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Microscopy Research and Technique Mar 2021To investigate intrinsic physicochemical properties and interactions of three different calcium hydroxide-based medications via means of different analytical methods....
To investigate intrinsic physicochemical properties and interactions of three different calcium hydroxide-based medications via means of different analytical methods. Two-commercial premixed medications: TempCanal(TCmx) and ProCalR(PCmx) and powder-form ProCal(PCpw) with glycerin were used. Vibrational modes were analyzed using Raman spectroscopy. Spectral mapping of samples was carried out using characteristic vibrational modes of calcium hydroxide and barium sulfate. Crystalline and amorphous phases were studied with X-rays powder diffraction analysis. Topographic features were examined by scanning electron microscope examination and quantitative analysis was determined using energy-dispersive X-ray spectroscopy analysis. Strong OH stretch of in Raman spectra were observed at 3,697 and 3,615 cm for TCmx and reference, respectively. However, OH mode was not observed for PCmx and PCpw. Moreover, some peaks in the fingerprint areas of TCmx and PCpw overlapped with each other. The characteristic vibration bands of barium sulfate and calcium hydroxide were observed in all samples, and no new peak was observed in the Raman spectra of samples. Calcium hydroxide-based medications were seen as differed in their chemical composition. No new crystalline or amorphous phase peak was observed. Only calcium hydroxide and barium sulfate were matched in X-rays powder-diffraction analysis. Energy-dispersive X-ray spectroscopy analysis showed that amount of Ba and S elements in the PCpw were lower than TCmx and PCmx whereas, for Ca in the PCpw was higher than TCmx and PCmx. The present study revealed the structural difference among different forms of calcium hydroxide-based medications. The vehicle and substrates of the tested medications altered the physicochemical properties of the compound via electrostatic interactions.
PubMed: 32959430
DOI: 10.1002/jemt.23600 -
Journal of Applied Crystallography Oct 2023The room-temperature and low-temperature structure(s) of BaNaNbO (BNN) have been debated since the structure was proposed in the 1960s. This work revisits the structures...
The room-temperature and low-temperature structure(s) of BaNaNbO (BNN) have been debated since the structure was proposed in the 1960s. This work revisits the structures and phase transitions of BNN, combining high-resolution X-ray and neutron powder diffraction with density functional theory calculations. Temperature-dependent high-resolution X-ray powder diffraction patterns are collected from 4 to 918 K, and sequential batch Rietveld refinement using a symmetry mode approach to describe the structure is used to extract the main structural changes as a function of temperature. The data show that the average structure of BNN is best described by the 2 space group, and no other structural phase transitions were observed below the ferroelastic transition. The symmetry mode analysis, combining results from diffraction and density functional theory, shows significant octahedral tilting and corrugations of both the 1 and 2 sites along the direction. A strong correlation between the spontaneous strain and the octahedral tilting was observed, and a potential connection with emerging microstructure at low temperatures is proposed, all enabled by the symmetry mode approach used in this work.
PubMed: 37791369
DOI: 10.1107/S1600576723006969 -
Acta Crystallographica Section B,... Apr 2021Dehydrocoupling of the adduct of dimethylamine and borane, NH(CH)-BH leads to dimethylaminoborane with formal composition N(CH)-BH. The structure of this product depends...
Dehydrocoupling of the adduct of dimethylamine and borane, NH(CH)-BH leads to dimethylaminoborane with formal composition N(CH)-BH. The structure of this product depends on the conditions of the synthesis; it may crystallize either as a dimer in a triclinic space group forming a four-membered ring [N(CH)-BH] or as a trimer forming a six-membered ring [N(CH)-BH] in an orthorhombic space group. Due to the denser packing, the six-membered ring in the trimer structure should be energetically more stable than the four-membered ring. The triclinic structure is stable at low temperatures. Heating the triclinic phase above 290 K leads to a second-order phase transition to a new monoclinic polymorph. While the crystal structures of the triclinic and orthorhombic phases were already known in the literature, the monoclinic crystal structure was determined from powder diffraction data in this study. Monoclinic dimethylaminoborane crystallizes in space group C2/m with the boron and nitrogen atoms located on the mirror plane, Wyckoff position 4i, while the carbon and hydrogen atoms are on the general position 8j.
