Co-Assembled Supramolecular Nanostructure of Platinum(II) Complex through Helical Ribbon to Helical Tubes with Helical Inversion.

We demonstrated the morphology transformation of co-assemblies based on terpyridine-based ligands (1R and 1S) possessing R- or S-alanine analogues and their platinum(II) complex (2R-Pt and 2S-Pt). The right-handed helical ribbon of the co-assembly formed with 0.5 equivalents of 2R-Pt to 1R was converted into the left-handed helical ribbon with 0.6 equivalents of 2R-Pt. The left-handed helical ribbon structure of the co-assembly became a tubular structure in the presence of 0.8-1.0 equivalents of 2R-Pt. The morphology transformation via helical inversion at the supramolecular level was due to an orientation change of the amide groups caused by non-covalent Pt⋅⋅⋅Pt interactions between the terpyridine of 2R-Pt and that of 2R-Pt. This study provides insights into controlling the morphology of the transformation of helical ribbons into tubular structures through helicity inversion in co-assembled supramolecular nanostructures based on platinum(II) complexes.