Weak C–H···π and C–H···F Interactions Form Higher-Order Supramolecular Structures in Cytosine and Uracil (Z)-4′-Benzamido-2′-butenyl Derivatives

In this paper, eight closely related structures of ( Z )-4′-benzamido-2′-butenyl cytosine and uracil derivatives were analyzed to evidence how variations on the molecular level affect their supramolecular structures. The N–H···O, N–H···N, and C–H···O hydrogen bonds mainly participate in supramolecular assembling of these molecules, but C–H···F hydrogen bonds in the molecules containing a fluorine atom at the 5-position of the pyrimidine ring or the 4-position of the phenyl ring were also observed. Hydrogen bonds in two of eight structures built two-dimensional network, while in the remaining six structures weak C–H···π or/and C–H···F interactions expand two-dimensional networks into three-dimensional, thus having a crucial role in the formation of higher-order supramolecular structures.