AQUEOUS MEDIUM SYNTHESIS AND CHARACTERIZATION OF MIXED-LIGAND FLUORO COMPLEXES OF MANGANESE(III) CONTAINING O-DONOR CO-LIGANDS

Ligand Modified and Light Switched On/Off Single-Chain Magnets of {Fe ₂ Co} Coordination Polymers via Metal-to-Metal Charge Transfer

Diradicals or Zwitterions: The Chemical States of <i>m</i> -Benzoquinone and Structural Variation after Storage of Li Ions

Thermally Induced Reversible Metal-to-Metal Charge Transfer in Mixed-Valence {Fe ^III ₄ Fe ^II ₄ } Cubes

A novel lithium salt, lithium(trifluoromethanesulfonyl) (trifluoroethoxysulfonyl) imide {Li [(CF3SO2) (CF3CH2OSO2) N], Li[TEO-TEST]}, and the corresponding nonaqueous electrolytes of 1. 0 mol/L Li[TFO-TESI] in a mixture of ethylene carbonate/ethyl methyl carbonate(EC/EMC, 3 : 7, volume ratio) were prepared. The structure, composition and purity of the as-prepared Li [TEO-TESI] were confirmed by nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), mass spectrometry (MS), elemental analysis(EA), and ion chromatography(IC). The thermal properties of Li [TEO-TEST] and its nonaqueous electrolytes, 1. 0 mol/L Li[TEO-TEST]-EC/EMC (3 : 7), were characterized by differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA). The fundamental properties of nonaqueous electrolyte solution of Li [TEO-TEST] were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry(CV), chronoamperometry and scanning electron microscope(SEM). The nonaqueous electrolytes of Li[TEO-TESI] shows excellent electrochemical stability, and does not corrode Al below 4. 2 V. Both Li/synthetic graphite and synthetic graphite/LiCoO2 cells using Li[TEO-TEST] show good cycling performances at room temperature, and the graphite/LiCoO2 cells using Li [TEO-TEST] shows much better capacity retention after 100 cycles than those using LiPF6.

A novel way of preparing an intumescent flame retardant (IFR) and its master batch by the reactive extrusion of melamine phosphate and pentaerythritol, together with a polypropylene (PP) carrier, in a twin‐screw extruder has been established. The effect of the PP carrier resin on the flame retardancy and water resistance of the intumescent‐flame‐retarding PP materials was investigated by using the limited oxygen index (LOI), UL94 test, elemental analysis (EA), thermogravimetric analysis (TGA) and water solubility testing, respectively. In addition, the mechanism of the carrier effect was analysed by melt flow index (MFI), scanning electron microscopy (SEM), and TGA. The experimental results show that with increasing content of carrier resin (PP) in the IFR master batch from 0 to 15 wt%, the flame retardancy LOI of the PP/IFR (25 wt% loading) blend increased from 29.5 to 32, and the UL94 level at 1.6 mm thickness was improved from failure to a V‐0 rating. In addition, the water resistance of a flame‐retarded composite at 25 wt% IFR loading was greatly improved, i.e. after treatment with hot water at 70 °C for 168 h, the reducing rate of element N in the IFR/PP blend decreased from 18.3% with 5 wt% carrier resin to 12.9% with 15 wt% carrier resin, and the LOI reduction rate decreased from 15.3% without any carrier resin to 10.9% with 15 wt% carrier resin, while the flame‐retarded PP with an IFR master batch containing 10–15 wt% carrier resin maintained its UL94 V‐0 rating at 3.2 mm thickness. The improvement in flame retardancy was attributed to the improved flame‐retardant (FR) dispersion due to the carrier resin, while the improved water resistance was explained by the lowered water solubility of the IFR, the improved FR dispersion and the improved compatibility of the FR with the matrix resin due to the carrier resin. Reactive extrusion is a novel way to obtain pelletissed IFRs without powder pollution and their corresponding flame‐retarding materials with a number of desired properties. Copyright © 2004 Society of Chemical Industry

<i>N</i> -Heterocycles Extended π-Conjugation Enables Ultrahigh Capacity, Long-Lived, and Fast-Charging Organic Cathodes for Aqueous Zinc Batteries

