A New Luminescent Terbium 4-methylsalicylate Complex as a Novel Sensor for Detecting the Purity of Methanol

A new dinuclear terbium complex [Tb 2 (4-msal) 6 (H 2 O) 4 ]·6H 2 O ( 1 ) (4-msal = 4-methylsalcylate) was synthesized. Its structure was determined by single crystal X-ray diffraction, and the complex was characterized by PXRD, FT-IR, fluorescence, TGA and DTA. Complex 1 exists as discrete molecules that are linked by extensive O–H … O hydrogen bonds into a 3D network. The luminescence lifetimes of 3 μ m methanol solution and solid sample of 1 are 1.321 and 1.009 ms, respectively. The quantum yield of solid sample is 6.0%. The luminescence quenched more than 50% when 3% (vol/vol) different impurities (acetone, acetonitrile, chloroform, dichloromethane, dioxane, DMF, DMSO, ethanol, ether, ethyl acetate, glycol, H 2 O, hexane, TEA, THF and toluene or their mixture) were added. The inverse linear relationship between the L g value of fluorescence intensity and the volume ratio of the minor component (to a maximum of 20%) is interpreted in terms of L g I = a − bX ( I : luminescence intensity; X : volume ratio of impurities in methanol; a , b are constants). So 1 is a potential luminescent sensor for analyzing the purity of methanol.