Homochiral Metal–Organic Frameworks Embedding Helicity Based on a Semirigid Alanine Derivative

Abstract

Five novel homochiral metal–organic frameworks (HMOFs) have been synthesized using a semirigid alanine-derived ligand and varied auxiliary N-donor ligands, namely, [Cu2(TMAla)2(bipy)2]·10H2O (1) and [Cu(TMAla)(bpea)0.5(H2O)]·H2O (2), Ln(TMAla)(HTMAla)(phen) (Ln = Eu, 3; Tb, 4; Gd, 5), where H2TMAla = terephthaloyl-mono(l-alanine), bipy = 4,4′-bipyridine, bpea = 1,2-bis(4-pyridyl)ethane, phen = 1,10-phenanthroline. Crystallographic analysis indicates that all the complexes contain homochiral left- and/or right-handed helical chains, which are constructed by TMAla fragments and metal ions. Meanwhile, the introduction of auxiliary N-donor ligands gives rise to the formation of HMOFs with different structural topologies. Complex 1 shows a three-dimensional (3D) quartz-dual net with a 4-connected (75·9) topology in the presence of bipy. Complex 2 possesses a novel 3D pillared-layer framework with a (3,4,4)-connected (6·104·12)(63)2(64·102) topology by using bpea instead of bipy. Complexes 3–5 are isomorphous a...