Single-turn helix-coil strands stabilized by metal ⋯metal and π-π Interactions of the alkynylplatinum(II) terpyridyl moieties in meta -phenylene ethynylene foldamers

Abstract

Dinuclear alkynylplatinum(II) terpyridyl complexes with oligomeric bridge consisting of five repeating meta-phenylene ethynylene (mPE) units have been found to exhibit a strong tendency to fold back onto themselves to form short helical strands through the stabilization of Pt ⋯Pt and π-π interactions. The steric bulk of the terpyridine ligands and the length of the oligomeric bridge have been found to affect the extent of the intramolecular Pt ⋯Pt interaction that governs the stabilization of the short helical strand in solution. Their folding properties via Pt ⋯Pt and π-π stacking interactions have been studied by 1H NMR, 2D ROESY NMR, electronic absorption, and emission spectroscopies. © 2011 American Chemical Society.