PubMed: 33843738
DOI: 10.1107/S2052520621001979 -
Crystal Growth & Design Sep 2023The pathological crystallization of ammonium urate inside the urinary tract is a well-documented medical condition; however, structural studies of the biogenic material...
The pathological crystallization of ammonium urate inside the urinary tract is a well-documented medical condition; however, structural studies of the biogenic material have proven challenging owing to its propensity to precipitate as a powder and to exhibit diffraction patterns with widely varying intensities. Using block Rietveld refinement methods of powder diffraction data, here we identify ammonium urate hydrate (AUH) as a likely component in natural uroliths. AUH has a planar 2-D hydrogen-bonded organic framework of urate ions separated by ammonium ions with water molecules residing in bisecting channels. AUH is stable up to 150 °C for short time periods but begins to decompose with prolonged heating times and/or at higher temperatures. Changes in the solid-state structure and composition of synthetic material over a temperature range from 25 to 300 °C are elucidated through thermogravimetric and spectroscopic data, combustion analysis, and time-resolved synchrotron powder X-ray diffraction studies. We contend that biogenic ammonium urate is more accurately modeled as a mixture of AUH and anhydrous ammonium urate, in ratios that can vary depending on the growth environment. The similar but not identical diffraction patterns of these two forms likely account for much of the variability seen in natural ammonium urate samples.
PubMed: 37692332
DOI: 10.1021/acs.cgd.3c00789 -
Molecules (Basel, Switzerland) Nov 2020A large amount of the current literature dedicated to solid states of active pharmaceutical ingredients (APIs) pays special attention to polymorphism of flavonoids....
A large amount of the current literature dedicated to solid states of active pharmaceutical ingredients (APIs) pays special attention to polymorphism of flavonoids. Taxifolin (also known as dihydroquercetin) is an example of a typical flavonoid. Some new forms of taxifolin have been reported previously, however it is still unclear whether they represent polymorphic modifications. In this paper, we tried to answer the question about the taxifolin polymorphism. Taxifolin microtubes and taxifolin microspheres were synthesized from raw taxifolin API using several methods of crystal engineering. All forms were described with the help of spectral methods, scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), and thermal analysis (TA). SEM reveals that the morphology of the solid phase is very specific for each sample. Although XRPD patterns of raw taxifolin and microtubes look similar, their TA profiles differ significantly. At the same time, raw taxifolin and microspheres have nearly identical thermograms, while XRPD shows that the former is a crystalline and the latter is an amorphous substance. Only the use of complex analyses allowed us to put the puzzle together and to confirm the polymorphism of taxifolin. This article demonstrates that taxifolin microtubes are a pseudopolymorphic modification of raw taxifolin.
Topics: Chemistry, Pharmaceutical; Magnetic Resonance Spectroscopy; Molecular Structure; Particle Size; Quercetin; Spectrum Analysis; Structure-Activity Relationship; Thermogravimetry; X-Ray Diffraction
PubMed: 33233608
DOI: 10.3390/molecules25225437 -
Journal of Pharmaceutical Sciences Jan 2023The review summarizes the current state of knowledge of mannitol as an excipient in lyophilized injectable small and large molecule formulations. When compared with... (Review)
Review
The review summarizes the current state of knowledge of mannitol as an excipient in lyophilized injectable small and large molecule formulations. When compared with glycine, the physicochemical properties of mannitol make it a desirable and preferred bulking agent. Though mannitol is a popular bulking agent in freeze-dried formulations, its use may pose certain challenges such as vial breakage or its existence as a metastable crystalline hemihydrate in the final cake, necessitating appropriate mitigation strategies. The understanding of the phase behavior of mannitol in aqueous systems, during the various stages of freeze-drying, can be critical for the optimization of freeze-drying cycle parameters in multi-component formulations. Finally, using a decision tree as a guiding tool, we demonstrate the use of orthogonal techniques for attaining a stable and cost-effective lyophilized drug product containing mannitol.
