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Objective: To develop effective alternatives to natural enzymes, it is crucial to develop nanozymes that are economical, resource efficient, and environmentally conscious. Carbon nanomaterials that have enzyme-like activities have been extensively developed as substitutes for traditional enzymes., Methods: Carbide-derived carbons (CDCs) were directly synthesized via a one-step electrochemical method from a MAX precursor using an ammonium bifluoride electrolyte at ambient conditions. The CDCs were characterized by systematic techniques., Results: CDCs showed bienzyme-like activities similar to that of peroxidase and superoxide dismutase. We systematically studied the dependence of CDC enzyme-like activity on different electrolytes and electrolysis times to confirm activity dependence on CDC content. Additionally, the synthesis mechanism and CDC applicability were elaborated and demonstrated, respectively., Conclusion: The demonstrated synthesis strategy eliminates tedious intercalation and delamination centrifugation steps and avoids using high concentrations of HF, high temperatures, and halogen gases. This study paves the way for designing two-dimensional material-based nanocatalysts for nanoenzyme and other applications., (Copyright © 2022 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.)

Antimicrobial and cytotoxic activities of several ammonium derivatives of diterpenoids steviol and isosteviol have been investigated in vitro. The results have showed that these compounds possess high antibacterial activity against MRSA strains and cytotoxic effect against cancer cell lines MCF-7, M-HeLa, A-549, PC3, HepG2, T98G. Lead compounds 4 and 5 were detected, which, in the case of the MCF-7 cell line (human breast adenocarcinoma), showed IC 50 at the doxorubicin level with a selectivity index of 5.0-5.2. Flow cytometry and laser confocal microscopy analysis demonstrated that the mechanism of cytotoxic effects of the tested compounds on MCF-7 cells could be associated with the induction of apoptosis along the mitochondrial pathway. At the same time, they did not cause hemolysis and showed only slight cytotoxicity with respect to normal human cells of embryonic lung (Wi-38). The obtained results allow us to consider the studied compounds as promising scaffolds for the design of new effective antibacterial drugs and anticancer agents targeting mitochondria., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

C(1)-Ammonium enolates are powerful, catalytically generated synthetic intermediates applied in the enantioselective α-functionalisation of carboxylic acid derivatives. This minireview describes the recent developments in the generation and application of C(1)-ammonium enolates from various precursors (carboxylic acids, anhydrides, acyl imidazoles, aryl esters, α-diazoketones, alkyl halides) using isothiourea Lewis base organocatalysts. Their synthetic utility in intra- and intermolecular enantioselective C-C and C-X bond forming processes on reaction with various electrophiles will be showcased utilising two distinct catalyst turnover approaches., (© 2020 The Authors. Published by Wiley-VCH GmbH.)

Confronting the complexity of marine biofouling, no single ecofriendly technology has been reported for efficient anti-biofouling. Combination of multiple antifouling factors should be one of the strategies for strengthening the anti-biofouling performance. Here we synthesized quaternary ammonium modified SiO 2 nanoparticles (QAS-SiO 2 ) and incorporated them into self-polishing polymer (SP) to get the coatings combining self-renewal ability, micro-nano structured topography, and bactericidal function. The coatings acquired underwater superoleophobic surface after immersion in artificial seawater due to their micro-nano structured surface together with the hydrolyzed SP. In comparison with unmodified SiO 2 , QAS-SiO 2 had better compatibility with SP and caused less increment of self-polishing rate. Synergistic antifouling effect was interestingly observed between self-renewal ability and bactericidal function in both the laboratory assay based on the adhesion of Shewanella loihicas and natural field trial. The micro-nano structured topography contributed to underwater superoleophobicity but did not exhibit its impact on antifouling performance. QAS-SiO 2 can also slightly inhibit the adhesion of diatoms and reduce the settlement of plantigrades of the mussel. In addition, we also demonstrated the coatings with lower quantity of biofilm exhibited less settlement of plantigrades of mussel., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier Inc. All rights reserved.)

