A new azo-complex [(L)CuII(NO3)] [L = (E)-3-(pyridin-2-yldiazenyl)naphthalen-2-ol (HL)], was prepared via a one-pot synthetic method at 60 °C and was structurally characterized by IR, EA, PXRD and single crystal X-ray diffraction. In addition, TGA studies indicated that the complex was stable in air. The redox properties were determined by cyclic voltammetry, which revealed that the complex could be utilized as a catalyst for water oxidation under mild conditions. Subsequently, the complex was employed as a catalyst to take part in water oxidation reaction in the presence of a CeIV salt utilized as an oxidant at pH 11 in PBS (Phosphate Buffered Saline) solution. The results suggested that the catalyst exhibited a high stability and activity toward water oxidation reaction under these conditions with an initial TOF of 4.0 kPa h−1. Calculation methodology was performed to study the mechanism of the reaction, which revealed that in this catalytic process, the initial oxidation of Cu(II) to Cu(III) occurred by the formation of an intermediate “Cu(III)–O–O–Cu(III)”. The formation of this intermediate, resulted in a release of oxygen and closing of the catalytic cycle.

Herein we report the molecular structures and electronic properties of ionic, hydrophobic half-sandwich complexes with formula [η5-Cp*Ir(L)(Cl)](OTf) (1), [η5-Cp*Rh(L)(Cl)](OTf) (2), [η5-Cp*Ir(L)(H2O)](OTf)2 (3) and [η5-Cp*Rh(L)(H2O)](OTf)2 (4), where L is 1-(2-pyridylazo)-2-naphthol. The electrochemical properties of these complexes have been investigated, and they displayed good electronic properties for use as water oxidation catalysts. Interestingly, the color of their solutions is unambiguously transformed from brown to green at pH = 12; the color changes of 1, 2 and 4 are especially apparent. For this reason, their use as pH sensors for detecting solution pH values can be explored.

Herein we report the molecular structures and electronic properties of ionic, hydrophobic, half-sandwich complexes of the formula [η5-Cp*Rh(L)(MeOH)] (1) and [η6-CyRu(L)(H2O)] (2), where L is azo-dye compound of (p-(2-hydroxy-1-naphthylazo)benzenesulfonic acid sodium salt). Both these complexes have been investigated electrochemically and found to display good electronic properties for use as water-oxidation catalysts potentially.

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.

Herein we report the molecular structures and electronic properties of ionic, hydrophobic half-sandwich complexes with formula [η5-Cp*Ir(L)(Cl)](OTf) (1), [η5-Cp*Rh(L)(Cl)](OTf) (2), [η5-Cp*Ir(L)(H2O)](OTf)2 (3) and [η5-Cp*Rh(L)(H2O)](OTf)2 (4), where L is 1-(2-pyridylazo)-2-naphthol. The electrochemical properties of these complexes have been investigated, and they displayed good electronic properties for use as water oxidation catalysts. Interestingly, the color of their solutions is unambiguously transformed from brown to green at pH = 12; the color changes of 1, 2 and 4 are especially apparent. For this reason, their use as pH sensors for detecting solution pH values can be explored.

Herein we report the molecular structures and electronic properties of ionic, hydrophobic, half-sandwich complexes of the formula [η5-Cp*Rh(L)(MeOH)] (1) and [η6-CyRu(L)(H2O)] (2), where L is azo-dye compound of (p-(2-hydroxy-1-naphthylazo)benzenesulfonic acid sodium salt). Both these complexes have been investigated electrochemically and found to display good electronic properties for use as water-oxidation catalysts potentially.

A new azo-complex [(L)CuII(NO3)] [L = (E)-3-(pyridin-2-yldiazenyl)naphthalen-2-ol (HL)], was prepared via a one-pot synthetic method at 60 °C and was structurally characterized by IR, EA, PXRD and single crystal X-ray diffraction. In addition, TGA studies indicated that the complex was stable in air. The redox properties were determined by cyclic voltammetry, which revealed that the complex could be utilized as a catalyst for water oxidation under mild conditions. Subsequently, the complex was employed as a catalyst to take part in water oxidation reaction in the presence of a CeIV salt utilized as an oxidant at pH 11 in PBS (Phosphate Buffered Saline) solution. The results suggested that the catalyst exhibited a high stability and activity toward water oxidation reaction under these conditions with an initial TOF of 4.0 kPa h−1. Calculation methodology was performed to study the mechanism of the reaction, which revealed that in this catalytic process, the initial oxidation of Cu(II) to Cu(III) occurred by the formation of an intermediate “Cu(III)–O–O–Cu(III)”. The formation of this intermediate, resulted in a release of oxygen and closing of the catalytic cycle.