Two birds with one arrow: a functionalized Al(iii) MOF acts as a fluorometric sensor of dopamine in bio-fluids and a recyclable catalyst for the Biginelli reaction

Abstract

The appropriate and reliable detection tool for dopamine is still beyond the reach of modern pharmaceutical researchers. To fulfill this concern, herein, we have developed a bio-friendly, aqua-stable boronic acid functionalized Al(III) metal–organic framework (MOF) for ultra-low-level selective “turn-on” detection of dopamine with high sensitivity (limit of detection (LOD) = 3.5 nM). It is the first structurally well-characterized CAU-10 MOF for turn-on fluorescence sensing of dopamine. The material is not only able to detect dopamine in aqueous and HEPES buffer solutions but also has the ability to detect dopamine in real samples (e.g. human blood serum and urine). A cost-effective sensor paper strip was developed for the rapid and on-site detection of this neurotransmitter. The formation of a five membered chelate complex due to the nucleophilic attack of the –OH groups of dopamine on the empty p_π-orbital of the B atom of the boronic acid group is the most possible reason for an increase in the emission intensity of the material, which was also confirmed by different analytical techniques. Furthermore, the catalytic activity of the material was checked for the Biginelli condensation reaction of benzaldehyde, ethylacetoacetate and urea towards the synthesis of dihydropyrimidinones. The functionalized MOF exhibited remarkable activity and recyclability towards the catalytic reaction.