We report on the synthesis of C 3 -symmetric enantiopure cage molecules 1 , which exhibit remarkable to exclusive enantioselective recognition properties toward chiral ammonium neurotransmitters. Strong changes in the substrate selectivity are also observed when different stereoisomers of 1 are used. Furthermore, protonation/deprotonation induces a reversible modification of the conformation of 1 , which switches from an imploded to an inflated form, leading to ejection and reuptake of the guest initially encaged inside the cavity.

A cobalt-tripeptide complex (CoGGH) is developed as an electrocatalyst for the selective six-electron, eight-proton reduction of nitrite to ammonium in aqueous buffer near neutral pH. The onset potential for nitrite reduction occurs at -0.65 V vs Ag/AgCl (1 M KCl). Controlled potential electrolysis at -0.90 V generates ammonium with a faradaic efficiency of 90 ± 3% and a turnover number of 3550 ± 420 over 5.5 h. CoGGH also catalyzes the reduction of the proposed intermediates nitric oxide and hydroxylamine to ammonium. These results reveal that a simple metallopeptide is an active functional mimic of the complex enzymes cytochrome c nitrite reductase and siroheme-containing nitrite reductase.

Thioamides bearing electron-withdrawing groups on the thiocarbonyl carbon atom react with benzynes [generated by the hexadehydro-Diels-Alder cycloisomerization] in an unprecedented fashion. Namely, the dihydrobenzothiazole products are consistent with a pathway involving initial formation of a stabilized ammonium ylide by a rare type of [3 + 2]-cycloaddition reaction. The fate of this species depends upon the nature of the R group(s) attached to the ylide nitrogen atom. The demonstration of new modes of reactivity represents the major advance arising from this study.

The first catalytic, broadly applicable, efficient, γ-, diastereo-, and enantioselective method for addition of O-substituted allyl-B(pin) compounds to phosphinoylimines (MEM=methoxyethoxymethyl, pin=pinacolato) is presented. The identity of the most effective catalyst and the optimal protecting group for the organoboron reagent were determined by consideration of the steric and electronic requirements at different stages of the catalytic cycle, namely, the generation of the chiral allylboronate, the subsequent 1,3-borotropic shift, and the addition step. Aryl-, heteroaryl-, alkenyl- and alkyl-substituted vicinal phosphinoylamido MEM-ethers were thus accessed in 57-92 % yield, 89:11 to >98:2 γ:α selectivity, 76:24-97:3 diastereomeric ratio, and 90:10-99:1 enantiomeric ratio. The method is scalable, and the phosphinoyl and MEM groups may be removed selectively or simultaneously. Utility is highlighted by enantioselective synthesis of an NK-1 receptor antagonist., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A benchtop stable, bifunctional reagent for the redox-neutral cyclopropanation of olefins has been developed. Triethylammonium bis(catecholato)iodomethylsilicate can be readily prepared on multigram scale. Using this reagent in combination with an organic photocatalyst and visible light, cyclopropanation of an array of olefins, including trifluoromethyl- and pinacolatoboryl-substituted alkenes, can be accomplished in a matter of hours. The reaction is highly tolerant of traditionally reactive functional groups (carboxylic acids, basic heterocycles, alkyl halides, etc.) and permits the chemoselective cyclopropanation of polyolefinated compounds. Mechanistic interrogation revealed that the reaction proceeds via a rapid anionic 3- exo- tet ring closure, a pathway consistent with experimental and computational data.