Background: Curcumin, a curcuminoid derived from turmeric (Curcuma longa), has been extensively studied for various bioactivities. However, its limited water solubility and sensitivity to light restrict its therapeutic applications. In recent years, researchers have been exploring ways to enhance the properties of curcumin. In the current investigation, curcumin was transformed into its nanoform by utilizing d-glucose in an aqueous phase at room temperature, creating water-soluble nanocurcumin. Since this study focuses on altering the architecture of the curcumin sphere, it has been examined explicitly for antioxidant activity through well-defined in vitro assays. Materials and Methods: Nanocurcumin was synthesized through the conversion of curcumin using d-glucose. The zeta potential of nanocurcumin was measured to assess its water solubility. The orientation of curcumin in its nanoform was confirmed through ultraviolet–visible (UV–Vis) spectroscopy and photoluminescence. High-resolution transmission electron microscopy (HR-TEM) was employed to provide evidence of its potential assembly. At the same time, Fourier-transform infrared (FTIR) analysis was conducted to discern alterations in peaks and stretches indicative of the transition to the nanoform. The prepared nanocurcumin was examined for superoxide and free radical scavenging activities, given curcumin’s well-known antioxidant properties. Results: The zeta potential measurement of nanocurcumin yielded a mean value of −53.4 mV. The nanoform orientation of curcumin was confirmed through UV–Vis spectroscopy, revealing a shift in the maximum absorption from 450 to 430 nm. Photoluminescence analysis, conducted with excitation at a wavelength of 478 nm, recorded a significant 5.01-fold increase in fluorescence intensity, from 193.6 to 971.8 a.u., accompanied by a slight shift in the emission maxima peak. HR-TEM was done, and various field images have been taken. Some images illustrated the probable assembly of curcumin into a spherical nanoform with a shell-like structure embedded inside the glucose sphere. Fourier-transform infrared analysis indicated alterations in some peaks and stretches due to the transition to the nanoform. Upon examination of the prepared nanocurcumin for superoxide and free radical scavenging activity, a noteworthy enhancement in superoxide scavenging activity was observed, increasing from 21.42 ± 5.01% in the native form to 69.94 ± 5.84% in the nanoform at a concentration of 10 µg/mL of curcumin. Conversely, a slight reduction in free radical scavenging activity was noted, decreasing from 55.57 ± 5.16% in native curcumin to 47.43 ± 6.83% in the nanoform at the same concentration. Conclusion: The water-soluble curcumin synthesized in this study can be regarded as an advanced molecule with the potential to address diseases mediated by oxidative stress effectively.

Due to their antimicrobial activity, parabens (i.e. alkyl esters of p-hydroxybenzoic acid) are widely used as preservatives in several industries (pharmaceutical, food, cosmetic). Although being extremely effective, their usage is hampered by their low aqueous solubility. Several formulation strategies can be applied to enhance their solubility, one of which is formation of water-soluble cyclodextrin (CD) complexes. Formation of inclusion complexes has been proved to be a good approach to increase solubility of lipophilic drugs and other active ingredients. Some research has been done in this field. However, a complete and comprehensive study on how the alkyl chain length of parabens influences the complex formation, aggregation and formation of insoluble complexes is still lacking. Phase-solubility studies showed that all the very water-soluble hydroxypropylated CDs form linear (AL) type phase-solubility profiles with all tested parabens. The poorly soluble βCD did also form AL-type profiles with methyl and ethyl paraben while the βCD complexes of propyl and butyl paraben have limited solubility in water and, thus displayed B-type profiles. The paraben complexes of αCD and γCD all had limited solubility in water and, thus, displayed B-type phase-solubility profiles. Fourier-transformed infrared spectroscopy, Differential scanning calorimetry and X-ray powder diffraction were applied to elucidate the nature of the solid phases from the phase-solubility studies. They consistently showed the presence of solid pure paraben over the CD concentration range studied when AL-type profiles were observed, and precipitation of poorly soluble paraben/CD complexes when B-type were observed (i.e. during and after the B-type plateau region). These studies demonstrate that the composition of solid phases is related to the type of phase-solubility profile. It was also shown that in aqueous CD solutions, paraben solubilization increase with increasing side chain length (i.e. methyl < ethyl < propyl < butyl), as well as, with increasing size of the CD cavity (i.e. αCD < βCD < γCD). This statement is valid for linear region of phase-solubility diagrams (i.e. A- and B-type).

