A gadolinium MOF acting as a multi-responsive and highly selective luminescent sensor for detecting o-, m-, and p-nitrophenol and Fe3+ ions in the aqueous phase

Abstract

A microporous Gd-MOF, [Gd₆(L)₃(HL)₂(H₂O)₁₀]·18H₂O·x(solvent) (1), has been successfully synthesized by a solvothermal reaction between Gd(NO₃)₃·6H₂O and the multidentate π-conjugated ligand, H₄L, which has a Lewis basic pyridyl site (H₄L = 5,5′-(pyridine-2,5-diyl)-isophthalic acid). The crystal structure shows that compound 1 consists of Gd₃ units, which are further interlinked by multicarboxylate ligands to form a 2D network. A solid sample of 1 emits bright blue light, which can be assigned to H₄L ligand-centered emission. Interestingly, the luminescence of finely ground particles of 1 dispersed in water shows high sensitivity and selectivity towards trace amounts of o-, m-, and p-nitrophenol (NP) and Fe³⁺ ions with good linearity, which indicates that 1 can be used as a multi-responsive luminescence sensor for the detection of o-, m-, and p-NP and Fe³⁺ ions in an aqueous system.