Pyrene labelled Zn(2+)-cyclen 1 and bis-Zn(2+)-bis-cyclen 2 complexes were synthesized. The reversible coordination at physiological pH of Zn(2+)-cyclens to phosphate anions and to imide moieties, as present in thymine and uracil nucleotides, is well known. In the presence of analytes bearing a phosphate and an imide or two phosphate groups the formation of a ternary complex consisting of two pyrene-labelled metal complexes and the analyte molecule, is observed. The close proximity of the pyrene labels in the complex induces pyrene excimer emission, which is observable by the unarmed eye. By this, the presence of UMP, UDP, UTP and TTP in buffered aqueous solution is signalled, while other nucleotides are not able to induce excimer emission. In the same way, Zn(2+)-cyclen-pyrene acts as luminescent chemosensor for PP(i) and fructose-1,6-bisphosphate in aqueous buffer.

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Fluorescent probes for the detection of protein phosphorylation on SDS-PAGE are presented. The probes were designed using a dinuclear metal-chelate phosphate recognition unit and an environmentally sensitive fluorophore. The specificity of the probes is determined by their binding site selectivity toward phosphate ions and the emission response induced by the change in the electrostatic environment of the fluorophore upon binding to a phosphorylated amino acid residue. The staining is fully reversible due to the noncovalent binding of the probe. Gel bands with less than 100 ng of phosphorylated alpha-casein are detectable with the new probes on a normal UV-table without specialized equipment like a laser-based gel scanner or a cooled camera detector.

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