A metal–organic framework with dual fluorescent emission based on 3-aminoisonicotinate: luminescence thermometry and Fe3+ sensing in hybrid membranes

Abstract

This work comprises the characterization of a 3D metal–organic framework (MOF), namely, {[Zn(μ-3isoani)₂]·4H₂O}_n, synthesized through the coordination of 3-aminoisonicotinic acid (H3isoani) with Zn²⁺ ions. The assembly of the building blocks resulted in a doubly interpenetrated open 3D crystalline structure with a quartz-like topology that possessed solvent-accessible voids occupied with water molecules. The compound exhibited excellent photoluminescence properties with a dual fluorescent emission arising from the organic molecule as corroborated by calculations using the time-dependent density functional theory (TD-DFT). The independent nature of each emission band with temperature inspired us to study the compound as a ratiometric luminescent thermometer. Notably, it showed the best performance in the 200–300 K range. In addition, the MOF was dispersed in polymethylmethacrylate (PMMA) for the construction of an easy-handled membrane via the solution-casting method for detecting aqueous Fe³⁺ ions with a competitive K_SV value of 3.7 × 10³ M⁻¹ and a limit of detection (LOD) of 2.8 × 10⁻⁵ M.