Macrocyclic Dinuclear Copper Research Articles

A new preparation of a bifunctional crystalline heterogeneous copper electrocatalyst by electrodeposition using a Robson-type macrocyclic dinuclear copper complex for efficient hydrogen and oxygen evolution from water.

The development of low-cost, stable bifunctional electrocatalysts, which operate in the same electrolyte with a low overpotential for water splitting, including the oxygen evolution reaction and the hydrogen evolution reaction, remains an attractive prospect and a great challenge. In this study, a water soluble Robson-type macrocyclic dicopper(ii) complex has been used for the first time as a catalyst precursor for the generation of a copper-based bifunctional heterogeneous catalyst film, which can be used for both HER and OER at a near neutral pH. In sodium borate buffer at pH 9.20, this complex decomposed to give a Cu(OH)2/Cu2O-based thin film on FTO that catalyzes both hydrogen production and water oxidation. The morphology, nature and composition of the thin film were fully characterized by scanning electron microscopy, powder X-ray diffraction, X-ray photoelectron, and energy dispersive X-ray spectroscopies. The catalyst film showed high stability during the course of electrolysis in either the cathodic or the anodic direction for more than 4 h. Faradaic efficiencies of ∼92% for HER and ∼96% for OER were achieved. The switch between the two half-reactions of catalytic water splitting was fully reversible in nature.

Design and synthesis of two macrocyclic dinuclear copper(II) complexes with reversible binding of nitric oxide

Abstract Two new macrocyclic dinuclear copper(II) complexes, [Cu2L1(MeOH)2]·(ClO4)2 (1) and [Cu2L2(EtOH)2]·(ClO4)2 (2) have been synthesized and characterized by ES-MS spectra and X-ray crystallography determination. The coordination polyhedron of Cu(II) ions in each complex can be described as approximately square pyramind, where the apical position is occupied by a labile coordinated alcoholic molecule. The reactions of complexes with nitric oxide (NO) cause an immediate color change, and the formation of NO complexes has been further confirmed by UV/Vis spectrophotometry. The binding constants are calculated to be 1.71 × 103 M− 1 and 2.0 × 103 M− 1 in 0.2 M anaerobic phosphate buffer solution (PBS), respectively. The control experiments reveal that the binding of NO to complexes is reversible. Moreover, the interactions of the complexes with calf thymus DNA (CT-DNA) have been measured by UV/Vis, cyclic voltammetry and viscosity study. The moderate binding ability and unobvious DNA cleavage ability account for their low toxicity towards DNA. Overall, the results reveal that these two complexes can be served as potential NO regulators.

Fluorescent detection of phosphate anion by a highly selective chemosensor in water

A macrocyclic dinuclear copper complex, [Cu 2 II( 1)Br 4]·2H 2O has been synthesized and characterized by X-ray crystallography, in which each metal ion is pentacoordinated in a square pyramidal environment and the macrocycle is folded to form a boat-shaped empty cavity. As studied by an indicator displacement assay, the dinuclear complex shows strong selectivity for phosphate over sulfate, nitrate, perchlorate and halides in water at physiological pH.

Anion Recognition and Sensing by a New Macrocyclic Dinuclear Copper(II) Complex: A Selective Receptor for Iodide

A macrocyclic dinuclear copper complex, [Cu(2)(II)(1)Br(3)(H(2)O)]Br, has been synthesized and characterized by X-ray crystallography, in which the macrocycle is folded to form a bowl-shaped cavity. The sensing ability of the receptor has been studied for halides by UV-vis spectroscopy in water-acetonitrile (1:3, v/v) and water. The results indicate that the new receptor exhibits a strong affinity and selectivity for iodide.

Two novel compartmental macrocyclic dinuclear copper(II) complexes with μ 2-Cl and μ 2-OAc bridges

Two novel compartmental macrocyclic dinuclear copper(II) complexes with different bridging ligands, formulated as [ Cu 2 II ( L ) ( μ 2 -Cl ) ] · 1.5 ( H 2 O ) ( 1) and [ Cu 2 II ( L ) ( μ 2 -OAc ) ] · ( DMF ) ( 2), are characterized by X-ray single-crystal diffraction where LH 3 is a pentadentate ligand obtained from the Schiff base condensation between 3,5-di- tert-butyl-2-hydroxybenzaldehyde and 2,6-bis(aminomethyl)-4-chlorophenol in a molar ratio of 2:1. Due to the use of different bridges and bulky t-bu groups, different molecular conformation and dimeric packing structures are observed.

