The Design, Synthesis And Fluorescence Response Investigation Of Aromatic Groups Functionalized Polysiloxanes

In this paper,on the basis of fluoranthene and its derivatives with excellent fluorescence properties,two fluorescent fluoranthene derivative groups were attached to the polysiloxane chain to form a kind of polymer with polysiloxane as main chain,and fluorescent groups on both ends of the main chain using a Knoevenagel/Diets-Alder reaction.As a result,a new fluoranthene derived polymer was designed and synthesized via simple and facile ways.It is expected that the linear polymer not only retained the excellent fluorescent properties of fluoranthene derivatives,but also can be used as a fluorescent probe to detect iron ions.The structures of the obtained fluoranthene derived polymers were characterized and analyzed by NMR spectrometer,elemental analyses and so on.In addition,the thermodynamic properties were also studied by thermogravimetric analysis.The given results show that,the Knoevenagel/Diels-Alder was carried out successfully,and the obtained product has an excellent thermodynamic stability.The fluorescence response of the fluoranthene derived polymers in detecting metal cations in THF solution was investigated by using fluorescence spectrophotometer.It was found that among the fluoranthene derived polymer's solutions upon different alkali metal and transition metal cations,only the solution upon iron ions occurred fluorescence quenching phenomenon.The other metal cations had nearly effect on the fluorescence spectra.And what' more,the selective fluorescence response ability was also investigated.Compared with other metal cations,fluoranthene derived polymers have higher selectivity towards iron ions.The fluorescence response ability in detecting iron ions was further investigated.It was found that the fluorescence intensity gradually decreased as the concentration of iron ions raised.The obtained Stern-Volmer curves are upward and give the result that the detective effect of fluoranthene derived polymers became increasingly higher as the concentration of iron ions rose.What' more,the proposed fluorescence quenching mechanism was researched by variation temperature fluorescence experiment and fluorescence lifetime test.Based on the excellent fluorescence properties and ability of detecting iron ions of above fluoranthene derived polymers,we further designed and synthesized a new polyphenyl benzene derived polymer.Because of its special structure,polyphenyl benzene derived polymer can efficiently inhibit the ?-? interaction between different molecules,and can limit the conjugation extent of each aromatic ring in same molecule.The selective fluorescence response ability towards iron ions was studied by fluorescence testing.It was found that polyphenyl benzene derived polymer in THF solution had excellent selective response ability towards iron ions,and the obtained Stern-Volmer curves are upward.What' more,the proposed fluorescence quenching mechanism was studied in detail by UV-vis absorption spectroscopy and the calculation result of rate constant Kq of bimolecular quenching process.