Structure determination of riboflavin by synchrotron high-resolution powder X-ray diffraction

The crystal structure of the stable form of vitamin B2 or riboflavin (C17H20N4O6) was solved using high-resolution powder X-ray diffraction (PXRD). The high-resolution PXRD pattern of riboflavin was recorded at room temperature at the European Synchrotron Radiation Facility (Grenoble, France). The starting structural model was generated using a Monte Carlo simulated annealing method. The final structure was obtained through Rietveld refinement. The positions of the H atoms belonging to hydroxy groups were estimated from computational energy minimizations. The symmetry is orthorhombic with the space group P212121 and the following lattice parameters: a = 20.01308, b = 15.07337 and c = 5.31565 Å.

Mechanochemical Synthesis and Physicochemical Characterization of Previously Unreported Praziquantel Solvates with 2-Pyrrolidone and Acetic Acid

Two new solvates of the widely used anthelminthic Praziquantel (PZQ) were obtained through mechanochemical screening with different liquid additives. Specifically, 2-pyrrolidone and acetic acid gave solvates with 1:1 stoichiometry (PZQ-AA and PZQ-2P, respectively). A wide-ranging characterization of the new solid forms was carried out by means of powder X-ray diffraction, differential scanning calorimetry, FT-IR, solid-state NMR and biopharmaceutical analyses (solubility and intrinsic dissolution studies). Besides, the crystal structures of the two new solvates were solved from their Synchrotron-PXRD pattern: the solvates are isostructural, with equivalent triclinic packing. In both structures acetic acid and 2-pyrrolidone showed a strong interaction with the PZQ molecule via hydrogen bond. Even though previous studies have shown that PZQ is conformationally flexible, the same syn conformation as the PZQ Form A of the C=O groups of the piperazinone-cyclohexylcarbonyl segment is involved in these two new solid forms. In terms of biopharmaceutical properties, PZQ-AA and PZQ-2P exhibited water solubility and intrinsic dissolution rate much greater than those of anhydrous Form A.

Exploration of the Cs Trapping Phenomenon by Combining Graphene Oxide with α-K6P2W18O62 as Nanocomposite

A graphene oxide-based α-K6P2W18O62 (Dawson-type polyoxometalate) nanocomposite was formed by using two types of graphene oxide (GO) samples with different C/O compositions. Herein, based on the interaction of GO, polyoxometalates (POMs), and their nanocomposites with the Cs cation, quantitative data have been provided to explicate the morphology and Cs adsorption character. The morphology of the GO-POM nanocomposites was characterized by using TEM and SEM imaging. These results show that the POM particle successfully interacted above the surface of GO. The imaging also captured many small black spots on the surface of the nanocomposite after Cs adsorption. Furthermore, ICP-AES, the PXRD pattern, IR spectra, and Raman spectra all emphasized that the Cs adsorption occurred. The adsorption occurred by an aggregation process. Furthermore, the difference in the C/O ratio in each GO sample indicated that the ratio has significantly influenced the character of the GO-POM nanocomposite for the Cs adsorption. It was shown that the oxidized zone (sp2/sp3 hybrid carbon) of each nanocomposite sample was enlarged by forming the nanocomposite compared to the corresponding original GO sample. The Cs adsorption performance was also influenced after forming a composite. The present study also exhibited the fact that the sharp and intense diffractions in the PXRD were significantly reduced after the Cs adsorption. The result highlights that the interlayer distance was changed after Cs adsorption in all nanocomposite samples. This has a good correlation with the Raman spectra in which the second-order peaks changed after Cs adsorption.

Electrochemical sensing of dextrose and Photocatalytic activities by nickel ferrite nanoparticles synthesized by probe sonication method

Background: Electrochemical sensing has been widely used as a glucose sensor. Methods: In the present work, we have investigated the application of nickel ferrite (NiFe2O4) nanoparticles (NFNPs) for dextrose sensing applications. NFNPS were synthesized by using a simple and low-cost probe sonication method (PSM). The structural, optical and electrochemical properties of prepared nanoparticles were measured by using XRD, FTIR and DRS techniques. Results: The PXRD pattern confirmed the formation of inverse spinel structure for NFNPs with a face-cente red cubic (FCC) structure. The diffuse reflectance spectral studies revealed the energy band gap of NFNPs as deduced to be 2.50 eV by using Kubelka-Munk function. The efficiencies in the photocatalytic degradation of Acid Red 88 (AR-88) and Acid Blue 88 (AB-88) dyes were found to be better with 93.45% and 84.45%, respectively. The EIS parameters corroborated the significant reduction in the charge transfer resistance of NFNPs electrode. The sensing of dextrose in acidic solution by using NFNP through carbon paste electrode was successful. Conclusion: The obtained sensing and photocatalytic results revealed that the synthesized NFNPs could be a better electrode material for the detection of dextrose with high electrode reversibility, in addition to its excellent photocatalytic characteristics towards the dye degradation.

