Self-assembly of a quadrangular prismatic covalent cage templated by zinc ions:A selective fluorescent sensor for palladium ions

Herein we report a covalent cage TPE-Zn_(4)based on a tetraphenylethylene molecule via subcomponent self-assembly,which is templated by zinc ions.TPE-Zn_(4)features a quadrangular prismatic cage structure,which is characterized by NMR,mass spectrum,and single-crystal X-ray diffractions.TPE-Zn_(4)emitted orange fluorescence(λ_(em)=620 nm)in DMSO solution under the irradiation of UV light(λ_(ex)=395 nm)and can be applied as a fluorescence sensor for selectively detecting Pd^(2+).The fluorescence of TPE-Zn_(4)was quenched by Pd^(2+)in DMSO solution,and a very low detection limit of 62.3 n M was achieved.Mechanism studies reveal that the Pd^(2+)can replace the Zn^(2+),and the heavy atom effect and chelation-enhanced quenching effect between the Pd^(2+)and the cage probably cause the fluorescence quenching.