Supramolecular hydrogen-bonded networks in cytosinium succinate and cytosinium 4-nitrobenzoate cytosine monohydrate.

In cytosinium succinate (systematic name: 4-amino-2-oxo-2,3-dihydropyrimidin-1-ium 3-carboxypropanoate), C(4)H(6)N(3)O(+) x C(4)H(5)O(4)(-), (I), the cytosinium cation forms one-dimensional self-assembling patterns by intermolecular N-H...O hydrogen bonding, while in cytosinium 4-nitrobenzoate cytosine monohydrate [systematic name: 4-amino-2-oxo-2,3-dihydropyrimidin-1-ium 4-nitrobenzoate 4-aminopyrimidin-2(1H)-one solvate monohydrate], C(4)H(6)N(3)O(+) x C(7)H(4)NO(4)(-) x C(4)H(5)N(3)O x H(2)O, (II), the cytosinium-cytosine base pair, held together by triple hydrogen bonds, leads to one-dimensional polymeric ribbons via double N-H...O hydrogen bonds. This study illustrates clearly the different alignment of cytosine molecules in the crystal packing and their ability to form supramolecular hydrogen-bonded networks with the anions.