Colorimetric sensing of anions by a neutral biphenyl based amide receptor

Abstract

A new colorimetric sensor for fluoride is described. Compound 1 shows an open structure and its behaviour is compared with that of two related closed compounds 2 and 3. In all cases, the red colour developed in the presence of fluoride can be related to deprotonation processes, however ligand 1 gives rise to a faster colour change than 2 or 3 because of its higher flexibility. Other halides as well as carboxylates have been studied and the stoichiometry and complexation constants for the corresponding ligands have been determined.

State-of-the-Art of (Bio)Chemical Sensor Developments in Analytical Spanish Groups

“…Homoditopic biphenyl thiourea derivatives have been prepared to be used in carboxylate sensing. Experimentals carried out with these ligands have demonstrated that the conformation of the free ligand has a strong influence on both complex stoichiometry and geometry [ 113 , 114 ]. Several bis-coronands from biphenyl have been prepared and their complexing and sensing properties for alkaline, alkaline-earth and transition cations have been studied [ 115 ] and one of them demonstrated to be a selective fluorescent sensor for mercury [ 116 ].…”