The Influence of Halide Substituents on the Structural and Magnetic Properties of Fe6Dy3 Rings

Accurate binding of porous aluminum molecular ring catalysts with the substrate

Metal molecular rings are a class of compounds with aesthetically pleasing symmetry and fundamentally useful properties. The reported work generally focuses on the ring center cavity, and there is little known about those on the ring waist. Herein, we report the discovery of porous aluminum molecular rings and their performance and contribution to the cyanosilylation reaction. We develop a facile ligand induced aggregation and solvent regulation strategy towards AlOC-58NC and AlOC-59NT with high purity, high yield (75% and 70%, respectively) and gram-level scale-up. These molecular rings exhibit a "two-tier" pore feature involving the general central cavity and newly observed equatorial semi-open cavities. AlOC-59NT with two types of one-dimensional channels showed good catalytic activity. The interaction of the aluminum molecular ring catalyst with the substrate has been crystallographically characterized and theoretically confirmed, showing a ring adaptability process that involves the capture and binding of the substrate. This work provides new ideas for the assembly of porous metal molecular rings and to understand the overall reaction pathway involving aldehydes and is expected to inspire the design of low-cost catalysts through structural modifications.

Crystal structures of three β-halolactic acids: hydrogen bonding resulting in differing Z′

The crystal structures of three β-halolactic acids have been determined, namely, β-chlorolactic acid (systematic name: 3-chloro-2-hydroxypropanoic acid, C3H5ClO3) (I), β-bromolactic acid (systematic name: 3-bromo-2-hydroxypropanoic acid, C3H5BrO3) (II), and β-iodolactic acid (systematic name: 2-hydroxy-3-iodopropanoic acid, C3H5IO3) (III). The number of molecules in the asymmetric unit of each crystal structure (Z′) was found to be two for I and II, and one for III, making I and II isostructural and III unique. The difference between the molecules in the asymmetric units of I and II is due to the direction of the hydrogen bond of the alcohol group to a neighboring molecule. Molecular packing shows that each structure has alternating layers of intermolecular hydrogen bonding and halogen–halogen interactions. Hirshfeld surfaces and two-dimensional fingerprint plots were analyzed to further explore the intermolecular interactions of these structures. In I and II, energy minimization is achieved by lowering of the symmetry to adopt two independent molecular conformations in the asymmetric unit.

Terminal Ligand and Packing Effects on Slow Relaxation in an Isostructural Set of [Dy(H2 dapp)X2 ]+ Single Molecule Magnets*

We report three structurally related single ion Dy compounds using the pentadentate ligand 2,6-bis((E)-1-(2-(pyridin-2-yl)-hydrazineylidene)ethyl)pyridine (H2 dapp) [Dy(H2 dapp)(NO3 )2 ]NO3 (1), [Dy(H2 dapp)(OAc)2 ]Cl (2) and [Dy(H2 dapp)(NO3 )2 ]Cl0.92 (NO3 )0.08 (3). The (H2 dapp) occupies a helical twisted pentagonal equatorial arrangement with two anionic ligands in the axial positions. Further influence on the electronic and magnetic structure is provided by a closely associated counterion interacting with the central N-H group of the (H2 dapp). The slow relaxation of the magnetisation shows that the anionic acetates give the greatest slowing down of the magnetisation reversal. Further influence on the relaxation properties of compounds1 and 2 is the presence of short nitrate-nitrate intermolecular ligand contact opening further lattice relaxation pathways.