Enhancing Dissolution Rate and Antibacterial Efficiency of Azithromycin through Drug-Drug Cocrystals with Paracetamol

Cocrystallization is a promising approach to alter physicochemical properties of active pharmaceutical ingredients (hereafter abbreviated as APIs) bearing poor profile. Nowadays pharmaceutical industries are focused on preparing drug-drug cocrystals of APIs that are often prescribed in combination therapies by physicians. Physicians normally prescribe antibiotic with an analgesic/antipyretic drug to combat several ailments in a better and more efficient way. In this work, azithromycin (AZT) and paracetamol (PCM) cocrystals were prepared in 1:1 molar ratio using slow solvent evaporation method. The cocrystals were characterized by Fourier transform infrared (FTIR), Raman spectroscopy, powder X-ray diffraction (PXRD), differential scanning calorimeter (DSC), thermo gravimetric analysis (TGA) and high-performance liquid chromatography (HPLC). Vibrational spectroscopy and DSC confirmed that both APIs interact physically and showed chemical compatibility, while PXRD pattern of the starting material and products revealed that cocrystal have in a unique crystalline phase. The degree of hydration was confirmed by TGA analysis and result indicates monohydrate cocrystal formation. The HPLC analysis confirmed equimolar ratio of AZT:PCM in the cocrystal. The in vitro dissolution rate, saturation solubility, and antimicrobial activity were evaluated for AZT dihydrate and the resulting cocrystals. The cocrystals exhibited better dissolution rate, solubility and enhanced biological activities.

Fluconazole-tartaric acid co-crystal formation and its mechanical properties

Introduction: The formation of co-crystal is widely studied to obtain more favourable physicochemical properties than the pure active pharmaceutical ingredient (API). The co-crystal formation between an anti-fungal drug, fluconazole (FLU), and tartaric acid (TAR) has been investigated and its impact on mechanical properties has also been studied. Methods: The co-crystal of FLU-TAR (1:1) molar ratio was prepared by ultrasound-assisted solution co-crystallization (USSC) method with ethanol as the solvent. Polarization microscopy was used to observe the crystal morphology. Meanwhile, powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) methods were used to characterise the co-crystal formation. The mechanical properties of the co-crystal, such as flowability and tablet-ability, were compared with pure FLU. Results: Photomicroscopes revealed the unique crystal morphology of the USSC product was different from the two starting components. The typical PXRD pattern was shown by the USSC product, which indicated the formation of FLU-TAR co-crystal. In addition, the DSC thermogram revealed 169.2°C as the melting point of the FLU-TAR co-crystal, which is between the melting points of FLU and TAR. It indicates that FLU-TAR co-crystal has better flowability and tablet-ability than pure FLU. Conclusion: FLU-TAR co-crystal is one of the alternative solid forms for a raw material in pharmaceutical tablet preparation because it has better mechanical properties than pure fluconazole.

Enhancing solubility and antibacterial activity using multi-component crystals of trimethoprim and malic acid

Aim: To improve the solubility and antibacterial activity of trimethoprim (TMP) by preparing its multicomponent crystals with malic acid (MA). Methods: Multicomponent crystals of TMP-MA were prepared by solvent co-evaporation. The solid-state properties were characterised by powder X-ray diffraction (PXRD), differential thermal analysis (DTA), Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM) analyses. The solubility was investigated in an aqueous medium, while the antibacterial activity against Escherichia coli was investigated using the agar disk diffusion method. Results: The PXRD pattern of the TMP-MA binary system differed from the starting materials, supporting the formation of a new crystalline phase (equimolar ratio). The DTA thermogram showed a single, sharp, endothermic peak at 212.5 °C attributable to the TMP-MA multicomponent crystal's melting point. FT-IR spectroscopy showed a solid-state interaction involving proton transfer between TMP and MA. The multicomponent crystal displayed a 2.5-fold higher solubility and had increased antibacterial activity compared to TMP alone. Conclusions: The TMP-MA binary system forms salt-type multicomponent crystals that significantly increase solubility and antibacterial activity. Multicomponent crystal formation is a viable technique for modifying the physicochemical properties of active pharmaceutical ingredients.

