Abstract
Kryptofix 5 forms complexes with a variety of metal cations. The coordination with the crown ether moiety affects only slightly the emission wavelength of the free Kryptofix 5 ligand (lambda(max) = 425 nm) in a buffer (pH = 9) solution, but the emission intensity of this blue fluorescence can increase strongly upon complex formation, probably owing to the rigidity of the complex. This applies ...
Abstract
Kryptofix 5 forms complexes with a variety of metal cations. The coordination with the crown ether moiety affects only slightly the emission wavelength of the free Kryptofix 5 ligand (lambda(max) = 425 nm) in a buffer (pH = 9) solution, but the emission intensity of this blue fluorescence can increase strongly upon complex formation, probably owing to the rigidity of the complex. This applies e.g. to Ba2+, Zn2+, Cd2+, Hg2+, Ag+ and La3+. A second group of metal ions such as Al3+, Pb2+, Sb3+, Bi3+, Te4+, Gd3+ and Th4+ causes a large red shift of the fluorescence of free Kiyptofix 5 to approximately lambda(max) = 500 nm. This green fluorescence resembles that of Kryptofix 5 in acidic solution. It is suggested, that the second group of metal ions is also coordinated to the pyridine nitrogen atoms of the quinoline substituents. (C) 2014 Elsevier B.V. All rights reserved.
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