Supramolecular polymerization of chiral platinum(ii) complexes: transformable nanoassemblies and their amplified circularly polarized luminescence

Abstract

Herein, we report four pairs of enantiomeric platinum(II) complexes D/L-Pt-1–Pt-4 with minor structural variations that have been found to lead to distinct self-assembly behaviors and form various well-defined nanostructures. Notably, Pt-1 exhibits polymorphic self-assembly with well-defined nanostructures, such as nanorings, nanotwists, dendritic twists, and microbelts, in various conditions through the interplay of different non-covalent interactions. Importantly, two pairs of enantiomers D/L-Pt-1–Pt-2 show significantly amplified effects for circular dichroism (CD) and circularly polarized luminescence (CPL) in their corresponding nanoassemblies. Moreover, the self-assembly process can be governed by the Pt···Pt/π–π stacking, the solvophobic interactions, and electrostatic repulsion provided by the positively charged tridentate cyclometalated platinum(II) moieties. The detailed supramolecular polymerization pathway was systematically investigated by spectroscopy, X-ray single-crystal diffraction, and electron microscopy studies.