Refinement of pore size at sub-angstrom precision in robust metal-organic frameworks for separation of xylenes.

The demand for xylenes is projected to increase over the coming decades. The separation of xylene isomers, particularly p- and m-xylenes, is vital for the production of numerous polymers and materials. However, current state-of-the-art separation is based upon fractional crystallisation at 220 K which is highly energy intensive. Here, we report the discrimination of xylene isomers via refinement of the pore size in a series of porous metal-organic frameworks, MFM-300, at sub-angstrom precision leading to the optimal kinetic separation of all three xylene isomers at room temperature. The exceptional performance of MFM-300 for xylene separation is confirmed by dynamic ternary breakthrough experiments. In-depth structural and vibrational investigations using synchrotron X-ray diffraction and terahertz spectroscopy define the underlying host-guest interactions that give rise to the observed selectivity (p-xylene < o-xylene < m-xylene) and separation factors of 4.6-18 for p- and m-xylenes.

Genome-wide analysis of Jatropha curcas MADS-box gene family and functional characterization of the JcMADS40 gene in transgenic rice.

BACKGROUND: Physic nut (Jatropha curcas), an inedible oilseed plant, is among the most promising alternative energy sources because of its high oil content, rapid growth and extensive adaptability. Proteins encoded by MADS-box family genes are important transcription factors participated in regulating plant growth, seed development and responses to abiotic stress. However, there has been no in-depth research on the MADS-box genes and their roles in physic nut. RESULTS: In our study, 63 MADS-box genes (JcMADSs) were identified in the physic nut genome, and classed into five groups (MIKCC, Mα, Mß, Mγ, MIKC*) according to phylogenetic comparison with Arabidopsis homologs. Expression profile analysis based on RNA-seq suggested that many JcMADS genes had the strongest expression in seeds, and seven of them responded in leaves to at least one abiotic stressor (drought and/or salinity) at one or more time points. Transient expression analysis and a transactivation assay indicated that JcMADS40 is a nucleus-localized transcriptional activator. Plants overexpressing JcMADS40 did not show altered plant growth, but the overexpressing plants did exhibit reductions in grain size, grain length, grain width, 1000-seed weight and yield per plant. Further data on the reduced grain size in JcMADS40-overexpressing plants supported the putative role of JcMADS genes in seed development. CONCLUSIONS: This study will be useful in order to further understand the process of MADS-box genes involved in regulating growth and development in addition to their functions in abiotic stress resistance, and will eventually provide a theoretical basis for the functional investigation and the exploitation of candidate genes for the molecular improvement of physic nut.

Two 3D Isostructural Ln(III)-MOFs: Displaying the Slow Magnetic Relaxation and Luminescence Properties in Detection of Nitrobenzene and Cr2O72.

Two new three-dimensional isostructural lanthanide metal-organic frameworks (Ln(III)-MOFs), [LnL(H2O)3]·3H2O·0.75DMF (1-Ln; Ln = Dy(III) and Eu(III) ions, H3L = biphenyl-3'-nitro-3,4',5-tricarboxylic acid, DMF = N,N'-dimethylformamide), were synthesized and characterized. The appearance of temperature-dependent out-of-phase (χ″M) signal reveals that complex 1-Dy displays slow magnetic relaxation behavior with the energy barrier (ΔUeff) of 57 K and a pre-exponential factor (τ0) of 3.89 × 10-8 s at 1200 Oe direct current field. The luminescence explorations demonstrated that 1-Eu exhibits high quenching efficiency and low detection limit for sensing nitrobenzene and Cr2O72-. Meanwhile, the fluorescence intensity of the quenched 1-Eu samples will be resumed after washing with DMF or water, indicating that 1-Eu may be used as a highly selective and recyclable luminescence sensing material for sensing nitrobenzene and Cr2O72- anion.

Four new lanthanide-organic frameworks: selective luminescent sensing and magnetic properties.

Four new isostructural lanthanide-organic frameworks, [Ln(L)(H2O)2]·H2O·CH3CN (1-Ln) (Ln = Eu, Tb, Dy, and Gd), have been successfully synthesized via solvothermal reactions with a semi-rigid V-shaped multicarboxylate ligand 2-(2',4'-dicarboxylphenoxy) benzoic acid (H3L) and Ln(NO3)3·6H2O. 1-Ln shows 2D layer-by-layer frameworks with interlayer channels decorated by carboxylate groups. 1-Eu exhibits excellent luminescence properties, and therefore, is chosen as a probe for sensing different metal ions and anions. Consequently, 1-Eu displays high selectivity and sensitivity for Fe(3+) and Cr(6+) ions, simultaneously, through the luminescence quenching effect, and thus, should be an excellent candidate for probing these pollutant metal ions. In addition, antiferromagnetic exchange interactions also exist between the Dy(3+) ions in 1-Dy.