Production of hydrogen by oxidative steam reforming of methanol over Cu/SiO2 catalysts

Selective production of hydrogen by oxidative steam reforming of methanol (OSRM) was studied over Cu/SiO₂ catalyst using fixed bed flow reactor. Textural and structural properties of the catalyst were analyzed by various instrumental methods. TPR analysis illustrates that the reduction temperature peak was observed between 510?K and 532?K at various copper loadings and calcination temperatures and the peaks shifted to higher temperature with increasing copper loading and calcination temperature. The XRD and XPS analysis demonstrates that the copper existed in different oxidation states at different conditions: Cu₂O, Cu⁰, CuO and Cu(OH)₂ in uncalcined sample; CuO in calcined sample: Cu₂O and metallic Cu after reduction at 600?K and Cu⁰ and CuO after catalytic test. TEM analysis reveals that at various copper loadings, the copper particle size is in the range between 3.0?nm and 3.8?nm. The Cu particle size after catalytic test increased from 3.6 to 4.8?nm, which is due to the formation of oxides of copper as evidenced from XRD and XPS analysis. The catalytic performance at various Cu loadings shows that with increasing Cu loading from 4.7 to 17.3?wt%, the activity increases and thereafter it decreases. Effect of calcination shows that the sample calcined at 673?K exhibited high activity. The O₂/CH₃OH and H₂O/CH₃OH molar ratios play important role in reaction rate and product distribution. The optimum molar ratios of O₂/CH₃OH and H₂O/CH₃OH are 0.25 and 0.1, respectively. When the reaction temperature varied from 473 to 548?K, the methanol conversion and H₂ production rate are in the range of 21.9–97.5% and 1.2–300.9?mmol?kg^?1?s^?1, respectively. The CO selectivity is negligible at these temperatures. Under the optimum conditions (17.3?wt%, Cu/SiO₂; calcination temperature 673?K; 0.25 O₂/CH₃OH molar ratio, 0.5 H₂O/CH₃OH molar ratio and reaction temperature 548?K), the maximum hydrogen yield obtained was 2.45?mol of hydrogen per mole of methanol. The time on stream stability test showed that the Cu/SiO₂ catalyst is quite stable for 48?h.     

Monomeric Copper(II) Sites Supported on Alumina Selectively Convert Methane to Methanol

Monomeric Cu^II sites supported on alumina, prepared using surface organometallic chemistry, convert CH₄ to CH₃OH selectively. This reaction takes place by formation of CH₃O surface species with the concomitant reduction of two monomeric Cu^II sites to Cu^I, according to mass balance analysis, infrared, solid‐state nuclear magnetic resonance, X‐ray absorption, and electron paramagnetic resonance spectroscopy studies. This material contains a significant fraction of Cu active sites (22 %) and displays a selectivity for CH₃OH exceeding 83 %, based on the number of electrons involved in the transformation. These alumina‐supported Cu^II sites reveal that C?H bond activation, along with the formation of CH₃O‐ surface species, can occur on pairs of proximal monomeric Cu^II sites in a short reaction time.     

Reaction mechanisms of methanol oxidation by FeIVO biomimetic complex

Density functional theory calculations were carried out to investigate the reaction mechanism of methanol oxidation mediated by [(bpg)Fe^IVO]⁺ ( A ). Two models (CH₃CN‐bound ferryl model B and CH₃OH‐bound ferryl model C ) were also studied in this work to probe ligand effect. Mechanistically, both direct and concerted hydrogen transfer (DHT and CHT) pathways were explored. It is found that the initial step of methanol oxidation by A is C? H bond activation via a DHT pathway. Addition of different equatorial ligands has considerable influence on the reaction mechanisms. Methanol oxidation mediated by B commences via O? H bond activation; in sharp contrast, the oxidation mediated by C stems from C? H bond activation. Frontier molecular orbital analysis showed that the initial C? H bond activation by all these model complexes follows a hydrogen atom transfer (HAT) mechanism, whereas O? H bond activation proceeds via an HAT or proton transfer. © 2016 Wiley Periodicals, Inc.     

