Sugar-nucleobase hydrogen bonding in cytidine 5′-monophosphate nucleotide-cadmium coordination complexes

Hydrogen bonds are the fundamental factors stabilizing DNA and RNA macromolecules. Based on their base-pair sequences, DNA and RNA perform various biological functions. A key feature of these sequences is their linkage via hydrogen bonds. The hydrogen bonding between sugars and nucleobases in RNA sequences is one of the major reasons behind several mutagenic disorders that can cause numerous genomic instabilities, various genetic diseases, and RNA rearrangement problems. Chemists explore hydrogen bonding stability in nucleic acids, which is crucial for understanding molecular-level differentiations with potential applications in the early diagnosis of hereditary diseases. In this work, five types of coordination polymers of CMP and dCMP, {[Cd(CMP)(bpa)(H₂O)₃]·2H₂O}n (1), {[Cd(dCMP)₂(bpa)(H₂O)₂]·4H₂O}n (2), {[Cd(azpy)(H₂O)₄](CMP)·3H₂O}n (3), {[Cd(dCMP)₂(azpy)(H₂O)₂]·4H₂O}n (4), and {[Cd(CMP)(bpe)(H₂O)₃]·2H₂O}n (5) (azpy = 4,4′-azopyridine, bpa = 1,2-bis(4-pyridyl)ethane, and bpe = 1,2-bis(4-pyridyl)ethylene), were designed and studied. All complexes were fully characterized by employing the single-crystal X-ray diffraction method. Complex 1 is a 2D coordination polymer, whereas complexes 2-5 are 1D coordination polymers. Significantly, a novel sugar-nucleobase hydrogen bonding interaction was discovered in complexes 1, 3, and 5 for the first time, thus introducing a new supramolecular interaction that can be used in self-assembly and molecular recognition. The chirality in the supramolecular assemblies of the five complexes was comprehensively analyzed using single-crystal and solid-state CD spectra.