Preparation Of Fluorescent Probes Based On Poly(Pyridinium Salt)s And Their Sensing Property

Conjugated polymers with delocalized ? electronic system exhibit abundant photoelectric properties and good light,thermal stability.Thus,they have been widely applied in many fields,for example: organic light emitting diodes(OLED),organic field effect transistor(OFET),solar cell,organic laser,chemical and biological sensors,and so on.In the field of sensors,molecular wire structure of conjugated polymers allows for collective response and,therefore,optical amplification of fluorescent signals.The large number of optically active units along the polymer chain increase the sensitivity for ultra-low detection,relative to small molecules.In recent years,fluorescent sensors based on conjugated polymers have developed rapidly because of their high selectivity,sensitivity and stability.In this dissertation,we synthesized a series of poly(pyridinium salt)s with cationic on main chain and studied the photoelectric and sensing properties.1.The synthesis and characterization of poly(pyridinium salt)s.We prepared P1,P2,P3 and P4 with different counterions by ring-transmutation polymerization.We characterized and confirmed their chemical structures by nuclear magnetic resonance(NMR),elemental analysis(EA),Infrared Spectroscopy(IR)and gel permeation chromatography(GPC).2.We studied the effects of counterions on photophysical,electrochemical and thermal properties by UV-vis absorption spectra,Fluorescent spectra,electrochemical workstation and thermogravimetry analysis.We also studied the sensing properties of P1 for DNA.These results indicate that electrostatic attraction and weak intercalation interaction between P1 and ct DNA can induce aggregate,and restrict the structure torsional of P1,thereby,reducing energy consumption which results in enhancement of fuorescence intensity.The addition of DNase I in mixture of P1 and ct DNA solution resulted in rapid diminution of fluorescence intensity,which indicated the regeneration of the free chemosensor P1.This result demonstrates that P1 can be used to monitor the deoxyribonuclease activity and hydrolysis process.3.The research on sensing properties of P4 for Heparin.In Tris-HCl buffer solution(2mM,pH = 7.4),UV-vis titration spectra and fluorescence spectra indicated that there was strong interaction between P4 and heparin,forming a combination of about 1:1 stable complexes.The selectivity experiments showed the high specificity for heparin.Furthermore,dynamic light scattering experiments demonstrated that the hydrodynamic diameter of P4-heparin complex increased from 90 nm to 820 nm with the increase of heparin concentration.