Design And Synthesis Of Colorimetric And Fluorescent Sensor For Fluoride Ion

The design of chemosensors which could selectively recognize and signal the presence of a specific analyte,has been one of the main directions of supramolecular chemistry.Detection of anions has played an important role in supramolecular chemistry,in which detection of fluoride ion was particularly important significance. In this dissertation,according to the concept of the chemosensor design,i.e.,structural change would always bring property change,a series of ftmctional organic molecules were designed and synthesized and their applications to chemosensors(colorimetrical and fluorescent sensors) were also explored.The main results were summarized as follows:With ninhydrin and p-methyl phenol as raw material,a heterocyclic compound with iso-indolyl imidazolyl groups was synthesized through two-step reaction,which was further developed as a high sensitive and selective colorimetric-fluorescent sensor for developed as a high sensitive and selective colorimetric-fluorescent sensor for fluoride ion.In the presence of fluoride ion,both UV-Vis spectra and fluorescence spectra of compound solution would change obviously,and the change of colour and fluorescent could even be observed by naked eyes.Moreover,the compound showed good selectivity with fluoride ion,even in the presence of Cl^-,Br^-,I^-,HSO₄^-,H₂PO₄^-.Two types of simple Schiff base compounds were synthesized in the use of salicylaldehyde and 2-hydroxy-1-naphthaldehyde with aqueous hydrazine,and their detecting mechanisms for fluoride ion were investigated by means of colorimetrical, fluorescent and NMR studies.In the presence of fluoride ion,both UV-Vis spectra and fluorescence spectra of compound solution would change obviously,and the change of colour and fluorescent could even be observed by naked eyes.Moreover the compound showed good selectivity with fluoride ion,even with Cl^-,Br^-,I^-,HSO₄^-, H₂PO₄^- presented in.The detecting mechanism was that upon addition of fluoride ions, intramolecular hydrogen bonds of the receptor were broken and intermolecular hydrogen bonds between the receptor and fluoride ion was formed.Two types of simple Schiff base compounds comprising flexible chain were synthesized in the use of salicylaldehyde and 2-hydroxy-1-naphthaldehyde with butanediamine,and their detecting mechanisms for fluoride ion were investigated by means of colorimetrical and fluorescent studies.In the presence of fluoride ion, fluorescence spectra of compound solution would change obviously,and the change of fluorescent could even be observed by naked eyes.Fluoride ions and compounds formed 1:1 complexation.The influence of flexible groups on the fluorescent properties and detecting sensitivity of those compounds was discussed.It has been found the existence of flexible chain would reduce the complex ability of molecular.Two types of simple Schiff base compounds comprising rigid chain were synthesized in the use of salicylaldehyde and 2-hydroxy-1-naphthaldehyde with p-phenylenediamine,and their detecting mechanisms for fluoride ion were investigated by means of colorimetrical and fluorescent studies.In the presence of fluoride ion,both UV-Vis spectra and fluorescence spectra of compound solution would change obviously,and the change of colour and fluorescent could even be observed by naked eyes.Moreover,the compound showed good selectivity with fluoride ion,even with Cl^-,Br^-,I^-,HSO₄^-,H₂PO₄^- presented in.The influence of rigid groups on the complex ratio to fluoride ions and the detecting sensitivity of those compounds were discussed.In the rigid molecular structure frame,the distance between two OH groups of receptor became lager,and its complex ratio to F^- ions changed to 1:2.