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Three new metal-organic frameworks (MOFs), namely, {[Zn 2 (abtc)(bpa)(H 2 O)]·5H 2 O} n (1) , {[Cd 3 (abtc) 2 ]·2H 3 O} n (2) and [Cd 3 (H 2 abtc) 3 (bpp)(μ 2 -OH 2 ) 2 (H 2 O) 3 ] n (3) [bpa = bis(4-pyridyl)amine, bpp = 1,3-bis(4-pyridyl)propane] have been constructed mainly from the ligand of 3,3′,5,5′-azobenzene-tetracarboxylic acid (H 4 abtc) and metal centers of Zn 2+ or Cd 2+ . Single crystal X-ray diffraction analysis reveals that compounds 1 and 2 display 3D frameworks, while compound 3 displays a 2D layered structure consisting of intriguing 1D rhombic chains and bpp ligands. The solid-state luminescent properties of three products are investigated at room temperature. Furthermore, fluorescence measurements indicated that the complex 1 could sensitively sense Fe 3+ ions and nitrobenzene molecules. [ABSTRACT FROM AUTHOR]

A novel metal-organic framework, [Zn(HL)(HO)]·[EMI] ( 1), has been hydro/solvothermally synthesized in the presence of [EMI]Br ionic liquid (IL) (HL = 2,2′,4,4′-quaterphenyl tetracarboxylic acid, EMI = 1-ethyl-3-methylimidazolium). The interesting feature of 1 is that the HL ligands connect Zn(II) ions to afford a fascinating meso-helical chains with left- and right-handed helical loops in one single strand along the c axis, which are further connected by O-H···O hydrogen bonds to generate a 3D supramolecular framework. The free IL [EMI] cations are filled in the voids of the framework. The title complex was characterized by elemental analysis, IR spectra, thermogravimetric analysis, single-crystal X-ray crystallography and powder X-ray diffraction. More interesting, the fluorescence of 1 shows fast and reversible detection of NB vapour, which exhibits its potential as NB sensor. [ABSTRACT FROM AUTHOR]

Abstract: τ-Histidinoalanine, with an unusual cross-link between His and Ala, is the central component of theonellamides, a family of bioactive peptidic natural products. Previous syntheses of this residue were plagued with low regioselectivity in the alkylation step. Herein, we report two novel routes to τ-histidinoalanine, involving alkylation of Boc-His-OMe with a serine-derived β-lactone and β-bromoalanine, respectively, as the electrophiles. The use of Mg(OTf)2 as a catalyst was found to be essential to ensure high regioselectivity for the τ-isomer, presumably due to the formation of a six-membered ring chelation involving the π-nitrogen atom of histidine. [Copyright &y& Elsevier]

Two new coordination polymers (CPs), [InCl(H 2 bidc) 2 (H 2 O)] n ( 1 ) and [Sc(Hbidc)(OH)(H 2 O)] n ( 2 ) (H 3 bidc = benzimidazole-5,6-dicarboxylic acid) were synthesized through a solvothermal approach. 1 exhibits a 1D infinite chain, which further constructs a 3D supramolecular framework via hydrogen bonds. 2 features a 3D supramolecular framework consisting of left- and right-handed chiral layers, which contain the left- and right-handed chiral spiral chains. The adjacent layers stack through π–π stacking interactions between benzene and imidazole rings. 1 exhibits excellent catalytic reactivity for the Strecker reaction and can be recycled four consecutive reactions with more than 95% conversion yields. [ABSTRACT FROM AUTHOR]

To enhance aldose reductase (ALR2) inhibition and add antioxidant ability, phenolic hydroxyl was introduced both to the quinoxalinone core and C3 side chain, resulting in a series of derivatives as ALR2 inhibitors. Biological activity tests suggested that most of the derivatives were potent and selective inhibitors with IC 50 values ranging from 0.059 to 6.825 μM, and 2-(3-(4-hydroxystyryl)-7-methoxy-2-oxoquinoxalin-1(2 H )-yl)acetic acid ( 6b ) was the most active. Particularly, it was encouraging to find that some derivatives endowed with obvious antioxidant activity, and among them the phenolic 3,4-dihydroxyl compound 6f with 7-hydroxyl in the quinoxalinone core showed the most potent activity, even comparable with the well-known antioxidant Trolox. Structure-activity relationship and docking studies highlighted the importance of phenolic hydroxyl both in C3 side chain and the core structure for constructing potent ALR2 inhibitors with antioxidant activity. [ABSTRACT FROM AUTHOR]

Uninuclear europium (Eu), as well as binuclear Eu and terbium (Tb), complexes were synthesized using acrylic acid (AA) as the first ligand and 1,10-phenanthroline (Phen) as the second ligand. The relative weight ratio of the europium (III) (Eu3+) to terbium (III) (Tb3+) ions of the binuclear complex was 1:1 as determined via energy dispersive X-ray analysis. The structures of the Eu(AA)3Phen and Eu0.5Tb0.5(AA)3Phen complexes were characterized by Fourier transform infrared spectroscopy. A series of tri-cellulose acetate (TCA)/ the Eu(AA)3Phen and TCA/Eu0.5Tb0.5(AA)3Phen composites were prepared by solution blending, and their luminescent properties were investigated by fluorescence spectrophotometry. The excitation spectra of all composites indicated that the TCA matrix probably affected the energy absorption and transfer of organic ligands. In TCA/Eu0.5Tb0.5(AA)3Phen composites the introduced Tb3+ions had some influence on energy absorption and transfer of organic ligands; the energy transfer process of the complex is suggested to be as follows: Phen→AA→Tb3+ion→Eu3+ion. The emission spectra indicated that the luminescent intensity of the TCA/Eu0.5Tb0.5(AA)3Phen composites was noticeably stronger than that of the TCA/Eu(AA)3Phen composites, suggesting that the comparatively stable and high-efficiency energy transfer process was only slightly influenced by the TCA matrix. In summary, the TCA/Eu0.5Tb0.5(AA)3Phen (90/10) composite possesses fine luminescent properties for potential usage as red fluorescent materials. [ABSTRACT FROM AUTHOR]

Abstract: A novel, non-acid series of nitroquinoxalinone derivatives was synthesized and tested for their inhibitory activity against aldose reductase as targeting enzyme. All active compounds displayed an 8-nitro group, and showed significant activity in IC50 values ranging from 1.54 to 18.17μM. Among them 6,7-dichloro-5,8-dinitro-3-phenoxyquinoxalin-2(1H)-one (7e), exhibited the strongest aldose reductase activity with an IC50 value of 1.54μM and a good SAR (structure–activity relationship) profile. [Copyright &y& Elsevier]

Abstract: KMgF3 and KMgF3: Eu samples were firstly fabricated by molten salt synthesis (MSS) method in NH4HF2 flux without any surfactants. The NH4HF2 flux was utilized as both the reactant and the fluxing agent. The products with uniform and regular morphologies were characterized by X-ray diffraction (XRD), thermal stability (TG), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectra. The luminescent properties show that the obtained KMgF3 sample got a broad band blue emission at about 430nm arising from the trace oxygen and the color center, and the KMgF3: Eu sample exhibited fantastic emission under the excitation of different wavelengths. [Copyright &y& Elsevier]

A diagram is presented which shows the molecular strucxture of synthesis of chiral α-amino esters through catalysis of carbenoid based bond.