For rapid development of initial solvent extraction processes, knowledge of the solubility and partition behavior of surfactants and solubility enhancers is required. Unfortunately, experimental solubility data for many common surfactants and solubility enhancers in aqueous and organic solvents have not been reported. There are also few references to the partitioning behavior of these additives between water and common extraction solvents. In this paper, the solubility and partition coefficients were measured at 293 K for a range of additives in solvent systems of varying polarities and classes: ethyl acetate, isobutyl alcohol, toluene, methyl ethyl ketone, methyl tert-butyl ether, and 0.2 mol·L-1 potassium phosphate buffer (pH 7). The additives chosen were based on common usage and represent a cross-section of the surfactant classes: UCON LB-625, P2000, Triton X-100, sodium dodecyl sulfate (SDS), Tween 20, Tween 80, hexadecyltrimethylammonium bromide (CTAB), ammonium sulfate, and methyl-β-cyclodextrin. The partition behavior of these additives (except Tween 20) was also investigated. The effect of ionic strength, pH, and cosolvents on the partition coefficient was also determined to provide a database for surfactant and solubility enhancer behavior in order to allow for rapid optimization of initial extraction processes. The solubility results showed that the antifoams were extremely soluble in the organic solvents but had limited solubility in water. The nonionic surfactants were soluble in all solvents tested. The anionic surfactant was soluble in all solvents tested, with the exception of toluene. The cationic surfactant and ammonium sulfate had limited solubility in most solvents. The methyl-β-cyclodextrin had varying degrees of solubility depending on polarity. The partition results can largely be predicted from the solubility data, with the exception of the nonionic surfactants. For all of the compounds that partitioned, the behavior could also be predicted based on solvent polarity, with larger partition coefficients for the more polar solvents. These data can be used to design initial extraction processes containing these additives and, by analogy, for other related additives as well.

Exclusion of unsuitable CNS drug candidates based on their physicochemical properties and unbound fractions in biomatrices for brain microdialysis investigations

Diclofenac Salts, Part 7: Are the Pharmaceutical Salts with Aliphatic Amines Stable?

Poly(ethylene glycol) (PEG)-grafted polyaniline (PANi) copolymers were prepared by incorporating a chlorine end-capped methoxy PEG (mPEGCl) of molecular weight of about 2000 onto the leucoemeraldine form of PANi via N-alkylation. The microstructures and compositions of the mPEG-grafted PANi (mPEG-g-PANi) copolymers were characterized by FT-IR, elemental analysis, UV−visible absorption spectroscopy, thermogravimetric (TG) analysis and X-ray photoelectron spectroscopy (XPS). The graft concentration (degree of N-alkylation) can be controlled by adjusting the molar feed ratio of mPEGCl to the number of repeat units of PANi. The mPEG-g-PANi copolymers showed enhanced solubility in common organic solvents and water. The electrical conductivity of the mPEG-g-PANi copolymer film decreased by a factor of 5 at the mPEG graft concentration of 0.05. The mPEG-g-PANi copolymer with a high graft concentration was very effective in preventing platelet adhesion.

