Synthesis And Properties Of Fluorine Anion Chemosensors Based On Organosilicon

Fluorine has unique physico-chemical properties because of the maximum electron cloud and the smallest anion radius.And fluoride anions have interrelated with the life of organism.So the design and synthesis of new type fluoride chemosensors,which could identify anions in aqueous solution,has become the focus of the researchers.There are many types of chemosensors for F-,such as hydrogen bonding receptor,displacement ensembles using metal ions and so on.But reactive chemosensors have been more advantaged.Because it can be used to identify fluoride anions efficiently in aqueous solution.So this thesis take detailed and in-depth study about organosilicon system,which can easily induce bond breaking.This kind of reactive chemosensors can provide a consoildated foundation,whether in stability or sensitivity,which can improve the recognition about fluoride anions in aqueous solution.In this thesis,a total of three type of chemosensors were synthesized.And then they were prepared with graphene to nanocomposite materals.(1)Chalcone/Aurones compounds 1-3(2)Picolinamide compounds 4 and 5(3)Fluorescein compound 61.Synthesis and characteristic of the compounds:Six compounds of three series have been synthesized.And these compounds were characterized by NMR,MS and crystal structure.The nanocomposites,which were prepared by the compounds with graphene by ?-? stracking,were characterized by IR,SEM,EDS and so on.2.Recognition properties of the compounds for fluoride chemosensorsIn this thesis,recognition properties of the compounds for fluoride anions in aqueous solution were investigated.Because of the existence of organosilicon group as recognition site,fluoride anion can be signal identified by compounds 1-6 in aqueous solution.Compounds1-3 and 5 belong to the typical fluorescent 'turn-off' type.After the addition of fluoride anions,the fluorescence changes more than 50%.Especially the fluorescence of compound 2 was reduced more than 80% and obvious fluorescence quench can be observed by naked eyes.Compounds 4 and 6 are fluorescent 'turn-on' type.The solution of compound 6 changed from colorless to bright yellow after fluoride anions was added.It was found that the fluorescence detection limit of compound 6 was 6.17× 10-7?M.3.The nanocomposites of fluoride anion recognition properties:Graphene oxide was introduced into the system in order to increase the recognition sensitivity for fluorescence anions.The nano-composites were prepared by the ?-? stracking between compounds and graphene oxide.And the characteristics of compounds 1-6 have been retained.In addition,the proformance of chemosensors,which need hydrophilicity,high sensitivity and short response time,are improved.Compared with compound 2,the saturation equivalent of GO-2 decreased more than 80%.And the response time decreased from 4000 s to < 5s.It is believed that the excellent conductivity and hydrophilicity of graphene oxide are very effective to improve the recognition of fluoride anions.In a word,the design and synthesis of chemosensors have a good performance in the recognition of fluoride anion in aqueous solution,which is a good foundation for the future biological applications.