Atoms Of Cu Research Articles

Nature of C-C coupling and strategy of tuning the catalytic activity of Cu-N-C catalysts for electro-reduction of CO2 to ethanol

With high atomic utilization and remarkable catalytic activity, Cu-N-C type catalysts display great potential for electro-catalysis in CO2 reduction. However, the relationship between the active moiety and catalytic activity of generating high-value C2 products is still unclear, and the explicit screening criteria is scarcity. Herein, based on the first-principle simulation, the structure-performance relationship on Cu-N-C type catalysts has been investigated by modulating the CO2 reduction process as the number of Cu atom (Cu1, Cu2, Cu3) and the ligand environment (B, C, N, O, P, S) changed. We find the adsorption strength of intermediate *CO strongly affect the possibility of C-C coupling, which can be determined by Bader charge on Cu atom, mainly depending on the number of loaded atomic Cu on Cu-N-C catalysts. Furthermore, the Bader charge can be refined by adjusting the coordination atom of Cu, thus optimizing catalytic activity for the CO2 to ethanol. The moderate Bader charge value, between +0.35 and +0.45, enables the catalyst to behave as a potentially excellent activity with low limiting potential for generating ethanol. More importantly, an intrinsic descriptor, composed of the radius, electronegativity, and number of valence electrons of coordination atoms (φ=∑χ∑r*∑np), was established to characterize the catalytic activity of Cu-N(X)-C catalysts for producing ethanol. Two excellent catalysts, Cu3-N2O2 (-0.51 V) and Cu3-N3S (-0.64 V), are screened out for the CO2RR to generate ethanol. This work discloses theoretical basis for catalytic selectivity of C2 products on Cu-N-C catalysts and provides a regulating and screening principle for high performance catalysts to ethanol.

CO Intermediate‐Assisted Dynamic Cu Sintering During Electrocatalytic CO2 Reduction on Cu−N−C Catalysts

AbstractThe electrochemical CO2 reduction reaction (eCO2RR) to multicarbon products has been widely recognized for Cu‐based catalysts. However, the structural changes in Cu‐based catalysts during the eCO2RR pose challenges to achieving an in‐depth understanding of the structure–activity relationship, thereby limiting catalyst development. Herein, we employ constant‐potential density functional theory calculations to investigate the sintering process of Cu single atoms of Cu−N−C single‐atom catalysts into clusters under eCO2RR conditions. Systematic constant‐potential ab initio molecular dynamics simulations revealed that the leaching of Cu−(CO)x moieties and subsequent agglomeration into clusters can be facilitated by synergistic adsorption of H and eCO2RR intermediates (e.g., CO). Increasing the Cu2+ concentration or the applied potential can efficiently suppress Cu sintering. Both microkinetic simulations and experimental results further confirm that sintered Cu clusters play a crucial role in generating C2 products. These findings provide significant insights into the dynamic evolution of Cu‐based catalysts and the origin of their activity toward C2 products during the eCO2RR.

Phase decomposition behavior and its impact on mechanical properties in bulk nanostructured Cu-20 at.%Fe supersaturated solid solution

Extended solid solution of immiscible systems, achieved by extreme processing approaches, can be transformed into nanostructured composites via phase decomposition, which are drawing great research attention for their excellent thermal stability and high strength. Here we fabricated the supersaturated solid solution of Cu-20 at.%Fe, a typical immiscible alloy, in bulk state by high pressure torsion, which provides a great freedom over powders for studying the microstructure evolution and mechanical properties in the process of the phase decomposition in immiscible alloys. We found that in the Cu-Fe solid solution, spinodal decomposition of the Fe phases took place at the initial stage of annealing through volume diffusion. This process gives rise to: (1) metastable γ-Fe particles in the Cu grains with coherent Fe/Cu interface, and (2) the more stable α-Fe phase at the grain boundaries. This process was accompanied by moving boundary reaction which first proceeded in the pattern of spinodal decomposition and then changed into classical nucleation-growth mode with the depletion of Fe atoms in Cu. The resultant Cu-Fe nanocomposites were jointly strengthened by the ultrafine Cu and α-Fe grains according to the rule of mixture, including grain boundary strengthening and the hardening of nanoscale γ-Fe precipitates in the Cu grains. The effects of different strengthening mechanisms were scrutinized and their contributions to mechanical properties were quantitatively evaluated. This work sheds light onto the opportunity of designing and fabricating nanostructured composites via phase decomposition in immiscible systems.

