Solvent Media Research Articles

Intricacies of Carbon Dot Photoluminescence for Emerging Applications: A Review.

Discoveredin 2004, carbon dots (CDs) have already traversed a long journey, generating many promising research directions. Its cheapness, ease of synthesis, high water-solubility, tunable emission, and excellent biocompatibility make it a single-point solution to many problems, and tremendous efforts were invested into understanding the structure-property-function relationship, which eases the engineering of the CD properties suitable for a desired application. From the usual random choice of precursors or carbon materials as a starting point in the early days, more systematic approaches are now available for choosing proper starting materials and appropriate experimental conditions (solvent medium, reaction temperature, reaction duration, pH, etc) to customize its photoluminescence. The presence of impurities has a crucial role in the outcome and applicability of photoluminescence. Recently, a significant focus has been on the long-wavelength emissive CDs, particularly in the red to near-infrared (NIR) regions, for better penetration into live cells and to circumvent autofluorescence problems. Proper design can harvest phosphorescence from CDs. Many excellent reviews are available, focusing on different facets of CD prospects. Hence, we will only highlight the importance of the optical properties of CDs. We will mention some of the new works that have appeared in the last five years.

Stereochemical tuning, post-synthesis crosslinking and quaternizing to tune the membrane performance of ultra-stable polyamine nanofiltration membranes

Solvent resistant and pH-stable nanofiltration membranes play a crucial role in solvent or water reuse across various industries, including pharma, chemical, dairy and mining, where stringent pH conditions and chemical stability are imperative. Previous research introduced a chlorine-resistant top-layer for nanofiltration membranes, using 1,2,4,5-tetra(bromomethyl)benzene and 1,2-diaminocyclohexane, with also exceptional stability at extreme pH values and a broad solvent resistance thanks to its crosslinked nature. To further optimize this remarkably stable and versatile membrane material, the unique property of 1,2-diaminocyclohexane, i.e. its stereochemistry, is employed here to manipulate membrane properties through diastereomerism and enantiomeric excess. Filtration experiments employing different 1,2-diaminocyclohexane isomers revealed significant variations in membrane performance, emphasizing the impact of stereochemistry on separation performance. Adjusting the enantiomeric excess of 1,2-diaminocyclohexane resulted in notable changes in membrane permeability and rejection, highlighting the general power of stereochemical control in membrane synthesis. Additionally, post-synthesis modifications, including further crosslinking and quaternization, allowed to tune the membrane structure and performance in both aqueous and solvent media, offering opportunities for optimization towards specific applications. SEM and XPS providing insights into membrane morphology and composition, confirmed the influence of stereochemistry and post-synthesis modifications on membrane properties. These findings demonstrate the efficacy of stereochemistry manipulation and post-synthesis techniques in tailoring pH-stable and solvent resistant nanofiltration membranes for specific applications, paving the way for advanced membrane design.

Use of green polar aprotic solvents TamiSolve® NxG, DMSO and methyl-THF for the synthesis of asymmetric polyimide-based biogas purification membranes

Valorization of biogas to biomethane through membrane-based purification of its multi-component stream primarily consisting of CH4 and CO2, holds significant potential as a crucial renewable energy source. Industrial membrane units classically comprise of membranes synthesized using non-solvent induced phase separation (NIPS), with polymer processing typically performed using conventional solvents, such as N-N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), etc. However, use and subsequent waste handling of these solvents present significant hazards, due to their toxicological nature, therefore calling for a shift to employ safer and ‘greener’ materials to facilitate sustainable production of these membranes. In current work, a novel and sustainable methodology for synthesis of CO2/CH4 gas separation flat-sheet asymmetric membranes was developed with commercially available Matrimid® 5218 polyimide, using TamiSolve® NxG, dimethylsulfoxide (DMSO) and 2-methyltetrahydrofuran (MeTHF) as green solvent medium. NIPS thermodynamic and kinetic aspects of the novel system were fundamentally analyzed through determination of ternary phase diagrams and viscosity profiles. Membranes were systematically tested for gas separation performance by varying Tamisolve-DMSO-MeTHF solvent ratios. Mixed gas CO2/CH4 separation factors in the range of 13 to 41, along with CO2 permeances upto 186 GPU were achieved. Furthermore, chemical crosslinking was applied in view of plasticization resistance of the membranes. Matrimid® membranes crosslinked with hyperbranched polyethylenimine (PEI) successfully displayed stability against CO2-induced plasticization upto CO2 feed partial pressures of 22 bar. The developed membrane synthesis method provides a sustainable framework for synthesizing polyimide-based membranes with tunable gas separation performances.

