The Synthesis And Fluorescent Property Of3-tetrazolylcoumarins

Coumarins are an important type of bioactive fluorescent compounds, and possesse many good fluorescent properties. Coumarins have been widely used in the fields of medicine, fluorescent dyes, and fluorescent sensors. Twelve new3-tetrazolylcoumarins were designed and synthesized in this paper in order to obtain new coumarins with good fluorescent properties and potential applications.The synthetic routes of3-tetrazolylcoumarins were as follows:5-Substitutedphenyl-1H-tetrazoles were synthesized from substituted-benzonitriles (H,2-Cl,4-OCF3,4-COOMe) and sodium azide, and then reacted with CICH2CN and K2CO3in DMF to produce2-acetonitrile-5-substitutedphenyltetrazoles.2-acetonitrile-5-substitutedphenyltetrazoles were reacted with4-substitutedsalicylaldehyde (4-NEt2,4-OH,4-OCH3) by base catalyst Et2NH in C2H5OH at25℃to produce3-tetrazolyliminocoumarins.3-tetrazolylcoumarins were produced from the hydrolysis of3-tetrazolyliminocoumarins under acidic conditions at80℃. The structures of these target products were characterized by FT-IR、1H NMR、13C NMR、 MS.The study and evaluation of the fluorescent properties of3-tetrazolylcoumarins in CH2Cl2showed that all3-trialzoylcoumarins possessed good fluorescent properties, the maximum UV/vis absorption wavelengths were at365～422nm, the maximum emission wavelengths were at425～500nm, the Stokes shifts were at60～78nm, and the fluorescence quantum yields were at0.63～0.85.3-tetrazolylcoumarins possessed higher fluorescence quantum yields compared to the corresponding3-triazolylcoumarins, and possessed a short shift of the emission spectra towards long wavelengths compared to the corresponding3-carboxylcoumarins. These fluorescent properties of3-tetrazolylcoumarins were probably caused by electron-withdrawing ability and rigid structure of tetrazolyl system.This paper also synthesized a tetrazolyliminocoumarin-based fluorescence sensor M. Sensor M was able to recognize Cu2+selectively in C2H5OH/H2O (2:1, v/v) solution with the selective fluorescent quenching over the presence of other metal ions. It showed good sensitivity and selectivity for Cu2+in C2H5OH/H2O (2:1,v/v) solution.