Highly Selective Recognition of Adenine Nucleobases by Synthetic Hosts with a Linked Five-Six-Five-Membered Triheteroaromatic Structure and the Application to Potentiometric Sensing of the Adenine Nucleotide

A new structure for an adenine-selective host molecule, featuring the pertinent link of five-six-five-membered heteroaromatic rings and two carbamoyl NH sites, was developed. This structure provides a correctly oriented array of complementary hydrogen bonding sites for the adenine nucleobase, which exploits both Watson-Crick and Hoogsteen-type interactions. The complexation with adenine nucleobases by multiple hydrogen bonding was supported by (1)H NMR spectroscopy. This type of host displayed high selectivity in complexation, with an accompanying fluorescent response to lipophilized adenosine in CHCl(3). Furthermore, a remarkably selective potentiometric response was attained for adenosine 5'-monophosphate over 5'-GMP, 5'-CMP, and 5'-UMP by using an ion-selective electrode with a PVC-supported solvent polymeric membrane. This indicates recognition of water-soluble nucleotide guests through the membrane-water interface. These findings are expected to form a reliable basis for the development of artificial sensing systems for mononucleotides in biological systems.