Localized surface plasmon resonance of Ag nanoparticle thin films deposited by direct-current magnetron sputtering

This study investigates the localized surface plasmon resonance (LSPR) of Ag nanoparticle (NP) thin films deposited by magnetron sputtering on an alkaline-free aluminosilicate-glass substrate at a substrate temperature of 600 °C. The equivalent film thickness was controlled to be 5, 10, 20, and 50 nm by adjusting the deposition time. The deposited Ag thin films formed NPs with uniform diameter and spacing for all Ag thicknesses. The NP diameters ranged approximately from 16 to 88 nm, corresponding to the equivalent film thickness. Due to the formation of isolated NPs, all Ag thin films exhibited a singlet LSPR peak in their extinction spectra. The LSPR peak position in the extinction spectra shifted with the refractive index of the environmental solvent media when the Ag NP thin films were immersed in these media. In addition, the insertion of a MgO, Nb2O3, or TiO2 underlayer shifted the LSPR peak position in the extinction spectra according to the refractive index of each underlayer material. A peak shift corresponding to the refractive index of the environmental solvent media was also observed for Ag NP thin films deposited on underlayers. The relatively low sensitivity of the LSPR peak shift to the refractive index of the environmental solvent media suggests that the solvent media only covered the top surface of the Ag NPs distributed on the substrate but did not infiltrate the spaces between them. The results of this study demonstrate the applicability of sputter-deposited Ag NP thin films to solid LSPR devices.

Electrochemical Method for the Assay of Organic Peroxides Directly in Acetonitrile.

Lipid peroxidation is a major process that determines the quality of various oil samples during their use and storage, in which the primary products are hydroperoxides (HP'S). HP'S are very stable compounds at ambient conditions and are harmful to human health. Therefore, the evaluation of the degree of oil oxidation is an excellent tool for ensuring food safety. The peroxide value (PV) is the main parameter used for quality control in oils. Herein, we propose an alternative electrochemical method to the classical iodometric titration method most widely used for determining the PV. Our approach is based on the electrochemical quantification of hydroperoxides/peroxides in an organic solvent medium (acetonitrile and organic ammonium salt) using a composite electrocatalyst-glassy carbon electrode modified with 2D-nanomaterial graphitic carbon nitride doped with Co3O4. Calibration was made by the method of standard addition using benzoyl peroxide (BPO) as a model peroxide compound, dissolved in chloroform and added to fresh Rivana-branded anti-cellulite oil, used as a model oil sample. Calibration plots showed a linear response and the very good reproducibility of the analytical result (R2 ˃ 0.99). Further, in terms of accuracy, the method showed good results, since the BPO quantitative analysis was close to the theoretical response. In addition, the accuracy of the electrochemical method was compared with that of the standard iodometric titration method for determining the PV of vegetable fats (according to a standard method). Finally, using the electrochemical method, the concentration of peroxides was determined in a real sample-an anti-cellulite oil of the trademark Rivana with an expired shelf life.

