Zinc-cyclen coordination to UTP, TTP or pyrophosphate induces pyrene excimer emission

Pyrene labelled Zn2+-cyclen 1 and bis-Zn2+-bis-cyclen 2 complexes were synthesized. The reversible coordination at physiological pH of Zn2+-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, Zn2+-cyclen-pyrene acts as luminescent chemosensor for PPi and fructose-1,6-bisphosphate in aqueous buffer.