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ACS Omega Jun 2024A three-dimensional heterobimetallic porous structure with the formula {[YTbL(OH)(HO) (DMF)] ·1.5HO·DMF} (L = 3-amino-4-hydroxybenzoate) () has been synthesized and...
A three-dimensional heterobimetallic porous structure with the formula {[YTbL(OH)(HO) (DMF)] ·1.5HO·DMF} (L = 3-amino-4-hydroxybenzoate) () has been synthesized and characterized by single crystal and powder X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), inductively coupled plasma mass spectrometry (ICP-MS), electrophoretic mobility, and Fourier transform infrared (FTIR) spectroscopy. The structure presents two metal environments: a bioaugmented isosceles wedge (mm2) MO and a tricapped trigonal prism (-6m2) MNO. These configurations facilitate the creation of channels with a diameter of 10.7 Å, enabling its utilization as an active catalyst where the heterobimetallic nature of the assembly will be explored. This mixed-metal metal-organic framework has been tested in the cycloaddition of epoxides with carbon dioxide as well as in the cyanosilylation and hydroboration reactions of carbonylic substrates. Additionally, a monometallic analogue has been synthesized for comparative evaluation of their catalytic performances. Both the mixed metal and monometallic variants exhibit outstanding activity in the cyanosilylation and hydroboration of carbonyls and in the synthesis of carbonates under CO pressure. However, only the latter exhibits high recyclability.
PubMed: 38911723
DOI: 10.1021/acsomega.4c03109 -
Spectrochimica Acta. Part A, Molecular... Jun 2024The synthesis of carbon quantum dots (CQDs) using chemical precursors with different organic groups is a strategy to improve optical properties and expand applications...
The synthesis of carbon quantum dots (CQDs) using chemical precursors with different organic groups is a strategy to improve optical properties and expand applications in several fields of research such as Analytical Chemistry. Ascorbic acid and riboflavin are widely used in human food supplementation, making quality monitoring of these vitamin supplements relevant and necessary. In this work, disodium ethylenediaminetetraacetic, sodium thiosulfate and urea were applied to obtain CQDs through a single-step microwave-assisted synthesis. The CQDs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, infrared spectroscopy, zeta potential measurements, ultraviolet-visible spectroscopy and photoluminescence spectroscopy. The synthesized nanoparticles exhibited satisfactory and stable optical properties with luminescence at 430 nm, water solubility, and fluorescence quantum yield of 8.9 %. They were applied in the quantification of ascorbic acid and riboflavin in vitamin supplements. The fluorescence mechanisms observed were dynamic quenching for the CQDs/Cr(VI) sensor, followed by a return of fluorescence in the presence of ascorbic acid, and static quenching and inner filter effect in the interaction with riboflavin. Factorial designs 2 and 2 were used to optimize the analytical parameters. The CQDs/Cr(VI) sensor used in the determination of ascorbic acid, employing an on-off-on strategy, resulted in a linear range of 0.5 to 50 µg mL and a limit of detection of 0.15 µg mL. The ratiometric fluorescence used in the determination of riboflavin resulted in a linear range of 0.1 to 7 µg mL and a limit of detection of 0.09 µg mL. The analytical results for ascorbic acid were compared to the reference method of the Brazilian pharmacopeia, showing accuracy and precision according to the Brazilian Health Regulation Agency. Therefore, the synthesized CQDs were used to determine ascorbic acid and riboflavin in vitamin supplements, and the application of this nanomaterial can be expanded to different analytes and matrices, using simple and low-cost analysis techniques.
PubMed: 38909560
DOI: 10.1016/j.saa.2024.124669 -
Inorganic Chemistry Jun 2024A remarkable increase in the luminescent intensity of Er-doped CaF up-conversion phosphors was achieved, showing an approximate enhancement of over 1100-fold. This...
A remarkable increase in the luminescent intensity of Er-doped CaF up-conversion phosphors was achieved, showing an approximate enhancement of over 1100-fold. This enhancement was realized by incorporating Yb, Al, Sr, and gold nanospheres and nanorods. The substantial improvement in up-converting luminescence effectively enhances sensitivity and efficiency at low excitation power densities. The up-conversion phosphors, consisting of (Ca,Sr)F:Er,Yb,Al, were easily prepared using excess NHF flux at 950 °C for 30 min. The structural confirmation of interstitial Al ions within the CaF lattice was achieved through synchrotron powder X-ray powder diffraction. The significant enhancement of up-conversion emission and their mechanisms in the phosphors were vividly represented through energy transfer, interstitials and local distortions, and localized surface plasmon resonances when excited with a 980 nm diode laser.
