Basic Aqueous Media Research Articles

Lysine-mediated surface modification of cellulose nanocrystal films for multi-channel anti-counterfeiting

Utilizing advanced multiple channels for information encryption offers a powerful strategy to achieve high-capacity and highly secure data protection. Cellulose nanocrystals (CNCs) offer a sustainable resource for developing information protection materials. In this study, we present an approach that is easy to implement and adapt for the covalent attachment of various fluorescence molecules onto the surface of CNCs using the Mannich reaction in aqueous-based medium. Through the use of the Mannich reaction-based surface modification technique, we successfully achieved multi-color fluorescence in the resulting CNCs. The resulting CNC derivatives were thoroughly characterized by two dimensional heteronuclear single quantum coherence nuclear magnetic resonance (2D HSQC NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron (XPS) spectroscopy. Notably, the optical properties of CNCs were well maintained after modification, resulting in films exhibiting blue and red structural colors. This enables the engineering of highly programmable and securely encoded anti-counterfeit labels. Moreover, subsequent coating of the modified CNCs with MXene yielded a highly secure encrypted matrix, offering advanced security and encryption capabilities under ultraviolet, visible, and near-infrared wavelengths. This CNC surface-modification enables the development of multimodal security labels with potential applications across various practical scenarios.

Practical and Selective Syntheses of S‐Acyl and N‐Acyl Glutathiones with N‐Acyl Imidazoles in Water

AbstractA selective, mild, convenient, and green protocol for the preparation of S‐acyl and N‐acyl glutathiones is described involving the chemical modification of glutathione (GSH) with N‐acyl imidazoles at room temperature in water. The syntheses of S‐acyl glutathiones were achieved in very high yields using 1 equiv. of an N‐acyl imidazole in water at room temperature, without the need of a base. Double acylation of GSH with various N‐acyl imidazoles in weakly basic aqueous media in the presence of N‐hydroxysuccinimide (HOSu) as the activating reagent followed by selective deprotection of the S‐acyl group with aqueous ammonia at room temperature gave high yields of N‐acyl glutathiones. Moreover, the reaction could accommodate a diverse range of carboxylic acids such as (hetero)benzoic acids, phenylacetic acids, aliphatic acids from short‐chain fatty acids (including acetic acid), long‐chain polyunsaturated fatty acids, secondary or tertiary amino acids, and carboxylic acids containing clickable functional groups, fluorescent probes, or drugs.

High performance Co3O4/Sn-ZnO nanocomposite photocatalyst for removal of methylene blue dye

Methylene blue is a toxic, carcinogenic, and non-biodegradable synthetic dye discharged from factories and industries that causes severe harm to human health and environmental pollution. Therefore, in this work, Co3O4/Sn-ZnO nanocomposite was synthesized using a simple sol–gel method for efficient photocatalytic removal of methylene blue dye in an aqueous basic medium. The structural, optical, photoluminescence, morphological, and compositional properties were studied. The XRD result revealed that the crystal size increases as the full width at half maxima (FWHM) decreases when Co3O4 are coupled with Sn-ZnO. From UV-visible diffusive reflectance and photoluminescence spectroscopies, a narrowing of the band gap and a reduction of the charge carrier’s recombination rate were observed, respectively. The photocatalytic efficiency and degradation rate constant of 95.1% and 0.03251 min−1 were recorded for methylene blue dye upon the use of optimized catalyst dosage of 60 mg Co3O4/Sn-ZnO nanocomposite catalyst under an irradiation time of 100 min at room temperature for optimized pH value of 9 in an aqueous basic medium.

Immobilised Ruthenium Complexes for the Electrooxidation of 5-Hydroxymethylfurfural.

