The second order hyperpolarizability of cis azobenzene isomer

The second order hyperpolarizability of cis azobenzene isomer (γ_c) was obtained by measuring the third harmonic generation (THG) variation of an azobenzene doped polymer film when the film was optically pumped to create a large amount of cis isomers via photoisomerization. A steady state theory was developed to treat the THG intensity variation by considering the optical pump induced redistribution and reorientation of azobenzene in the polymer film and the contribution of cis isomer to the THG signal. The ratio of γ of cis and trans molecule, (γ_c/γ_t), was found to be 0.51. After the γ_t was obtained from the time-resolved optical Kerr effect (OKE) measurement, γ_c was deduced to be 5.6 × 10⁻³³ esu. The result shows that the optical nonlinearity of cis isomer is clearly not negligible.     

Synthesis of novel analogues of zanamivir as neuraminidase inhibitors

<正>A versatile synthesis of novel zanamivir analogues modified at C-4 and C-8 positions was described.The formation of amides from the acid with corresponding amines,followed by click chemistry generated the triazole substituted compounds as novel analogues of neuraminidase inhibitors in good yields.     

Mild Hydrothermal Synthesis and Optical Properties of the Complex Fluoride KMgF_3 Doped with Eu

Perovskite complex fluorides have attracted great interests due to their particular physical properties such as antiferromagnetic characteristics1, photoluminescence behavior2. Complex fluorides are usually prepared by solid state reactions at high-temperature. In spite of inert atmosphere, it is inevitable to contain a bit of oxygen. This has great effect on the luminescent character of rare earth ions. There are also reports about synthesizing some binary fluorides by high-temperature hy…     

Studies on New Additions to 5-Methoxy-2 (5H)-Furanone: 1, 4-Addition of Grignard Reagents, and 1,3-Dipolar Cycloaddition of Silyl Nitronates

Recently, much effort has been made in the development of generally applicable organic synthesis of 5-alkyloxy-2(5H)-furanones due to their essential structure entities in the synthesis of some biologically active natural products and their application as useful intermediates in organic synthesis1. Their reactions such as Michael addition, Diels-Alder reaction and photocatalyzed conjugate addition have been studied extensively2-4.However, Michael addition reaction of Grignard reagents to 5-m…     

An Acid‐Catalyzed Fragmentation Reaction of a Triamine‐Linked Acridine Dimer

An acid‐catalyzed cleavage of the C‐N^? bond from N^?‐(2,3,4,5‐tetrahydroxyvaleryl) substituted side chain and/or its acetonide form of a triamine‐linked acridine dimer is de scribed. An envisaged multi‐neighboring group‐assisted solvolysis reaction mechanism is proposed.     

Characterization of polyphenol compounds from the roots and stems of Parthenocissus laetevirens by high‐performance liquid chromatography/tandem mass spectrometry

A facile method based on high‐performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC/(–)ESI‐MSⁿ) has been established for the analyses of polyphenol compounds in the root and stems of Parthenocissus laetevirens. Two characteristic fragments [C₃O₂ (68 Da) and C₂H₂O (42 Da)] were utilized for the structural identification of polyphenols. Based on the reference standards, the fragment C₃O₂ was presented when the compound possessed a 2,3‐dihydro‐1H‐indene‐4, 6‐diol moiety. Meanwhile, the C₂H₂O fragment (42 Da) yielded from the resorcinol ring was confirmed by resveratrol and three synthesized compounds identified as (E)‐5‐styrylbenzene‐1,3‐diol, (E)‐4‐styrylphenol and (E)‐4‐(3,4,5‐trimethoxystyryl)phenol. FTICR‐MSⁿ was performed to further confirm the structures of the fragments. Overall, 15 polyphenol compounds were characterized. Three polyphenol compounds were initially and tentatively characterized from P. laetevirens for the first time, and one was proposed as a novel compound. Furthermore, a pair of stereoisomers was readily distinguished by breakdown curves, and the trans‐, cis‐isomers could be identified by HPLC/DAD‐UV spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and Disproportionation of Mixed Ligand Indium Organometallics Involving Ethyl and β‐Diketonate Chelate Lig‐ands

Twelve compounds either of type Et₂ln(diket) or Etln(diket)₂ (diket = β‐diketonate) have been synthesized, and all these compounds tend to disproportionate into Et₃ln and ln(diket)₃ at moderately high temperature. Compounds of the latter type are much more thermally stable than those of the former. Moreover, ln(CH₃COCHCOCH₃)₃ has been synthesized and its crystal structure has been determined.     

λ-central BMO estimates for commutators of singular integral operators with rough kernels

The authors establish λ-central BMO estimates for commutators of singular integral operators with rough kernels on central Morrey spaces. Moreover, the boundedness of a class of multisublinear operators on the product of central Morrey spaces is discussed. As its special cases, the corresponding results of multilinear Calderon-Zygmund operators and multilinear fractional integral operators can be deduced, resDectivelv.     

The first two‐dimensional barium coordination polymer based on neutral and deprotonated 4‐formylbenzoic acid

A two‐dimensional barium(II) coordination polymer, [Ba(4‐FBA)₂(4‐FBAH)]_n (4‐FBA^? = 4‐formylbenzoate), has been synthesized by the reaction of barium carbonate and 4‐formylbenzoic acid. The barium(II) ion is nine‐coordinated by eight O atoms from six deprotonated 4‐FBA^? ligands and one O atom from the terminal 4‐FBAH ligand. Adjacent barium(II) ions are linked by the 4‐FBA^? ligand to furnish a two‐dimensional lamellar structure which exhibits blue fluorescent emission in the solid state at room temperature. Copyright © 2007 John Wiley & Sons, Ltd.