Design And Synthesis Of Benzoyl Hydrazone Derivatives For Metal Ion Recognition

As we all know, fluorescent chemosensor and colorimetric chemosensor are thetwo most common photochemical sensors, because of their real-time fast, efficientyand sensitivity, simple, inexpensive, high selectivity and many other advantages, theyhave been widely used in the detection of metal ions of environment and biological.In this paper, several photochemical probes were designed and synthesized base onbenzoyl hydrazone derivatives. The interactions between the metal ions andcompounds were investigated by the fluorescence spectrophotometry and UV-visspectroscopy. Herein, we presented several new methods for the quantitative assayesof metal ions. This paper was divided into four chapters to elaborate.In the first chapter, we provide an overview of the working principle and severalcommon response mechanisms of photochemical sensors, also briefly summed up theuse and development of fluorescent and colorimetric sensors for detect metal ions inrecent years.In the second chapter, three compounds of hydrazone derivatives which named2-thenaldehyde-4-dimethylaminobenzoylhydrazone (1),2-furaldehyde-4-dimethyla-minobenzoylhydrazone (2) and benzaldehyde-4-dimethylamino benzoylhydrazone (3)were synthesized and fully characterized. Compound1selective bound with Hg2+over Co2+, Zn2+, Pb2+, Ni2+, Cu2+, Cd2+, Ca2+and Mg2+in acetonitrile. A1:1stablecomplex of1-Hg2+formed with binding constant as9.73×104L mol-1. The solutionchanged from colorless to yellow which was used as colorimetric assay for Hg2+. Forcompound2, it showed spectral response to Hg2+, Cd2+and Zn2+and1:1metalcomplexes formation. However, compound3didn’t show spectral response for testingmetal ions. Obviously, S and O of heterocycle participate in coordination of metalcomplex. The binding sites from various atoms assemble for coordination plays keyrole for selective sensing events.In the third chapter, compound4named2-pyridine-carboxaldehyde-4-dimethylaminobenzoylhydrazone was synthesized and characterized by1H NMR,13CNMR and MS. The interactions between the metal ions and compound4were investigated by UV-vis spectroscopy. Results indicated that compound4showed ahighly selective response to copper ion. Compound4itself has no color in50%acetonitrile/water buffered at pH=7.40, the addition of Cu2+led the solution to turnfrom colorless to bright yellow quickly, whereas the presence of other metal ions hadno change, for example Zn2+, Ca2+, Mg2+, Ag+, Fe3+, Ni2+, Pb2+, Hg2+, Cd2+, Co2+, Li+and K+. The absorbance at422nm and the concentration of Cu2+presented goodlinear relationship from1.0×10-7mol L-1to8.0×10-6mol L-1with a correlationcoefficient of0.9976(n=16), the detection limit of method was8.2×10-8mol L-1.Determination of copper ion in water was successfully carried out.In the fourth chapter, a fluorescence chemosensor, N, N–dimethyl pyridinebenzaldehyde-4–dimethylaminobenzoylhydrazone (5) was synthesized and confirmedby1H NMR，13C NMR and MS. The interactions between the metal ions andcompound5were investigated by the fluorescence spectrophotometry and UV-visspectroscopy. Results indicated that compound5showed a highly selective responseto Cu2+. The addition of Cu2+induced a dramatic enhancement in the fluorescence ofcompound5by12.5folds, whereas the other metal ions had little fluorescencequenching, for example Fe3+, Zn2+, Pb2+, Hg2+, Cd2+, Co2+, Ni2+, Li+, K+, Ca2+, Mg2+and Ag+. The ratio of compound5with Cu2+was1:1and the binding constant was2.0×107L mol-1.