Nucleobase recognition by artificial receptors possessing a ferrocene skeleton as a novel modular unit for hydrogen bonding and stacking interactions

Novel ferrocene-modified artificial nucleobase receptors were designed and synthesized. The nucleobase receptors possess hydrogen-bonding and pi-stack ing interaction sites that act simultaneously for binding to 1-butylthymine utilizing the pivot character of the ferrocene skeleton. Diamidopyridine w as chosen for the hydrogen-bonding moiety, and various polynuclear aromatic s were used for pi-stacking one. The two components were tethered to the cy clopentadienyl rings via ethynediyl and oxymethylene spacers. The binding a ffinity of the receptors to 1-butylthymine was found to be dependent on the aromatic structures. Thus, the association constants for perylene-linked r eceptors were approximately doubled compared to those of aromatic-free ones , an energy difference of similar to 0.5 kcal/mol. Detailed comparisons bet ween the 10 receptors clarified the value of the pivot character of the fer rocene for construction of the intermolecular interaction site.