Self-assembly of an unpolar enantiomerically pure helicate-type metalla-cryptand

Chiral tetraketone ligands are obtained by Claisen-type condensation of 4-bromoacetophenone with the acetone ketal of L-tartraic acid diethylester and lead with gallium( III) or iron( III) ions in self-assembly processes to dinuclear helicate-type cryptands which are able to bind lithium cations.