Spectrophotometric determination of quercetin using micelles of cetyltrimethylammonium bromide in a low ratio methanol–water mixture

A simple and achievable UV-Vis spectrophotometric method for the micro-quantitative determination of quercetin has been developed and validated. This method relies on the formation of supramolecular assemblies of quercetin (QR) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) in a 5 % methanolic aqueous solution. In this solvent medium, CTAB in the presence of QR has a critical micelle concentration of 1.2·10-3 mol l-1 at 24 °C, determined through conductometry. Important analytical parameters such as wavelength, composition of methanol-water mixture, CTAB concentration (cCTAB), and pH were optimized. Under the optimum experimental conditions (l = 397 nm, 5 % methanol as solvent, cCTAB = 2.0·10-3 mol l-1, and pH = 6.0), Beer's law was valid for QR concentrations up to 16.9 mg ml-1. The Ringbom optimum QR concentration range was 1.0 - 16.9 mg ml-1. The method sensitivity was 2.03·104 l mol-1 cm-1 (the molar absorptivity) and 0.13 mg ml-1 (limit of detection). The applicability of the proposed method for quantifying QR in pharmaceutical formulations was demonstrated. Furthermore, the proposed UV-Vis spectrophotometric method was successfully applied to the reliably assay of QR, even in the presence of vitamin C.

Pulsed Electric Field (PEF) Treatment Results in Growth Promotion, Main Flavonoids Extraction, and Phytochemical Profile Modulation of Scutellaria baicalensis Georgi Roots.

This study aims to explore the effect of pulsed electric field (PEF) treatment as a method very likely to result in reversible electroporation of Scutellaria baicalensis Georgi underground organs, resulting in increased mass transfer and secondary metabolites leakage. PEF treatment with previously established empirically tailored parameters [E = 0.3 kV/cm (U = 3 kV, d = 10 cm), t = 50 µs, N = 33 f = 1 Hz] was applied 1-3 times to S. baicalensis roots submerged in four different Natural Deep Eutectic Solvents (NADES) media (1-choline chloride/xylose (1:2) + 30% water, 2-choline chloride/glucose (1:2) + 30% water, 3-choline chloride/ethylene glycol (1:2), and 4-tap water (EC = 0.7 mS/cm). Confocal microscopy was utilized to visualize the impact of PEF treatment on the root cells in situ. As a result of plant cell membrane permeabilization, an extract containing major active metabolites was successfully acquired in most media, achieving the best results using medium 1 and repeating the PEF treatment twice (baicalein <LOQ, baicalin 12.85 µg/mL, wogonin 2.15 µg/mL, and wogonoside 3.01 µg/mL). Wogonin concentration in NADES media was on par with the control (plants harvested on the day of the experiment, ultrasound-mediated methanolic extraction, Cwogonin = 2.15 µg/mL). After successful extraction, PEF treatment allowed the plants to continue growing, with the lowest survival rate across treated groups being 60%. Additionally, an enhancement in plant growth parameters (length and fresh mass of the roots) and significant changes in the S. baicalensis root phytochemical profile were also observed.

Influence of Solvent Dielectric Constant on the Complex Coacervation Phase Behavior of Polymerized Ionic Liquids.

Complex coacervation is an associative phase separation process of oppositely charged polyelectrolyte solutions, resulting in a coacervate phase enriched with charged polymers and a polymer-lean phase. To date, studies on the phase behavior of complex coacervation have been largely restricted to aqueous systems with relatively high dielectric constants due to the limited solubility of most polyelectrolytes, hindering the exploration of the effects of electrostatic interactions from differences in solvent permittivity. Herein, we prepare two symmetric but oppositely charged polymerized ionic liquids (PILs), consisting of poly[1-[2-acryloyloxyethyl]-3-butylimidazolium bis(trifluoromethane)sulfonimide] (PAT) and poly[1-ethyl-3-methylimidazolium 3-[[[(trifluoromethyl)sulfonyl]amino]sulfonyl]propyl acrylate] (PEA). Due to the delocalized ionic charges and their chemical structure similarity, both PAT and PEA are soluble in various organic solvents with a wide range of dielectric constants, ranging from 16.7 (hexafluoro-2-propanol (HFIP)) to 66.1 (propylene carbonate (PC)). Notably, no significant correlation is observed between the solvent dielectric constant and the phase diagram of the complex coacervation of PILs. Most organic solvents lead to similar phase diagrams and salt resistances regardless of their dielectric constants, except two protic solvents (HFIP and 2,2,2-trifluoroethanol (TFE)) showing significantly low salt resistances compared to the others. The low salt resistance in these protic solvents primarily arises from strong hydrogen bonding between PILs and solvents as evidenced by 1H NMR and small-angle neutron scattering (SANS) experiments. Our finding suggests that for the coacervation of PILs, particularly those with delocalized and weak charge interactions, entropy from the counterion release and polymer-solvent interaction χ parameter play a more important role than the electrostatic interactions of charged molecules, rendered by the dielectric constant of the solvent medium.