PubMed: 38906836
DOI: 10.1021/acs.inorgchem.4c01814 -
International Journal of Biological... Jun 2024Evaluation of the controlled release of ciprofloxacin (CIP.HCl) and the antibacterial efficacy of alginate (ALG)-based nanocarriers constitute the primary objectives of...
Evaluation of the controlled release of ciprofloxacin (CIP.HCl) and the antibacterial efficacy of alginate (ALG)-based nanocarriers constitute the primary objectives of the current work. Herein, ALG-based nano-structures were prepared by the co-precipitation method and thoroughly analyzed using different characterization techniques, i.e., fourier transform infrared (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and zeta potential (ZP). The intense peaks emerged at 500, 545, and 750 cm due to the CeO bond. Peaks that appeared at 550-600 cm and 525 cm are due to the stretching vibrations of FeO and ZnO bonds, respectively. Lowering of the peaks from 1640 to 1630 cm and 1420 to 1384 cm were observed in ALG-based nanocomposite (NC) due to the interaction of ALG with metal oxides (MO), which confirmed the formulation of CeO/ZnFeO/ALG nanocomposite. The diffraction peaks at 28.6, 56.6, 76.5, 37, 47.9, 62.3, 74, 13, 21 confirmed the synthesis of MO (crystallite size 15.74 nm) and CeO/ZnFeO/ALG (12 nm). In accordance with morphological studies, CeO/ZnFeO oxides had a uniform distribution throughout the relatively smooth and permeable surface of the ALG-based NC. Ciprofloxacin (CIP) was used as a model drug. Negative values of ZP revealed that CIP-loaded nanocomposite (CeO/ZnFeO/ALG/CIP) had more stability than CeO/ZnFeO/ALG. The maximum percentage of loading around 25 % on ALG NC was examined using the optical density (OD) method at pH 5.5. Correlation coefficients from the first order (0.971), Korsmeyer (0.9858), and Hixson (0.9021) models show the best-fitted models of the release profile in all circumstances. The release mechanism was investigated using various kinetics models. The controlled drug released was observed around 17 % at 40 °C after 3 h at pH 7.4, which is almost identical to the body temperature of a human, which is 37 °C. Similarly, after 24 h, sustained and controlled in-vitro release of the drug was studied, and it was 37, 72, and 74 % at pH 2.2, 7.4, and 9.4, respectively. Thus, prepared ALG-based NC is suitable for the controlled in-vitro release of (CIP.HCl). Metal oxides (CeO/ZnFeO) and ALG-based nanocomposite (CeO/ZnFeO/ALG) showed great antibacterial activity against Staphylococcus aureus (S. aureus) like 15 mm and 14 mm than Escherichia coli (E. coli).
PubMed: 38906345
DOI: 10.1016/j.ijbiomac.2024.133274 -
Inorganic Chemistry Jun 2024This report describes the synthesis and characterization of two heterometallic Li-Zn coordination isomers [LiZn(tbaoac)] (tbaoac = -butyl acetoacetato) that have been...
This report describes the synthesis and characterization of two heterometallic Li-Zn coordination isomers [LiZn(tbaoac)] (tbaoac = -butyl acetoacetato) that have been isolated separately by the same stoichiometric reaction run in different organic solvents. The 6-coordinated zinc isomer () was synthesized in acetone with high yield, while the 5-coordinated one () was readily obtained from ethanol. The isomer has a low solubility in organic solvents such as alkanes and haloalkanes, while its counterpart exhibits a good solubility in almost all common solvents. Two isomeric molecules feature similar centrosymmetric tetranuclear cyclic assemblies, which are different in their arrangement of tbaoac ligands. While all ligands act as μ-type in the structure of , the two tbaoac groups chelating Li appear as μ-type in , thus providing an additional coordination for Zn ions. However, the real structural transformation between these isomers was shown to be more complex than simply making or breaking a couple of Zn-O bonds. X-ray single-crystal structure analysis, powder X-ray diffraction, multinuclear NMR, DART mass spectrometry, ICP-OES analysis, and TGA have been employed for the characterization of the isomers. The combination of powder X-ray diffraction and H NMR investigation revealed that isomer can be quantitatively transformed to in ethanol, while the reverse conversion instantly takes place in acetone.
PubMed: 38905706
DOI: 10.1021/acs.inorgchem.4c00634 -
Journal of the American Chemical Society Jun 2024Flexible metal-organic materials (FMOMs) with stepped isotherms can offer enhanced working capacity in storage applications such as adsorbed natural gas (ANG) storage....
