Bifunctional colorimetric chemosensing of fluoride and cyanide ions by nickel-POCOP pincer receptors.

Three Ni(ii)-POCOP pincer complexes [NiCl{CH-4-OH-2,6-(OPPh)}], 1; [NiCl{CH-4-OH-2,6-(OPtBu)}], 2 and [NiCl{CH-4-OH-2,6-(OPiPr)}], 3 were studied as bifunctional molecular sensors for inorganic anions and acetate. In CHCN, fluoride generates a bathochromic shift with a colorimetric change for 1-3 with a simultaneous fluorescence turn on, this optical effect is based on deprotonation of the para-hydroxy group of the POCOP ligand. On the other hand, in a neutral aqueous solution of 80 vol% CHCN, additions of cyanide produce a distinct change of color by forming very stable complexes with the nickel-based receptors 1-3 with log K in the range of 4.