Theoretical and Experimental Study of Complex Ions from Reactions of Al+ (Cu+) with Amine Molecules

The gas phase reactions of metal ions (Al⁺, Cu⁺) with amine molecules [CH₃NH₂=MA, (CH₃)₂NH=DMA] were investigated using a laser ablation‐molecular beam method. The directly associated product complex ions,Al⁺‐MA and Al⁺‐DMA, and the dehydrogenation product ions, Cu⁺(CH₂NH) and Cu⁺(C₂H₅N), as well as hydrated ion Cu⁺(NC₂H₅·H₂O), have been obtained and recorded from the reactions of the metal ions and organic amine molecules, and density functional theory (B3LYP) calculations have been performed to reveal the optimized geometry, energetics, and reaction mechanism of the title reactions with basis set 6‐311+G(d,p) adopted.     

N2O Reductase Activity of a [Cu4S] Cluster in the 4CuI Redox State Modulated by Hydrogen Bond Donors and Proton Relays in the Secondary Coordination Sphere

The model complex [Cu₄(μ₄‐S)(dppa)₄]²⁺ ( 1 , dppa=μ₂‐(Ph₂P)₂NH) has N₂O reductase activity in methanol solvent, mediating 2 H⁺/2 e^? reduction of N₂O to N₂+H₂O in the presence of an exogenous electron donor (CoCp₂). A stoichiometric product with two deprotonated dppa ligands was characterized, indicating a key role of second‐sphere N?H residues as proton donors during N₂O reduction. The activity of 1 towards N₂O was suppressed in solvents that are unable to provide hydrogen bonding to the second‐sphere N?H groups. Structural and computational data indicate that second‐sphere hydrogen bonding induces structural distortion of the [Cu₄S] active site, accessing a strained geometry with enhanced reactivity due to localization of electron density along a dicopper edge site. The behavior of 1 mimics aspects of the Cu_Z catalytic site of nitrous oxide reductase: activity in the 4Cu^I:1S redox state, use of a second‐sphere proton donor, and reactivity dependence on both primary and secondary sphere effects.     

Bis[bis­(methoxy­carbimido)amine‐κ2N,N′]bis­(perchlorato‐κO)copper(II) bis­[bis­(methoxy­carbimido)amine‐κ2N,N′]bis­(methanol‐κO)copper(II) bis­(perchlorate) methanol disolvate

The title compound, [Cu(ClO₄)₂(C₄H₉N₃O₂)₂][Cu(C₄H₉N₃O₂)₂(CH₄O)₂](ClO₄)₂·2CH₃OH, comprises two independent Cu^II species lying on different inversion sites. In the Cu complexes, a distorted octa­hedral geometry arises (from basic square‐planar N₄ coordination) from the weak coordination of two perchlorate ions (as Cu—O) in one species and two methanol mol­ecules in the other (also as Cu—O). Inter­actions between the O atoms of the perchlorate anions or methanol groups and the imide or amine NH groups afford an extensive inter­molecular hydrogen‐bonding network.     

Methanol[1‐(methoxymethanimidoyl)‐2‐(pyridin‐2‐ylmethyl)guanidine]bis(perchlorato)copper(II)

The title complex, [Cu(ClO₄)₂(C₉H₁₃N₅O)(CH₃OH)], was synthesized from a methanolysis reaction of N‐(methylpyridin‐2‐yl)cyanoguanidine (L³) and copper(II) perchlorate hexahydrate in a 1:1 molar ratio. The Cu^II ion is six‐coordinated by an N₃O₃ donor set which confers a highly distorted and asymmetric octahedral geometry. Three N‐donor atoms from the chelating 1‐(methoxymethanimidoyl)‐2‐(pyridin‐2‐ylmethyl)guanidine (L^3m) ligand and one O atom from the methanol molecule define the equatorial plane, with two perchlorate O atoms in the apical sites, one of which has a long Cu—O bond of 2.9074 (19) Å. The dihedral angle between the five‐ and six‐membered chelate rings is 8.21 (8)°. Two molecules are associated into a dimeric unit by intermolecular N—H...O(perchlorate) hydrogen bonds. Additionally, the weakly coordinated perchlorate anions also link adjacent [Cu(ClO₄)₂(L^3m)(CH₃OH)] dimers by hydrogen‐bonding interactions, resulting in a two‐dimensional layer in the (100) plane. Further C—H...O hydrogen bonds link the two‐dimensional layers along [100] to generate a three‐dimensional network.     

