Histidine-Controlled Homochiral and Ferroelectric Metal–Organic Frameworks

A new multifunctional enantiopure ligand, (S)-2-(1,8-naphthalimido)-3-(4-imidazole)propanoate (s-nip), containing a homochiral center derived from l-histidine and a strong π···π stacking 1,8-naphthalimide synthon, has been used to prepare three novel metal–organic frameworks. The frameworks of [Zn(s-nip)2]n (1) and {[Co(s-nip)2]·(H2O)0.5}n (2) are isostructural three-dimensional (3D) homochiral supramolecular structures organized one-dimensional (1D) ribbons by strong hydrogen bonds and π···π interactions, which display ferroelectric behavior at room temperature. The complex [Cu(nia)2·(H2O)5]n (3) was constructed under a hydrothermal in situ ligand synthesis reaction, in which the new ligand 2-(1,8-naphthalimido)-3-(4-imidazole)acrylate (nia) was formed from the s-nip ligand via a dehydrogenation reaction. The two-dimensional network of 3 stacks into a 3D structure via π···π interactions resulting in 1D hydrophilic channels.