En-Cui Yang

Post-synthesis of Zr-MOR as a robust solid acid catalyst for the ring-opening aminolysis of epoxides

Zirconosilicate with the MOR topology (Zr-MOR) was successfully prepared using a two-step post-synthesis strategy from pre-dealumination of a H-MOR zeolite and subsequent dry impregnation of Cp2ZrCl2. The incorporated Zr species mainly existed in the form of isolated tetrahedrally coordinated Zr in the MOR framework. It was found that the mechanism of the post-synthetic incorporation of Zr involved interaction between the Cp2ZrCl2 molecules and silanols at defects generated by steaming and acid treatment. In comparison with Ti- and Sn-silicate analogues, the as-synthesized Zr-MOR zeolite showed high activity and regioselectivity in the ring-opening aminolysis of epoxides to β-amino alcohols under ambient and solvent-free conditions, which was related to the impact of the Lewis acid sites of the catalysts, the basicity of the amines and competitive adsorption of the reactant molecules. Moreover, the Zr-MOR zeolite could be reused at least five times without loss of activity and regioselectivity.

A dynamic microporous magnet exhibiting room-temperature thermal hysteresis, variable magnetic ordering temperatures and highly selective adsorption for CO2

A dynamic microporous magnet shows reversible temperature-tuned single-crystal-to-single-crystal transformations by stepwise losing of coordinated and lattice water molecules, exhibiting an unusually observed room-temperature hysteresis loop, variable magnetic ordering temperatures and high adsorption selectivity for CO2 over N2.

Oximato-derived metal complexes with triangular and linear magnetic subunits: Synthesis, structure, and magnetism

ABSTRACT Three oximato-based oligomeric metal complexes, {[Cu3(H2O)(µ3-OH)(mpko)3(NO3)]·3H2O·NO3} (1), {[Cu6(μ3-OH)2(mpko)6(Br)4]·8H2O} (2), and {[Fe3(mpko)6]·ClO4·2.5CH3CN} (3) (mpkoH = 1-(pyrazin-2-yl)ethanone oxime), were synthesized by varying different spin carriers, and structurally and magnetically characterized. Structural determinations reveal that 1 is a discrete triangular {Cu3(μ3-OH)}5+ molecule with two adjacent metal ions further bridged by chelating-bridging mpko− ligands. Complex 2 features a centrosymmetric hexanuclear entity with two triangular {Cu3(μ3-OH)}5+ subunits extended by a pair of bridging μ-Br− anions. By contrast, 3 exhibits an approximately linear trinuclear entity with central FeIII ion connected with two external FeII ions by six crystallographically unique mpko− ligands. Strong antiferromagnetic interactions with the coupling constant up to 223(1) cm−1 are observed in the triangular subunits of 1 and 2. In 3, the central FeIII ion with S = 5/2 is almost magnetically isolated with the terminal FeII ions with S = 0.

Two 3-Amino-1,2,4-triazole-based Manganese(II) Complexes Incorporated With Different Dicarboxylate Coligands: Synthesis, Structure, and Magnetism

Two 3-amino-1,2,4-triazole (Hatz)-based magnetic complexes, {[Mn3(H2O)2(Hatz)2(sip)2]·2H2O}n (1) and {[Mn(H2O)3(Hatz)(bda)]·H2O}n (2) (sip3− = 5-sulfoisophthalate and bda2− = trans-butenedioate), were respectively prepared by varying dicarboxylate-containing coligands, and were structurally and magnetically characterized. Structural determinations reveal that 1 exhibits a two-dimensional layered structure with linear {Mn3(μ-N1,N2-Hatz)2}6+ subunits extended by tritopic sip3− connectors. By contrast, 2 is an infinite zigzag chain constructed from octahedral Mn(II) ions and μ-N1,N4-Hatz linkers. Magnetically, typically antiferromagnetic interaction observed in the local MnII3 subunit of 1 mediated by mixed μ-syn, syn-COO− and μ-N1,N2-Hatz heterobridges is slightly stronger than that of 2 transmitted by single μ-N1,N4-Hatz mediator.