Caged Na+ and K+ ligands: photochemical properties, application for membrane transport studies and selective fluorimetric detection of alkali ions
In many biological studies the generation of fast cation concentration jumps without mechanical disturbance of the biological system is of considerable interest. We have recently reported the synthesis of photo-cleavable cryptands 1 and 2 substituted with a 2-nitrophenyl group at one of the cryptand bridges as alkali ion selective ligands (2,3,5). These cryptands are suitable for binding alkali as well as alkaline earth cations (caged-cations) and releasing the complexed cation after a short pulse of UV light, due to the cleavage of the substituted cryptand bridge. This results in a drastical decrease of the stability of the cation/ligand complex (2,5). Cryptands 3 and 4 were synthesized as fast, selective and sensitive indicators for alkali cations in aqueous solution. Fluorescence and cation binding properties of these ligands are discussed.
KeywordsProtonation Constant Alkali Cation Photochemical Property Alkaline Earth Cation Concentration Jump
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