Flexible metal-organic materials (FMOMs) with stepped isotherms can offer enhanced working capacity in storage applications such as adsorbed natural gas (ANG) storage. Unfortunately, whereas >1000 FMOMs are known, only a handful exhibit methane uptake of >150 cm/cm at 65 atm and 298 K, conditions relevant to ANG. Here, we report a double-walled 2-fold interpenetrated diamondoid () network, [NiL(μ-HO)], comprising a new azo linker ligand, ( = ()-3-(pyridin-4-yldiazenyl)benzoate) and 8-connected dinuclear molecular building blocks. exhibited gas (CO, N, CH) and liquid (C8 hydrocarbons)-induced reversible transformations between its activated narrow-pore phase and , a large-pore phase with . 33% increase in unit cell volume. Single-crystal X-ray diffraction (SCXRD) studies of the as-synthesized phase , , and revealed that structural transformations were enabled by twisting of the azo moiety and/or deformation of the MBB. Further insight into these transformations was gained from variable temperature powder XRD and variable pressure powder XRD. Low-temperature N and CO sorption revealed stepped Type F-II isotherms with saturation uptakes of 422 and 401 cm/g, respectively. exhibited uptake of 200 cm/cm (65 atm, 298 K) and a high CH working capacity of 166 cm/cm (5-65 bar, 298 K, 33 cycles), the third highest value yet reported for an FMOM and the highest value for an FMOM with a Type F-II isotherm.
PubMed: 38904843
DOI: 10.1021/jacs.4c03555 -
Designed Monomers and Polymers 2024The C3-symmetry ionic polymer PPyTri has been designed with multi-walled carbon nanotubes (MWCNTs) or graphene nanoplatelets (GNPs) and studied as an ultrasensitive...
The C3-symmetry ionic polymer PPyTri has been designed with multi-walled carbon nanotubes (MWCNTs) or graphene nanoplatelets (GNPs) and studied as an ultrasensitive electrochemical sensor for trace Hg(II) detection. The synthesis approach incorporated attaching three pyridinium cationic components with chloride anions to the triazine core. The precursors, BPy, were synthesized using a condensation process involving 4-pyridine carboxaldehyde and focused nicotinic hydrazide. The polymer PPyTri was further modified with either MWCNTs or GNPs. The resulting ionic polymer PPyTri and its fabricated nanocomposites were characterized using infrared (IR), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and powder X-ray diffraction (XRD). The analysis revealed that both the polymer and its nanocomposites have semi-crystalline structures. The electroactivity of the designed nanocomposites toward Hg + 2 ions revealed that among the nanocomposites and bare copolymer, the glassy carbon electrode (GCE) adapted with the PPyTri GNPs-5% exhibited the greatest current response over a wide range of Hg + 2 concentrations. The nanocomposite-modified electrode presented an excellent sensitivity of 83.33 µAµM - 1 cm - 2, a low detection limit of 0.033 nM, and a linear dynamic range of 0.1 nM to 0.01 mM (R2 = 0.9945).
PubMed: 38903406
DOI: 10.1080/15685551.2024.2360746 -
Journal of Synchrotron Radiation Jul 2024The demand for powder X-ray diffraction analysis continues to increase in a variety of scientific fields, as the excellent beam quality of high-brightness synchrotron...
High-throughput and high-resolution powder X-ray diffractometer consisting of six sets of 2D CdTe detectors with variable sample-to-detector distance and innovative automation system.
The demand for powder X-ray diffraction analysis continues to increase in a variety of scientific fields, as the excellent beam quality of high-brightness synchrotron light sources enables the acquisition of high-quality measurement data with high intensity and angular resolution. Synchrotron powder diffraction has enabled the rapid measurement of many samples and various in situ/operando experiments in nonambient sample environments. To meet the demands for even higher throughput measurements using high-energy X-rays at SPring-8, a high-throughput and high-resolution powder diffraction system has been developed. This system is combined with six sets of two-dimensional (2D) CdTe detectors for high-energy X-rays, and various automation systems, including a system for automatic switching among large sample environmental equipment, have been developed in the third experimental hutch of the insertion device beamline BL13XU at SPring-8. In this diffractometer system, high-brilliance and high-energy X-rays ranging from 16 to 72 keV are available. The powder diffraction data measured under ambient and various nonambient conditions can be analysed using Rietveld refinement and the pair distribution function. Using the 2D CdTe detectors with variable sample-to-detector distance, three types of scan modes have been established: standard, single-step and high-resolution. A major feature is the ability to measure a whole powder pattern with millisecond resolution. Equally important, this system can measure powder diffraction data with high Q exceeding 30 Å within several tens of seconds. This capability is expected to contribute significantly to new research avenues using machine learning and artificial intelligence by utilizing the large amount of data obtained from high-throughput measurements.
