Four silver-based coordination polymers, {Ag(L)2(BF4)}∞ (1), {Ag(H2BTC)(L)·(H3BTC)}∞ (2), {Ag2(H2BTEC)(L)2·3.33H2O}∞ (3), and Ag(H25SSA)(L)∞ (4), were synthesized using ...thiomorpholine-4-carbonitrile (L) as the primary ligand and three aromatic polyoxoacids as coligands: trimesic (H3BTC), pyromellitic (H4BTEC), and 5-sulfosalicylic acid (H35SSA). Compounds 1 and 3 are two-dimensional, while 2 and 4 are one-dimensional. L acts as a bis-monodentate ligand, while the Ag(I) ion is three-coordinated in 2 and four-coordinated in all of the other compounds. The tetrahedral coordination of Ag(I) in 3 leads to an almost complete absence of intermolecular interactions with the metal center. All compounds show reasonable photocatalytic activity for photocatalytic degradation of mordant blue 9 dye, with reaction rates in the 0.036–0.056 min–1 range. Changes in the reaction rates can be correlated with the type and coordination of the coligand. Complex 3 exhibits photoluminescence at 77 K, while 4 exhibits photoluminescence at both room temperature and 77 K. Luminescence lifetimes indicate electronic transitions of singlet parentage, where transitions are allowed. A TD-DFT study determined the contributions of individual singlet–singlet electronic excitations to the fluorescence, indicating that metal– intraligand transitions are responsible for luminescence in both complexes.
Pt(II) and Pd(II) complexes (1 and 2, respectively) with thiomorpholine-4-carbonitrile (TM-CN), an N-substituted thiomorpholine derivative, were synthesized from tetrachlorido precursors in water. ...Structural analysis has shown that 1 represents the first monomeric metal complex with this ligand type with an axial M–S bond with respect to the TM-CN ring chair conformation, while in 2 a typical equatorial M–S bond position with respect to the ring chair conformation was observed. A detailed DFT investigation revealed that axial conformers are more stable for molecular forms of both metals, while intermolecular interactions in the crystals stabilize the axial conformer for Pt(II) and the equatorial conformer for Pd(II). The magnitude of this stabilization in the case of 2 is large enough to change the most stable axial conformer in the molecular form to the equatorial conformer in the crystal. Further investigation of the strength of individual intermolecular interactions revealed significant differences of some interactions between the two structures. The likely cause of the difference in the crystal structures of experimentally obtained complexes is the fact that 1 and 2 exhibit different dominant interactions: C–H/M and C–H/S are more dominant in 1 and C–H/Cl interactions are more dominant in 2. In addition, DFT calculations have shown that while the axial position of the Pt–S bond with respect to the ring chair conformation results in a significantly shorter C–H/Pt interaction distance than that in the hypothetical equatorial conformer, there is very little difference in C–H/Pd interaction distances in conformers with axial and equatorial positions of Pd–S bond with respect to the ring chair conformation.
Zinc–ferrite, nickel–ferrite and mixed nickel–zinc ferrites were successfully synthesized via the thermal decomposition method from acetylacetonate complexes. To control the particle size and enhance ...dispersibility in an aqueous medium, starch, a natural and biocompatible compound, was used for the first time for coating such magnetic powders. X-ray powder diffraction (XRPD) was performed to study the structural properties of all samples. The presence of a single-phase spinel structure as well as the cation distribution in both sites of all investigated magnetic powders was confirmed. The values of unit cell parameters obtained from the results of the Rietveld analysis decreased, while the average crystallite size increased with increasing Ni2+ content. The average microstrain parameters unambiguously showed a change in the spinel structure with cation distribution. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) analyses were also utilized to characterize the synthesized materials, corroborating the XRPD data. The obtained results indicated that functionalization by starch was successfully achieved.
Herein, the synthesis, structural and crystal field analysis and optical spectroscopy of Mn4+ doped metal titanates ATiO3 (A = Ca, Mg) are presented. Materials of desired phase were prepared by ...molten salt assisted sol-gel method in the powder form. Crystallographic data of samples were obtained by refinement of X-ray diffraction measurements. From experimental excitation and emission spectra and structural data, crystal field parameters and energy levels of Mn4+ in CaTiO3 and MgTiO3 were calculated by the exchange charge model of crystal-field theory. It is found that crystalline field strength is lower (Dq = 1831 cm−1) in the rhombohedral Ilmenite MgTiO3 structure due to the relatively longer average Mn4+O2− bond distance (2.059 Å), and higher (Dq = 2017 cm−1) in orthorhombic CaTiO3 which possess shorter average Mn4+O2− bond distance (1.956 Å). Spectral positions of the Mn4+2Eg → 4A2g transition maxima is 709 nm in MgTiO3 and 717 nm in CaTiO3 respectively in good agreement with calculated values.
