Synthesis And Property Study On Eu(â…¢)Complex With Terminal Cholesterol Modified Poly(N-isopropylacrylamide)

Firstly,2-Chloropropionyl cholesterol was synthesized, then, using the method of atom transfer radical polymerization(ATRP), the monomer of N-isopropylacrylamide was initiated and the polymerization was occurred in DMF/H2O, obtained poly(N-isopropylacrylamide) with terminal cholesterol groups of hydrophobicity (Ch-PNIPAM). Then, by rare earth Europium(â…¢) ion with excellent fluorescence property and thiophene formyl a-trifluoro acetone(TTA) as small molecule ligand coordinated with the Ch-PNIPAM, the Eu(â…¢)-Ch-PNIPAM and the Eu(â…¢)-Ch-PNIPAM-TTA complexes were prepared, meanwhile, investigated the temperature-responsive property and fluorescence. Finally, taking complexs with different molecular weight as the research object, respectively conducted intensive studies on the relationship between fluorescence intensity and temperature of the complexes, the results are found:The polymerization kinetics shows a good controllability, and the molecular weights distribution is between1.06and1.12The Ch-PNIPAM and their Europium(â…¢) complexes show sensitive temperature-responsive property, and the lower critical solution temperature(LCST) of Ch-PNIPAM are30.9℃, due to the effect of terminal cholesterol groups of hydrophobicity, which reduce in different degrees, compared with the LCST(32℃) of PNIPAM. Meanwhile, the addition of Eu(â…¢) can also elevate the LCST of the complexes. All of the complexes have excellent fluorescence performance, compared to the peak strength of EuCl3in the excitation and emission spectra, the compound’s was significant enhanced, and the fluorescence spectrum presents5dâ†'7FJ (J=0,1,2,3) characteristic emission of Europium(â…¢) in613nm. As the temperature increases, the fluorescence intensity of the complexes revealed a general trend of increase, and a obviously phase separation can be seen, we consider used the characteristics in the study of fluorescent molecular thermometer.