Search

By assembling CoII ions and a combination of 5-(4-pyridyl)tetrazole (4-ptz) and formate ions, two distinct metal-organic frameworks, [Co3(4-ptz)5(HCOO)(H2O)2] and [Co3(4-ptz)4(dmf)2(HCOO)2 ] (dmf= N, N′-dimethylformamide), were synthesized. They were both characterized by single-crystal X-ray diffraction, IR spectroscopy, thermogravimetric analysis, and powder X-ray diffraction. Structural analyses revealed that by slightly modulating the coordination environment of the trinuclear cobalt cluster, two complexes were formed featuring unusual six-connected nets reminiscent of a pyrazole-type linear trinuclear cobalt cluster as compared with the classic eight-connected bcu topology. In addition, [Co3(4-ptz)5(HCOO)(H2O)2] interacted strongly with CO2, with an adsorption enthalpy of 29.2 kJ mol−1, and in a selectivity study, the uptake ratios of CO2/N2 (from a 15:85 mixture) and CO2/CH4 (50:50 mixture) were 77.6 and 37.7, respectively. Magnetic studies on both complexes revealed weak antiferromagnetic coupling between the CoII ions. [ABSTRACT FROM AUTHOR]

In the current research, the moisture-resistant of Mg-MOF-74 was successfully improved by coating with two-dimensional (2-D) hexagonal boron nitride (h -BN) during the facile hydrothermal synthesis process. Both TEM and SEM results revealed that 2-D h -BN is coated on Mg-MOF-74's surface. The crystal structure, morphology, surface area, thermal stability and CH 4 uptake capacity of Mg-MOF-74 were not drastically influenced by coating with h -BN as examined by XRD, FTIR, SEM, and TEM. Further, the coated Mg-MOF-74 demonstrated better stability than uncoated Mg-MOF-74, when being exposed to high humidity, in terms of surface area and CH 4 uptake capacity. It was observed that the coated Mg-MOF-74 with 1 ​wt % h -BN has reached to 1959 ​m2 ​g−1 surface area and CH 4 uptake capacity of 43 ​cm3 ​g−1 after exposure to high humidity for a duration of 1 month. Thus, this research work has opened a new window towards the improvement of the water stability of Mg-MOF-74. [Display omitted] • The water resistance capacity of Mg-MOF-74 could be improved by coating with two dimensional materials h -BN. • Application of h -BN as coating material of Mg-MOF-74. • h -BN coated Mg-MOF-74 provide high surface area and enhanced CH 4 uptake capacity. • The sample Mg-MOF-74@1 wt.% h -BN exhibited the highest water stability. [ABSTRACT FROM AUTHOR]

Three new Cd(II) polymers [Cd 2 (L 240 ) 2 I 4 ] n ( 1 ), [Cd(L 240 )(SCN) 2 ] n ( 2 ), and [Cd(L 240 )(N 3 ) 2 ] n ( 3 ) have been synthesized via the reaction of 3-phenyl-5-(2-pyridyl)-4-(4-pyridyl)-4 H -1,2,4-triazole (L 240 ) with CdI 2 or in the presence of distinct pseudohalide anions (SCN − and N 3 − ). Single-crystal X-ray diffraction indicates that complex 1 features a 1D coordination chain and further forms a 2D supramolecular network extended via π⋯π stacking interactions. Complex 2 shows a 2D layered coordination network and complex 3 has a 3D diamond framework. In complexes 1 – 3 , the Cd II centers adopt the same octahedral geometry, whereas the L 240 ligands show distinct (μ 3 , η 2 ), (μ 4 , η 3 ), and (μ 2 , η 2 ) binding modes, respectively. These results reveal that such polymeric networks can be well modulated by the halide anion (I − ) and pseudohalide anions of SCN − and N 3 − . Thermal stability and fluorescence for complexes 1 – 3 have been studied. [ABSTRACT FROM AUTHOR]

Observations of lamellar like fringes in iron-carbon-filled vertically aligned carbon nanotubes (CNTs) produced by pyrolysis of ferrocene and rapid cooling methodologies (controlled quenching) have been investigated. The quantitative phase analysis of encapsulated Fe3C, γ-Fe, and α-Fe by X-ray diffraction reveals that controlling the phase-percentage leads to control of the crystal habit and of magnetic properties. Large coercivities and variable saturation magnetizations were observed. In addition, we reported a thorough study of the hysteresis behavior, the Barkhausen effect which has to be possibly associated with the formation of interfacial-defects in the crystal areas in contact with CNT layers. [ABSTRACT FROM AUTHOR]

The stabilization of γ-Fe inside carbon nanotubes (CNTs) and its magnetic-coupling with α-Fe or Fe 3 C has attracted a great interest for the possible control of the hysteresis-loss processes in magnetic hyperthermia. Being interested in exploring further the stabilization-dynamics of this phase (γ-Fe), we have performed novel investigations on the fabrication and manipulation of filled CNTs films (buckypapers) with major focus on the effects of vapour-flow- and cooling-rate synthesis-parameters. X-ray diffractograms (XRD) and Rietveld refinements evidence an unusual stabilization of γ-Fe upon cooling, with a maximum relative abundance of 26 % after a slow-cooling step of 30 min. In-situ post-growth manipulation of the CNT-structure, in presence of tris(tetramethylcyclopentadienyl)‑gadolinium (III), allows for a particularly efficient functionalization of the CNT-walls, with in-situ surface-deposition of an amorphous Gd-phase. The rapid-cooling approach employed in the post-growth Gd-functionalization-step is found to have beneficial effects on the γ-Fe stabilization, with an enhanced relative abundance of 30 %, as extracted from Rietveld refinements. Extended characterization through magnetometry, evidence a dependence of the coercive-field value on both cooling and flow-rate parameters. The reported dataset confirms the existence of a magnetic-coupling within the encapsulated nanocrystals, with the unit-cell-volume being in the order of 45.9 Å3. [Display omitted] • We report a novel investigation on the fabrication and manipulation of filled CNTs. • New insights on the effects of flow- and cooling-rate CVD-parameters are presented. • We show an unusual stabilization of γ-Fe upon-cooling. • Tris(tetramethylcyclopentadienyl)Gd(III) was employed for the CNT-functionalization. • A dependence of the coercive-field value on both cooling and flow-rate is shown. [ABSTRACT FROM AUTHOR]

