The interactions of bis-phenanthridinium–nucleobase conjugates with nucleotides: adenine-conjugate recognizes UMP in aqueous medium

Among series of novel bis-phenanthridinium–nucleobase conjugates, the adenine derivative revealed high (log Ks=6.9 M−1) and selective affinity toward complementary nucleotide (UMP), accompanied by specific change in the UV–vis spectrum of phenanthridine subunits, differing significantly from changes caused by addition of other nucleotides. High stability and selectivity of adenine-conjugate/UMP non-covalent complex is, according to the molecular modeling studies, correlated to the number of inter- and intramolecular aromatic stacking interactions between phenanthridinium subunits, covalently attached adenine and added UMP, while the selectivity of adenine-conjugate toward UMP in respect to other nucleotides is most likely the consequence of additional hydrogen bonding between UMP and adenine.