N-oxide-functionalized pillared Cd(II) porous metal−organic frameworks: Gas sorption and luminescent behavior.

Two similar N-Oxide-functionalized pillared Cd(II) metal-organic frameworks (MOFs), {[Cd(dpdcdo)(bpe) 0.5 (H 2 O)]·DMF·H 2 O} n (1) and {[Cd(dpdcdo)(bpe) 0.5 (H 2 O)]·DMA} n (2) [DMF ​= ​N,N-dimethylformamide, DMA ​= ​N,N-dimethylacetamide], have been obtained based on axially chiral 2,2′-dipyridine-3,3′-dicarboxylate-1,1′-dioxide (H 2 dpdcdo) ligand and rigid trans -1,2-bis(4-pyridyl)ethene (bpe) pillar. The N-Oxide group decorated in the channel of the Cd(II)-MOFs could provide effective "open donor sites" to enhance their affinity toward CO 2 molecule. The gas adsorption properties of the Cd(II) framework have been investigated by N 2 , H 2 , CH 4 , and CO 2 gases, and it reveals good CO 2 uptake, CO 2 sorption affinity, and sorption selectivity of CO 2 over CH 4 at ambient temperature. In addition, the solid-state luminescence properties of MOFs 1 and 2 have been conducted at room temperature, and they exhibit luminescent emission upon H 2 dpdcdo ligand. Two similar 3D pillared porous Cd(II) metal−organic frameworks with 1D channels have been synthesized based on an axially chiral N-Oxide functional carboxyl ligand. The gas adsorption behaviors exhibit good CO 2 selectivity over CH 4. The luminescent behaviors display emission upon the N-Oxide functional ligand. [Display omitted] • The pyridine-N-Oxide functional ligand possess superior characteristics than pyridine-N ligand. • Two similar 3D pillared porous Cd(II) MOFs possess 1D channels with N-Oxide donor sites and carboxylic O sites. • The gas adsorption behaviors show good capacity and selectivity for CO 2 over CH 4. • The luminescence behaviors display emission upon the N-Oxide functional ligand. [ABSTRACT FROM AUTHOR]