Facile Layer Diffusion Technique for Synthesis of Terbium-Based Metal Organic Framework for Fluorometric Sensing of Hydroquinone

Abstract

Abstract A photoluminescent terbium(III)-based Metal Organic Framework (MOF) was synthesized at room temperature by layer diffusion method utilising mixed carboxylate linkers (4,4'-oxybis(benzoic acid) and benzene-1,3,5 tricarboxylic acid). Synthesized MOF has crystalline nature and rod-shaped morphology and is thermally stable up to 455°C. From elemental analysis, Carbon, oxygen, and terbium were all found to be present in the synthesized MOF. The fluorescence emission spectra and theoretical results revealed that carboxylate linkers functioned as sensitizers for Tb(III) photoluminescence which resulted in four distinct emission peaks at 495, 547, 584, and 621 nm corresponding to the transitions 5D4→7F6, 5D4→7F5, 5D4→7F4, and 5D4→7F3. Using synthesized MOF as fluorescent probe, hydroquinone was detected in aqueous medium with a detection limit of 0.048 μM, remarkable recovery (95.6-101.1%), and relative standard deviation less than 2.25%. The quenching phenomenon may be ascribed by electron transfer from synthesized probe to oxidized hydroquinone via carboxylic groups on the surface of MOF, which is further supported by photo-induced electron transfer mechanism. This study introduces a cheaper, faster, and more accurate method for hydroquinone detection.