Fluorescent Sensing and Discrimination of ATP and ADP Based on a Unique Sandwich Assembly of Pyrene-Adenine-Pyrene

It is still a challenging task to discriminate adenosine-5'-triphosphate (ATP) from various nucleoside triphosphates, such as GTP, CTP, UTP, and TTP. The ability to distinguish ATP from adenosine diphosphate (ADP) by fluorescent signals is also urgently desired. Herein, we report two pyrene-based zinc complexes as nucleoside polyphosphate receptors with high selectivity for ATP and ADP based on fluorescence and NMR studies. A unique pyrene-adenine-pyrene sandwich assembly was observed in the case of compound 1 with ATP or ADP, resulting in the increase of monomer fluorescence intensity; whereas the other bases of nucleoside triphosphates, such as GTP, CTP, UTP, and TTP were not sandwiched, resulting in a switch in the monomer-excimer fluorescence of pyrene. The different binding patterns of various nucleobases with a pyrene-pyrene assembly make 1 a highly selective fluorescent sensor for ANP (N= di, tri). In the case of compound 2, the first 0.5 equivalents of ATP induced a strong excimer emission, whilst ADP induced a large enhancement in the monomeric fluorescent peak. This fluorescence change makes 2 an efficient sensor to discriminate ATP from ADP.