Abundantly available biomass-based platform chemicals, including 5-hydroxymethylfurfural (HMF), are essential stepping stones in steering the chemical industry away from fossil fuels. The efficient catalytic oxidation of HMF to its diacid derivative, 2,5-furandicarboxylic acid (FDCA), is a promising research area with potential applications in the polymer industry. Currently, the most encouraging approaches are based on solid-state catalysts and are often conducted in basic aqueous media, conditions where HMF oxidation competes with its decomposition. Efficient molecular catalysts are practically unknown for this reaction. In this study, we report on the synthesis and electrocatalysis of surface-bound molecular ruthenium complexes for the transformation of HMF to FDCA under acidic conditions. Catalyst immobilisation on mesoporous indium tin oxide electrodes is achieved through the incorporation of phosphonic acid anchoring groups. Screening experiments with HMF and further reaction intermediates revealed the catalytic route and bottlenecks in the catalytic synthesis of FDCA. Utilising these immobilised electrocatalysts, FDCA yields of up to 85 % and faradaic efficiencies of 91 % were achieved, without any indication of substrate decomposition. Surface analysis by X-ray photoelectron spectroscopy (XPS) post-electrocatalysis unveiled the desorption of the catalyst from the electrode surface as a limiting factor in terms of catalytic performance.

Copper catalysis the synthesis of functionalized glycine-based sulphonamides: In silico and in vitro antibacterial studies

The synthesis of functionalized glycine-based sulphonamides via copper catalyzed N-arylation reaction and the in silico, in vitro antibacterial studies is reported. The procedure involved the initial synthesis of substituted p-toluenesulphonamides and substituted benzenesulphonamides by the reaction of glycine with p-toluenesulphonyl chloride and benzenesulphonyl chloride respectively in aqueous basic medium. The syn[1]thesized compounds were acetylated by reacting them with acetic anhydride and sodium acetate followed by acylation and amidation to yield amidated p-toluenesulphonamides and benzenesulphonamides respectively. Copper catalyzed N-arylation of the amidated products with aryltriolborates resulted in the synthesis of benzene, and 2-chlorophenyl derivatives of the amidated products. The synthesized compounds were characterized using FTIR, 1HNMR and elemental analysis and the spectra were in agreement with the assigned structures. The in silico antibacterial studies revealed that the compounds possess significant antibacterial potency in the respective bacteria cells and could be further employed as potential anti-bacterial agents. The in vitro antimicrobial study revealed that most of the synthesized compounds possess antibacterial activities.

Synthesis and Characterization of Bola-Amphiphilic Porphyrin-Perylenebisimide Architectures.

We report on the synthesis and characterization of a family of three water-soluble bola-amphiphilic zinc-porphyrin-perylenebisimide triads containing oligo carboxylic-acid capped Newkome dendrons in the periphery. Variations of the perylenebisimide (PBI) core geometry and dendron size (G1 and G2 dendrons with 3- and 9-carboxylic acid groups respectively) allow for tuning the supramolecular aggregation behavior with respect to variation of the molecular architecture. The triads show good solubility in basic aqueous media and aggregation to supramolecular assemblies. Theoretical investigations at the DFT level of theory accompanied by electrochemical measurements unravel the geometric and electronic structure of the amphiphiles. UV/Vis and fluorescence titrations with varying amounts of THF demonstrate disaggregation.

Copper catalyzed alkaline aerobic lignin depolymerization: effect of botanical origin and industrial extraction process on reactivity supported through characterization

Various lignins were depolymerized to aromatics in basic aqueous media under aerobic catalytic conditions. Emphasis was placed on characterization to explain the results observed. Correlations between structures and reactivity are given.

Recent Advances in the Extraction of Pectin from Various Sources and Industrial Applications.

Pectin is a structural polysaccharide present in plants that primarily consists of galacturonic acid units. This Review discusses the chemistry of pectin, including its composition and molecular weight. Pectin is conventionally extracted from agricultural waste (fruit and vegetable peels) using an acidic or basic aqueous medium at high temperatures. These processes are time- and energy-consuming and also result in severe environmental problems due to the production of acidic effluents and equipment corrosion. As pectin usage is increasing in food industries for developing different products and it is also used as an excipient in pharmaceutical products, better extraction procedures are required to maximize the yield and purity. The Review encompasses various alternate green approaches for the extraction of pectin, including traditional acid extraction and various emerging technologies such as deep eutectic solvent-based extraction, enzyme-assisted extraction, subcritical fluid extraction, ultrasound-assisted extraction, and microwave-based extraction, and evaluates the yield and physicochemical characteristics of the extracted pectin. This work aims to provide a platform for attracting more thorough research focused on the engineering of novel and more efficient green methods for the extraction of pectin and its utilization for various biotechnological purposes.

