Crystal structure and packing analysis of nitrofurantoin N,N-dimethylformamide solvate

The N, N′-dimethylformamide solvated crystal of the drug nitrofurantoin has been prepared and analysed by single-crystal X-ray diffraction. The two co-crystallized molecules, in the 1 : 1 stoichiometric ratio, are linked by a medium/strong N–H···O hydrogen bond (N···O is 2.759 (3) Å) and a weaker C–H···O interaction to form isolated supramolecular adducts, that in turn are packed into the lattice framework mainly through C–H···O hydrogen bonds. Two-dimensional fingerprint plots of Hirshfeld surfaces are used to visualize, analyze and compare intermolecular interactions found in the title compound and in similar structures.     

Trace element concentration differences in regions of human brain by INAA

Studies have shown that there is a potential relationship between the levels of trace elements in cerebral tissues and neurological disorders. However, there are few publications available on the elemental composition of these tissues as well as for different regions of the brain. The aim of this study was to investigate trace element differences in various regions of the human brain from an elderly population of normal individuals. Brain samples from 31 individuals of both genders, aged 51–95 years were provided by the Brain Bank of the Brazilian Aging Study Group of the São Paulo University, Medical School. The tissues from the regions of the hippocampus, cerebellum and frontal, parietal, temporal, occipital cortex were dissected using a titanium knife, ground, freeze-dried and then analyzed by instrumental neutron activation analysis (INAA). Samples and element standards were irradiated with a neutron flux at the IEA-R1 nuclear research reactor for Br, Fe, K, Na, Rb, Se and Zn determinations. One-way ANOVA test (p < 0.05) was used to compare the results which showed significant differences for several elements among the brain regions. Most of our brain analysis results agreed with the literature data. The results were also submitted for brain region classification by cluster analysis.     

Aloe djiboutiensis: Antioxidant Activity,Molecular Networking-Based Approach and In Vivo Toxicity of This Endemic Species in Djibouti

For the first time, the study of the antioxidant activity, the characterization of the phytoconstituants, and the evaluation of in vitro and in vivo toxicity of A. djiboutiensis leave and latex are performed. The antioxidant activity of both latex (ADL) and the methanolic extract of leaves (ADM) is determined using 1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis 3-ethylbenzothiazoline-6-sulphonic acid (ABTS) scavenging radical methods and ferric reducing/antioxidant power (FRAP) assay. The phytochemical study of latex is done using Liquid Chromatography-Mass Spectrometry (LC-MS/MS) and a molecular networking-based approach. The evaluation of in vivo toxicity is performed on mice by oral gavage with a suspension of ADL. Our results show that weak antioxidant activity of ADL and ADM in opposition to their high polyphenol, 83.01 mg and 46.4 mg expressed in gallic acid equivalent (GAE)/g of dry weight (DW), respectively, and flavonoid contents 13.12 mg and 4.25 mg expressed in quercetin equivalent (QE)/g dry weight (DW), respectively. Using the Global Natural Products Social Molecular Networking (GNPS) website, nine (9) anthraquinones derivatives, ten (10) chromones derivatives, two (2) flavonols/ chromones isomers are annotated in the molecular network. The treated mice do not display abnormalities in their general physical appearance and biochemistry parameters, compared to the controls. Only glucose and calcium levels are slightly higher in male treated mice compared to the vehicles.     

Mixing of electronic states in pentacene adsorption on copper

By combining experimental and theoretical approaches, we study the adsorption of pentacene on copper as a model for the coupling between aromatic molecules and metal surfaces. Our results for the interface electronic structure are not compatible with a purely physisorption picture, which is conventionally employed for such systems. Nay, we demonstrate electronic mixing between molecular orbitals and metal electronic states.     

Direct separation of the enantiomers of ramosetron on a chlorinated cellulose‐based chiral stationary phase in hydrophilic interaction liquid chromatography mode

Ramosetron is an enantiopure active pharmaceutical ingredient marketed in Japan since 1996 and later in a few Southeast Asian countries predominantly as an antiemetic for patients receiving chemotherapy. In this study, a simple and rapid high‐performance liquid chromoatography method for the separation of ramosetron and its related enantiomeric impurity by using hydrophilic interaction liquid chromatography mode is presented. Chiral resolution was performed on an analytical column (100 mm × 4.6 mm id) packed with 3 μm particles of cellulose‐based Chiralpak IC‐3 chiral stationary phase. Using a mobile phase containing acetonitrile–water–diethylamine (100:10:0.1, v/v/v) and setting the column temperature at 35°C, the resolution value was 7.35. At a flow rate of 1 mL/min, the enantioseparation was completed within 5 min. The proposed method was partially validated and it has proven to be sensitive with limit of detection and limit of quantitation of the (S)‐enantiomer impurity of 44.5 and 133.6 ng/mL.     

Thermodynamic and Pseudo Binary Phase Diagram of REBa2Cu3O7-x-"Ba2Cu5O7" systems

In this work the effect of oxygen pressure on the primary crystallisation fields for REBa₂Cu₃O_7-x(RE=Nd, Sm, and Eu) has been studied. A DTA apparatus has been modified in order to carry out analyses under gas pressure, so the trend of temperatures of peritectic decomposition of the REBa₂Cu₃O_7-xphases and of the eutectic equilibrium involving REBa₂Cu₃O_7-x phases and flux mixture "Ba₂Cu₅O₇" have been studied at oxygen pressures of 0.21, 1, and 10 atm. This showed that primary crystallisation fields spread at the increase of the oxygen pressure and allowed us to calculate the enthalpies of reactions of REBa₂Cu₃O_7-xphases too. This revised version was published online in July 2006 with corrections to the Cover Date.