Palladium‐Catalyzed Aerobic Intermolecular Cyclization of Acrylic Acid with 1‐Octene to Afford α‐Methylene‐γ‐butyrolactones: The Remarkable Effect of Continuous Water Removal from the Reaction Mixture and Analysis of the Reaction by Kinetic,ESI‐MS,and XAFS Measurements

Further study of our aerobic intermolecular cyclization of acrylic acid with 1‐octene to afford α‐methylene‐γ‐butyrolactones, catalyzed by the Pd(OCOCF₃)₂/Cu(OAc)₂ ? H₂O system, has clarified that the accumulation of water generated from oxygen during the reaction causes deactivation of the Cu cocatalyst. This prevents regeneration of the active Pd catalyst and, thus, has a harmful influence on the progress of the cyclization. As a result, both the substrate conversion and product yield are efficiently improved by continuous removal of water from the reaction mixture. Detailed analysis of the kinetic and spectroscopic measurements performed under the condition of continuous water removal demonstrates that the cyclization proceeds in four steps: 1) equilibrium coordination of 1‐octene to the Pd acrylate species, 2) Markovnikov‐type acryloxy palladation of 1‐octene (1,2‐addition), 3) intramolecular carbopalladation, and 4) β‐hydride elimination. Byproduct 2‐acryloxy‐1‐octene is formed by β‐hydride elimination after step 2). These cyclization steps fit the Michaelis–Menten equation well and β‐hydride elimination is considered to be a rate‐limiting step in the formation of the products. Spectroscopic data agree sufficiently with the existence of the intermediates bearing acrylate (Pd? O bond), η³‐C₈H₁₅ (Pd? C bond), or C₁₁H₁₉O₂ (Pd? C bond) moieties on the Pd center as the resting‐state compounds. Furthermore, not only Cu^II, but also Cu^I, species are observed during the reaction time of 2–8 h when the reaction proceeds efficiently. This result suggests that the Cu^II species is partially reduced to the Cu^I species when the active Pd catalytic species are regenerated.     

Darstellung und Charakterisierung von Phthalocyanin-π-Kation-Radikalen von H+, Mg2+ und Cu2+

Preparation und Characterization of Phthalocyanine-π-Cation-Radicals of H⁺, Mg²⁺, and Cu²⁺ The preparation of phthalocyanine-π-cation-radicals (Pc(?1)) of H⁺, Mg²⁺, Cu²⁺ is described. MgClPc(?1) and Cu(NO₃)Pc(?1) · HNO₃ are isolated as stoichiometrically pure, stable redbrown solids. Contrary to the phthalocyanines(?2) (Pc(?2)) these are very soluble with redviolet colour in organic solvents in the presence of R? COOH (R ? H, CF₃, CCl₃). The electronic absorption absorption spectra (UV-VIS) are remarkably solvent-dependent. This solvent effect is due to a reversible radical association. Monomeric radical species exist in nonpolar (CH₂Cl₂), dimeric in polar solvents (CH₃NO₂, C₂H₅OH). The UV-VIS, infrared (IR), and resonance-raman (RR) spectra of MgClPc(?1) and Cu(NO₃)Pc(?1) · HNO₃ are discussed and compared with the analogoues spectra of MgPc(?2) · 2 H₂O and MgPc(?2) · HCl. Although there are only minor differences in the chemical composition and the electronic structure the spectroscopic data vary significantly for every complex. Especially the IR spectrum is suitable for a quick demonstration of the π-cation-radicals. The diagnostic bands are at ca. 1350 and 1450 cm^?1.     

[Cu(phen)2(μ‐IDA)Cu(phen)](ClO4)2·CH3OH: tridentate and monodentate binding to two copper(II) species by a bridging ligand

The stoichiometric reaction of 1,10‐phenanthroline (phen), imino­di­acetic acid (IDA‐H₂) and Cu(ClO₄)₂ in a H₂O–CH₃OH (2:1) solution yields μ‐imino­diacetato‐2:1κ⁴O,N,O′:O′′‐tris(1,10‐phenanthroline)‐1κ⁴N,N′;2κ²N,N′‐dicopper(II) diperchlorate methanol solvate, [Cu₂(C₄H₅NO₄)(C₁₂H₈N₂)₃](ClO₄)₂·CH₃OH. The IDA ligand bridges the two Cu^II ions via a carboxyl­ate group and uses one further N and an O atom of the second carboxylate group to complete a fac‐tridentate coordination at one Cu centre. A phen ligand completes a distorted square‐pyramidal coordination at this metal atom, although there is weak coordination by a perchlorate O atom at a sixth position. The second Cu centre has a distorted trigonal–bipyramidal coordination to two phen moieties and a carboxyl­ate O atom.     