PH-responsive intermediary layer cross-linked micelles from zwitterionic triblock copolymers and investigation of their drug-release behaviors.

ABC-type triblock copolymers, namely poly[(ethylene glycol)methyl ether]-block-poly(tert-butyl methacrylate)-block-poly[2-N-(diisopropylamino)ethyl methacrylate] (MPEG-b-PBuMA-b-PDPA), were first synthesized and then the middle blocks were successfully converted into poly(methacrylic acid) to obtain MPEG-b-PMAA-b-PDPA zwitterionic triblock copolymers. These block copolymers were soluble in water and formed micellar aggregates with complex cores via hydrogen bonding interactions between MPEG and PMAA blocks below pH 4.0. When the pH was between 5.0 and 7.0, due to charge compensation between partially protonated PDPA and partially ionized PMAA blocks, micelles with polyion complex cores were observed. If the solution pH was above 8.0, deprotonation of tertiary amine groups provided a hydrophobic character to the PDPA block, which resulted in the formation of PDPA-core micelles while MPEG/anionic PMAA hybrid blocks formed hydrated coronas. Intermediary layer cross-linked (ILCL) micelles from PDPA-core micelles were also prepared by cross-linking the inner PMAA shell. The hydrophobic drug dipyridamole (DIP) was used to investigate the release profile of ILCL micelles. DIP can be loaded to the PDPA cores of the micelles in basic aqueous media. An increase in the degree of cross-linking causes slower release for the model drug. It was concluded that the more complex matrix formation in the intermediary layer of the micelles via cross-linking retards the drug release from the core.

Waterborne spontaneous and robust coating of POSS nanoparticles on hydrophobic surfaces for application as an advanced separator in lithium ion batteries

Waterborne spontaneous and robust coating of the catechol-functionalized polyoctahedral silsesquioxane (CA-POSS) is studied on the surface of hydrophobic substrates as a model organic-inorganic hybrid material. The CA-POSS was synthesized at room temperature, which readily produces an instant thin layer coating on the hydrophobic substrates such as mica film and polyethylene (PE) separator. The CA-POSS instantly forms nano-scale level coating with robust adhesion upon contact with the substrate surfaces in a basic aqueous medium at ambient conditions, unlike common coating methods that use prepared POSS particle dispersion. The surface roughness of the CA-POSS coated PE separator (PE-CAP) and mica was observed in AFM analysis. The PE-CAP separator showed highly enhanced hydrophilicity, electrolyte wettability, mechanical strength, and thermal stability. The PE-CAP separator is studied in lithium ion batteries (LIBs) using LiCoO2 cathode and Lithium metal anode has shown the highest specific capacity of ∼171.3 mAh g−1 with capacity retention of ∼99 % after 100 cycles in comparison to pristine PE separator (∼159.4 mAh g−1, 92 %).

Practical study on the impact of injection conditions in gradient elution mode for the analysis of therapeutic proteins when using very short columns

The impact of injected sample volume on apparent efficiency has been studied for very short columns in a systematic way. For large molecules such as therapeutic proteins, it was found that relatively large volumes can be injected onto ultra-short RPLC and IEX columns (i.e. L < 50 mm) without significantly affecting the quality of the separation. This favourable behavior is due to the on-off elution mechanism of large molecules and to the fact that therapeutic protein samples are formulated in aqueous-based media, which is the weakest solvent in RPLC and IEX. Therefore, their peak is strongly focused at the column inlet even when large volume is injected, and pre-column peak dispersion is compensated. However, ultra-short HILIC columns do not seem to be favorable, as they require for very low injection volume to avoid detrimental peak splitting and breakthrough effects. Such peak distortion is related to the inherent solvent mismatch between sample diluent (aqueous) and mobile phase strength (highly organic in HILIC). When studying mass load, the ranking of the elution modes was the same, and the largest relative mass could be injected onto IEX columns (as large as 10% sample to sorbent mass), without affecting the separation quality.

Synthesis and characterization of Anderson-Evans type polyoxometalates, antibacterial properties.

