Three 2D complexes with helical chains constructed from pimelic acid and rigid bis (imidazole) ligand: Syntheses, structures, thermal and photoluminescent properties

Three new complexes, namely, [M(Pim)(L)] (M = Co (1), Cd (2), Pim = Pimelic acid, L = 1,4-bis(1-imidazolyl)-benzene), [Zn(Pim)(L)]·H2O (3), have been synthesized hydrothermally from the self-assembly of the transtion metal ions (M2 +) with flexible aliphatic dicarboxylate ligand (Pim) and the rigid bis(imidazole) ligand(L). Both complexes 1 and 2 consist of left- and right-handed single-helical chains and present a two-dimensional (2D) layer with 36-hxl topology. Complex 3 displays a 2D structure constructed by right-handed single-helical chains and left-handed double-helical chains with intercrossed arrangement. Furthermore, thermogravimetric analyses for 1–3 and the photoluminescent properties of 2 and 3 have also been studied.