•Mn4+ doped titanates CaTiO3 and MgTiO3 via Molten salt assisted sol-gel method.•Calculated crystal field parameters and energy levels of Mn4+ in the hosts.•Smallest fraction of covalence in the Mn4+-O2− bonding in MgTiO3 among ATiO3.•The Mn4+2Eg → 4A2g emission transition in MgTiO3 is at the highest energy among ATiO3
Magnetic structure of ZnFe2O4 normal spinel is re-examined. Antiferromagnetic structure non-collinear model is established within Ca2 space group having four different crystallographic/magnetic sites ...for 32 Fe3+ spins within magnetic unit cell.
•Magnetic structure of ZnFe2O4 normal spinel is re-examined.•Antiferromagnetic non-collinear structure model is established within Ca2 space group.•Four different crystallographic/magnetic sites contain 32 Fe3+ spins within magnetic unit cell.
•Magnetite nanoparticles (Fe3O4 NPs) were successfully used as a catalyst for aniline polymerization.•For aniline oxidation environmentally-friendly oxidant hydrogen peroxide was ...used.•Electroconducting polyaniline (PANI) in good yield was synthesized using small amount of Fe3O4 NPs.•Without Fe3O4 NPs, under the same other conditions, the reaction did not give PANI.•Effect of Fe3O4 NPs/aniline mass ratio and the reaction time on properties of PANI was studied.
Nowadays, there is a growing interest to find environmentally-friendly, simple and economical routes for the synthesis of polyaniline (PANI), one of the most important conducting polymers. For the oxidative polymerization approach hydrogen peroxide (H2O2) is highly recommended oxidant due to ecological aspects, since the product of its reduction is only water. However, its usage as an oxidant, aimed to produce conductive PANI with reasonable reaction rate, needs a catalyst. Here we report the preparation of conductive PANI in good yield by the oxidative polymerization of aniline using magnetite nanoparticles (Fe3O4 NPs) as a catalyst and H2O2 as an oxidant, with added very small amount of ammonium peroxydisulfate as the initiator. Synthesized Fe3O4 NPs (size 10–50 nm) were characterized by X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM). It was found that without Fe3O4 NPs, under otherwise same conditions, the reaction product is not PANI. The effect of mass ratio Fe3O4 NPs/aniline and polymerization time on the structure and physicochemical properties of prepared PANI was studied by various techniques. FTIR, Raman, UV–vis-NIR and electrical conductivity measurements confirmed the existence of conducting emeraldine salt form of PANI. XRPD revealed unchanged crystalline structure of Fe3O4 NPs upon polymerization and semi-crystalline structure of PANI. EPR spectra showed peaks assigned to PANI and Fe3O4 NPs. Described simple, environmentally improved synthetic route opens possibilities for the syntheses of conductive PANI-like polymers from other aromatic amines by using environmentally-friendly oxidant H2O2 and Fe3O4 NPs catalyst which can replace more expensive catalysts such as peroxidase enzymes.
Para-aminodiphenylamine (p-ADPA) was successfully polymerized by simple, economical and environmentally improved procedure. Magnetite nanoparticles (Fe3O4 NPs) were found to successfully catalyze the ...oxidation of p-ADPA in the presence of hydrogen peroxide (H2O2), an eco-friendly and clean oxidant, with a very small amount of ammonium peroxydisulfate (APS) as an initiator. In this manner, the amount of by-products occurring during the reaction is drastically reduced. The oxidation of p-ADPA proceeded also in the absence of Fe3O4 NPs, but far more slowly than the catalyzed process. The influence of the mass ratio Fe3O4NPs/p-ADPA on the properties of products was systematically studied by different characterization techniques. Spectroscopic measurements (UV-Vis-NIR, FTIR, Raman, EPR) indicate that the polymerization products are polyaniline emeraldine salt-like polymers and their measured electrical conductivity is one of the highest values reported in the literature for p-ADPA oligomerization/polymerization products (1.8∙10-2 S cm-1). X-ray powder diffraction (XRPD) measurements revealed highly crystalline structure of Poly(p-ADPA) samples synthesized with Fe3O4 NPs, while scanning electron microscopy (SEM) showed layered and prismatic-shaped particles as prevailing in their morphology.
