Anhydrous adenine: Crystallization, structure, and correlation with other nucleobases

The crystal structure of anhydrous adenine has been determined using a single crystal grown by a unique approach using a sublimation process. Anhydrous adenine crystallizes in the monoclinic space group P2(1)/c with a = 7.891(3) angstrom, b = 22.242(8) angstrom, c = 7.448(3) angstrom, beta = 113.193(5)degrees, V = 1201.6(3) angstrom(3), and Z = 8. The two molecules in the asymmetric unit are connected via two N-H center dot center dot center dot N hydrogen bonds, and the crystal structure is stabilized by two sets of N-H center dot center dot center dot N hydrogen bonds, one across the center of symmetry connecting the imidazole moiety to the pyridine moiety and the other linking the next asymmetric unit resulting in a sheet motif.