two synthetic strategies: supramolecular assemblies as the precursor and molten salt as the medium. We designed porous CN rods with triazine-heptazine homojunctions (THCNs) using a melem supramolecular aggregate (Me) and melamine as the precursors and a KCl/LiBr salt mixture as the liquid reaction medium. The triazine/heptazine ratio is controlled by varying the relative amounts of the chosen precursors, and the molten salt treatment enhances the structural order of the interplanar packing units for the THCN skeleton, leading to rapid charge migration. The resulting built-in electric field induced by the triazine-heptazine homojunction enhances photogenerated charge separation; the optimal THCN catalyst exhibits an excellent H2 evolution rate via photocatalytic water splitting, which is ∼24 times as high as that of reference bulk CN, with long-term stability.

Alkaline Fading of Malachite Green in β-Cyclodextrins

The basic hydrolysis of Malachite Green (MG) in the presence of β-Cyclodextrin (β-CD) has been studied using UV-Vis spectroscopic techniques and at 20 °C. β-CD was found to catalyze the basic hydrolysis. Indeed, this basic hydrolysis is catalyzed by the interaction cyclodextrin hydroxyl group, in its deprotonated form with the carbocation in the host-guest complex. The proposed model has been successfully applied to a reaction catalyzed by CD. It considers two simultaneous pathways in the aqueous medium involving free hydroxyl ions and the substrate-CD complex. The model allows us to obtain the kinetic parameters including the bimolecular rate constant between MG and HO− in bulk water (kw = 1.47 ± 0.01 mol−1s−1), the rate constant between MG and the deprotonated hydroxyl group of β-CD inside the host-guest complex (kCD = 0.25 ± 0.03 s−1) and the binding constant of MG inside the β-CD (KS = 2500 ± 50). This behavior is like the hydrolysis of Cristal Violet (CV) in the same reaction media.

Efficient Enzymatic Synthesis of Carbamates in Water Using Promiscuous Esterases/Acyltransferases.

Biocatalysis provides an attractive approach to facilitate synthetic reactions in aqueous media. Motivated by the discovery of promiscuous aminolysis activity of esterases, we exploited the esterase fromPyrobaculum calidifontisVA1 (PestE) for the synthesis of carbamates from different aliphatic, aromatic, and arylaliphatic amines and a set of carbonates such as dimethyl-, dibenzyl-, or diallyl carbonate. Thus, aniline and benzylamine derivatives, aliphatic and even secondary amines could be efficiently converted into the correspondingbenzyloxycarbonyl(Cbz)- or allyloxycarbonyl (Alloc)-protected products in bulk water, with (isolated) yields of up to 99%.