A Temperature‐Responsive Smart Europium Metal‐Organic Framework Switch for Reversible Capture and Release of Intrinsic Eu³⁺ Ions

Abstract

Stimuli‐responsive structural transformations are emerging as a scaffold to develop a charming class of smart materials. A EuL metal‐organic framework (MOF) undergoes a reversible temperature‐stimulated single‐crystal to single‐crystal transformation, showing a specific behavior of fast capture/release of free Eu3+ in the channels at low and room temperatures. At room temperature, compound 1a is obtained with one free carboxylate group severing as further hook, featuring one‐dimensional square channels filled with intrinsic free europium ions. Trigged by lowering the ambient temperature, 1b is gained. In 1b, the intrinsic free europium ions can be fast captured by the carboxylate‐hooks anchored in the framework, resulting in the structural change and its channel distortion. To the best of our knowledge, this is the first report of such a rapid and reversible switch stemming from dynamic control between noncovalent and covalent Eu–ligand interactions. Utilizing EuL MOF to detect highly explosive 2,4,6‐trinitrophenol at room temperature and low temperature provides a glimpse into the potential of this material in fluorescence sensors.

Crystal structure of poly[bis(μ4-4,4′-(1,2-phenylenebis(oxy))dibenzoato-κ4 O:O′:O′′:O′′′)bis(μ3-4,4′-(1,2-phenylenebis(oxy))dibenzoato–κ3 O:O′:O′′)(μ2-1-(4-((1H-imidazol-1-yl)methyl)benzyl)-1H-imidazole-κ2 N:N′)tetracobalt(II)], C94H62O24N4Co4

“…Molecular building blocks associated with polydentate carboxylic acid are widely used in chiral catalysis, optoelectronic materials, hematopathology, and medicine [6][7][8]. In our laboratory, we synthesized a novel cobalt coordination polymer constructed by polydentate carboxylic acid in combination with 1-(4-((1H-imidazol-1-yl)methyl)benzyl)-1H-imidazole as ancillary ligand.…”

Crystal structure of catena-poly-{aqua-[μ2-1,2-bis((1H-imidazol-1-yl)methyl)benzene-κ2 N:N′]-[μ2-4,4′-(dimethylsilanediyl)dibenzato-κ3 O,O′:O′]nickel(II)}, C30H30N4NiO5Si

“…Generally, the construction of MOFs can be controlled by the deliberate design and judicious choice of the organic ligands, solvents, and metal atoms [5][6][7]. Among them, the organic ligand as well as the coordination geometry of metal centers are especially important in the assembly of novel motifs [8,9]. In this work, we used a bicarboxylate ligand, a N-donor ligands, and Ni…”

Crystal structure of poly-[bis{μ2-N-(4-(1H-imidazol-1-yl)phenyl)-4-(1H-imidazol-1-yl)-N-phenylaniline-κ2 N:N′)}-(μ2-naphthalene-2,6-dicarboxylato)-(μ4-naphthalene-2,6-dicarboxylato)dicadmium(II)], C36H25N5O4Cd

“…It is well known that carboxylates are excellent building blocks for the construction of coordination polymers because the carboxylate groups may induce core aggregation and link these discrete clusters into an extended framework by virtue of its bridging ability [5][6][7][8][9][10]. Taking these into account, we chose naphthalene-2,6-dicarboxylate and N-(4-(1H-imidazol-1-yl)phenyl)-4-(1H-imidazol-1-yl)-N-phenylaniline as neutral ligand, generating the title compound.…”