An aniline trimer-based multifunctional sensor for colorimetric Fe3+, Cu2+ and Ag+ detection, and its complex for fluorescent sensing of L-tryptophan

The detection of metal ions and amino acids by the aniline oligomer-based receptor has not been reported yet, to the best of our knowledge. In this study, an efficient multifunctional cation-amino acid sensor (CAS) with aniline moiety and chiral thiourea binding site was synthesized by the reaction of aniline trimer and (S)-(+)-1-phenyl ethyl isothiocyanate. CAS can sense Fe3+, Cu2+, Ag+ ions, and L-tryptophan. These results can be recognized by the naked eye. The appropriate pH range for the quantitative analysis of Fe3+, Cu2+, and Ag+ by CAS in DMSO/water (30 vol% water) was evaluated. The interaction between CCS and metal ions was analyzed by H-1 NMR titration. The detection limits of CAS for the Cu2+, Ag+, and Fe3+ were 0.214, 0.099, and 0.147 mu M, respectively. Moreover, the CAS-Cu2+ complex can act as a turn-on fluorescence sensor for L-tryptophan. On the contrary, there is no response upon the addition of other amino acids, such as L-histidine, L-proline, L-phenylalanine, L-threonine, L-methionine, L-tyrosine, and L-cystine to CAS-Cu2+ complex. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

A novel multifunctional cation-amino acid sensor (CAS) was synthesized in this study for the detection of metal ions and amino acids, with low detection limits. The CAS-Cu2+ complex can act as a fluorescence sensor for L-tryptophan.