The influence of the water on the stability of complexes of 6,6′-Bis(diphenylphosphinoyl)-2,2′-bipyridyl with lanthanide ions was studied. An increase in the stability value of the complexes is observed with a decrease in the ionic radius of the metal. An increasing of the water content in acetonitrile leads to decrease the stability of the complexes. Moreover the stability of the complexes became independent on ionic radii of metals.
Investigation of proteins interactions with luminescent europium complex is interesting for the practical task of sensitive protein detection, as well as to study fundamental problems of peptide-lanthanide interplay. Presented work is devoted to examine the spectroscopic properties of europium complex (europium trinitrate (2,2'-bipyridyl-6,6'- dikarbonilazandiil)tetrakis (methylene) phosphonate) and to study its interaction with human serum albumin using various spectroscopic techniques. This complex has unique optical ability such as high values of the phosphorescence intensity in aqueous solutions, which exceeds the intensity of many other known coordination complexes of rare earth elements.