Purification of Hydrogen from CO with Cu/ZSM-5 Adsorbents

The transition to a hydrogen economy requires the development of cost-effective methods for purifying hydrogen from CO. In this study, we explore the possibilities of Cu/ZSM-5 as an adsorbent for this purpose. Samples obtained by cation exchange from aqueous solution (AE) and solid-state exchange with CuCl (SE) were characterized by in situ EPR and FTIR, H₂-TPR, CO-TPD, etc. The AE samples possess mainly isolated Cu²⁺ cations not adsorbing CO. Reduction generates Cu⁺ sites demonstrating different affinity to CO, with the strongest centres desorbing CO at about 350 °C. The SE samples have about twice higher Cu/Al ratios, as one H⁺ is exchanged with one Cu⁺ cation. Although some of the introduced Cu⁺ sites are oxidized to Cu²⁺ upon contact with air, they easily recover their original oxidation state after thermal treatment in vacuum or under inert gas stream. In addition, these Cu⁺ centres regenerate at relatively low temperatures. It is important that water does not block the CO adsorption sites because of the formation of Cu⁺(CO)(H₂O)_x complexes. Dynamic adsorption studies show that Cu/ZSM-5 selectively adsorbs CO in the presence of hydrogen. The results indicate that the SE samples are very perspective materials for purification of H₂ from CO.     

Ion–Molecule Reactions of “Rollover” Cyclometalated [Pt(bipy−H)]+ (bipy=2,2′‐bipyridine) with Dimethyl Ether in Comparison with Dimethyl Sulfide: An Experimental/Computational Study

The ion–molecule reactions of dimethyl ether with cyclometalated [Pt(bipy?H)]⁺ were investigated in gas‐phase experiments, complemented by DFT methods, and compared with the previously reported ion–molecule reactions with its sulfur analogue. The initial step corresponds in both cases to a platinum‐mediated transfer of a hydrogen atom from the ether to the (bipy?H) ligand, and three‐membered oxygen‐ and sulfur‐containing metallacycles serve as key intermediates. Oxidative C? C bond coupling (“dehydrosulfurization”), which dominates the gas‐phase ion chemistry of the [Pt(bipy?H)]⁺ ion with dimethyl sulfide, is practically absent for dimethyl ether. The competition in the formation of C₂H₄ and CH₂X (X=O, S) in the reactions of [Pt(bipy?H)]⁺ with (CH₃)₂X (X=O, S) as well as the extensive H/D exchange observed in the [Pt(bipy?H)]⁺/(CH₃)₂O system are explained in terms of the corresponding potential‐energy surfaces.     

Simulating the active sites of copper-trafficking proteins. Density functional structural and spectroscopy studies on copper(I) complexes with thiols,carboxylato, amide and phenol ligands

A series of mononuclear binary and ternary Cu(I) complexes with formato, formamide, methylphenol, and methanethiolato ligands were optimized at DFT-B3LYP/6-31G** (BS1) and DFT-B3LYP/6-311++G** (BS2) levels of theory. The solvent effect was taken into account via PCM method (BS1W and BS2W, respectively). The coordination arrangement for [Cu^I(SCH₃/S(H)CH₃)(OOCH)]^?/0 and [Cu^I(SCH₃/S(H)CH₃)(O(H)(C₆H₄)CH₃)]^0/+ was pseudo-linear and for [Cu^I(SCH₃/S(H)CH₃)(OOCH)(OC(H)NH₂)]^?/0 was pseudo-trigonal. The [Cu^I(S-S(H)CH₃/Cu^I(S-SCH₃)]^+/0 link even to amide carbonyl and to general O(H)R residues (R=C₆H₅CH₃). [Cu^I(SCH₃)₂(O(H)(C₆H₄)CH₃)]^? went towards dissociation of the O(H)(C₆H₄)CH₃ ligand, whereas [Cu^I(S(H)CH₃)₂(O(H)(C₆H₄)CH₃)]⁺ converged nicely, maintaining the hydroxy function linked to the metal. The trends of total electronic energies seemed to be significant, suggesting that linear Cu^IS₂ coordination is more suitable than Cu^IS, Cu^IS₃ and Cu^IS₄ arrangements. The formation energies of [Cu^I(S(H)CH₃/SCH₃)(OOCH)]^0/?1 were higher than those of [Cu^I(S(H)CH₃/SCH₃)₂]^+/? on starting from [Cu^I(S(H)CH₃/Cu^I(SCH₃)]^+/0 by ca. 11–9 kcal mol^?1 (BS2W). The structural arrangements, bond distances, and angles as well as computed spectroscopic parameters resulted in good agreement with experimental data for corresponding synthetic complexes and with metal site regions of several copper(I)-proteins. These data help in interpreting structural data of complex biological systems and in constructing reliable force fields for molecular mechanics computations.     

