A Naphthalimide-Based Fluorescence "Off-on-Off" Chemosensor for Relay Detection of Al3+ and ClO. Front Chem 2019;7:549. [PMID: 31428604 PMCID: PMC6687763 DOI: 10.3389/fchem.2019.00549]

A novel Al³⁺ chemosensor NPA was designed and synthesized on basis of the mechanism of ICT and CHEF. Upon addition of Al³⁺, the probe NPA displayed a bright green fluorescence under UV radiation and visual color change from yellow to colorless. Spectrum titrations showed that NPA could be recognized as a fluorescent turn-on probe with 10^-8 M detection level. The probe was successfully applied in real water sample and test paper. More important, NPA-Al³⁺ complex were used as a fluorescent turn-off probe for the detection of ClO^- with the detection as low as 2.34 × 10^-8 M. The performance of NPA to Al³⁺ and NPA-Al³⁺ complex to ClO^- demonstrated that NPA could be served as a sensitive probe and exhibit INHIBIT logic gate behavior with Al³⁺ and ClO^- as inputs.

Colorimetric and fluorescent chemosensor for highly selective and sensitive relay detection of Cu2+ and H2PO4- in aqueous media

In this manuscript, a new colorimetric and fluorescent chemosensor (T) was designed and synthesized, it could successively detect Cu²⁺ and H₂PO₄^- in DMSO/H₂O (v/v=9:1, pH=7.2) buffer solution with high selectivity and sensitivity. When added Cu²⁺ ions into the solution of T, it showed a color changes from yellow to colorless, meanwhile, the green fluorescence of sensor T quenched. This recognition behavior was not affected in the presence of other cations, including Hg²⁺, Ag⁺, Ca²⁺, Co²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Cr³⁺, and Mg²⁺ ions. More interestingly, the Cu²⁺ ions contain sensor T solution could recover the color and fluorescence upon the addition of H₂PO₄^- anions in the same medium. And other surveyed anions (including F^-, Cl^-, Br^-, I^-, AcO^-, HSO₄^-, ClO₄^-, CN^- and SCN^-) had nearly no influence on the recognition behavior. The detection limits of T to Cu²⁺ and T-Cu²⁺ to H₂PO₄^- were evaluated to be 1.609×10^-8M and 0.994×10^-7M, respectively. In addition, the sensor T also could be served as a recyclable component and the logic gate output was also defined in sensing materials. The test strips based on sensor T were fabricated, which acted as a convenient and efficient Cu²⁺ and H₂PO₄^- test kits.