A rigid and porous metal-organic frameworks with 1D rhombus channels and double walls: Selective adsorption of CO2 over N2, iodine capture, and fluorescence

Abstract

A porous metal-organic frameworks (MOFs) of [Cd(pbica)2]·1.5DMF·2CH3OH (1, Hpbica = 2-(pyridin-4-yl)-1H-benzo[d]imidazole-5-carboxylic acid) was synthesized under solvothermal reactions. The compound is constructed from the [Cd2(COO)4N4] secondary building unit (SBU) bridged by a new pyridine-carboxylate dual ligand of pbica−, with a 8-connected bcu net. There are 1D channels with double walls of the ligands and rhombus windows sized at 10.5 × 10.5 Å2, giving a void volume of 45% and permanent porosity to selective adsorb CO2 over N2 at low temperature. The nanosized channels are suitable to capture I2 vapor with a maximal uptake of 0.66 g I2 per gram de-solvated 1, and the housed I2 molecules can be released in ethanol. Solid of 1 exhibits a blue emission at 450 nm, originating from intra-ligand π-π* transformation.