ABSTRACT
The construction and development of metal-organic nanotubes (MONTs) with nanoscale interior channel diameters for potential applications is of great interest. An angular nitrogen-rich ligand, 3,6-bis(2-ethylimidazole)-2-methylpyrimidine (beim-CH3), was designed to construct MONTs by coupling with the V-shaped carboxylate ligands of benzophenone 4,4'-dicarboxylic acid (H2bpndc) and 4,4'-oxybisbenzoic acid (H2obba). Two new MONTs were synthesized and named NCD-166 ([Zn(bpndc)(beim-CH3)]·H2O) and NCD-167 ([Zn(obba)(beim-CH3)]·H2O), and they were isostructural and have almost identical tube inner diameters of approximately 1.76 nm. Benefiting from the abundantly exposed nitrogen and oxygen atoms in their tube walls and open nanoporous channels, they display superior adsorption capacities for Eu3+ (150.90 mg g-1) and high adsorption selectivity (>96%) in the low-concentration solutions. Additionally, it was revealed that the adsorption effect of ether oxygen on rare earth elements was significantly better than that of carbonyl oxygen. The adsorption isotherm conformed to the Langmuir model and the adsorption kinetics obeyed the pseudo-second-order model. These results clearly indicate that such novel MONTs are favorable sorbents for REEs.
ABSTRACT
It is a significant challenge to construct chiral metal-organic frameworks (CMOFs) by developing a facile and green preparation strategy. In this work, CMOFs were first synthesized via a mechanochemical process by combining a truncated mixed ligand strategy and defect engineering theory. The simple, green, and rapid construction strategy could solvent-freely harvest gram-scale CMOFs with a hierarchical micro/mesoporous structure. The as-synthesized CMOFs were evaluated by Aldol asymmetric catalysis and exhibited excellent catalytic performance (conversion was up to 97.1%, the ee value was 44.3%, and the activity was still good after 5 cycles).