Synthesis of a Tetracopper Assembly Complex Comprised of One Macrocyclic Dinuclear Copper Unit and Two Mononuclear Copper Units: Intramolecular Electron Transfer Relevant to Multicopper Oxidase

Abstract The dinuclear copper(II) complex [Cu2(L1)](ClO4)2·CH3OH·2H2O (1) of a macrocyclic ligand H2L1, derived from the cyclic [2:2] condensation of 2,6-diformyl-4-methylphenol and 1,1,1-tri(aminomethyl)ethane, has been prepared as the type 3 copper site for modeling multicopper oxidase: 1 has two auxiliary amino groups on the macrocyclic framework. The condensation of 1 with two molecules of 2-formylpyridine through the amino groups afforded [Cu2(L2)](ClO4)2·2DMF (2). This has a Cu···Cu separation of 4.434(1) Å with no direct bridge between the two copper atoms, owing to the involvement of the auxiliary 2-pyridylmethylimino residue in coordination. The condensation of 1 with two molecules of 3-[N,N-di(2-pyridylmethyl)aminomethyl]-5-methylsalicylaldehyde in the presence of Cu(ClO4)2·6H2O afforded the tetracopper assembly complex [Cu4(L3)](ClO4)4·3H2O (3), which is comprised of a macrocyclic dinuclear Cu2(II,II) unit and two mononuclear Cu(II) units, {Cu(II)–Cu2(II,II)–Cu(II)}. Cyclic voltammograms of 3 exhibit a two-electron redox process at −0.77 V (vs Ag/Ag+) followed by two one-electron redox processes at −0.85 and −1.29 V. Coulometric studies combined with spectroscopic and EPR studies demonstrate that the redox process at −0.77 V involves the reduction of two mononuclear Cu(II) units followed by an intramolecular electron transfer from one of the reduced Cu(I) units to the dinuclear Cu2(II,II) unit: {Cu(II)–Cu2(II,II)–Cu(II)}/{Cu(I)–Cu2(II,II)–Cu(I)} → {Cu(I)–Cu2(I,II)–Cu(II)}. The resulting {Cu(I)–Cu2(I,II)–Cu(II)} species is further reduced to {Cu(I)–Cu2(I,II)–Cu(I)} at −0.85 V and to {Cu(I)–Cu2(I,I)–Cu(I)} at −1.29 V.

Structures of Bimetallic Assemblies Derived from a Macrocyclic Dinuclear Copper(II) Complex and [Cr(ox)3]3− or [Co(CN)6]3−

Abstract A dinuclear copper(II) complex, [Cu2(L)](ClO4)2, of the macrocyclic ligand (H2L) derived from the [2:2] condensation of 2,6-diformyl-4-methylphenol and 1,3-diaminopropane, was reacted with [Cr(ox)3]3− and [Co(CN)6]3− to produce [Cu2(L)]3[Cr(ox)3]2·6MeOH (1) of a discrete octanuclear structure and [Cu2(L)]3[Co(CN)6]2·6MeOH·2DMF (2) of a 2-D grid structure, respectively.

Cyanide and imidazolate bridged macrocyclic dinuclear CuII complexes: Synthesis, structure and magnetic properties

Reaction of [Cu 2L](ClO 4) 4 with CH 3CN in acetonitrile, and Him in DMF gave cyanide and imidazolate bridged macrocyclic dinuclear copper (II) complexes with the formula [Cu 2L(CN)](ClO 4) 3 ( 1) and [Cu 2L(im)](ClO 4) 2 · 0.7Br · 0.3Cl, ( 2), respectively (L = N[(CH 2) 2NHCH 2(C 6H 4- p)CH 2NH(CH 2) 2] 3N). In 2, each Cu(II) atom is coordinated with four macrocyclic nitrogen atoms and one imidazolate N atom, forming a slightly distorted square pyramidal geometry. Magnetic susceptibility measurements of 1 and 2 show that the two Cu(II) atoms of the binuclear unit are antiferromagnetically coupled with g = 2.148, J = −86.09 cm −1 for 1, and g = 2.047, J = −38.20 cm −1 for 2. The correlation between the structures and the J values is discussed.