Diastereoselective Cascade Double Michael Addition to Access Bridged Coumarins, Oxindoles and Spirooxindoles: A Sustainable Strategy for Synthesis of Anticancer Molecules.

An efficient and concise synthesis of highly functionalized bridged coumarins has been developed through a diastereoselective double Michael addition reaction of p-quinols with various 4-hydroxy coumarins under catalyst-free conditions in H2O-DMSO (8:2). The method has been applied to oxindoles for the synthesis of a variety of bridged-oxindoles and bridged-spiroxindoles in presence of a DABCO base using H2O-EtOH (8:2) as solvent medium. The strategy is simple, highly atom economical as there is no by-product and environmentally benign (E-factor = 0.1-0.9). The synthesized compounds were screened against triple-negative breast cancers and found that bridged coumarin (3a) and oxindole (5d) compounds exhibit potent anti-cancer activity at 6.6 and 8.8 µM (IC50) concentrations respectively. Further analysis revealed that 3a and 5d caused elevated early and total apoptosis by arresting the MDA-MB-468 cells in G2/M phase of the cell cycle. Overall, our results demonstrate that bridged coumarin (3a) and oxindole (5d) compounds-based approach attenuates the cancer progression and may pave a path for the translational outcome.

Electronic, structural and nonlinear optical investigation of manganese carbonyl complexes of isatin derivatives by DFT.

Isatin-Schiff bases have wide applications in chemistry. The π conjugated electronic system and heterocylic structure of these materials make them valuable for use as photosensitized materials. The delocalization of π-electrons throughout the structure causes the UV-vis absorption spectra to shift to longer wavelengths. In this study, the isatin manganese carbonyl complex shifted the UV-vis absorption wavelength to a longer wavelength (vis. 400-700nm) compared with our previous studies. The isatin derivatives (ISE (3[4-ethyl(phenyl)imino][indoline-2-one]), ISB (3[4-butly(phenyl)imino][indoline-2-one])) and their Mn carbonyl complexes MnISE ((ISE)Mn(CO)3), and, MnISB ((ISB)Mn(CO)3) were investigated via density functional theory (DFT) in different solvent media. The most stable complexes were found in medium polarity THF. The calculated HOMO-LUMO energy gap shows that the charge transfer occurs within the molecule. The HOMO-LUMO energy gap was increased with increasing solvent polarity for all investigated compounds. The smaller energy gap indicates that charge transfer occurs within the Mn(II) complex, in contrast to ISE and ISB, which exhibit larger energy gaps. As a result, the maximum absorption of Mn complexes shifts to the visible region. MnISB has the smallest HOMO-LUMO energy gap in THF. Additionally, the global reactivity parameters indicated that the MnISE complex has the highest electrophilicity index. DFT calculations have also been performed to investigate polarizability and first-order hyperpolarizability of these compounds. In water, the ISE had higher NLO values than the other structures did. These results indicate that all the studied molecules in different solvents could be good candidates for use in photosensitized and nonlinear optical materials. Geometries were determined at the DFT level via the LANL2DZ basis set for Mn and cc-PVTZ for other atoms in the molecules with the B3LYP functional. The UV-vis absorption spectra and HOMO-LUMO energies of ISE, ISB, and their Mn complexes were calculated by Time-dependent DFT (TDDFT) with CAM-B3LYP using the same basis sets. The UV-vis absorption spectra of ISE were also measured in acetonitrile and compared with the calculated spectra, which were consistent with the experimental results. All calculations were repeated in different solvents with the polarizable continuum model (PCM).

