Two Concomitant Polymorphs of 1,2-Naphthoquinone-2-semicarbazone

Heating-Induced Phase Transition of Bupropion Hydrobromide Polymorphs

Rufinamide: Crystal structure elucidation and solid state characterization

[Zn(FZ)2Cl2] (1) (FZ = Voriconazole, (2R,3S)-2-(2,4-difluorophenyl)-3(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-yl)butan-2-ol), has been obtained through the reaction of zinc chloride and FZ and has been characterized by FT-IR, UV–vis and fluorescence spectra, elemental analysis (EA), single crystal X-ray diffraction, powder X-ray diffraction and thermogravimetric analysis (TGA). FZ was also characterized by FT-IR, UV–vis spectra, single crystal X-ray diffraction and TGA. FZ crystallizes in the chiral space group P21 and 1 crystallizes in chiral space group P1 with a mononuclear structure. In 1, there are three kinds of hydrogen bonding interactions and weak stacking interactions which generate a 3-D architecture. The primary antimicrobial results show that 1 exhibits potent activity against Aspergillus (Aspergillus niger, Aspergillus terreus, Aspergillus fumigatus and Aspergillus flavus) and Candida species (Candida albicans, Candida krusei, Candida glabrata and Cryptococcus neoformans), higher than that of free FZ. Fluorescence spectra of 1 and FZ have been discussed.

Synthesis and Properties of Erbium Isopropoxides: Structural Characterization of Er5O(OPri)13

The liquid-mediated phase transformation of an amorphous form to a crystalline heptahydrate form of guanosine 5′-monophosphate was studied in antisolvent crystallization using methanol–water mixtures as solvents. Three steps were monitored: the formation of the amorphous form, dissolution of the amorphous form, and growth of the heptahydrate crystals using in situ Raman spectroscopy, focused beam reflectance measurement (FBRM), and particle vision measurement (PVM) and off-line methods like viscosity, thermal gravimetric analysis (TGA), and powder X-ray diffraction (PXRD). Effects of the antisolvent fraction, initial concentration, and addition rate of the antisolvent on the transformation process were discussed. Solid forms, solute concentration, particle size, counts, induction time, metastable zone width, solution viscosity, and amorphous slurry viscosity were all measured for 18 experiment runs. The induction time of the crystalline hydrate increased with the supersaturation but decreased with the increasing viscosity of the amorphous slurry. Both are not as expected. The induction time correlates nicely in the opposite direction with the viscosity of the amorphous slurry concentration. The amorphous slurry viscosity is about 20 times higher than the solution viscosity. Viscosity of the amorphous slurry was discovered to be a crucial factor influencing the transition of the amorphous slurry to the crystalline form in the pre-exponential component of the classical nucleation rate equation. The metastable zone boundaries of the amorphous and heptahydrate crystalline forms were shown in a plot of the solute concentration versus the mass fraction of methanol in the mixed solvent. The amorphous and heptahydrate crystalline forms can be selectively produced under all the conditions of this study. The pre-exponential factor of the nucleation rate equation factor is crucial in comprehending the transformation from an amorphous to a crystalline state.

The molten reaction of 2-naphthol, 4-(aminomethyl)pyridine, and 4-pyridinecarboxaldehyde at about 180 degrees C yields trans-2,3-dihydro-2,3-di(4'-pyridyl)benzo[e]indole (1) which possesses two chiral centers, rather than an expected Betti-type reaction product with only one chiral carbon center. The same reactions, using 3-pyridinecarboxaldehyde, 4-cyanobenzaldehyde, or 3- cyanobenzaldehyde instead of 4-pyridinecarboxaldehyde produce the related compounds trans-2,3-dihydro-2-(4'-pyridyl)-3-(3"-pyridyl)benzo[e]indole (2), trans-2,3-dihydro-2-(4'-pyridyl)-3-(4"-cyanophenyl)benzo[e]indole (3), and trans-2,3-dihydro-2-(4'-pyridyl)-3-(3"-cyanophenyl)benzo[e]indole (4), respectively. This reaction proceeds with a high degree of stereoselectivity with a trans/cis ratio of about 98:2 at elevated temperature. Compounds 1, 2, and 4 crystallize in a noncentrosymmetric space group (Pca2(1), Pca2(1), and Cc), while compound 3 has a chiral space group (P2(1)). These successfully acentric packing arrangements are probably due to the molecule bearing both two chiral centers and potential hydrogen-bonding groups. Furthermore, the reaction of racemic 6-hydroxy-2'-methyl-2-naphthaleneacetic acid with ethyl-2-cyano-1-(4'-pyridyl)acrylic acetate in the presence of piperidine gives 1-pyridyl-2-ethoxycarbonyl-3-amino-1H-naphtho[2,1-b]pyran-2'-methylacetic acid (5), which likewise crystallizes in a chiral space group. All of compounds are second harmonic generation (SHG) active, and have a very strong SHG response approximately about 8.0, 5.0, 12.0, 6.0, and 1.4 (for 1-5 compounds) times that of urea. Ferroelectric property measurements indicate that compounds 1, 2, 4, and 5 may display ferroelectric behavior.