Sodium praseodymium orthophosphate Na 3 Pr(PO 4 ) 2 was prepared using high temperature molten salt method and structurally characterized by single-crystal X-ray diffraction (SC-XRD) analysis. Its structure can be modeled as a four-dimensional (4D) commensurately modulated structure with orthorhombic superspace group Pca 2 1 (0 1/3 0)000 or as a conventional 3D superstructure description. The structure contains PrO 8 , NaO 6 , NaO 7 and PO 4 polyhedra, which are in six types of linear array along the a -axis. Furthermore, the excitation and emission spectra, decay time and Commission International de l’Éclairage (CIE) chromaticity index of Na 3 Pr(PO 4 ) 2 were studied. Under blue light excitation (468 nm), the powdered Na 3 Pr(PO 4 ) 2 calcined at 1200 °C shows the strongest red emission at around 610 nm, which originates from the 3 P 0 → 3 H 6 and 1 D 2 → 3 H 4 transformations of Pr 3+ ion. [ABSTRACT FROM AUTHOR]

A new benzylisoquinoline alkaloid (•)-N-methoxycarbonyl-norjuziphine (1) was isolated from Litsea cubeba. Its structure was identified by extensively spectroscopic techniques and confirmed by the single-crystal X-ray diffraction analysis. Compound1showed cytotoxicity against HL-60 and MCF-7 cells, with IC50values of 18.1 and 15.0 μM, respectively, comparable to 3.1 and 17.5 μM of the cisplatin (positive control). [ABSTRACT FROM AUTHOR]

The application of colloidal delivery systems for the encapsulation, protection and increased bioavailability of bioactive ingredients has recently gained increasing interest. The aim of this work was to prepare corn protein hydrolysate-based vitamin D 3 (CPH-VD 3 ) nanocomplexes. UV and FT-IR spectra indicated the existence of non-covalent interactions (i.e. hydrogen bonding) between CPH and VD 3 . The result from X-ray diffraction further suggested the formation of amorphous structure of VD 3 after its complexation with CPH. Additionally, dynamic light scattering and transmission electron microscope showed that the CPH-VD 3 complexes exhibited a spherical structure with a size scale from 102 to 121 nm. The encapsulation and loading efficiency of VD 3 could reach 97% and 9%, respectively. Furthermore, the complexation obviously avoided spontaneous particle aggregation of VD 3 against ionic strength ([NaCl] ≤ 200 mmol/L). The remaining ratio of the encapsulated VD 3 after exposure to high levels of UV light was as high as 72%. More importantly, in vitro bioaccessibility of VD 3 could be up to 95% for the complexes. This study demonstrated that CPH could serve as a novel nano-vehicle for VD 3 and it opens up the possibility of using CPH to construct the colloidal delivery system. [ABSTRACT FROM AUTHOR]

Nine selaginellin derivatives, including a novel isoquinoline-type selaginellin named selaginisoquinoline A ( 1 ), and three ethoxy selaginellins P–R ( 2 – 4 ), were isolated from the plant of Selaginella pulvinata . Their structures were determined by extensive spectroscopic analyses, and single-crystal X-ray diffraction, as well as CD calculations. Selaginisoquinoline A ( 1 ) is a racemate due to quinone methide-phenol tautomerism; while in the case of selaginellins P–R ( 2 – 4 ), whose tautomerism was blocked by alkylation of C10–OH, the interesting racemization process is induced by axial chirality and molecular rotation, thus existing as a pair of slowly interconverting enantiomers. Compounds 3 , 5 and 9 showed moderate cytotoxicity against BGC-823 human gastric cancer cell line. All compounds, including four enantiomers, exhibited good antifungal activities against four pathogenic fungi cell lines with MIC 80 values in the range of 4–32 μg/mL. [ABSTRACT FROM AUTHOR]

Ta (3.3 nm)/- (3.3 nm) integrated films deposited on substrates by magnetron sputtering, annealed at various temperatures in a ultra-high vacuum, have been studied as diffusion barrier layers between and for application in interconnection. The images of transmission electron microscopy (TEM) prove that the cross-sectional interfaces of //-/ sample annealed at 600°C are clear and sharp. No -silicide peaks can be found from the X-ray diffraction (XRD) patterns of the 850°C annealed sample, but the sheet resistance of the sample increases abruptly. Moreover, large grooves are found from the image of atomic force microscopy (AFM) for the 850°C annealed sample, implying the failure of the diffusion barrier. The integrated /- barrier layer retains thermally stable nature up to at least 800°C, indicating that the /- integrated film is an excellent diffusion barrier between and . [ABSTRACT FROM AUTHOR]