Macrocyclic dinuclear copper(II) complex with a novel chloride bridged zigzag chain

A macrocyclic dinuclear copper complex Cu 2LCl(ClO 4) · H 2O, where L=15,31-dimethyl-3,11,19,27,33,35-hexaazapentacyclo[27.3.1.1. 5,91. 13,171. 21,25]-hexatriaconta-5,7,9(33),13,15,17(34),21,23,25(35),29,31,1(36)-dodecaene-34,36-diol, has been synthesized and characterized by single-crystal X-ray diffraction. In the complex, each Cu(II) ion is coordinated with three macrocyclic nitrogen atoms and one phenolate oxygen anion. The dinuclear copper complexes are linked by the bridged Cl − to form a novel zigzag chain with a folded chair conformation.

Magnetostructural Correlations in Bis(&mgr;(2)-phenoxide)-Bridged Macrocyclic Dinuclear Copper(II) Complexes. Influence of Electron-Withdrawing Substituents on Exchange Coupling.

Macrocyclic dicopper(II) complexes derived from 2,6-di(R)formylphenols and various linking diamines are surveyed and their magnetic and structural properties assessed. For those systems with "flat" dinuclear centers and no electronic perturbations associated with electron-withdrawing ligands or ligand groups, the complexes exhibit a "straight-line" relationship between exchange integral and phenoxide bridge angle. Within the angle range 98.8-104.7 degrees, 11 complexes are included with -2J in the range 689-902 cm(-)(1). When electron-withdrawing species are present, either as ligands or as groups bound to the macrocycle itself, considerable suppression of the antiferromagnetic exchange component is observed. Single-crystal X-ray diffraction studies are reported for three complexes. [Cu(2)(L1)(H(2)O)(2)]F(2)(CH(3)OH)(2) (1) crystallized in the triclinic system, space group P&onemacr;, with a = 8.1878(5) Å, b = 9.0346(7) Å, c = 10.4048(7) Å, alpha = 103.672(6) degrees, beta = 101.163(5) degrees, gamma = 104.017(5) degrees, and Z = 1. [Cu(2)(L2)Cl(2)] [Cu(2)(L2) (H(2)O)(2)]Cl(ClO(4)).5.5H(2)O (2) crystallized in the monoclinic system, space group P2(1)/n, with a = 14.4305(5) Å, b = 24.3149(8) Å, c = 18.6584(8) Å, beta = 111.282(3) degrees, and Z = 4. [Cu(2)(L3)(H(2)O)(2)](BF(4))(2) (3) crystallized in the triclinic system, space group P&onemacr;, with a = 8.6127(4) Å, b = 8.6321(7) Å, c = 10.8430(10) Å, a = 74.390(10) degrees, beta = 86.050(10) degrees, gamma = 76.350(10) degrees, and Z = 2. Square pyramidal copper ion stereochemistries are observed in all cases, with axially coordinated halogens or water molecules. Strong antiferromagnetic exchange is observed for all complexes (-2J = 784(8) cm(-)(1), Cu-O-Cu 103.65(10) degrees (1); -2J = 801(11) cm(-)(1), Cu-O-Cu 102.4(3), 107.5(3), 102.9(3), 106.1(3) degrees (2); -2J = 689(3) cm(-)(1), Cu-O-Cu 98.8(4) degrees (3)). The presence of electron-withdrawing CN groups on the periphery of the macrocyclic ligand leads to substantially reduced antiferromagnetic exchange.

Macrocyclic dinuclear copper complexes as model systems for the type-3 active site

Macrocyclic dinuclear copper complexes as model systems for the type-3 active site

Dioxygen Binding to a Macrocyclic Dinuclear Copper(I) Monooxygenase Model System. Ambient and High Pressure Kinetics

Dioxygen Binding to a Macrocyclic Dinuclear Copper(I) Monooxygenase Model System. Ambient and High Pressure Kinetics

Oxidation reactions of a macrocyclic dinuclear copper(I) dioxygen complex and a dinuclear copper(II) complex

Recently a solution phase copper(I) dinuclear complex of the ligand 3,6,9, 16, 19,22-hexaazatricyclo-[22.2.1.1 11,14 ]-octacosa-1(26),2,9,11,13,15,22,24-octaene, (FD) 2 (DIEN) 2 , and its dioxygen adduct were spectroscopically characterized. In this report, the use of the dinuclear complex in performing oxidation reactions with hydroquinones, phenols, catechols, ascorbic acid, and 3,4-dimethylaniline in a 3:1 mixture of methanol and acetonitrile is described