The spontaneous addition of water to diphenyl- and to dimethyl-ketene in dioxane–H2O and dioxane–D2O mixtures is third order in the stoicheiometric water concentration, [H2O]s, when [H2O]s≲ 1.5M. At higher water concentrations (up to 19M) the observed order falls, and the patterns of the results for the two ketenes are similar, but differ in detail. The isotope effect kH2O/kD2O= 1.7–2.3 for all the systems studied. The addition of ethanol to diphenylketene in dioxane–ethanol mixtures has a kinetic pattern very similar to that for addition of water to this ketene, except that the change to a lower order occurs when [EtOH]S≃ 5M. The variation of the activation parameters with medium composition is also very similar for all these spontaneous additions: at low water or ethanol concentrations Ea= 1 ± 1 kcal mol–1, and ΔS‡=–60 ± 8 cal K–1 mol–1; at higher concentrations Ea rises somewhat, and ΔS‡ becomes less negative. The results are considered in the light of previous work. It is concluded that water and alcohol add to ketenes by a common mechanism in non-hydroxylic solvents of low dielectric constant, and that this involves a cyclic, hydrogen-bonded transition state such as (1). Hydroxide ions (ca. 5 × 10–3M) have no effect on the rate of water addition in dioxane, but hydrogen ions have powerful effects: the addition to diphenylketene is inhibited, that to dimethylketene is catalysed. These observations are explained. The isotope effect kH3O+/kD3O+≃ 1.9 for the catalysis. We propose a catalytic mechanism with a cyclic transition state (3) involving a dominant slow proton transfer to the ketene β-carbon atom.

Formation of bowl-shaped nanoparticles by self-assembly of cinnamic acid-modified dextran

Polymorphic behavior of an NK1 receptor antagonist.

The main objective of the present study was to develop a novel and stable pioglitazone loaded solid dispersions with enhanced solubility and dissolution rate. Different drug-to-carrier ratios were prepared by employing hot melt extrusion technique. These formulations were characterized for solid state properties by differential scanning calorimetry, X-ray powder diffraction and FT-IR spectral studies. Formulations were further evaluated for dissolution and stability studies. The aqueous solubility of pioglitazone, in present formulation was improved by the presence of both the polymers. Solid-state characterization indicated pioglitazone was present as amorphous material in formulation with Soluplus and polyethylene glycol, due to efficient entrapment in polymer matrix. The diffraction patterns of solid dispersion indicated the amorphous nature of pioglitazone in solid dispersions. The dissolution rate of all the solid dispersions was found to be rapid when compared to pure pioglitazone. Pioglitazone in pure form has very slow dissolution rate, when compared with the solid dispersions. Thus the solid dispersion prepared with Soluplus and polyethylene glycol would be useful for delivering poorly soluble pioglitazone with enhanced solubility and dissolution rate. Key words: pioglitazone, soluplus, solid dispersions, melt extrusion technique.

Photoresponsive submicron-sized hollow spheres obtained from amphiphilic azobenzene-containing random copolymer

The field research program involving the development of technology for arid shallow land burial (SLB) sites is described. Results of field testing of biointrusion barriers installed at an active low-level radioactive waste disposal site (Area G) at Los Alamos are presented. A second experiment was designed to test the ability of a capillary barrier to effectively convey water infiltrating a SLB trench around and away from underlying buried wastes. The performance of the capillary barrier was tested in the field for a barrier of known thickness (2 m), slope (10%), and slope length (2 m), and for one combination of porous materials (a crushed tuff-clay (2% w/w) mixture overlying Ottawa sand) subjected to a known water addition rate. The waste management implications of both studies are also discussed.

Characterization, solubility and stability of amentoflavone polymorphs

Two new energetic salts were prepared through the combination of 3,6-dihydrazinyl-1,2,4,5-tetrazine dichloride ([H2DHT]Cl2) and disodium 5,5′-azobis(tetrazolate) pentahydrate (Na2AZT·5H2O) in different pH conditions. Under acidic conditions, the 1:1 salt [H2DHT][AZT]·2H2O (2·2H2O) was isolated, while neutral pH gave access to the formation of the 2:1 salt ([HDHT]2[AZT]·4H2O; 3·4H2O). Both compounds were characterized by IR and NMR spectroscopy, thermal analysis (thermogravimetric analysis and differential scanning calorimetry), as well as single crystal and powder X-ray diffraction. Based on experimental data, compound 2·2H2O was found to be more thermally stable, with a decomposition temperature of Tdec = 107 °C, compared to compound 3·4H2O (Tdec = 99 °C). Non-covalent interactions (hydrogen bonds and π–π interactions) were evaluated to better understand the structure–property relationships, revealing the effect of crystal packing on the overall energetic properties.

Apatinib mesylate (ATM) is an orally administrated anticancer agent for the treatment of advanced gastric cancer. Single-crystal structures of four ATM solid forms, including two anhydrous polymorphs (I and II) and hydrates (HA and HB), were elucidated by single-crystal X-ray diffraction. The properties of these various forms were fully characterized by powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Fourier transform-infrared spectroscopy, and Raman spectroscopy. The discrepant molecule conformations, H-bonding interactions, and packing arrangements in the crystal structures were analyzed associated with the hygroscopicity of forms I and II. Various form transformations induced by either moisture or solution conditions were examined, and the relative stability was established. The results revealed that HA is the most thermodynamically stable form and is superior to the currently marketed form.