Colorimetric and fluorogenic anion sensors of 2′-(p-nitrophenyl)-imidazol[4′,5′-f]-1, 10-phenanthroline[5,6-f] and its complex of Ru(bipy)22+

2'-(p-nitrophenyl)-imidazol[4',5'-f]-1,10-phenanthroline[5,6-f] (1) and its [image omitted] complex (2) were synthesised and studied for the anion sensing by UV-vis, fluorescence and H-1 NMR titration experiments. Compounds 1 and 2 exhibited obviously different changes between reactions with AcO-, F-, H2PO4- and with other halogens, i.e. Cl-, Br-, I-, in any of the UV-vis, fluorescence and H-1 NMR titration spectra in DMSO experiments. With an 89nm red shift, 1 was convenient to be employed to detect anions with the naked eye. Complexed with the electron withdrawing metal ion, 2 had the stronger interaction with anions to be detected than 1 had.