Novel semi-interpenetrating polymer network (IPN) hydrogel microspheres of chitosan (CS) and hydroxypropyl cellulose (HPC) were prepared by emulsion-cross-linking method using glutaraldehyde (GA) as a cross-linker. Chlorothiazide (CT), a diuretic and anti-hypertensive drug with limited water solubility, was successfully encapsulated into IPN microspheres. Various formulations were prepared by varying the ratio of CS and HPC, percentage drug loading and amount of GA. Microspheres were characterized by Fourier transform infrared (FTIR) spectroscopy to investigate the formation of IPN structure and to confirm the absence of chemical interactions between drug, polymer and cross-linking agent. Scanning electron microscopy (SEM) was performed to study the surface morphology of the microspheres. SEM showed that microspheres have smooth surfaces. Particle size, as measured by laser light scattering technique, gave an average size ranging from 199–359 μm. Differential scanning calorimetry (DSC) was performed to know the formation of IPN structure. X-ray diffraction (X-RD) studies were performed to understand the crystalline nature of the drug after encapsulation into IPN microspheres. Encapsulation of drug up to 76% was achieved as measured by UV spectroscopy. Both equilibrium and dynamic swelling experiments were performed in 0.1 N HCl. Diffusion coefficients (D) for water transport through the microspheres were estimated using an empirical equation. In vitro release studies indicated the dependence of release rate on the extent of cross-linking, drug loading and the amount of HPC used to produce the microspheres; slow release was extended up to 12 h. The release data were also fitted to an empirical equation to compute the diffusional exponent (n), which indicated that the release followed the non-Fickian trend.

Olmesartan medoxomil (OLM) is a selective angiotensin II antagonist that effectively lowers blood pressure. It has a poor rate of absorption when taken orally, a maximum bioavailability of about 26%, and limited solubility in water. OLM is therefore categorized as class II in the Biopharmaceuticals Classification System (BCS), suggesting that it has high permeability and low solubility. By generating nanomicelles, this work attempts to increase the aqueous solubility and dissolution rate of OLM. Mixed polymeric nanomicelles made up of soluplus (SLP) with tween 80 (TWN80) and SLP with d-α tocopheryl polyethylene glycol 1000 succinate (TPGS), had been prepared in different gravimetric ratios. The nanomicelles holding OLM were developed using the film hydration technique and assessed for their particle size, polydispersity index (PDI), entrapment efficiency (EE%), and drug loading capacity (DL%), of the micellar dispersion. The optimized F4 formula comprising 100 mg SLP and 60 mg TWN 80 displayed a particle size of about 71.1±1.28 nm, PDI of 0.116±0.021, an EE% of 92±1.5, a DL% of 11.5±1.43, and enhanced in-vitro release compared to aqueous drug suspension. Using iodine as a hydrophobic probe, the critical micelle concentration (CMC) of F4 was determined to be 0.0112±0.001 mg/ml, which is lower than the theoretically computed CMC of 0.01284 mg/ml calculated using an equation. The preparation of F4 by the direct dissolution method was also established at different stirring periods (3,12, and 24 hours) and by two techniques, to evaluate the effect of the preparation method on particle size, PDI, EE%, and DL%. The results showed a significantly larger particle size, PDI, and lower EE% (p&lt;0.05) than the thin film hydration method. Furthermore, the physical and chemical characteristics of F4 mixed nanomicelles were monitored over three months, both at room temperature and under refrigerated circumstances (4°C), and it was determined that the nanomicelles remained stable. The morphological analysis was conducted using a field emission scanning electron microscope (FESEM), which detected the presence of nanostructures with a spherical form and a diameter that matched the particle size measurements. The results of the existing study confirmed that OLM mixed nanomicelles are likely nanocarriers to improve solubility.

Quetiapine fumarateis a typical antipsychotic with a short half-life of 6 h and is administered multiple times daily. In this study, a copolymer for controlled delivery of quetiapine fumarate will be developed. In order to prevent side effects and improve patient compliance, hydroxypropyl methylcellulose K15M (HPMC K15M) was included in the formulation of the quetiapine fumarate oral sustained-release tablets at a concentration of 10–30%. A series of analytical methods were used to determine the characteristics of the prepared hydrogels, including Fourier transform-infrared spectroscopy, Differential scanning calorimetry, X-ray diffraction, and Scanning electron microscope. At two different pH values (1.2 and 6.8), swelling and release studies were conducted. A variety of release kinetic models was used to study drug release mechanisms. A non-Fickian diffusion mechanism released hydrogels prepared from quetiapine fumarate. It was found that swelling was increased by increasing the amount of HPMC K15M. Compared to the other batches (10–20%), the produced tablets with 30% HPMC K15M content had a better release profile after 20 h of dissolution. Because of the effective matrix complex’s limited solubility in water, the drug diffuses through the gel layer at a steady rate rather than dissolving quickly.