Stable Indium-Pyridylcarboxylate Framework: Selective Gas Capture and Sensing of Fe³⁺ Ion in Water

Abstract

By employing a pyridyl-decorated dicarboxylic acid ligand, 3-(2',5'-dicarboxylphenyl)pyridine acid (H₂dcpy), a three-dimensional In³⁺-based metal-organic framework, H₃O[In₃(dcpy)₄(OH)₂]·3DMF·4H₂O (1), with a good chemical stability toward acid and base has been synthesized. The compound 1 shows an uncommon (3,8)-connected tfz-d; UO₃ topological net based on linear In₃(COO)₄(OH)₂ clusters and also contains one-dimensional open channels. Particularly, 1 contains two types of dcpy^2- linkers, in which the pyridyl group in one participates in coordination with the In³⁺ ion, whereas that in the other is uncoordinated but hangs in the inner sides of the channels as functionalized sites. Gas adsorption experiments demonstrate that 1 is able to selectively adsorb C₂H₂, C₂H₄, and CO₂ over CH₄. Simultaneously, 1 shows a highly selective and sensitive fluorescence detection toward Fe³⁺ ion in water with good recyclability.