PubMed: 38900456
DOI: 10.1107/S1600577524003539 -
Journal of Microscopy Jun 2024The structural nature and geometry, as well as the lattice-relative orientation, of an arrangement of crystal defects in a highly textured Eu-doped composite of two...
Epifluorescence microscopy study of a quadruple node of triple junctions of grain boundaries in a Eu-decorated highly textured composite of (Cl, Br)(K, Rb) and I(K, Rb) solid solutions.
The structural nature and geometry, as well as the lattice-relative orientation, of an arrangement of crystal defects in a highly textured Eu-doped composite of two alkali-halide solid solutions was studied by epifluorescence microscopy (EFM) using the doping ion as a fluorochrome. A three-dimensional reconstruction and a skeleton type model, as built from a sequence of EFM images of different optical cross-sections of this arrangement, are presented. Structurally, this arrangement is a quadruple node (QN) of triple junctions of grain boundaries. The QN core geometry is that of a tetragonal tristetrahedron (TTTH), centred at the QN site, whose tetrahedron vertices and edges are on the QN triple junctions and grain boundaries, respectively, whereas the tristetrahedron tetragonal axis is nearly parallel to the lattice [001]-axis. The measured values of the angles between triple junctions and between the grain boundaries forming them are reported. The distinct chemical compositions of the composite solid solutions are discussed to be responsible, in last instance, for the tristetrahedron departure from a cubic configuration. Collaterally, certain families of translationally periodic almost-parallel (TPAP)-wall-like regions which consist of TPAP-columns of TPAP-spindle-like singularities, as well as certain zigzag arrays of columns of this like, existing into the QN grains, are reported to be observed. Three-dimensional reconstructions of typical individuals of these families and arrays as well as of their constituent parts are presented and geometrically analysed. These families and arrays are discussed to be families of tilt subboundaries, whose constituent dislocations are decorated by cylindrical second-phase europium di-halide precipitates, and regularly faceted tilt subboundaries, respectively. Crystal growing and sample preparation, composite structural characterisation by powder and single-slab X-ray diffraction (PXRD and SSXRD, respectively), microscopy and fluorescence-cube unit optics, image processing, electronic three-dimensional reconstruction and measuring methodologies, are all described in detail.
PubMed: 38899727
DOI: 10.1111/jmi.13341 -
Dalton Transactions (Cambridge, England... Jun 2024A series of zinc(II) thioamidate complexes [Zn{SC(Pr)NR}] for R = Pr ( = 2) (2), Bu (3) ( = 1), Ph (4) ( = 2) and Cy (5) ( = 2) and one cadmium(II) thioamidate complex...
A series of zinc(II) thioamidate complexes [Zn{SC(Pr)NR}] for R = Pr ( = 2) (2), Bu (3) ( = 1), Ph (4) ( = 2) and Cy (5) ( = 2) and one cadmium(II) thioamidate complex [Cd{SC(Pr)NBu}], (6), were designed and synthesised as single-source precursors for AACVD ZnS and CdS. Solid-state structures of all four zinc(II) compounds revealed distorted tetrahedral or trigonal bipyramidal geometries, with varying tendencies for dimeric association, mediated by {Zn-S} bridging bonds. The thermogravimetric analysis identified the {Bu} derivertive, 3, as the most promising precursor based on its low decomposition onset (118 °C) and clean conversion to ZnS. This was attributed to the greater availability of β-hydrogen atoms promoting the pyrolysis mechanism. The corresponding cadmium thioamide 6 was found to crystallise as a trimetallic molecule which lacked the thermal stability to be considered viable for AACVD. Hence, 3 was used to deposit ZnS thin films by AACVD at 200-300 °C. Powder X-ray diffraction confirmed phase-pure growth of hexagonal wurtzite ZnS, with approximate crystallite sizes of 15-20 nm. Scanning electron microscopy revealed densely packed spherical nanoclusters. The morphology and crystallinity were most consistent for depositions between 250-300 °C. Energy dispersive X-ray spectroscopy indicated slightly sulfur-deficient stoichiometries.
PubMed: 38896487
DOI: 10.1039/d4dt01278j