Two novel 8-hydroxyquinoline metallic derivatives, (E)-2-[(2,3,4,5-tetrafluorophenyl)ethenyl]-8-hydroxyquinolate zinc (5) and (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinolate zinc (6) were synthesized and characterized by 1H NMR, ESI-MS, FT-IR and elemental analysis. Photoluminescence spectra revealed that the complexes showed strong fluorescence with maximum emissions at 575 and 607 nm. Compared with that of complex 5, the fluorescence quantum yield and average fluorescence lifetime of complex 6 were efficiently reduced. The heavy atom effect of Cl and distinct molecular interactions were found to play an important role in modulating or improving the properties of the complexes. Multilayer organic light-emitting diodes (OLEDs) were fabricated using these complexes. The results show they are good candidates for yellow OLEDs with maximum luminance of 7123 cd m−2 for compound 5 and 9143 cd m−2 for compound 6, as well as luminance efficiencies of 2.26 cd A−1 and 2.60 cd A−1, respectively. As the substituents are changed from fluorine to chlorine, the organic electroluminescent device based on the complex 6 shows overall better performance than that of complex 5. The calculated HOMO–LUMO energy gaps for complexes 5 and 6 were in good agreement with the experimental results.

•Binuclear [{(DMOX)CdCl}2(μ-Cl)2] (1) and mononuclear [(Dm-Pybox)CdCl2] (2) have been synthesized and characterized.•The supramolecular structures of complexes 1 and 2 feature helical chains fabricated by C–H⋯Cl hydrogen bond interactions.•Bimetallic complex 1 is efficient in catalyzing C–N cross-coupling of amine with aryl halide.Binuclear [{(DMOX)CdCl}2(μ-Cl)2] (DMOX = 4,5-dihydro-2-(4,5-dihydro-4,4-dimethyloxazol-2-yl)-4,4-dimethyl-oxazole) (1) and mononuclear [(Dm-Pybox)CdCl2] (Dm-Pybox = 2,6-bis[4′,4′-dimethyloxazolin-2′-yl]pyridine) (2) were obtained by reacting CdCl2 with DMOX and Dm-Pybox ligands, respectively. In the solid state, the supramolecular structures of 1 and 2 feature helical chains fabricated by C–H⋯Cl hydrogen bond interactions. The C–N cross-coupling reactions catalyzed by the two complexes were also investigated in homogeneous system. The results show that binuclear complex 1 exhibit significantly enhanced catalytic activity for C–N cross-coupling reactions.Bimetallic complex [{(DMOX)CdCl}2(μ-Cl)2] (1) is efficient in catalyzing C–N cross-coupling of amine with aryl halide.

We reported here the self-assembly of two supramolecular structures based on similar trimeric Zn(II) units that are built from novel 2-substituted 8-hydroxyquinoline ligands and coordination Zn(II) ions. The aggregation behavior of zinc salt and ligand in solution was investigated by a variety of techniques, including 1H NMR, UV-vis and photoluminescence (PL). In the solid state, the supramolecular structures can be controlled by the substituted groups (–NO2 and –F) via intermolecular interaction, such as π⋯π stacking, C–H⋯O, and C–F⋯F–C interactions. As a result, the two trimeric Zn(II) complexes exhibit disparate photophysical properties. The present research holds great promise in the development of novel multinuclear Zn(II) materials, and may contribute to the understanding of structure–property relationships.

This work reports the self-assembly of three cadmium complexes 1–3 from one 2-substituted 8-hydroxyquinoline ligand (HL). The skeleton exhibits an unprecedented structural diversification and fabricates one mononuclear and two different tetranuclear Cd(II) building units in response to the counteranions NO3−, OAc− and I−, respectively. The self-assembly behavior of the cadmium salts and the HL in MeOH was subsequently investigated using UV-vis spectroscopy. In the solid state, the supramolecular structures of 1–3 feature unique helical chains or a 3D network via non-covalent interactions, such as π⋯π stacking, C–H⋯π, hydrogen bonding and halogen-related interactions. As a result, the three Cd(II) complexes exhibit disparate photophysical properties. This unique capability may provide a useful strategy to tune the optical properties of multinuclear materials, which could be exploited as important components for optoelectronic devices.

•Two complexes 1 and 2 were synthesized and characterized.•The supramolecular structures of 1 and 2 feature two different helical chains.•Both of the two helical structures were constructed by non-covalent interactions.Based on two 2-substituted 8-hydroxyquinoline ligands containing NO2 and Cl, two complexes [Co(L2)2(pyridine)2] (1) and [Cu(L3)2] (2) were synthesized and characterized with single-crystal X-ray diffractions, powder X-ray diffractions (PXRD), thermal analyses (TGA) and elemental analyses (EA). In the solid state, the supramolecular structures of 1 and 2 feature two different two-folded helical chains, which were constructed by non-covalent interactions, such as π⋯π stacking, CH⋯π, CH⋯O, CCl⋯π and Cl⋯Cl interactions. The present research holds great promise in the development of novel functional helical structure, and may contribute to the understanding of helical organized systems in biology.Two complexes [Co(L1)2(pyridine)2] (1) and [Cu(L2)2] (2) were fabricated by self-assembly of M(II) ions with two novel 2-substituted-8-hydroxyquinoline ligands. The supramolecular structures of 1 and 2 feature two different two-folded helical chains and thereby 3D networks via non-covalent interactions.

We reported here the self-assembly of two supramolecular structures based on similar trimeric Zn(II) units that are built from novel 2-substituted 8-hydroxyquinoline ligands and coordination Zn(II) ions. The aggregation behavior of zinc salt and ligand in solution was investigated by a variety of techniques, including 1H NMR, UV-vis and photoluminescence (PL). In the solid state, the supramolecular structures can be controlled by the substituted groups (–NO2 and –F) via intermolecular interaction, such as π⋯π stacking, C–H⋯O, and C–F⋯F–C interactions. As a result, the two trimeric Zn(II) complexes exhibit disparate photophysical properties. The present research holds great promise in the development of novel multinuclear Zn(II) materials, and may contribute to the understanding of structure–property relationships.