Structural, Thermal and Surface Properties of a Formulated Sunscreen: Zn/Al-nitrate Layered Double Hydroxide Intercalated with 4-aminobenzoic Acid

Intercalation of 4-amino benzoic acid (4-AB) into Zn/Al-nitrate layered double hydroxide (ZAL2) to form Zn/Al-4AB (ZALAB) compound was successfully synthesized from nitrate salt by using direct co-precipitation method. ZALAB compound was confirmed by Powder X-ray diffraction (PXRD) pattern with a basal spacing of 15.3 Å. The presence of COO- and C6H5NH2 functional groups of 4-AB at 1,517 and 1,178 cm–1 in Fourier transform infrared (FTIR) spectrum reinforced 4-AB intercalated into the resulting compound. Based on the thermal analysis, 4-AB in ZALAB compound was more stable compared to pure 4-AB. Breuneur, Emmet and Teller/Barret-Joyner-Halenda (BET/BJH) analyses demonstrated that ZALAB compound is a mesopores-type IV compound with 4.25 m2/g surface area. This material is an irregular shape with different sizes of particles. ZALAB is a potential sunscreen formulation that minimizes the harmful effect on the skin, improving pharmaceutical technology in the skincare treatment. HIGHLIGHTS 4-amino benzoic acid (4-AB) is a sunscreen composed of carboxylic and aromatic groups that potentially filter UV-B radiation Layered double hydroxide (LDH) is known as an ionic clay that is based on the brucite (Mg (OH)2) -like cations layers containing intercalated charge-balancing anions and water Intercalation of 4-amino benzoic acid (4-AB) into Zn/Al-nitrate layered double hydroxide (ZAL2) to form Zn/Al-4AB (ZALAB) was synthesized using direct co-precipitation method ZALAB material has a higher thermal stability compared to 4-AB in pure form GRAPHICAL ABSTRACT

Bioconjugate synthesis, phytochemical analysis, and optical activity of NiFe2O4 nanoparticles for the removal of ciprofloxacin and Congo red from water

In this paper, Jr.NiFe2O4 nanoparticles (NPs) were synthesized first time using the leaves extract of Juglans regia via a straightforward process. The physio and phytochemical analysis of plant confirm the presence of macromolecules which function as bio-reductant and stabilize the nanoparticles. The Jr.NiFe2O4 NPs were characterized by UV–visible, FTIR spectroscopy, PXRD pattern, SEM and TGA/DTA analysis. The nanoparticles proved to be optically active having a value of indirect bandgap of energy in the range of 1.53 eV. The Jr.NiFe2O4 NPs have the ability in scavenging 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) free radicals and showed 58.01% ± 1.2% scavenging activity at 100 µg/mL concentrations. The photocatalytic degradation study of ciprofloxacin (CIP) and Congo red (CR) reveals that the highest degradation rate was acquired for CIP using pH = 3, at 254 nm, while 85% of removal rate was analysed for CR. The kinetic studies in case of CR removal followed pseudo-first-order model with thermodynamic parameters (∆G° = − 5.87 kJ mol−1 K, ΔH° = 1393.50 kJ mol−1 and ΔS° = 22.537 kJ mol−1 K) with error analysis. Overall, these data recommend an innovative inspiring application of a plant-mediated synthesis of Jr.NiFe2O4 NPs.

Tin Doped Barium Titanate (BaTiO3) Synthesized through Molten Salt Method as Promising Dielectric Material

Tin doped barium titanate (BaTiO3) was prepared through NaCl-KCl eutectic melt at 800 ºC. The synthesized materials were well characterized using powder-X-ray diffraction (PXRD) and FESEM-EDX spectroscopy. Cubic structure was observed in the PXRD pattern of tin doped sample. The crystallite size of tin doped barium titanate nanoparticles was found to be around 17 nm. Nanorods and aggregated nanocubes like structure were observed in the FESEM images and elemental ratio of doped ions was confirmed by energy dispersive X-ray spectrum (EDX). Electrical properties observed for the synthesized material were found better than those reported in the literature prepared by other methods. The dielectric constant and dielectric loss were measured in the temperature range of 100-400 K and the frequencies varying from 10 kHz to 10,000 kHz. The tin doped barium titanate showed rod type morphology with an unprecedented high dielectric constant of ~17,500 at 10 Hz. Dielectric constant values decreased with increasing frequency. The change in dielectric constant with frequency was well explained by Maxwell-Wanger polarization effect. The impedance and ionic transference number (tion) were also measured.