2-Fold Interpenetrating Bifunctional Cd-Metal–Organic Frameworks: Highly Selective Adsorption for CO₂ and Sensitive Luminescent Sensing of Nitro Aromatic 2,4,6-Trinitrophenol

Abstract

A robust primitive diamond-type topology 3-D metal-organic framework (MOF) of {[Cd₄(hbhdpy)₂(bdc)₃(DMA)₂]·(H₂O)₄}_n (1, DMA = N,N-dimethylacetamide) was constructed from the planar secondary building units of the dinuclear cadmium clusters, Cd₂(μ₂-O)₂, and two linear organic linkers of the new multidentate Schiff base of 4-(2-hydroxy-3-methoxy-benzyli-denehydrazino-carbonyl)-N-pyridin-4-yl-benzamide (Hhbhdpy) through the solvothermal reaction. 1 presents a 2-fold interpenetrating network along with confined narrow channels and rich acylamide groups as well as potential metal open sites for excellent selective CO₂ uptake over CH₄/N₂ and high luminescent response for 2,4,6-trinitrophenol (TNP) in DMA solution under ambient conditions. With 2-amino-1,4-dicarboxy-benzene (H₂bdc-NH₂) replacing H₂bdc, an amine-functionalized MOF of {[Cd₄(hbhdpy)₂(bdc-NH₂)₃ (DMA)₂]·(H₂O)₄}_n (1-NH₂) as an isomorphism of 1, was synthesized under the same reaction conditions. Compared with 1, the corresponding bifunctional features of 1-NH₂ is more obvious. To the best of our knowledge, it is the first reported interpenetrating Cd-MOFs with highly sensitive luminescence response for TNP molecules combined with excellent selectivity for CO₂/N₂ and CO₂/CH₄.