Modeling the zinc chelating rosette nanotube

Hybrid Guanine/Cytosine (G∧C) is a well-established motif that forms nanotubular architectures via self-assembly process. Six G/C motifs form the rosette through hydrogen bonding and the rosettes stack on top of each other through π interaction to form the nanotubes. The chemo-physical properties of the tube are featured by the arrangement of the substituents on the G/C motifs. A zinc chelating pyridyl group attached to G/C motif has been synthesized and the metallated compound showed linearly aggregated bundles of nanotubes. Extensive molecular modeling work using molecular orbital theory at the PM5 semi-empirical level has been performed on the motif. It is found that nanotubes of the 3-pyridyl substituted G∧C motif traps zinc ions between the pyridyl groups of two adjacent rosettes of a single tube. A model has been suggested to explain the linear aggregation of the nanotubes.