One-dimensional double helical structure and 4-fold type [2+2] interpenetration of diamondoid networks with helical fashion

We have prepared unique homochiral structures by the self-assembly of a modified amino acid derivative (terephthaloylnionoalanine, L-TMA) with metal ions such as Zn(II) and Cd(II). An L-TMA ligand and Zn(II) ions formed a left-handed, homochiral, double helical chain. However, while L-TMA and Cd(II) ions topologically formed a diamondoid Cd-L-TMA network with 4-fold type [2 + 2] interpenetration, Cd-L-TMA can be morphologically considered as a three-dimensional network of left-handed, double helices. The double helical structure of Zn-L-TMA originated from the self-assembly of individual helical chains by hydrogen bonds and pi-pi interactions, whereas the double helical structures of Cd-L-TMA were observed in an interpenetrating diamondoid net.