Synthesis, binding and fluorescence studies of a new neutral H-bonding receptor for anions based on 3,5-bis(trifluoromethyl)phenylurea

The synthesis and anion binding studies of a new neutralreceptor 1,10-(2,20-(4,10-dimethyl-1,4,7,10-tetraazacyclododecane- 1,7-diyl)bis(2-oxoethane-2,1-diyl))bis(3-(3,5-bis(trifluoro-methyl)phenyl)urea) (L1) are reported. L1 is a macrocyclic ligand containing the 3,5-trifluoromethylphenylureido-binding fragment attached as a side arm on the tetraazacyclododecane. L1 is soluble in numerous organic solvents; the binding properties of L1 towards several simple anions (G) were investigated by NMR, UV–vis and fluorescence techniques in DMSO and CH3CN solutions. L1 is able to bind F2, Cl2 and AcO2 in both solvents; in addition, it binds Br2 in CH3CN. Fluoride shows the highest constant values in the halide series (F2 . Cl2 . Br2) and AcO2 is the most strongly bound among all the anions investigated. L1 is able to signal the presence of the anions in solution by fluore-scence change; in the case of acetate, this occurs in the visible range.