In-situ preparation of highly photocatalytic active octylimidazole functionalized CuO in deep eutectic solvent medium

In-situ preparation of highly photocatalytic active octylimidazole functionalized CuO in deep eutectic solvent medium

Highly Efficient and One-pot New Betti Bases: PEG-400 and Al2O3 Mediated Synthesis, Optimizations, and Cytotoxic Studies

Background: Multicomponent reactions (MCRs) have proven as one of the best alternatives to minimize several environmental consequences, mainly the use of hazardous chemicals, byproducts, and severe production processes. Literature reveals that MCRs with PEG-400 and metal oxide-based greener media provide a new and useful strategy for the construction of biologically potent organic systems. Objective: The present study aimed to synthesize newer Betti bases by a modified Betti reaction employing a highly efficient catalyst for the direct synthesis of a novel class of non-racemic amino benzyl naphthol ligands under green solvent media. The involvement of the articulated framework (4a-4j) was studied against nine cancer panels (NCI-60 cell lines) in terms of inhibiting/killing cancer cells. Methods: For the modification of the Betti reaction, we used 2-aminopyridin-3-ol, aromatic aldehydes, and a naphthol system using greener media employing PEG-400 and alumina as a prime active and highly selective catalyst. Furthermore, the antiproliferative activity against NCI-60 human cancer cell lines (GI50) was used for the development of pharmacologically active compounds and exhibited the single dose (10-5 M) study. Results: Based on greener media synthesis, recompenses of ease of workup, less reaction time, higher yield, and higher atom economy, as well as environmentally friendly, were reported. Betti bases were obtained at a yield of 87-98% and characterized by spectroscopic techniques. Among the synthesized scaffolds, compound 4b was found to be extra potent in melanoma cancer [MDAMB- 435], while compound 4h showed promising inhibition in leukemic cancer cell lines [HL- 60(TB) and MOLT-4]. Conclusion: A straightforward way for an efficient synthesis of Betti bases was developed via the reaction of naphthol and aldehydes with amines in PEG-400 media. An Al2O3 was effectively catalyzed in the Betti reaction in excellent yields without the formation of any other by-product in atom economy and environmentally benign way. The newly synthesized hybrids were tested in vitro against a panel of cancer cell lines, and some of the compounds exhibited significant inhibitory anti-proliferative effects. The most potent compounds (4b and 4h) showed interesting results, and compound 4b was found extra potent in melanoma cancer cell lines with -62% GI values.

Self-Healing Supramolecular Flexible Network of Zn(II): Exploring Chemo-Responsiveness, Antimicrobial Efficiency, and Variable Microelectronic Device Performances.