In the present work, the new aluminium-substituted polyoxometalates of the Anderson-Evans type have been prepared and structurally defined by the reaction of aluminium (III) chloride hexahydrate and sodium tungstate dihydrate/sodium molybdate dihydrate in an aqueous basic medium. Elemental analysis, FT-IR, TGA, 1H NMR, and 31P NMR analysis revealed that these polyoxometalates had the following formula: [Ph4P]3[Al(OH)6Mo6O18]·4H2O 1, [Ph4P]3[Al(OH)6W6O18]·4H2O 2, [C7H10N]3[Al(OH)6Mo6O18]·4H2O 3, [C7H10N]3[Al(OH)6W6O18]·4H2O 4. The compounds 1 and 2 show promising antibacterial activity against gram-positive Staphylcoccus aureus ATCC 25923 and gram-negative Escherichia coli ATCC 25922 bacteria.

Dispersive magnetic solid-phase extraction for synthetic PDE-5 inhibitors determination by high-performance liquid chromatography with tandem mass spectrometry

A dispersive magnetic solid-phase extraction (DMPSE) procedure has been developed to preconcentrate four synthetic phosphodiesterase type 5 (PDE-5) inhibitors (sildenafil, desmethylsildenafil, vardenafil and tadalafil) from different samples (human hair, energy drinks, lubricating gels and dietary supplements). The target compounds were isolated from the solid samples by solid-liquid extraction in basic aqueous medium and the extract was submitted to DMSPE using multiwalled carbon nanotubes/Fe3O4@polypyrrole (MWCNTs/Fe3O4@PPy). For this, 20 mg of the magnetic nanocomposite was added to 30 mL of sample solution/extract and vortexed for 10 min before proceeding to the desorption step using 1 mL of methanol. Analysis was carried out by liquid chromatography with tandem mass spectrometry using electrospray ionization and a triple quadrupole mass analyzer (LC-ESI-QqQ-MS/MS). Matrix-matched calibration was applied for quantification. Limits of detection ranged between 0.01 and 0.22 ng mL−1 for energy drinks and between 0.25 and 7.5 ng g−1 for hair, lubricating gels, and dietary supplements. Relative standard deviations in the 4.3–12.2% (n = 10) were obtained for repeatability studies. The trueness of the proposed method was studied by fortifying the samples at two concentration levels and recoveries in the 85–112% range were obtained. None of the PDE-5 inhibitors studied were detected in real samples.

Photooxidative Coupling of Thiols Promoted by Bromo(trichloro)methane in a Basic Aqueous Medium

AbstractA transition-metal- and organic-solvent-free oxidative coupling of thiols catalyzed by BrCCl3 and NaOH in an aqueous medium with oxygen as a green oxidant was established The facile and green method has a broad substrate scope in converting thiols into the corresponding disulfides with medium to excellent yields (up to 91%). This method could potentially be used to construct bioactive molecules containing disulfide bonds and to label bioactive molecules with disulfide bonds.

Isotonic, aqueous-based media as simple and suitable test media for short-term Haemonchus placei adult worm motility assay

The solvating power of test media used in anthelmintic assays is critical to the validity of assay results, especially when evaluating plant extracts. High solutes in media lowers its solvating power, altering the range of concentrations available for investigation and assay performance. To identify simplified, well-tolerated media for adult Haemonchus placei with improved solvating power, we investigated the impact of varying solutions of pH (2.5–8.5), salinity (19–154 mM), and normal saline (NS) incorporating dissolution enhancers (acetone, propylene glycol, DMSO and Tween-80; 10–40% v/v) on the nematode over 3 h at room temperature. The performance of identified media, NS and 20% Tween-80 in NS, were evaluated by preparing sample extracts (acetone extract Sarcocephalus latifolius, AESL20&10; and chloroform extract Vernonia amygdalina, CEVA20&10) stock solutions (20 and 10 mg/mL) in them, assessed their apparent dissolution, and each highest stock solution that dissolves the extracts evaluated for anthelmintic activity against H. placei. We found isotonicity to be the critical-to-worm survival factor as H. placei survived 100% in pH solutions 3.5–8.5, and saline solutions 39–154 mM. The dissolution enhancers, at 40%, gave no survival. At 30% and 20%, only Tween-80 gave 92.5% and 100% survival, respectively. At 10%, Tween-80, acetone, DMSO and propylene glycol gave 100%, 100%, 87.5% and 0% survival, respectively. In 20% Tween-80 in NS, AESL20&10 and CEVA20&10 dissolved, furnishing wider concentration range (20-0 mg/mL); whereas only AESL10 dissolved in NS (narrower concentration range, 10-0 mg/mL). The LC50s (mg/mL) of 7.67 (AESL10, NS) and 7.48 (AESL20, Tween-80 in NS) were not significantly different (p > 0.05), while CEVA20 (Tween-80 in NS) gave 2.67. Our findings show that NS and 20% Tween-80 in NS, as isotonic, aqueous-based media, are suitable, and well-tolerated as test media for adult H. placei in a short-term motility assay. Up to 30% Tween-80 could be used to enhance dissolution where necessary.

