Dinuclear Cu(II) complexes based on p‐xylylene‐bridged bis(1,4,7‐triazacyclononane) ligands: Synthesis,characterization, DNA cleavage abilities and evaluation of superoxide dismutase‐ and catalase‐like activities

Three new dinuclear Cu(II) complexes with the formulas [Cu₂(pxdmbtacn)Cl₄] ( 1 ), [Cu₂(pxdmbtacn)Cl_0.7(NO₃)_1.3(OH)₂(H₂O)_1.3]?6H₂O ( 2 ) and [Cu₂(pxdiprbtacn)Cl₄] ( 3 ) together with one previously reported complex, [Cu₂(pxbtacn)Cl₄] ( 4 ), were obtained from Cu(II) salts with three p‐xylylene‐bridged bis‐tacn ligands bearing pendant alkyl substituents or without pendant group. Complex 2 was structurally characterized as a centrosymmetric dinuclear molecule with each metal center being coordinated to some labile ligands in addition to one tacn ring. Based on the results of mass spectrometry and UV–visible spectroscopy, complexes 1 and 3 are capable of existing in aqueous solution as dinuclear species but 4 can partially form a dimer of the original dinuclear motif. Complexes 1 , 3 and 4 can all effectively cleave supercoiled DNA oxidatively in the presence of hydrogen peroxide. The superoxide dismutase (SOD) activities of 1 and 3 measured under physiological conditions are comparable to that of the native CuZnSOD enzyme but the enzymatic activity of 4 is about three‐ to fourfold lower. Furthermore, complexes 1 , 3 and 4 demonstrate moderate scavenging effect on hydrogen peroxide and their catalase activities are in the decreasing order of 3 > 1 > 4 .     

The first chlorogenic acid ester saponin from <Emphasis Type="Italic">Lonicera macranthoides</Emphasis>

An original triterpenoid saponin, named lonimacranthoide I, was isolated from the flower buds of Lonicera macranthoides (Caprifoliaceae). It has hederagenin as aglycone. Lonimacranthoide I is a rare chlorogenic acid ester acylated at C-23 of hederagenin. The structure of the saponin was established based on chemical and spectral methods.     

Facile Regioselective Synthesis of 5‐Hydroxy‐4,5‐dihydroisoxazoles from Acetylenic Ketones

5‐Hydroxy‐4,5‐dihydroisoxazoles were synthesized conveniently in good yields by tandem conjugate addition‐cyclization reaction of acetylenic ketones and hydroxylamine hydrochloride salt.     

Photochemical studies on acyclic alkyl aromatic ketones in the solid state: asymmetric induction and increased chemoselectivity

The acyclic alkyl aromatic ketones, 2-isobutyl-4-methyl-1-arylpentan-1-one derivatives were designed and synthesized for photochemical investigations. Irradiation of such compounds in acetonitrile solution led to the Yang cyclization and Norrish type II cleavage photoproducts with a ratio of 1:1, whereas the reaction conducted in the solid state using the ionic chiral auxiliary method led to only the Yang cyclization product with as high as 99% ee. Furthermore, the conformational transitions were first observed in the reaction.     

Correction to: Theoretical modeling and experimental evaluation of a magnetostrictive actuator with radial-nested stacked configuration

Nonlinear Dynamics -     

Uncertain random data envelopment analysis for technical efficiency

Fuzzy Optimization and Decision Making - Data envelopment analysis (DEA) is a classical and prevailing tool for estimating relative efficiencies of multiple decision making units (DMUs). However,...