The Zn(II)-supramolecular metallogel (i.e., Zn-Py) of 2,6-pyridinedicarboxylic acid was prepared through the addition of a metal source and 2,6-pyridinedicarboxylic acid as a low molecular weight gelator. The Zn-Py metallogel encapsulated N,N'-dimethylformamide as gel-immobilized polar aprotic solvent media. The mechanical features of the synthesized metallogel were investigated. The thixotropic behavior of the Zn-Py metallogel was also analyzed. The microscopic feature of the metallogel was imaged through FESEM and TEM studies. The EDS pattern of the metallogel ratified the role of different gel-building chemical constituents. The stimuli responsiveness of the metallogel was also tested. The metallogel-forming mechanistic protocol was visualized through FTIR and ESI mass spectroscopic analyses. The bioeffectiveness, i.e., antimicrobial potency, of Zn-Py was also studied. The antimicrobial efficiency against both Gram +ve and Gram -ve bacteria including Salmonella typhimurium (MTCC 98), Escherichia coli (MTCC 1667), Bacillus cereus (ATCC 13061), Listeria monocytogenes (MTCC 657), and Staphylococcus aureus (MTCC 96) was critically analyzed. The FESEM images of the live bacteria and damaged bacteria due to the action of the metallogel were experimentally investigated. The Zn-Py metallogel was also used to fabricate the heterojunction and Schottky-type photodetectors to show their excellent light-matter interaction and their potentiality as active material in optoelectronics. The electrical parameters of semiconductor diodes such as the p-n junction and Schottky diode fabricated by the synthesized Zn-Py metallogel were investigated. Outcomes of the experimental investigation demonstrated that the tested metallogel effectively showed p-n junction diode parameters, especially with the ideality factor (η) of 1.3 under a dark environment. This fabricated device efficiently depicted a great ON/OFF ratio of 33.4 at a reverse bias voltage of -2 V. The metal-semiconductor-metal (M-S-M) junction-type Schottky barrier diode was also fabricated using the Zn-Py metallogel where the Au/Zn-Py metallogel/Au-based device fabrication strategy was implemented.

Simulation of Solvatochromic Phenomena in Xanthione Using Explicit Solvent Methods.

Xanthione is a sulfated polycyclic aromatic hydrocarbon which exhibits unique anti-Kasha properties and substantial sensitivity to its medium. Due to this sensitivity however, this makes xanthione-based systems very difficult to simulate. Further, xanthione's is understood to be come more photostable in the presence of a highly polar medium, however whether these photophysical properties could be taken advantage of for certain applications remains to be seen. In clarifying long-held beliefs of specific solvent effects, we apply a rigorous theoretical solvent analysis in both implicit and explicit solvent mediums to elucidate a more complete description of solvent polarity sensitivity in xanthione using both quantum chemical and molecular dynamics techniques. Not only was it found that explicit solvation methods are vital in an accurate description of the system, only a handful of explicit solvent molecules in the simulation are required to yield an appropriate electronic description. This short work is vital to devising future applications for xanthione-based and other quantum technologies, and is an important foundation stone on this journey.

Fitting Scattering Profiles of Perfluorinated Sulfonic Acid Ionomer Dispersions

Proton exchange membrane fuel cells (PEMFC) provide a path to wider adoption of hydrogen energy systems. This is because the energy density afforded by hydrogen makes PEMFC a strong candidate for the medium- and heavy-duty transportation sectors, where high allowable costs can reduce the barrier to adoption. As such, the focus of PEMFC research is toward greater efficiency and durability to reduce lifetime vehicle costs. To this end, high oxygen permeability ionomers (HOPI) are of interest, as the material has already been shown to increase mass activity in the cathode catalyst layer due to reduced anion poisoning from shorter side chains, in addition to enabling high power density through reduced oxygen transport resistance. While the performance of electrodes cast from HOPI and HOPI blended with commercial perfluorosulfonic acid (PFSA) has been documented, questions remain regarding the behavior of the novel ionomer in the dispersions and inks from which catalyst layers are fabricated. The literature on conventional PFSA ionomers devotes much attention to the effects of solvent media on interactions of ionomer backbone and side chains to form aggregates, motivated by the possible relationship between aggregates in dispersion and the structure of the cast catalyst layer, and thereby cell performance. In the present work, we probe the characteristic sizes and interactions among ionomer aggregates in dispersions by small angle x-ray scattering (SAXS). We report properties of aggregates in both HOPI and a commercial PFSA ionomer over a series of ionomer concentrations and at different ratios of water and propanol in the solvent medium. From these dispersions, aggregate spacings are estimated by fitting to the interference peak in the scattering intensity profile, and sizes are determined by form factor fitting. Next, series of blended HOPI and PFSA ionomer are prepared and studied by SAXS to understand the morphology of ionomer blends in solution. We further evaluate ionomer blends with different durations of ultrasonication, which can provide insight into the effect of sonication on ionomer blend aggregates during ink preparation.