DK-I-56–1 (7‑methoxy‑2-(4‑methoxy‑d3-phenyl)-2,5-dihydro-3H-pyrazolo4,3-cquinolin-3-one), a recently developed deuterated pyrazoloquinolinone, has been recognized as a lead candidate for treatment of ...various neuropsychiatric disorders. During preclinical investigation of poorly water-soluble compounds such as DK-I-56–1, the application of nanotechnology could be advantageous due to improved safety and possibly increased bioavailability of nanosized formulation. DK-I-56–1 nanosuspensions stabilized by polysorbate 80, alone or in combination with poloxamers 188 i.e. 407 or d-α-tocopheryl polyethylene glycol 1000 succinate, were prepared using a small-scale media milling device. With particle size 208.7–250.6 nm and polydispersity index <0.250, selected nanodiseprsions were stable for three weeks. Pharmacokinetic and biodistribution studies following intraperitoneal administration of three types of formulation in mice indicated high plasma DK-I-56–1 levels after solution (10,228.6 ± 1037.2 ngh/ml) and nanosuspension (6770.4 ± 770.7 ngh/ml) but not suspension administration (966.0 ± 58.1 ngh/ml). However, distribution of DK-I-56–1 after solution was heavily influenced by its composition, and brain availability of nanosuspension was superior to that of solution formulation. In spontaneous locomotor activity test, the expected hyperlocomotor effect was observed after nanosuspension administration, without compromising impact of the vehicle/excipients used. Therefore, nanonization of drug compound assembled with proper selection of stabilizers may seemingly contribute further thorough testing of DK-I-56–1 preclinical efficacy.
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•Nanostructured cobalt ferrites' magnetic properties.•“Janus effect” of starch coating on cobalt ferrite magnetization.•Co-precipitation and hydrothermal methods/starch coating – ...increased magnetization.•Mechanochemical and microemulsion methods/starch coating – decreased magnetization.
To investigate the magnetic behavior of starch-coated cobalt ferrites, well-established synthetic methods, i.e., coprecipitation, mechanochemical, ultrasonically assisted coprecipitation, microemulsion, and microwave-assisted hydrothermal syntheses were chosen for their preparation. The obtained materials had pure single-phase spinel structures. Scanning and transmission electron microscopy analyses revealed that the morphology of the samples is not uniform, and particle aggregation is a dominant process. Fourier transform infrared spectra and thermogravimetric analysis confirmed the presence of starch in all–coated samples. The unusually higher saturation magnetization of starch-coated samples than their as-prepared analogs, obtained by coprecipitation, ultrasonically assisted coprecipitation, and microwave-assisted hydrothermal methods, might be explained by the Ostwald ripening mechanism induced by the coating process. A decrease in magnetization was noticed for the starch-functionalized nanomaterials synthesized by mechanochemical and microemulsion methods, in comparison to their as-prepared analogs, i.e., the size distribution of such nanoparticles is narrow, and the average diameter of the grains is near critical for the Ostwald ripening process.
•Phase and morphological analysis of urinary stones was done.•XRPD results show phase composition of all samples.•SEM results shows crystal growth and formation of selected samples.•Importance of ...using analytical techniques to examine materials that may also contribute to medical research.
In this paper we present the phase and morphological characteristics of urinary stones from Serbian patients. The study included for the first time the determination of the phase composition and a statistical analysis of the presence of different types of urinary stones in both men and women in Serbia. The main goal of study was representation of collected data for the first time. For past three years, more than 600 samples were collected from Serbian patients. The phase composition of all samples of urinary stones was investigated using XRD analysis. Morphology and chemical composition of phases in some characteristic samples was determinate by the SEM-EDS analysis. Results indicate that there are several different types of urinary stones that vary in mineral composition, chemistry and morphology. It was found that 312 (52%) of the 600 stones were composed of calcium oxalate minerals (CaOx): 17.3% of which were pure calcium oxalate monohydrate COM, 4% were pure calcium oxalate dihydrate COD; 200 (33.3%) were a mixture of CaOx and Hydroxyapatite HA, 19 (3.1%) were uric acid (uricite) UA and uric acid dihydrate UAD, 17 (2.8%) were a combination of UA and CaOx minerals, 41 (6.8%) were combination of CaP minerals and CaOx, 11 (1.9%) were cystine (Cy) stones. The obtained data shows the diversity of types of urinary stones. Morphological, chemical and XRPD analysis give us statistical data which shows that the most common urinary stones from Serbian patients are from CaOx group and in most of cases are associated with CaP.
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