Designing the major active site of Cu atom for OER via a composite electrocatalyst of Agx@HEO: Experiment and theory

Copper element with low chemical activity is hard to be used as the major active site for oxygen evolution reaction (OER). To improve its OER performance, a specialized structural and chemical environments need be designed. In this work, the composite electrocatalyst of Agn@HEO were synthesized by a simple co-precipitation plus annealing methods. With the aid of the elemental Ag0 atom, part of Cu ions in high entropy oxide (HEO) phases were gradually transferred to the elemental Cu0 atoms and mixed with Ag0 atom for CuAg alloy. This transition evidently altered the chemical environments of Cu element. Thanks to the largest molar percentage of Cu0 atom, the designed Ag1@HEO specimen exhibited the fairly low experimental OER overpotential of 249 (308) mV at the current density of 10 (100) mA cm−2 with the small Tafel slope of 55.2 mV dec-1 and stable electrocatalytic activity. Based on the density functional theory simulation, the theoretical OER overpotential of Cu active site could be adjusted along with the ridges of “volcanic” in both atomic and ionic environments, and achieved the smallest value of 213 mV as the d band center of Cu0 atom had a suitable value near the “volcanic” peak. This design strategy would be adopted to provide an effective enhancement scheme for OER on Cu active site.

Trace cerium/ yttrium addition for inhibiting sulfur-induced intermediate temperature embrittlement in ultrahigh-purity copper

Sulfur (S), as the common impurity prevalent in copper (Cu) and Cu-based alloys, often induces the intergranular embrittlement at intermediate temperatures even with a ppm concentration, a phenomenon variously called “intermediate temperature embrittlement” (ITE). However, the inhibition of such an embrittlement has been rarely reported. In this study, we investigate the influence of trace cerium/ yttrium (Ce/Y) addition on the ductility of the ultrahigh-purity Cu containing minute amounts of S impurities at temperatures between room temperature (RT) and 900 °C. The results show that both Ce and Y additions can improve the ductility of the CuS alloy at any test temperature, which is attributed to the inhibition of Ce/Y on the grain boundary (GB) segregation of S by forming the RE-S precipitates. By comparison, the modification of ITE caused by S impurities is not significant after trace Ce is introduced, while the addition of small amounts of Y can completely eliminate the ITE phenomenon at temperatures of 300–750 °C. This results from the size of the RE-S precipitates and the structure of the transition nanolayers between the RE-S precipitates and Cu matrix, which is dependent on the diffusion rates of the dissolved S, Ce and Y atoms in Cu during the tensile deformation. Our findings provide a comprehensive experimental and computational understanding on the fundamental mechanisms of rare earth elements inhibiting the embrittlement induced by impurities in metallic materials.

Facile synthesis of the atomically dispersed hydrotalcite oxide supported copper catalysts for the selective hydrogenation of 5–hydroxymethylfurfural into 2,5-bis(hydroxymethyl)furan

The selective hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF) using the atomically dispersed supported copper catalyst is investigated. The hydrotalcite oxide supported copper materials (Cu(x)HTO) are facilely prepared by coprecipitating metal precursors in a methanolic solution under a tuned pH. The surface characterization involving PXRD, TEM, H2/N2O-TPR, and XAS reveals unequivocal evidence for the presence of the atomically dispersed copper on HTO surface. XAS specifically indicates the formation of mononuclear copper species, and H2/N2O-TPR strongly supports the copper atoms of Cu(5)HTO are evenly distributed in 99% dispersion. Moreover, the reduced Cu(5)HTO (r-Cu(5)HTO) enables to completely hydrogenate HMF to BHMF under mild conditions, in comparison to the poor reactivity catalyzed by the hydrotalcite oxide supported copper nanoparticles (r-Cu(4)@HTO). The dramatic enhancement of HMF hydrogenation catalyzed by r-Cu(5)HTO can be attributed to the fine distribution of copper atoms which are situated homogeneously over HTO surface as well as chemically reactive for the carbonyl group.