Synthesis of 2-[2,3-dihydro-1,4-benzodioxin-6-yl(phenylsulfonyl)amino]-N-(un/substituted-phenyl)acetamides as anti-diabetic agents

Purpose: To synthesize a series of new 2-[2,3-dihydro-1,4-benzodioxin-6-yl(phenylsulfonyl)amino]-N-(un/substituted-phenyl) acetamides, and evaluate their anti-diabetic potentials.&#x0D; Methods: Synthesis of the parent compound N-(2,3-dihydro-1,4-benzodioxin-6-yl) benzenesulfonamide (3) was carried out by reacting 2,3-dihydro-1,4-benzodioxin-6-amine (1) with benzenesulfonylchloride (2) in aqueous basic medium under definite pH controls. After that 3 was further treated with various 2-bromo-N-(un/substituted-phenyl)acetamides (6a-l) to yield new compounds (7a-l) in polar aprotic solvent, DMF (dimethylformamide), using LiH as activator. The proposed structures of the synthesized compounds were confirmed using proton-nuclear magnetic resonance (1H-NMR) and infra-red spectroscopy (IR), and CHN analysis. Their anti-diabetic potential was evaluated by α-glucosidase enzyme inhibitory studies.&#x0D; Results: All the new compounds demonstrated weak (7a-h, 7j and 7l) to moderate (7i and 7k) inhibitory activities against α-glucosidase enzyme. IC50 (50 % inhibition concentration) values for 7i and 7k were 86.31±0.11 μM and 81.12±0.13 μM, respectively relative to acarbose (reference standard) with IC50 of 37.38±0.12 μM.&#x0D; Conclusion: All the synthesized compounds have weak to moderate activity against α-glucosidase enzyme. These compounds can thus be considered as possible therapeutic entrants for type-2 diabetes.

Facet-Dependent Ba Dissolution of Tetragonal BaTiO3 Single Crystal Surfaces

Tetragonal BaTiO3 with a high dielectric property is used as the principal material for multilayer ceramic capacitors (MLCCs), a core component of state-of-the-art electronic devices. However, Ba2+ at BaTiO3 surfaces can be dissolved in aqueous-based media, and such chemical instability has been a major obstacle to environmentally friendly aqueous-based MLCC processes. To understand the behavior of Ba2+ dissolution, we investigated H2O(l) and (H+ + Cl–)(aq.) adsorption on the single crystal surfaces of BaTiO3(100), (111), and (110) using density functional theory calculations. We found that the onset pH for Ba2+ dissolution is 1.65, 2.46, and 3.18 for BaTiO3(100), (111), and (110), respectively, indicating that the thermodynamics of Ba2+ dissolution are facet dependent. The onset pH and the coordination number (CN) of Ba on each surface shows a linear correlation, suggesting that the CN of Ba is a critical factor that can predict the Ba2+ dissolution thermodynamics.

Discovery of Polythioplatinate(II) [Pt3S2(SO3)6]10- and Study of Its Solution and Catalytic Properties.

