Dynamic scaffold of chiral binaphthol derivatives with the alkynylplatinum(II) terpyridine moiety

Abstract

Platinum(II)-containing complexes with inherently chiral binaphthol derivatives display a versatile scaffold between random coils and single-turn helical strands, in which the conformational transition is controlled by the Pt···Pt and π-π interactions of alkynylplatinum(II) terpyridine moiety upon solvent and temperature modulation. The bisignate Cotton effect in the circular dichroism spectra is indicative of the cooperative transformation from random coil state to a compact single-turn M- or P-helix. More importantly, as revealed by the appearance of new UV-vis absorption and emission bands during conformational change, the self-assembly of the platinum(II)-containing complex into a helical structure is assisted by the metal···metal and π-π interactions of the alkynylplatinum(II) terpyridine moieties. The folded structure with stabilization via metal···metal and π-π interactions has been supported by density functional theory calculations, which provide insights into the folded geometry of these kind of metallo-foldamers.