Supramolecular assembly of a phosphole-based moiety into nanostructures dictated by alkynylplatinum(ii) terpyridine complexes through non-covalent Pt⋯Pt and π–π stacking interactions: synthesis, characterization, photophysics and self-assembly behaviors

Abstract

A new class of platinum(II) terpyridine complexes with a phosphole-derived bridging alkynyl ligand have been prepared. The X-ray crystal structure of complex 2 has been determined, and reveals a polymeric zig-zag chain structure with the existence of π–π stacking interactions. The photophysical properties have also been studied, with ³MLCT/³LLCT phosphorescence exhibited in degassed CH₂Cl₂; the energy of which is varied by the π-conjugation of the terpyridine ligands. The solvent-induced assembly of complex 1 has been studied. The incorporation of hydrophobic hydrocarbon chains has been shown to play an important role in assisting the formation of self-assembled nanostructures via Pt⋯Pt, π–π stacking and hydrophobic–hydrophobic interactions. It has been established that an isodesmic growth mechanism operates in polar media to give nanospheres, while fibrous networks originate from the self-assembly of the complexes in non-polar media, predominantly driven by π–π stacking interactions.