CuSeO4 and Cu(SeO3OH)2·6H2O, two novel copper–selenium(VI) oxysalts

The two new copper(II) salts Cu(SeO4) and Cu(SeO3OH)2·6H2O were synthesized at low-temperature hydrothermal conditions (220 °C), and room temperature, respectively. Their atomic arrangements were studied based on single-crystal X-ray investigations [P21/n, a = 4.823(1), b = 8.957(2), c = 6.953(1) Å, β = 94.82(1)°, Z = 4; $$P{\overline 1}$$ , a = 6.133(1), b = 6.303(1), c = 8.648(2) Å, α = 70.45(1), β = 84.60(1), γ = 73.44(1)°, Z = 1]. Cu(SeO4) adopts the MnAsO4 structure type. It exhibits structural as well as topological relations with two formerly known isochemical compounds. They crystallize in the structure type ZnSO4 (mineral name zincosite, Pnma) respectively NiSO4 (Cmcm). The two minerals dravertite, CuMg(SO4)2, and hermannjahnite, CuZn(SO4)2, are isotypic with CuSeO4-P21/n; interestingly, also α-NaCu(PO4) belongs to this structure type: some rotation of the XO4 group allows a supplementary position for the Na atom. — Cu(SeO3OH)2·6H2O represents a new structure type. The protonated selenate group shows an extended Se—Oh bond distance (1.695 Å) as compared to the other Se—O bonds (1.614 to 1.626 Å). One OH dipole of the three independent H2O molecules represents a rather free hydrogen bond. For the other H atoms, the O—H···O lengths vary from 2.585 to 2.799 Å. Interestingly, the distance Ow7···Ow7 of only 2.791 Å does not represent an edge in a coordination polyhedron and it is not preliminary involved in the hydrogen bond scheme. All Cu2+ ions in the two title compounds are in a pronounced [4 + 2] coordination. The Cu2+[4+2] atoms in Cu(SeO4) are linked to chains along [100]; in Cu(SeO3OH)2·6H2O they are not connected among each other.

Theoretical study on the mechanism of CO2 adsorption and reduction by single-atom M (M = Cu, Co, Ni) doping C2N

The capture and further conversion of carbon dioxide into useful fuels and value-added chemicals is critical to addressing the growing problem of global warming and promoting sustainable human development. In this work, the adsorption and activation of CO2 on the surface of single-atom-doped C2N monolayers and the first-step reaction mechanism of CO2RR were investigated by density functional theory (DFT). The catalyst structure, CO2 adsorption configuration and electronic properties of CO2 activation on C2N surfaces decorated with transition metal single atoms of Cu, Co, and Ni were discussed. Cu/C2N, Co/C2N and Ni/C2N all have good CO2 adsorption performance by calculations. The calculation results of the first hydrogenation reaction of CO2RR show that the three materials of Cu/C2N, Co/C2N and Ni/C2N have lower energy barriers than the pristine C2N, which suggests that they are more favorable for the CO2RR reaction to proceed. The Cu/C2N surface is more inclined to adsorb CO2 and then combine with H atoms to form OCHO, but the Co/C2N and Ni/C2N surfaces are more inclined to hydrogenate CO2 to COOH in one step. The difference in the mechanism of the three material systems may be due to the difference of electrons and density of states on the 4s orbital of the outermost electron number of the doped transition metal atoms Cu, Co, Ni.

Crystallographic and optical properties of wide bandgap photovoltaic semiconductor system, Cu(Al,In)Se 2

We characterized the optical and electronic properties of chalcopyrite-type Cu(Al,In)Se2, which is a candidate for wide-bandgap solar cell materials. The bandgap energy was determined from diffuse reflectance spectra. The bandgap energy increased from 1.00 eV for CuInSe2 to 2.61 eV for CuAlSe2 with an increase in the Al content. The ionization energy corresponding to the energy levels of the valence band maximum (VBM) was determined using photoemission yield spectroscopy. The VBM level of the Cu(Al,In)Se2 system stayed relatively constant, but the conduction band minimum level increased with increasing Al content. To analyze the local structures of Cu and In atoms in Cu(Al,In)Se2, Cu and In K-edge X-ray absorption fine structure (XAFS) spectra were measured at SPring-8. We discuss the crystallographic characteristics of Cu(Al,In)Se2 based on the results of the XAFS analyses and a comparison of the phase diagrams of the Cu2Se–Al2Se3, Cu2Se–In2Se3, and Cu2Se–Ga2Se3 systems.

