Design, Synthesis And Spectra Study Of Cyanide Probes

Anion recognition is an area of growing interest in supramolecular chemistry due to its important role in a wide range of environment, clinical, and biological application. Among the various anions, cyanide is one of the most important anions due to it is being widely used in synthetic fibers, resins, herbicides, and the gold-extraction process. Unfortunately, the cyanide anion is extremely toxic, the detriment couldn’t be neglected. Thus, there is a need for an efficient sensing system for cyanide, to monitor the cyanide concentration from contaminant sources. However, the traditional cyanide receptors that relied on hydrogen-bonding show poor selectivity due to the interference from other anions. To overcome this limitation, reaction-based receptors for cyanide anion, which take the advantage of its nucleophilic character, have been developed recently. In this dissertation, three types of reaction-based receptors for cyanide ion were designed and synthesized, the colour and fluorescence changes that caused by the addition of cyanide to the receptors could be used as the signal output for cyanide recognition.A new method for the synthesis of rhodafluor was reported and a rhodafluor-based chromo-and fluorogenic probe2-3for cyanide ion was designed, synthesized and characterized. The probe comprises a spectroscopic unit of rhodafluor and a cyanide ion specific trifluoroacetylamino binding unit. An excellent selectivity toward CN in aqueous solution over a wide range of tested anions was observed. The probe itself is colorless and nonfluorescent because of its spirocyclicstructure, whereas ring-opening structure of the corresponding spirolactone induced by CN gives rise to strong fluorescence emission and also clear color change which can be observed by naked eyes. The detection limit of2-3for CN was measured to be2.66x10-8M, lower than the WHO’s limit for drinking water.On the basis of FRET from4-(N, N-dimethylamino)benzamide to fluorescein, a new ratiometric fluorescence probe3-3bearing a hydrazone binding unit was developed for highly selective and sensitive detection of CN. In DMF:H2O=9:1(v/v) system, compound3-3showed excellent selectivity toward CN. The nucleophilic attack of cyanide toward the hydrazone function group lead to the fluorescence resonance energy transfer from4-(N,N-dimethylamino)-benzamide to fluorescein. The fluorescence changed from blue to green and the solution color changed from colorless to red, which can be observed by naked eyes. The detection limit of3-3for CN was measured to be4.4x10-7M, lower than the WHO ’s limit for drinking water.A new ratiometric fluorescent cyanide probe4-1was developed based on the nucleophilic attack of CN toward the indolium group of a hybrid coumarin-hemicyanine dye. In buffer solutions, all of the background anions and cysteine have not any interference with the detection of CN. The nucleophilic attack of cyanide toward the indolium function group lead to the block of the ICT process, followed by the fluorescence changed from red to green and the solution color changed from grape to yellow. The detection limit of4-1for CN was6x10-7M and the associated constant reached1.78X105M-1.Based on the ICT mechanism a ratiometric fluorescence znic probe5-1was synthesized and the recognition behavior was studied in buffer solutions. The compound5-1showed good water solubility and high selectivity for sensing zinc ion, about12-fold increase in fluorescence intensity and a84nm red shift of fluorescence emission upon binding Zn2+in buffer aqueous. Compound5-1combined with Zn2+in a1:1stoichometric manner and the detection limit for Zn2+was calculated to be6.9x10-8M.A series of BODIPY derivatives6-4、6-5、6-6、6-7and6-8were synthesized through Suzuki reaction and the compounds were characterized by1H NMR. Further researches based on these fluorophore could be explored.