Water Clustering Modulates Activity and Enables Hydrogenated Product Formation during Carbon Monoxide Electroreduction in Aprotic Media

As the effects of climate change are becoming increasingly visible, carbon dioxide electroreduction reaction (CO2RR) is gaining popularity to convert waste carbon dioxide to value-added products. As carbon monoxide (CO) is a key intermediate for valuable products such as methane and ethylene, CORR is studied to bypass CO2 activation. Most of the work on CO2RR and CORR has focused on using water as a proton source as water’s hydrogen bonding supports key intermediates and acts as a proton source for hydrogenated products. Using nonaqueous solvents instead of water decreases the competitive hydrogen evolution reaction (HER) from water breakdown. Additionally mixed aqueous-nonaqueous systems allow for fundamental understanding of water’s role in electrochemical transformations when it is only available in limited quantities as a proton source. Here, we experimentally control water speciation and activity using aprotic solvent media during CORR. Remarkably, we show that aprotic solvents that support microheterogeneous water-water clusters leads to significant amounts of CORR products (methane and ethylene) with a maximum ethylene Faradaic efficiency of 22% in acetonitrile (χH2O = 0.2); the first report of CORR to C2+ products using water in an aprotic solvent. In contrast, microhomogeneous systems – where water integrates into the solvents’ intermolecular binding network at all length scales and has lower water activity – primarily support undesired HER. Insights gained expand our understanding of water activity and nonaqueous electrolyte design for other important transformations reactions beyond CO reduction such as CO2RR and HER.

Alkali metal-based tantalates ATaO3 (A= Na And K) decorated on functionalized carbon nanofiber employed as an electrocatalyst: An effective A-site variants for electrochemical sensing of antiviral drug in environmental samples

The “game changer” Hydroxychloroquine (HCN) has been regarded as a potential medication and a trial resort for COVID-19 treatment.The effluents containing elevated levels of HCN discharged from human waste and production sites pose considerable concern over aquatic ecosystems. In this regard, we have designed alkali metal tantalates ATaO3 (A= Na and K) based metal oxides synthesized via NADES abetted hydrothermal approach anchored to functionalized carbon nanofiber resulting in an efficient electrocatalyst. Utilizing Thymol-Menthol NADES as a solvent medium marks 100 % atom economy and provides the metal oxides with spectacular characteristics. The effective electrochemical sensing of the HCN was investigated through cyclic voltammetry and electrochemical impedance study by comparing the bare and the fabricated electrodes. Among the fabricated sensors, the excellent conjunction of NaTaO3 and F-CNF with plenty of surface-active sites provides a pronounced rapid charge transfer kinetics response. Furthermore, the comprehensive investigation of NaTaO3/F-CNF electrode benefits from an inclusive concentration range 0.001–141.16 µM, low detection limit 2.1 nM, good reproducibility, and good operational stability. These key factors point to the practical viability of the modified sensor toward the complete assessment of the HCN drug in real-time samples that unveil acceptable recovery results and mark its use in clinical science.