Following a supramolecular synthon rationale, a dicarboxylic acid derivative having a naphthalenediimide (NDI) core, namely, bis-N-carboxymethyl naphthalenediimide (NDI-G), was reacted with n-alkyl amines with varying alkyl chain lengths to generate a new series of primary ammonium dicarboxylate (PAD) salts. The majority of the salts (≈85 %) were found to gel various polar solvents. The gels were characterized by dynamic rheology and high-resolution electron microscopy. Single-crystal and powder X-ray diffraction analyses were used to study the supramolecular synthon present in one of the gelator salts (i.e., S8). Charge-transfer (CT)-induced gelation with donor molecules such as anthracene methanol (Ant) and pyrene (Py) was also possible with S8. The CT complex (S8.Ant) displayed anticancer activity as probed by cell migration assay on the highly aggresive breast cancer cell line MDA-MB-231. The DMSO gel of S8.Ant also displayed semiconducting behavior. To the best of our knowledge, simple organic salts with an NDI core that display such mulitifunctional properties are hitherto unknown., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In the race to achieve a sustainable urban wastewater treatment plant, not only the energy requirements have to be considered but also the environmental impact of the facility. Thus, nitrous oxide (N 2 O) emissions are a key-factor to pay attention to, since they can dominate the total greenhouse gases emissions from biological wastewater treatment. In this study, N 2 O production factors were calculated during the operation of a granular sludge airlift reactor performing partial nitritation treating a low-strength synthetic influent, and furthermore, the effect of temperature on N 2 O production was assessed. Average gas emission relative to conversion of ammonium was 1.5 ± 0.3% and 3.7 ± 0.5% while the effluent contained 0.5 ± 0.1% and 0.7 ± 0.1% (% N-oxidized) at 10 and 20 °C, respectively. Hence, temperature increase resulted in higher N 2 O production. The reasons why high temperature favoured N 2 O production remained unclear, but different theoretical hypotheses were suggested., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Weak partial agonists that promote a desensitized state of the α7 nicotinic acetylcholine receptor (nAChR) have been associated with anti-inflammatory effects. Exemplar compounds feature a tertiary or quaternary ammonium group. We report the synthesis, structure, and electrophysiological evaluation of 1-ethyl-4-phenylthiomorpholin-1-ium triflate, a weak partial agonist with a sulfonium isostere of the ammonium pharmacophore. These results offer new insights in understanding nAChR-ligand interactions and provide a new chemical space to target the α7 nAChR.

A tandem Brook rearrangement/silicon Polonovski reaction has been achieved by in situ generation of ammonium ylides via the oxidation of α-silyl-tertiary amines. Furthermore, we found that the oxidation of N-(1-cyano-1-silyl)methyl-tertiary amines with peracids induced the tandem Brook rearrangement/silicon Polonovski reaction/fragmentation to give formamide derivatives in moderate yields.

In this study, a group of novel water soluble chitosan ammonium salts with halogens were successfully synthesized, including chitosan-bromoacetate (CSB), chitosan-chloroacetate (CSC), chitosan-dichloroacetate (CSDC), chitosan-trichloroacetate (CSTC), and chitosan-trifluoroacetate (CSTF), and their antifungal activities against three kinds of phytopathogens were comparatively estimated by hypha measurement in vitro, respectively. The fungicidal assessment revealed that the synthesized chitosan derivatives had higher antifungal activity than chitosan. Especially, the inhibitory indices of CSTC and CSTF against three kinds of phytopathogens were higher than 70% at 1.0mg/mL. Generally, the antifungal activity decreased in the order: CSTF>CSTC>CSDC>CSC>CSB>chitosan. Apparently, the order of antifungal activity was consistent with the electronegativity of different substituted groups with halogens. The substituted groups with stronger electronegativity could augment the positive charge densities of cationic amino groups by drawing more electrons from the cationic amino groups of chitosan ammonium salts, which demonstrated that the protonation of amino groups was significant for the antifungal activity of chitosan derivatives., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Amphiphilic chitosan derivatives possess improved physico-chemical properties and could be used as carriers in drug delivery systems. The aim of this study was to investigate the behaviour of an amphiphilic system involving (5-pentyl) trimethylammonium and dodecyl aldehyde-modified chitosan. Amphiphilic chitosan derivatives were synthesized and characterized by (1)HNMR and ATR-FTIR spectroscopy. Self-assembled aggregates formed in aqueous solution have hydrophobic cores that were characterized by fluorescence spectroscopy using pyrene as probe and dynamic light scattering (DLS). The critical aggregation concentration of the aggregates in water varied from 0.004 to 0.037g/L and the average size distribution was in the 230-500nm range. The ζ-potential (+15.5 to +44.8mV) confirmed that the surfaces of the aggregates were positively charged and stable in physiological-like environments. TEM images suggest that the aggregates have a spherical shape, showing good agreement with DLS results. These results suggest that the synthesized copolymers have the capability of being used as carriers for hydrophobic drugs., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

