DPA Modified Fluorescent Conjugated Polymers For The Detection Of Hg(?), Cd(?) And Hydrazine

Fluorescent conjugated polymer is a kind of polymer compound with a large?-?*conjugated structure main chain.Fluorescent conjugated polymers have received extensive attention from scientific researchers due to their signal amplification effects,stable properties,and easy modification.Fluorescent conjugated polymers are widely used in the detection of metal ions and small organic molecules based on the modification of specific recognition groups on the side chains.In this article,we designed and synthesized two conjugated polymer fluorescence sensors with DPA(2,2'-dipicolylamine)as the recognition group,polythiophene derivative(PT-BDPA)and poly(phenylene ethynylene)conjugated polymer(PPE-DPA).The applications of two conjugated polymers in the detection of mercury ion,cadmium ion and hydrazine(N₂H₄)were studied.The main contents are as follows:First,a polythiophene derivative(PT-BDPA)was synthesized,and the products of each step were characterized by nuclear magnetic resonance spectrometer,mass spectrometer and so on.We find that PT-BDPA shows enhanced fluorescence response to Hg²⁺and Cd²⁺at different pH buffer solution.When pH is 3.0,Hg²⁺can significantly increase the fluorescence of PT-BDPA and Cd²⁺cannot hardly increase the fluorescence of PT-BDPA;when pH is 7.0,selective detection of Cd²⁺can be achieved by PT-BDPA after masking Hg²⁺.PT-BDPA has a wide linear range and lower detection limit for Hg²⁺and Cd²⁺detection under the optimized conditions.Finally,PT-BDPA has been used for the sequential detection of Hg²⁺and Cd²⁺in aquatic plants samples with satisfactory results.Secondly,the poly(phenylene ethynylene)conjugated polymer(PPE-DPA)was synthesized,and the products of each step were characterized by nuclear magnetic resonance spectrometer,mass spectrometer and so on.PPE-DPA was coordinated with copper ions to form a composite sensor(PPE-DPA-Cu²⁺),the fluorescence of the composite sensor could be enhanced by hydrazine.The experimental conditions for PPE-DPA-Cu²⁺to detect hydrazine were optimized,such as the water content of the system,pH,buffer solution,reaction time,etc.Under the best conditions,the composite sensor exhibits satisfactory detection performance,and exhibits strong anti-interference ability against various cations,anions,amino acids,organic amines,etc.PPE-DPA-Cu²⁺shows a linear response to hydrazine in the concentration range of1–70 nmol/L,and the detection limit is as low as 0.54 nmol/L.In addition,the sensor has also been successfully applied to the quantitative detection of hydrazine in water samples.