表面助剂改性对Cu/ZnO/Al2O3甲醇合成催化剂性能的影响

采用共沉淀-后浸渍方法制备了表面助剂改性的Cu/ZnO/Al₂O₃ (CZA)甲醇合成催化剂, 在固定床反应器上以合成气为原料分别考察了三种助剂(Zr、Ba和Mn)对CZA催化剂性能的影响; 以Zr为助剂时反应温度的影响; 并进行了催化稳定性试验. 利用粉末X射线衍射(XRD)、低温氮气吸脱附(N₂-sorption)、氧化亚氮(N₂O)反应吸附技术、X射线光电子能谱(XPS)、氢气程序升温吸脱附(H₂-TPD)、扫描电子显微镜(SEM)和高分辨透射电子显微镜(HR-TEM)技术对催化剂进行了表征.结果显示: 以Zr或Ba作为助剂能够明显提高CZA催化剂耐热前后的甲醇时空收率(STY); Mn的引入降低了CZA催化剂的耐热前活性; Zr的引入降低了CZA催化剂最高活性温度点, 增强了CZA催化剂的催化稳定性; 还原态CZA催化剂表面Cu⁰和ZnO都能吸附活化氢气, Cu⁰与ZnO的强相互作用有利于提高催化剂的性能, 耐热后催化剂性能的降低归因于Cu晶粒的长大. 在实验和表征结果基础上,提出了CZA催化剂上合成气制甲醇的“双向同步催化反应历程”.     

Cu/Cu2O Electrodes and CO2 Reduction to Formic Acid: Effects of Organic Additives on Surface Morphology and Activity

Copper/copper oxide (Cu/Cu₂O) electrodes are known to display interesting electrocatalytic performances for the reduction of CO₂, and thus, deserve further investigation for optimization. Here, we show that the addition of nitrogen‐based organic additives greatly improves the activity of these electrodes (higher current densities, greater selectivity, and higher faradaic yields). The best effector is found to be tetramethyl cyclam. For example, electrolysis at ?2.0 V versus Fc⁺/Fc in CO₂‐saturated DMF/H₂O (99:1, v/v) in the presence of this effector results in formic acid with almost 90 % faradaic yield. SEM and XPS analysis of the electrode surface reveals that the organic additive promotes the formation of active Cu⁰ nanoparticles from Cu₂O during electrolysis. This simple approach provides a straightforward strategy toward the optimization of Cu/Cu₂O electrodes.     

Photocatalytic reduction of CO2 with H2O on TiO2 and Cu/TiO2 catalysts

Photoinduced reduction of CO₂ by H₂O to produce CH₄ and CH₃OH has been investigated on wellcharacterized standard TiO₂ catalysts and on a Cu²⁺ loaded TiO₂ catalyst. The efficiency of this photoreaction depends strongly on the kind of catalyst and the ratio of H₂O to CO₂. Anatase TiO₂, which has a large band gap and numerous surface OH groups, shows high efficiency for photocatalytic CH₄ formation. Photogenerated Ti³⁺ ions, H and CH₃ radicals are observed as reactive intermediates, by ESR at 77 K. Cu-loading of the small, powdered TiO₂ catalyst (Cu/TiO₂) brings about additional formation of CH₃OH. XPS studies suggest that Cu⁺ plays a significant role in CH₃OH formation.     

A one‐dimensional coordination polymer with a capped [Cu4O4] cubane core assembled from 2‐(hydroxymethyl)pyridine

The one‐dimensional coordination polymer catena‐poly[[[di‐μ₂‐acetato‐tetrakis[μ₃‐(pyridin‐2‐yl)methanolato]tetracopper(II)]‐di‐μ₂‐diacetamidato] acetonitrile monosolvate], {[Cu₄(C₆H₆NO)₄(CH₃COO)₂(C₂N₃)₂]·CH₃CN}_n, has been prepared from the direct reaction of 2‐(hydroxymethyl)pyridine with Cu(OAc)₂·H₂O (OAc⁻ is acetate) in a methanol–acetonitrile mixture. The four Cu centres are bridged by four O atoms from discrete (pyridin‐2‐yl)methanolate ligands and two acetate groups, forming a capped [Cu₄O₄] cubane core. Each core is doubly bridged to each of two adjacent cores by [N(CN)₂]⁻ anions, resulting in one‐dimensional chains. The magnetic properties of the complex were also studied.     

