Chiral Cadmium(II) Metal–Organic Framework from an Achiral Ligand by Spontaneous Resolution: An Efficient Heterogeneous Catalyst for the Strecker Reaction of Ketones

Abstract

A thermally stable cadmium-based chiral metal-organic framework (MOF), {[Cd(L)(HO)(DMF)]·3DMF·2HO} (1; DMF = N,N-dimethylformamide), has been synthesized from an achiral ligand by spontaneous resolution. The MOF features 1D open channels with a large density of active metal sites and has a 3,6-c binodal net with a rare sit 3,6-conn topology. The metal-bound water and DMF solvents could be easily removed along with the guest molecules in the lattice upon activation to afford the desolvated framework 1'. It exhibits microporous nature, as confirmed by the gas-sorption measurements with carbon dioxide uptake of 43.2 cm g at 273 K. The open metal sites in the framework make it an outstanding heterogeneous catalyst in the Strecker reaction for the synthesis of α-aminonitriles in a solvent-free state at room temperature with excellent conversion yields.

Recent Progress in Asymmetric Catalysis and Chromatographic Separation by Chiral Metal–Organic Frameworks

“…Bharadwaj and co-workers [80] recently designed a thermally stable cadmium-based chiral MOF from an achiral v-shaped ligand by spontaneous resolution. The synthesis of bis[4-(3,5dicarboxyphenyl)-1H-3,5-dimethylpyrazolyl] methane (L 10 ) was accomplished in five steps using acetylacetone as the starting material.…”

“…Aoyama and co-workers [73] were the first to establish that homochiral MOFs can be achieved through self-crystallization. They reported an enantiomerically pure MOF, [Cd(L 8 )( Bharadwaj and co-workers [80] recently designed a thermally stable cadmium-based chiral MOF from an achiral v-shaped ligand by spontaneous resolution. The synthesis of bis[4-(3,5dicarboxyphenyl)-1H-3,5-dimethylpyrazolyl] methane (L 10 ) was accomplished in five steps using acetylacetone as the starting material.…”

Chiral Recognition of Racemic Proline based on Chiral Macrocyclic Nickel(II) Complex: Synthesis and Crystal Structures

“…Chiral resolution, occurring during the spontaneous resolution or chiral symmetry breaking, continues to be a subject of great interest in the pharmaceutical industry and material sciences . In our previous report, we observed chiral resolution of β‐ dl –phenylalanine by [Ni( RR ‐L)] 2+ and [Ni( SS ‐L)] 2+ (Scheme ) enantiomers selectively binding β‐ d ‐phenylalanine and β‐ l ‐phenylalanine to form [Ni( RR ‐L)(β‐ d ‐HPhe)](ClO 4 ) 2 and [Ni( SS ‐L)(β‐ l ‐HPhe)](ClO 4 ) 2 (L = 5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane, Phe = phenylalanine), respectively.…”

Syntheses, Structures and Properties of Three Coordination Polymers with 3D Network, 2D Lattice, 1D Ladder Structures

“…So far, the syntheses of chiral or acentric CPs have turned out to be a challenging task. It is particularly important that the rational design and controlled synthesis can originate from the metal centers and the organic ligands with variable geometries, and directional coordination bonds . The coordination of appropriate organic ligands to metal ions can not only give rise to metal‐to‐ligand or ligand‐to‐metal charge transfers, contributing to large second‐order nonlinearities, but also allow the organic chromophores to be arranged in orderly geometries, enabling multidirectional charge transfers and exhibiting interesting photoluminescence properties …”