We have discovered the first polythioplatinate(II), [PtII3S2(SO3)6]10- (1), which was synthesized in aqueous basic medium (pH 11) by hydrothermal heating at 150 °C. Polyanion 1 comprises a discrete, triangular assembly of three Pt2+ ions linked by two μ3-sulfido ligands, and their square-planar coordination geometry is completed by two terminal S-bound sulfito ligands. Polyanion 1 was isolated as a hydrated sodium salt, Na10[PtII3(μ3-S)2(SO3)6]·22H2O (Na-1), which was characterized in the solid state by single-crystal X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectra, and elemental analysis, in solution by 195Pt NMR and atomic absorption spectroscopy, and in the gas phase by electrospray ionization mass spectrometry. Density functional theory calculations were performed, and the 195Pt NMR chemical shifts of 1 were computed theoretically and shown to match well with the experimental data. Furthermore, the discrete title polyanion 1 was immobilized on mesoporous SBA-15 support and used as a precatalyst for the hydrogenation of o-xylene.

Boronate Affinity-Based Electrochemical Aptasensor for Point-of-Care Glycoprotein Detection.

As a class of oligosaccharide chain-containing proteins, glycoproteins are of great value in screening and early diagnosis of malignant tumors and other major diseases. Herein, we report a universal boronate affinity-based electrochemical aptasensor for point-of-care glycoprotein detection. Aptasensing of glycoproteins involves the specific recognition and capture of target glycoproteins by end-tethered nucleic acid aptamers and the site-specific labeling of ferrocene tags via the phenylboronic acid (PBA)-based boronate affinity interactions because the cis-diol sites of oligosaccharide chains on glycoproteins can selectively react with the PBA receptor groups to form cyclic phenylborates in aqueous basic media. Due to the presence of hundreds to thousands of cis-diol sites on a glycoprotein, a large number of ferrocene tags can be recruited for the signal-on aptasensing of glycoproteins at a low-abundance level, eliminating the need for extra amplification strategies. As a result, the boronate affinity-based electrochemical aptasensor is highly sensitive and selective for glycoprotein detection and tolerant to the false-positive results. The detection limit for α-fetoprotein (AFP) is 0.037 ng/mL, with a linear response ranging from 0.1 to 100 ng/mL. In addition to the merits of simple operation, short assay time, and low detection cost, the aptasensor is applicable to the detection of glycoproteins in serum samples and the point-of-care detection using disposable flexible electrodes. Overall, this work provides a universal and promising platform for the point-of-care detection of glycoproteins, holding great potential in screening and early diagnosis of glycoprotein-related malignant tumors and other major diseases.

One pot domino synthesis of new 3,5-disubstituted-tetrahydro-2H-1,3,5-thiadiazine-2-thiones (THTTs) as anti-inflammatory and antinociceptive candidates: A proof from in-vivo to in-vitro and in-silico mechanistic studies

A series of alkyl/aryl/aralkylamines or amino acids appended tetrahydro-2H-1,3,5-thiadiazine-2-thiones (4a-i, 5a-g, 6 and 7) were synthesized via one pot domino synthesis. The synthesis involved reacting alkyl/aryl/aralkylamines or amino acids with carbon disulfide employing basic aqueous medium and further cyclization with formaldehyde and alkyl/aryl/aralkylamines or amino acids. In addition, the carboxy-functionalized 1,3,5-thiadiazine-2-thione 6 was further subjected to esterification. All the structures were confirmed through spectral techniques i.e IR, 1H NMR, 13C NMR, and MS analysis. Furthermore, the newly synthesized compounds were biologically assessed via in vitro COX-2 and 5-LOX assays, in vivo anti-nociceptive and anti-inflammatory activities. Among the screened compounds, 6, 5f, and 7 exhibited highest inhibitory potency against COX-2 with IC50 values of 11.96, 13.54, and 13.93 μM, respectively. Moreover, compounds 6 and 7 exhibited excellent inhibitory potential against 5-LOX with IC50 values of 14.01 and 14.13 μM. The in-vivo anti-inflammatory bioassay studies showed that compounds 6, 7 and 5f dramatically reduced the paw edema size at 1 h and 3 h time intervals. In the anti-nociceptive activity, compound 6 showed pain protection comparative to Tramadol in all tested time intervals. In addition, studies of molecular docking revealed the compounds binding modes in the allosteric site of COX-2 and active site of 5-LOX, where these compounds exhibited higher binding scores and good binding interactions.