This work describes the synthesis of a series of quaternary ammonium salts and the assessment of their in vitro antileishmanial activity and cytotoxicity. A preliminary discussion on a structure-activity relationship of the compounds is also included. Three series of quaternary ammonium salts were prepared: (i) halomethylated quaternary ammonium salts (series I); (ii) non-halogenated quaternary ammonium salts (series II) and (iii) halomethylated choline analogs (series III). Assessments of their in vitro cytotoxicity in human promonocytic cells U-937 and antileishmanial activity in axenic amastigotes of L. (Viannia) panamensis (M/HOM/87/UA140-pIR-eGFP) were carried out using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) micromethod. Antileishmanial activity was also tested in intracellular amastigotes of L. (V) panamensis using flow cytometry. High toxicity for human U937 cells was found with most of the compounds, which exhibited Lethal Concentration 50 (LC50) values in the range of 9 to 46 μg/mL. Most of the compounds evidenced antileishmanial activity. In axenic amastigotes, the antileishmanial activity varied from 14 to 57 μg/mL, while in intracellular amastigotes their activity varied from 17 to 50 μg/mL. N-Chloromethyl-N,N-dimethyl-N-(4,4-diphenylbut-3-en-1-yl)ammonium iodide (1a), N-iodomethyl-N,N-dimethyl-N-(4,4-diphenylbut-3-en-1-yl)ammonium iodide (2a), N,N,N-trimethyl-N-(4,4-diphenylbut-3-en-1-yl)ammonium iodide (3a) and N,N,N-trimethyl-N-(5,5-diphenylpent-4-en-1-yl)ammonium iodide (3b) turned out to be the most active compounds against intracellular amastigotes of L. (V) panamensis, with EC50 values varying between 24.7 for compound 3b and 38.4 μg/mL for compound 1a. Thus, these compounds represents new "hits" in the development of leishmanicidal drugs.

The synthesis of the new diethyl ammonium salt of diethylammonium(E)-5-(1,5-bis(4-fluorophenyl)-3-oxopent-4-en-1-yl)-1,3-diethyl-4,6-dioxo-2-thioxohexaydropyrimidin-5-ide 3 via a regioselective Michael addition of N,N-diethylthiobarbituric acid 1 to dienone 2 is described. In 3, the carboanion of the thiobarbituric moiety is stabilized by the strong intramolecular electron delocalization with the adjacent carbonyl groups and so the reaction proceeds without any cyclization. The molecular structure investigations of 3 were determined by single-crystal X-ray diffraction as well as DFT computations. The theoretically calculated (DFT/B3LYP) geometry agrees well with the crystallographic data. The effect of fluorine replacement by chlorine atoms on the molecular structure aspects were investigated using DFT methods. Calculated electronic spectra showed a bathochromic shift of the π-π* transition when fluorine is replaced by chlorine. Charge decomposition analyses were performed to study possible interaction between the different fragments in the studied systems. Molecular docking simulations examining the inhibitory nature of the compound show an anti-diabetic activity with Pa (probability of activity) value of 0.229.

