'0'- and '8'-shaped complexes generated from a nano-sized oxadiazole-containing organic ligand with CdI2 and CuI

A new nano-sized rigid double-armed oxadiazole-bridged organic ligand, 2,5-bis{2-methyl-5-[2-(pyridin-3-yl)ethenyl]phenyl}-1,3,4-oxadiazole, C30H20N4O, L or (I), which adopts a cis conformation in the solid state, has been synthesized and used to create the two novel metallocycle complexes (2,5-bis{2-methyl-5-[2-(pyridin-3-yl-κN)ethenyl]phenyl}-1,3,4-oxadiazole)diiodidocadmium(II) dichloromethane monosolvate, [CdI2(C30H20N4O)]·CH2Cl2, (II), and di-μ-iodido-bis[(2,5-bis{2-methyl-5-[2-(pyridin-3-yl-κN)ethenyl]phenyl}-1,3,4-oxadiazole)copper(I)], [Cu2I2(C30H20N4O)2], (III). Molecules of complex (II) adopts a 20-membered `0'-shaped metallocycle structure with crystallographic mirror symmetry. The discrete units are linked into one-dimensional chains through intermolecular π-π and C-H...π interactions. In (III), the two I atoms and two Cu(I) atoms form a {Cu2(μ-I)2} cluster. One {Cu2(μ-I)2} cluster and two L ligands form two 20-membered monometallic rings in a head-to-head fashion, leading to a discrete centrosymmetric `8'-shaped metallocyclic complex. These metallocycles stack together via two kinds of intermolecular π-π interactions to generate a two-dimensional network in the ac plane. The luminescence properties of (I)-(III) were investigated in the solid state at room temperature and displayed an obvious red shift.