Bis{μ‐6,6′‐dimethoxy‐2,2′‐[propane‐1,2‐diylbis(iminomethylene)]diphenolato}bis[aquacopper(II)] dihydrate

In the title compound, [Cu₂(C₁₉H₂₄N₂O₄)₂(H₂O)₂]·2H₂O, the asymmetric unit consists of one half of the bis{μ‐6,6′‐dimethoxy‐2,2′‐[propane‐1,2‐diylbis(iminomethylene)]diphenolato}bis[aquacopper(II)] complex and two water molecules. Two Cu^II centres are bridged through a pair of phenolate groups, resulting in a complex with a centrosymmetric structure, with the centre of inversion at the middle of the Cu₂O₂ plane. The Cu atoms are in a slightly distorted square‐pyramidal coordination environment (τ = 0.07). The average equatorial Cu—O bond length and the axial Cu—O bond length are 1.928 (3) and 2.486 (3) Å, respectively. The Cu—O(water) bond length is 2.865 (4) Å, so the compound could be described as having a weakly coordinating water molecule at each Cu^II ion and two solvent water molecules per dimetallic unit. The Cu...Cu distance and Cu—O—Cu angle are 3.0901 (10) Å and 87.56 (10)°, respectively. The molecules are linked into a sheet by O—H...O and C—H...O hydrogen bonds parallel to the [001] plane.     

A DFT study of DMC formation on Rh‐doped Cu/AC surfaces

The activity and selectivity of heterogeneous catalysts can be significantly improved by dispersion of another active component in the metal substrate. The impact of Rh promoter on the formation of dimethyl carbonate (DMC) via oxidative carbonylation of methanol on Cu–Rh/AC (activated carbon) catalyst was investigated by density functional theory calculations. The most stable configurations of reacting species (CO, OH, CH₃O, monomethyl carbonate, and DMC) adsorbed on the Cu⁰(zero‐valent copper)/AC and Cu–Rh/AC surfaces were determined on the basis of the calculated results. The reaction energy and activation energy of the rate‐limiting steps on the Cu–Rh/AC and Cu⁰/AC surfaces were compared. The activation energies of the rate‐limiting step of CO insertion into dimethoxide are 206.3 and 304.8 kJ mol^?1 on the Cu–Rh/AC and Cu⁰/AC surfaces, respectively. The activation energies of the rate‐limiting step of CO insertion into methoxide are 78.5 and 92.7 kJ/mol on the Cu–Rh/AC and Cu⁰/AC surfaces, respectively. The calculated results indicate that the addition of Rh atom has a significant effect on decreasing the active energy the main pathway for DMC formation. © 2015 Wiley Periodicals, Inc.     

Self‐assembly properties of Salamo‐type trinuclear Cu(II) and Co(II) complexes based on the regulation of H+/OHˉ

A novel naphthalenediol‐based bis(salamo)‐type tetraoxime compound (H₄L) was designed and synthesized. Two new supramolecular complexes, [Cu₃(L)(μ‐OAc)₂] and [Co₃(L)(μ‐OAc)₂(MeOH)₂]·4CHCl₃ were synthesized by the reaction of H₄L with Cu(II) acetate dihydrate and Co(II) acetate dihydrate, respectively, and were characterized by elemental analyses and X‐ray crystallography. In the Cu(II) complex, Cu1 and Cu2 atoms located in the N₂O₂ sites, and are both penta‐coordinated, and Cu3 atom is also penta‐coordinated by five oxygen atoms. All the three Cu(II) atoms have geometries of slightly distorted tetragonal pyramid. In the Co(II) complex, Co1 and Co3 atoms located in the N₂O₂ sites, and are both penta‐coordinated with geometries of slightly distorted triangular bipyramid and distorted tetragonal pyramid, respectively, while Co2 atom is hexa‐coordinated by six oxygen atoms with a geometry of slightly distorted octahedron. These self‐assembling complexes form different dimensional supramolecular structures through inter‐ and intra‐molecular hydrogen bonds. The coordination bond cleavages of the two complexes have occurred upon the addition of the H⁺, and have reformed again via the neutralization effect of the OH^?. The changes of the two complexes response to the H⁺/OH^? have observed in the UV–Vis and ¹H NMR spectra.