A novel magnetic fluorescent chemosensor for Cu2+ based on self-assembled systems of azobenzene and α-cyclodextrin

Abstract

A novel fluorescent and colorimetric chemosensor for Cu²⁺ has been designed and fabricated. Host–guest interactions were used to construct inclusion complex magnetic nanoparticles (IFIC MNPs) from azobenzene-modified rhodamine 6G and α-cyclodextrin-modified Fe₃O₄@SiO₂. A selective ‘turn-on’ type fluorescence enhancement and an apparent colour change from colourless to yellow-green with Cu²⁺ ions in the fluorescence experiments, and light yellow to pink in the UV-visible spectra, can be achieved. Good selectivity and sensitivity for Cu²⁺can be gained with the IFIC MNPs, with a detection limit of 2.5 × 10⁻⁷ M in MeCN/H₂O = 1 : 1. Furthermore, the IFIC magnetic nanoparticles can be separated and recycled easily using a magnet due to their superparamagnetism.