A Dihydropyridine Derivative as a Highly Selective Fluorometric Probe for Quantification of Au3+ Residue in Gold Nanoparticle Solution

Novel dihydroquinoline derivatives (DHP and DHP-OH) were synthesized in one pot via a tandem trimerization-cyclization of methylpropiolate. DHP and DHP-OH possess strong blue fluorescence with high quantum efficiencies over 0.70 in aqueous media. DHP-OH displays a remarkable fluorescence quenching selectively to the presence of Au3+ through the oxidation of dihydropyridine to pyridinium ion as confirmed by NMR and HRMS. DHP-OH was used to demonstrate the quantitative analysis of Au3+ in water samples with the limit of detection of 33 ppb and excellent recovery (>95%). This fluorescent probe was also applied for the determination of Au3(+) residue in the gold nanoparticle solution and a paper-based sensing strip for the on-site detection of Au3(+).

Automated summary

Novel dihydroquinoline derivatives (DHP and DHP-OH) were synthesized in one-pot by the tandem trimerization-cyclization of methylpropiolate. DHP and DHP-OH exhibited strong blue fluorescence (>0.70 quantum efficiency) in aqueous media. DHP-OH showed remarkable fluorescence quenching selectively to Au3+ through oxidation of dihydropyridine to pyridinium ion, as confirmed by NMR and HRMS. DHP-OH was used for quantitative analysis of Au3+ in water samples (limit of detection: 33 ppb, recovery rate: >95%), as well as for detection of Au3(+) residue in gold nanoparticle solution and on-site detection using a paper-based sensing strip.