The G-C DNA base hybrid: Synthesis, self-organization and structural analysis

The guanine-cytosine base hybrid 1 is synthesized in five steps from the ma lononitrile dimer. One face of the molecule possesses the cytosine AAD hydr ogen bonding code and the other the guanine DDA code. The expression of thi s information leads to the self-organization of six molecules of 1 into a h exagonal supermacrocycle in the solid state through the formation of 18 str ong hydrogen bonds. This is the first structurally characterized example of a synthetic hexagonal assembly where the molecular program is unambiguous and all of the information required for exclusive rosette formation is cont ained within hydrogen bonding codes. 1 crystallizes in the very rare, high- symmetry cubic space group <Ia(3)over bar d>, with 96 molecules in the unit cell. The crystal is highly solvated and only ca. 35% occupied by molecule s of 1, with a criss-crossed network of channel voids generated by the over lapping of 1(6) hexamers.