Topics: Excipients; Mannitol; Freeze Drying; Drug Compounding; Freezing; Sucrose; Calorimetry, Differential Scanning
PubMed: 36030846
DOI: 10.1016/j.xphs.2022.08.029 -
Molecules (Basel, Switzerland) Nov 2021The reinvestigation of tetrazene single crystalline material by means of X-ray methods resulted in a slightly different structure when compared to previously published...
The reinvestigation of tetrazene single crystalline material by means of X-ray methods resulted in a slightly different structure when compared to previously published data. Reaction conditions responsible for different crystalline modification formation were investigated. Newly described C form was found to be the primary reaction product and the combined action of temperature and the presence of water over time is required for the transition to the A form. Both forms were described by X-ray powder diffraction. Tetrazene was also subjected to infrared and Raman spectroscopy, which allowed differentiating between the forms. The molecule was isotopically labeled with N atoms at two different locations (ring and nitrogen sidechain) and employed in assigning vibrational modes to the resulting bands. Differences between sensitivities to mechanical stimuli of the two modifications were investigated and found industrially insignificant. In the same vein, the performance of either modification in primer composition and primer was identical.
PubMed: 34885685
DOI: 10.3390/molecules26237106 -
IUCrData May 2020The crystal structure of di-ammonium potassium citrate, 2NH ·K·CHO , has been solved and refined using laboratory X-ray powder diffraction data and optimized using...
The crystal structure of di-ammonium potassium citrate, 2NH ·K·CHO , has been solved and refined using laboratory X-ray powder diffraction data and optimized using density functional theory. The KO coordination polyhedra are isolated. The ammonium cations and the hydro-phobic methyl-ene sides of the citrate anions occupy the spaces between the coordination polyhedra. Each hydrogen atom of the ammonium ions acts as a donor in a charge-assisted N-H⋯O, N-H⋯(O,O) or N-H⋯(O,O,O) hydrogen bond. There is an intra-molecular O-H⋯O hydrogen bond in the citrate anion between the hydroxide group and one of the terminal carboxyl-ate groups.
PubMed: 36337153
DOI: 10.1107/S2414314620006124 -
Journal of Synchrotron Radiation Mar 2024xrdPlanner is a software package designed to aid in the planning and preparation of powder X-ray diffraction and total scattering beam times at synchrotron facilities....
xrdPlanner is a software package designed to aid in the planning and preparation of powder X-ray diffraction and total scattering beam times at synchrotron facilities. Many modern beamlines provide a flexible experimental setup and may have several different detectors available. In combination with a range of available X-ray energies, it often makes it difficult for the user to explore the available parameter space relevant for a given experiment prior to the scheduled beam time. xrdPlanner was developed to provide a fast and straightforward tool that allows users to visualize the accessible part of reciprocal space of their experiment at a given combination of photon energy and detector geometry. To plan and communicate the necessary geometry not only saves time but also helps the beamline staff to prepare and accommodate for an experiment. The program is tailored toward powder X-ray diffraction and total scattering experiments but may also be useful for other experiments that rely on an area detector and for which detector placement and achievable momentum-transfer range are important experimental parameters.
PubMed: 38306298
DOI: 10.1107/S1600577523011086 -
Pharmaceuticals (Basel, Switzerland) Dec 2022Posaconazole is an API added as Form I for the production of oral suspensions, but it is found as Form-S in the final formulation. In this study, it was found that this...
Posaconazole is an API added as Form I for the production of oral suspensions, but it is found as Form-S in the final formulation. In this study, it was found that this polymorphic conversion, which may affect the bioavailability, is due to an interaction with water. However, the relatively poor wettability of posaconazole Form I renders the complete wetting of its particles and production of pure Form-S challenging. Consequently, for its isolation, Form I should be dispersed in water followed by application of sonication for at least 10 min. Pure posaconazole Form-S was characterised using X-ray powder diffraction (XRPD), Raman spectroscopy, attenuated total reflection (ATR) spectroscopy, thermogravimetric analysis (TGA) and optical microscopy. From these techniques, posaconazole Form-S was characterised as a hydrate form, which includes three molecules of water per API molecule.
PubMed: 36678561
DOI: 10.3390/ph16010065