Fluorescence Lifetime Measurements of Morin–Metal Ion Complexes

Fluorescence lifetimes of morin complexes of Be(II), Zn(II), Al(III), Ga(III), In(III), Th(IV), Zr(IV), and Sn(IV) extracted into isopentyl alcohol from the acid solution at various pH values were investigated. The result indicates that the Al(III), Ga(III), and In(III) complexes change their compositions according to the change of pH. More detailed investigations by the use of mole ratio method suggest that Al(III), Ga(III), and In(III) form complexes having two different mole ratios of 1 to 1 and 1 to 2 (metal ion: morin). Fluorescence lifetimes were changed according to the changes of the composition of the complex and the differences of the metal ion.