Structure−Function Studies on a Synthetic Guanosine Receptor That Simultaneously Binds Watson−Crick and Hoogsteen Sites

A series of receptors (11−16) designed to simultaneously bind the Watson−Crick and Hoogsteen
sites of guanosine were synthesized, and their binding of guanosine tri-O-pentanoate (32) was probed
via 1H NMR complexation studies in 5% DMSO-d6−chloroform-d. The guanosine receptors were
synthesized with aminonaphthalene or aminoquinoline auxiliary groups tethered to N-4 of cytosine
via a methylene or carbonyl group. A structure−function relationship was established allowing
energetic contributions made by components of nucleoside analogues to be probed and more general
design rules formulated that may guide the development of more efficacious DNA bases.