Series of Geländer oligomers with orthogonal rungs

Abstract

The synthesis and analyses of a series of “Geländer” oligomers with perpendicularly arranged rungs are reported. The synthesis is achieved by forming the axis with a statistical end-capped oligomerization, before the banister is wrapped around it by Eglinton couplings. The intrinsic helical chiral structures are characterized by NMR spectroscopy and mass- and photo spectrometry, and for the trimer, even the solid-state structure is determined. The dimeric, trimeric, and tetrameric structures are resolved into their enantiomers and their electronic circular dichroism is studied.