The Sommelet-Hauser rearrangement of N-benzylic ammonium ylides generated from ammonium salts is an interesting and useful transformation that enables one to convert a readily accessible C-N bond into a new C-C bond to an aromatic ring. The rearrangement was discovered by Sommelet in 1937, studied in detail by Hauser, and applied to organic synthesis by Sato until 1999. Further studies have not advanced because several competitive side reactions and structural limitations of the products severely limit the substrate scope and synthetic applications. In this Personal Account, a history of the research in problem solving and recent advances in the base-induced Sommelet-Hauser rearrangement are described. This synthetic method developed by my group provides efficient access to various types of α-aryl-α-amino acid and α-aryl-β-amino acid derivatives., (© 2015 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The conversion of the C[double bond, length as m-dash]O bond of ketones to a C[triple bond, length as m-dash]N bond is described. This conversion is catalyzed by copper salts with ammonium salts as the nitrogen source in the presence of molecular oxygen. A wide variety of ketones can be converted into the corresponding compounds containing a C[triple bond, length as m-dash]N bond. Based on the preliminary experiments, a plausible mechanism of this transformation is disclosed.

In this study, cationic dicetyldimethylammonium bromide (DCB) and anionic dicetyl phosphate (DCP) were mixed to form catanionic assemblies in water, and their colloidal morphology, size, charge characteristics, phase behavior, membrane fluidity, and in vitro biocompatibility are comprehensively investigated for the first time. Our results show that the catanionic DCB and DCP mixtures in water are capable of forming circular vesicles and this binary mixed system expresses the miscibility with deviation from the ideal mixing. Compared to the nanoscale DCB-rich vesicles, the DCP-rich vesicles have smaller size, higher negative zeta potential, higher main transition temperature, and better storage stability. The temperature and molecular cooperativity of the main transition phase for the DCP vesicles can be reduced by an addition of DCB. This work demonstrates that the head groups and the relative composition of the two considered dicetyl amphiphiles remarkably affect the phase behavior, membrane rigidity, encapsulation ability and in vitro biocompatibility of DCB/DCP vesicles. The iso-stoichiometric mixed DCB/DCP vesicle, showing low cytotoxicity, long storage time, and high drug loading, is a potential candidate for the drug delivery system., (Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.)

Asymmetric synthesis of P-chiral phosphorothioic monofluoridic acid ammonium salts was achieved via axis-to-center chirality transfer reactions by using phosphorothioic acid O-esters with a binaphthyl group, and the absolute stereochemistry of the salts was determined by X-ray analyses and by comparison of their CD spectra.

The construction of novel mechanically interlocked structures has become a topic of great current interest due to the requirements of topology and their potential application in molecular machines and devices. Rotaxane and catenane as two basic topological frameworks can be used to construct the fused structures. In the current investigation, a class of novel ammonium backbones were synthesized. The ammonium group incorporated in the linear part of the molecule can be used for templating rotaxane formation while the macrocyclic part of the molecule can be used for templating catenane formation. Accordingly, they were subjected to dynamic covalent chemistry, resulting in a series of [n]rota[n]catenane structures (n = 2, 3, 4). In this process, the N-hetero crown ethers were installed on ammonium template sites of linear and macrocyclic components all at once by a template-directed clipping reaction. The results showed that these novel building blocks could be assembled with high efficiencies. Finally, this investigation provides a foundation for future studies aimed at constructing complicated integrated structures or polymers with multiple topological units.

An organic nonlinear optical crystal ammonium hydrogen l-malate (AHM) has been synthesized. Single crystals of AHM have successfully been grown by the slow evaporation solution method. Optically clear single crystals having dimensions up to 23×9×4mm(3) have been grown. Single crystal X-ray diffraction study confirms that the AHM crystallizes in orthorhombic crystal system with space group P212121. The powder X-ray diffraction pattern of the grown crystal has been recorded. FT-IR spectrum was recorded to identify the various functional groups of AHM. The UV-vis-NIR transmission was analyzed for grown crystal. Thermal analysis was performed to find out thermal stability of the compound. Vickers microhardness measurements were carried and also work hardening coefficient has been found. The crystalline perfection of the grown crystal has been analyzed by HRXRD measurements. The second harmonic efficiency of AHM was found to be 1.2 times that of KDP., (Copyright © 2014 Elsevier B.V. All rights reserved.)

