This image illustrates the chemical structure of a purine molecule, highlighting the numbering of the carbon and nitrogen atoms. The purine structure consists of a pyrimidine ring (positions 1 to 6) ...

This molecule crystallizes in hydrogen bonded pairs, as is commonly found for purines and pyrimidines, but the structure is unusual in that the two bases do not lie in the same plane.

This diagram depicts the chemical structure of pyrimidine, a six-membered aromatic ring with two nitrogen atoms at positions 1 and 3 (highlighted in blue). The remaining positions are occupied by ...