Cytosine modules have been investigated for applications in supramolecular quadruple hydrogen bonded arrays. Notably, the importance of the C-5–H in the formation of unfolded and folded arrays by substitution to C-5–F was established. In addition, the incorporation of different alkyl chain lengths at N-1 and N-9 indicated that longer alkyl chains give rise to more of the unfolded rotamer, with the chain length and degree of unsaturation at N-1 having the major effect. Methyl cytosine modules were also able to readily form hetero-associated Upy–UCyt dimers as efficiently as the hexyl cytosine modules and a polyadipate telechelic polymer was used to prepare cytosine polymers.