In this study, we synthesized and tested in vitro and in vivo two groups of bis(ammonio)alkane-type compounds, 6a-9a and 6b-9b, which incorporate the orthosteric muscarinic agonist iperoxo into a molecular fragment of the M2-selective allosteric modulators W84 and naphmethonium. The agonist potency and efficacy of these hybrid derivatives at M1, M2 and M3 muscarinic receptor subtypes and their anticholinesterase activity were evaluated on isolated tissue preparations. Their analgesic action was then assayed in vivo in the acetic acid writhing test and the occurrence of peripheral and central cholinergic side effects was also determined. The investigated hybrids behaved as potent muscarinic agonists and weak cholinesterase inhibitors. These effects were more pronounced for bisquaternary salts bearing the naphmethonium moiety than for the W84-containing analogs, and resulted in a significant analgesic activity in vivo. A promising profile was displayed by the naphmethonium-related compound 8b, which combined the most potent antinociception among the test compounds with the absence of relevant cholinergic side effects., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Alginic acid was converted to a variety of ammonium alginate derivatives carrying diverse chemical cargo such as analgesics, antibiotics, and enzymes. These functional polymers could be fashioned into nanofibrous mats by electrostatic spinning. The therapeutic payload could be released in functional form by a simple ion exchange mechanism. Prospects in wound healing are discussed.

We have reported that compounds containing a biaryl linked unit (Ar-X-Ar') modulated Na(+) currents by promoting slow inactivation and fast inactivation processes and by inducing frequency (use)-dependent inhibition of Na(+) currents. These electrophysiological properties have been associated with the mode of action of several antiepileptic drugs. In this study, we demonstrate that the readily accessible (biphenyl-4-yl)methylammonium chlorides (compound class B) exhibited a broad range of anticonvulsant activities in animal models, and in the maximal electroshock seizure test the activity of (3'-trifluoromethoxybiphenyl-4-yl)methylammonium chloride (8) exceeded that of phenobarbital and phenytoin upon oral administration to rats. Electrophysiological studies of 8 using mouse catecholamine A-differentiated cells and rat embryonic cortical neurons confirmed that 8 promoted slow and fast inactivation in both cell types but did not affect the frequency (use)-dependent block of Na(+) currents.

Laccases attract attention due to their potential for manufacturing pharmaceutical intermediates from a wide array of phenolic and non-phenolic substrates that are sparingly soluble in water. Because of the high polarity of ionic liquids (ILs), they can dissolve polar and nonpolar compounds and are claimed as "green" alternative for volatile organic solvents. The main aim of this work was to find water-immiscible ILs suitable for Cerrena unicolor laccase. For that five ILs with bis(trifluoromethanesulfonyl)imide anions coupled with cations derived from natural alcohol - (1R,2S,5R)-(-)-menthol were synthesized, namely: (I) 3-butyl-1-[(1R,2S,5R)-(-)-menthoxymethyl]imidazolium, (II) 1-[(1R,2S,5R)-(-)-menthoxymethyl]-3-heptylimidazolium, (III) 1-[(1R,2S,5R)-(-)-menthoxymethyl]-3-methylpyridinium, (IV) heptyl[(1R,2S,5R)-(-)-menthoxymethyl]dimethylammonium, and (V) decyl[(1R,2S,5R)-(-)-menthoxymethyl]dimethylammonium ions. Laccase activity was tested in buffer saturated with ILs whereas stability tests in biphasic systems lasted 5 days. It was shown that ILs I, III-V did not significantly alter laccase activity (being 90-123% respective to the buffer) whereas IL II decreased reactivity in 20%. Stability tests revealed that ILs I, IV and V increased enzyme stability even more than in the buffer. For mathematical formalization of inactivation courses, isoenzyme model was applied but this model fitted experimental data only for sets obtained in the buffer (control) and in the presence of IL II. In the other cases, first-order reaction model was sufficient. This shows that ILs, even at very low concentrations, influence conformational stability of proteins, which is dependent on the cation structure. In general, the imidazolium (I) and ammonium (IV) salts with shorter alkyl chains supported laccase activity and stability.