Synthesis and Characterization of Axially Chiral Molecules Containing Dendritic Substituents

Abstract

Enantiomerically pure, axially chiral (S)-1,1′-bi-2-naphthol has been used as a core material to which Frechet-type dendritic wedges of the zeroth up to the fourth generation were attached, yielding the first axially chiral dendrimers 1−5. The chiroptical features of these compounds were studied and revealed an increasing molar optical activity for higher generations of dendrimers. This effect can be explained by a larger torsional angle between the naphthyl units, caused by steric repulsions between the dendritic wedges. However, the effect is marginal, indicating a high degree of flexibility present in the axially chiral dendrimers.