A new fluorescent chemosensor based on ۱-benzylidene thiosemicarbazide for sensitive detection of silver ions

Silver (Ag) is a precious metal widely used in various industrial fields includingelectronics, catalysis, photography and imaging due to its unique chemical and physicalproperties. Also, silver has an important role in medical science including application asantibacterial cream or antibiotic coating on medical devices such as catheters owing to itsantibacterial properties. However, silver can coordinate with some metabolites includingimidazole, carboxyl, amino and thiol functional groups in proteins/enzymes. Hence, it canbe deactivate protein/enzyme function in the human body which can cause many symptomsand diseases. Therefore, development of a simple, sensitive, fast and selective analyticalmethod for monitoring of silver concentration in environment and human body is great ofattention. Currently, determination of silver is based on conventional techniques such asinductively coupled plasma optical emission spectrometry, atomic absorption/emissionspectroscopy, inductively coupled plasma-mass spectrometry, surface-enhanced Ramanspectroscopy, electrochemical and microextraction methods and fluorescence spectroscopy.In this work, a new Schiff base named as ۱-benzylidene thiosemicarbazide (KH۱) wassuccessfully synthesized and was used as a sensitive and selective chemosensor for determination of trace amount of silver ion (Ag+). The fluorescence intensity enhanced byincreasing silver ion concentration at ۳۵۱ nm. Experimental parameters affecting thefluorescence intensity such as pH, type of solvent, concentration of KH۱, temperature andreaction time were studied and optimized. In addition, the synthesized probe exhibited goodselectivity for Ag+ compared to other metal ions such as Co۲+, Na+, K+, Cd۲+, Ba۲+, Cr۳+,Zn۲+, Cu۲+, Ni۲+, Ca۲+, Al۳+, Fe۲+, Hg+, Mn۲+ and Mg۲+ in aqueous solution.