Preparation Of PU-based Fluorescent Sensors And Investigation On The Properties Of Heavy Metal Ions Detection

Industry as an important part of economy,has caused a lot of environmental problems.And the industrial pollution of the environment problem is becoming increasingly serious.Due to the difficult treatment of heavy metals,it becomes the most serious pollution of the water pollution problem.Among the heavy metals,mercury is of high toxicity;it not only threatens biological health,but also causes great pollution to the environment,and has become one of the most concerns in the world.With the improvement of people's lives,human beings are paying much attention to environmental problems.Detection of heavy metal ions in water environment also becomes important accordingly.Fluorescent chemical sensors often lead to the change in fluorescence emission performance upon the contact with heavy metals.Because of the strong fluorescence emission intensity and stability of BODIPY fluorescent dyes,there are so many research about BODIPY in recent years have been developed.In this research,some novel chemosensors were designed and synthesized,which could detect Fe³⁺ / Hg²⁺ and Cu²⁺ with high sensitivity.?1?The structures of OS21,OS11,B3 a,B3b and B3 c were synthesized and studied by1H-NMR,Fourier transform infrared spectra?FTIR?,and High resolution mass spectrometry?HR-MS?.?2?By controlling the molecular ratio of hydrazine hydrate to BODIPY derivatives,two new sensors were obtained.The one contains two BODIPY units in each molecule?OS21?,the other contains one BODIPY unit in each molecule?OS11?.And B3 a / B3 b and B3 c exhibited high sensitivity and selectivity to Hg²⁺ / Fe³⁺ and Cr³⁺ ions.?3?The measurements show that OS11 is stable in pH range of 3.65-11.09,while OS21 is stable in pH range of 3.16-11.88.Upon the addition of Fe³⁺ and Hg²⁺ ions,fluorescence of OS11 and OS21 is quenched notably.And the color of OS11 and OS21 were also changed dramatically with the contacting of Fe³⁺and Hg²⁺.Job's plotindicated that the molar binding ratio of OS11 to Fe³⁺is 1:2,to Hg²⁺was 1:1.The molar binding ratio of OS21 to Fe³⁺ is 1:3,to Hg²⁺ was 1:1.Also,it is found that the sensor could detect Fe³⁺ and Hg²⁺ in 0.5?mol/L solution.?4?When Hg²⁺/ Fe³⁺,Cr³⁺added to B3 a,B3b,B3 c,the fluorescence of B3 a,B3b,B3 c is enhanced.And the colors of B3 a,B3b,B3 c were also changed with contacting of Hg²⁺ / Fe³⁺,Cr³⁺.And fluorescence intensity of B3 c enhanced with the increasing concentration of Fe³⁺ions.Moreover,when the concentration lowered to 2.5 × 10-6mol/mL,color change and strong fluorescence enhancement still could be seen.B3 a,B3b,B3 c still remained the sensing properties when being introduced to polyurethane?PU?.The functionalized PU films not only showed color change and fluorescence shift for detecting Hg²⁺ / Fe³⁺ and Cr³⁺ ions as their small molecular counterparts,but also triggered a new emission peak in 580 nm.Besides,the functionalized PU film PU-B3 a could absorb Hg²⁺ions more than 84 ?g/g in unit time and volume,PU-B3 b could absorb Hg²⁺ ions more than 80 ?g/g in unit time and volume,PU-B3 c could absorb Hg²⁺ions more than 76 ?g/g in unit time and volume.