1-D zigzag double-chain coordination polymers of transition metals derived from pyridine-2,3,5,6-tetracarboxylic acid

Three new 1-D zigzag coordination polymers {[M₂(pdtc)(bpy)₂(H₂O)₃]?·?4H₂O} _n [M?=?Zn (1), Ni (2), Co (3)] (H₄pdtc?=?pyridine-2,3,5,6-tetracarboxylic acid, bpy?=?2,2′-bipyridine) have been synthesized by the reactions of H₄pdtc and corresponding metal salts in the presence of bpy at room temperature and characterized by elemental analyses, IR, TGA, fluorescence, and X-ray diffraction. The main structural feature of 1–3 is the presence of octahedrally coordinated M1(II) and M2(II) centers sequentially bridged by pdtc ligands; bpy acts as a blocking ligand to avoid further polymerization. These coordination modes lead to 1-D double-chain structures. The 2-D or 3-D supramolecular structures of 1–3 are built up by π?···?π and hydrogen-bond interactions. Two (H₂O)₃ clusters are observed in 1–3. The zinc complex shows strong fluorescent emission at 325?nm.     

Catalyst-free three-component approach to efficient synthesis of chromeno[4,3-b]pyrrol-4(1H)-one derivatives

A mild, efficient, and environmentally benign one-pot synthesis of functionalized chromeno[4,3-b]pyrrol-4(1H)-ones by a three-component domino reaction of 4-aminocoumarins, arylglyoxal monohydrates, and 1,3-dicarbonyl compounds in refluxing ethanol without the use of catalyst is reported. The present protocol features operational simplicity, short reaction time, good yields, and the absence of aqueous workup procedure and chromatographic separation.     

Computational insight into asymmetric uranyl‐salophen coordinated with α, β‐unsaturated aldehydes and ketones

The study of the catalytic activity and activation mechanism of asymmetric uranyl‐salophens with α, β‐unsaturated aldehydes or α, β‐unsaturated ketones, is a research hotspot. In this paper, the complexes of the uranyl–salophen(U‐S) modified by unilateral benzene, coordinated with cyclohexenone, cyclopentenone and acrolein, were investigated using density functional theory calculations at the level of B3LYP/6‐311G(d, p) basis set. The results showed that the uranyl‐salophen(U‐S) weakened the large π bond between C = C and C = O of the α, β‐unsaturated aldehydes and ketones, making the unsaturated aldehydes and ketones activated. In addition, the molecular‐recognition selectivity of the asymmetrical uranyl‐salophen for cyclohexenone and cyclopentenone were much higher than for acrolein.     

Ethanol determination in frozen fruit pulps: an application of quantitative nuclear magnetic resonance

This study reports the chemical composition of five types of industrial frozen fruit pulps (acerola, cashew, grape, passion fruit and pineapple fruit pulps) and compares them with homemade pulps at two different stages of ripening. The fruit pulps were characterized by analyzing their metabolic profiles and determining their ethanol content using quantitative Nuclear Magnetic Resonance (qNMR). In addition, principal component analysis (PCA) was applied to extract more information from the NMR data. We detected ethanol in all industrial and homemade pulps; and acetic acid in cashew, grape and passion fruit industrial and homemade pulps. The ethanol content in some industrial pulps is above the level recommended by regulatory agencies and is near the levels of some post‐ripened homemade pulps. This study demonstrates that qNMR can be used to rapidly detect ethanol content in frozen fruit pulps and food derivatives. Copyright © 2015 John Wiley & Sons, Ltd.     

Efficient syntheses of zoledronic acid as an active ingredient of a drug against osteoporosis

The reaction of 1H-imidazol-1-ylacetic acid and two equivalents of phosphorus trichloride/phosphorous acid at 75?°C in sulfolane, or in the presence of catalytic amounts of [bmim][BF₄] afforded zoledronic acid in yields up to 75%. The joint use of the ionic liquid additive and sulfolane as the solvent was synergetic affording highly valuable zoledronic acid in a record yield of 93%.     

Initial lamellar thickness dependency of recrystallization behavior of poly(4‐methyl‐1‐pentene)

The isothermal crystallization and subsequent melting process in semicrystalline poly(4‐methyl‐1‐pentene) were investigated via temperature‐dependent small‐ and wide‐angle X‐ray scattering and Flash DSC techniques. In a phase diagram of inversed crystalline lamellar thickness and temperature, the crystallization and melting lines can be described by two linear dependencies of different slopes and different limiting temperatures at infinite lamellar thickness. Upon subsequent heating, recrystallization lines with different slopes were observed for samples with different lamellar thickness, indicating changes in surface free energy difference between stabilized crystallites and mesomorphic phase. The surface free energy of native crystallites with extended‐chain conformation decreased with increasing lamellar thickness due to a more ordered surface region and less chain ends which changes cooperatively with mesomorphic phase. The surface free energy of stabilized crystallites remained unchanged for all lamellar thickness. Therefore, the recrystallization lines with different slopes are consequences of changes in surface free energy of mesomorphic phase. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 219–224     

A Facile Route to the Synthesis of New 2,3-Disubstituted Benzocoumarins

Triphenylphosphine catalyzes the reaction between 2-hydroxy-1-naphthaldehyde and π-deficient acetylenes to give the newly prepared benzo[f]chromenes. The mechanism for the formation of products is discussed.     

Proton Nuclear Magnetic Resonance Spectrometry-Based Metabolic Characterization of Panax Notoginseng Roots

The radix of Panax notoginseng is an important herbal resource for clinics, commercial markets, and the health industry worldwide. The quality of P. notoginseng roots is known to be associated with its cultivation age. This study used ¹H-nuclear-magnetic-resonance-spectrometry-based metabolic profiling to characterize P. notoginseng roots. Twenty metabolites—including four ginsenosides—contributed to the composition of P. notoginseng according to age. A partial least-squares regression model using a combined data set from two solvent systems was the best predictor of cultivation age. Finally, receiver-operating-characteristic analysis was used to screen potential markers of P. notoginseng root age. These results may be applied to the development of medicinal and nutraceutical products using P. notoginseng roots.