Crystal structures of 1-(2-hydroxyphenyl)-3-phenyl-1,3-propanedione and 1-(1,3-benzodioxol-5-yl)-3-(2,4-dimethoxyphenyl)-1,3-propanedione

1-(2-Hydroxyphenyl)-3-phenyl-1,3-propanedione crystallizes in the triclinic space group (a=5.4233(5),b=13.910(1),c=17.036(1) Å, =68.311(6), =80.854(7), =78.760(8)°) as two independent enolic tautomers in which the hydroxyl and phenolic protons are hydrogen bonded to the ketonic oxygen atom. The structure was refined toR=0.039 for 2085I3(I) reflections. 1-(1,3-Benzodioxol-5-yl)-3-(2,4-dimethoxyphenyl)-1,3-propanedione, which belongs to the triclinic space group (a=7.3990(7),b=8.1239(5),c=14.004(1) Å, =86.673(6). =88.574(7), =64.885(7)°) also exists in the enolic form. The structure was refined toR=0.040 for 1564I3(I) reflections.     

Pareto-scheduling with family jobs or ND-agent on a parallel-batch machine to minimize the makespan and maximum cost

4OR - We study Pareto-scheduling on an unbounded parallel-batch machine that can process any number of jobs simultaneously in a batch. The processing time of a batch is equal to the maximum...     

Controlled synthesis of Bi- and tri-nuclear Cu-oxo nanoclusters on metal–organic frameworks and the structure–reactivity correlations

Precisely tuning the nuclearity of supported metal nanoclusters is pivotal for designing more superior catalytic systems, but it remains practically challenging. By utilising the chemical and molecular specificity of UiO-66-NH₂ (a Zr-based metal–organic framework), we report the controlled synthesis of supported bi- and trinuclear Cu-oxo nanoclusters on the Zr₆O₄ nodal centres of UiO-66-NH₂. We revealed the interplay between the surface structures of the active sites, adsorption configurations, catalytic reactivities and associated reaction energetics of structurally related Cu-based ‘single atoms’ and bi- and trinuclear species over our model photocatalytic formic acid reforming reaction. This work will offer practical insight that fills the critical knowledge gap in the design and engineering of new-generation atomic and nanocluster catalysts. The precise control of the structure and surface sensitivities is important as it can effectively lead to more reactive and selective catalytic systems. The supported bi- and trinuclear Cu-oxo nanoclusters exhibit notably different catalytic properties compared with the mononuclear ‘Cu₁’ analogue, which provides critical insight for the engineering of more superior catalytic systems.

The controlled synthesis of novel bi- and trinuclear Cu-oxo nanoclusters supported on UiO-66-NH₂ that show notably different catalytic properties in the photocatalytic formic acid decomposition reaction is reported.     

Dynamic Stereochemistry of M8Pd6 Supramolecular Cages Based on Metal-Center Lability for Differential Chiral Induction,Resolution, and Recognition

A series of isostructural supramolecular cages with a rhombic dodecahedron shape have been assembled with distinct metal-coordination lability (M₈Pd₆-MOC-16, M=Ru²⁺, Fe²⁺, Ni²⁺, Zn²⁺). The chirality transfer between metal centers generally imposes homochirality on individual cages to enable solvent-dependent spontaneous resolution of Δ₈/Λ₈−M₈Pd₆ enantiomers; however, their distinguishable stereochemical dynamics manifests differential chiral phenomena governed by the cage stability following the order Ru₈Pd₆ > Ni₈Pd₆ > Fe₈Pd₆ > Zn₈Pd₆. The highly labile Zn centers endow the Zn₈Pd₆ cage with conformational flexibility and deformation, enabling intrigue chiral-Δ₈/Λ₈−Zn₈Pd₆ to meso-Δ₄Λ₄−Zn₈Pd₆ transition induced by anions. The cage stabilization effect differs from inert Ru²⁺, metastable Fe²⁺/Ni²⁺, and labile Zn²⁺, resulting in different chiral-guest induction. Strikingly, solvent-mediated host–guest interactions have been revealed for Δ₈/Λ₈−(Ru/Ni/Fe)₈Pd₆ cages to discriminate the chiral recognition of the guests with opposite chirality. These results demonstrate a versatile procedure to control the stereochemistry of metal-organic cages based on the dynamic metal centers, thus providing guidance to maneuver cage chirality at a supramolecular level by virtue of the solvent, anion, and guest to benefit practical applications.     

Multisim2001在某随动系统电路仿真中的应用

在某随动系统原理教学单元的设计中,应用电路仿真软件Multisim2001对随动系统电路主要工作单 元进行电路仿真,使学员可以在计算机上直接观察到电路运行的过程和结果,并可以通过改变某参数观察结 果的变化。通过这种方法,可以更加直观地学习和了解随动系统的工作原理,提高学习效果,并拓宽知识面。     

Anomalously Large Pockels Effect in ZnO‐F Single Crystalline Films Deposited on Bare Glass

Large linear electrooptics (the Pockels effect) of up to 17 pm/V for the wavelength 435 nm has been observed in ZnO films doped by fluorine and deposited on bare glass. In order to describe the phenomenon observed, a complex approach, including self‐consistent band structure calculations together with the appropriate molecular dynamics simulations of the interfaces, was applied. The origin of the effect observed is linked to substantial charge density non‐centrosymmetry between the wurtzitelike crystalline films and the bare glass substrate, as well as to additional charge density polarisation caused by the fluorine.