FLUORESCENCE LIFETIMES OF METAL(III) CHELATES OF 5-SULPHOQUINOLIN-8-OL AND THEIR MODIFICATION BY THE INTERNAL HEAVY-ATOM EFFECT

For metal(III) [M(III)] 5-sulphoquinolin-8-olates, systematic studies of the atomic number effect in complexes exhibiting ligand fluorescenc e were carried out in aqueous solution. The fluorescence lifetimes of various chelates were investigated as a function of complexed metal io n, pH and metal-to-ligand ratio. The reported data for M(III) 5-sulpho quinolin-8-olates in aqueous solution include absorption and emission maxima, fluorescence quantum yields and fluorescence lifetimes, in add ition to calculated rate constants of fluorescence and intersystem cro ssing. It was found that the internal atomic number effect is sufficie nt to distinguish between different M(III) chelates in aqueous media o n the basis of their fluorescence lifetimes. The analytical applicabil ity is limited, however, by the influence of the metal-to-ligand ratio and pH sensitivity.