4D printing of pH-responsive bilayer with programmable shape-shifting behaviour

4D printing of smart materials has seen remarkable advancements in the domain of biomedical devices, with a particular focus on developing responsive and adaptive programmable structures. In this work, we report the 4D printing of two solvent-responsive hydrogels forming a bilayer that undergoes bidirectional actuation depending on the pH of the solvent. A strong interlayer adhesion between the hydrogels is formed without subjecting either of their surfaces to any chemical modification. These hydrogels have an interfacial toughness of 71.8 J/m2 and undergoes no delamination during actuation inside a solvent. Conventionally, pH-responsive actuators are only limited to simple 2D films prepared by solvent casting. However, our work focuses on the design and fabrication of complex bilayer and patterned structures using Direct-Ink Writing (DIW) approach. These printed structures actuate upon immersion in a solvent medium, and the actuation is reversible in nature. The influence of programmable variables on the morphed structure was studied systematically by modifying the rheological properties (in the range of 102−105 Pa.s) and printing parameters (optimized at a printing speed of 5mm/sec, with the extrusion pressure of 5−6 bar and nozzle diameter of 0.5 mm) of the 3D printed bilayer structure. The physicochemical properties of the printable hydrogel ink were tuned such that the same structure can respond to both acidic and basic pH (with non-morphing point at pH 7), by altering the directionality of actuation. We have demonstrated the applications of these pH-responsive actuators in smart valves.

A computational study of the size effect of SiO2 spherical nanoparticles in water solvent.

This study comprehensively describes the interaction between SiO2 spherical nanoparticles and water molecules as a solvent medium. Our goal is to provide valuable insights into the significance of nanoparticle size in understanding their behavior and the resulting changes in the physical properties of materials. Our results indicate that SiO2 nanoparticles exhibit a strong affinity for water, which increases with the nanoparticle size. Our investigation can be relevant for the design of new composite materials with applications ranging from medical prostheses to quantum electronics, optoelectronic devices, catalysis, and photoluminescence. We have concentrated on the study of the amorphous, where size effects seem to be more pronounced. A computational study was carried out within the molecular dynamics simulations framework available in the GROMACS-v2019.2 software, with force fields consistent with DFTand the CHARMM36 utilized in the molecular description of the systems. The water model used was the TIP3P implemented in CHARMM36 force fields. A comprehensive analysis of molecular interactions of various system configurations was performed, including radial distribution function (RDF), mean square displacement (RMSD), hydrogen bonding analysis,interfacial analysis, andstudying system size'seffect on mechanical properties.

Water-Induced Switching in Selectivity and Steric Control of Activity in Photochemical CO2 Reduction Catalyzed by RhCp*(bpy) Derivatives.

Photocatalytic reduction of CO2 to formic acid (HCOOH) was investigated in either organic or aqueous/organic media by employing three water-soluble [RhIIICp*(LH2)Cl]+ (LH2 = n,n'-dihydroxy-2,2'-bipyridine; n = 4, 5, or 6) in the presence of [Ru(bpy)3]2+, 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH) and triethanolamine (TEOA). Through studying the electron-donating effects of two hydroxyl groups introduced into the bipyridyl ligand, we found that the substituent positions greatly affect both the catalytic efficiency and selectivity in CO2 reduction. More importantly, the HCOOH selectivity shows a dramatic increase from 14 to 83% upon switching the solvent media from pure organic to an aqueous/organic mixture, where the H2 selectivity shows a reverse phenomenon. The enhanced HCOOH selectivity and the drastic decrease in the H2 yield are well rationalized by the fact that the catalytic CO2 hydrogenation is not only driven photochemically via the attack of RhIII(H)Cp*(LH2-·) on CO2 but also partly bypassed by a dark H2 addition reaction yielding [RhIII(H)Cp*(L)]- from [RhIIICp*(L)Cl]+, which was also separately investigated under dark conditions. A combination of experimental and theoretical approaches was made to clarify the pKa values of catalyst intermediates together with the abundant species responsible for the major catalytic processes. Our DFT studies unveil that the exceptionally large structural strain given by the steric contacts between the 6,6'-dihydroxyl groups and the Cp* moiety plays a significant role in bringing about an outstanding catalytic performance of the 6,6'-substituted derivative. The intrinsic reaction coordinate calculations were carried out to clarify the mechanism of hydride transfer steps leading to generating formate together with the heterolytic H2 cleavage steps leading to afford the key hydridorhodium intermediates. This study represents the first report on the water-induced high selectivity in CO2-to-HCOOH conversion, shedding new light on the strategy to control the efficiency and selectivity in the catalysis of CO2 reduction.