Janus-AT Bases: Synthesis, Self-Assembly, and Solid State Structures

The high yielding synthesis of heterocycles with defined H-bond accepting and donating capabilities
provides for the design of self-assembling structures and specific recognition of biological targets. Herein
we report the syntheses and solid-state structures of three self-complementary uracil/thymine derivatives
where each presents the standard ADA face inherently complementary to adenine and a synthetically
appended DAD face complementary to uracil/thymine. These heterocycles, which have never before
been reported or characterized, represent diaminopurine−uracil/thymine hybrids that, in two of the three
cases, relate to previously reported heterocyclic hybrids of G and C. All three heterocycles crystallized
to afford the first X-ray crystal structures of self-complementary heterocycles capable of ADA−DAD
pairing. The potential use in DNA and RNA recognition are briefly discussed.