Nanocompound-induced anti-softening mechanisms: Application to CuCr alloys

A nanocompound-induced anti-softening mechanism is proposed for preparing high strength and high conductivity CuCr alloys with favorable softening resistance. The mechanism is to introduce nanocompound at the Cu/Cr interface to suppress the coarsening of Cr precipitate. To verify the mechanism, Co and Ti are added to the CuCr alloy. CoTi compounds precipitate around the Cr precipitates after aging treatment. The coarsening of Cr and CoTi phases are both suppressed thanks to the low diffusion rates of Co and Ti atoms in Cu. Additionally, Cr and CoTi precipitates also inhibit the recrystallization. As a result, the CuCrCoTi alloy displays a higher softening temperature (>600 °C) than CuCr alloys.

Role of interface on irradiation damage of Cu−diamond composites using classical molecular dynamics simulations

Cu−diamond composites have been proposed as a candidate thermal management material for spacecraft electronics. Nevertheless, irradiation effects on the composites remain poorly understood at present. Here we focus on investigating the influence of Cu−diamond interfaces (CDIs) on energetic displacement cascades using atomistic simulations. Results show that a primary knock-on atom of Cu (PKA-Cu) can induce more significant damage than a PKA-C. Under almost all circumstances, the statistically averaged fraction of surviving interstitials is not only lower than that of vacancies but also no more than 1. Because of the unique nature in the mobility and interactions with CDIs, Cu interstitials exhibit the lowest concentration among all defects in most cases. The high residual rate of displaced defects in diamond makes it relatively difficult to heal. The structural damage is mainly manifested in a short-range disorder of diamond and a long-range disorder of Cu after irradiation. At elevated temperatures, the atomic displacement region may form compact chain-like defects to restrain lattice loosening. Despite the above, CDIs could act as effective sinks to facilitate the recombination and/or annihilation of irradiation-induced defects in all scenarios. This study provides an important insight into the understanding of the microscopic evolution of irradiation defects for the composites.

Deposition of Co islands on Cu(111) and Cu–Al(111): A comparative study from DFT calculations

The growth behaviors, stability and magnetic moments of Co islands on Cu(111) surface and Cu–Al(111) alloy surface were compared by means of Density Functional Theory calculations. Similar to the case of Pb-precovered Cu(111), it was found that the diffusivity of Co adatom on Cu–Al(111) was lower than that on Cu(111), which could suppress the agglomeration of Co atoms on Cu–Al(111). Such behaviors could be explained by the different electronic structures of surface atoms of Cu(111) and Cu–Al(111). Co adatoms deposited on one monolayer Co island descending a Co edge step to substrate terrace via push-out/exchange mechanism is more favored than direct hopping on both surfaces, and push-out/exchange descent is more favorable on Cu–Al(111) than Cu(111) with similar “Schwoebel-Ehrlich” barrier and larger exothermic reaction energy. Island formation energies calculated suggest layer-by-layer growth mode is more favored for Co islands deposited on Cu–Al(111) covered with Co films than that on Cu(111). In agreement with experiments, layer-by-layer growth is identified for Co islands on Cu–Al(111), suggesting perfect wetting of Cu–Al(111) by Co. Our calculations show Al impurities in Cu(111) enhance the stability and magnetic moments of Co islands, which may shed light on Co/Cu–Al(111) being potential applications in magnetic hyperthermia treatments.

Correlation of plastic deformation induced intermittent electromagnetic radiation characteristics with mechanical properties of Cu–Ni alloys

Abstract This paper presents experimental results on intermittent electromagnetic radiation during plastic deformation of Cu – Ni alloys under tension and compression modes of deformation. On the basis of the nature of electromagnetic radiation signals, oscillatory or exponential, results show that the compression increases the viscous coefficient of Cu – Ni alloys during plastic deformation. Increasing the percentage of solute atoms in Cu – Ni alloys makes electromagnetic radiation strength higher under tension. The electromagnetic radiation emission occurs at smaller strains under compression showing early onset of plastic deformation. This is attributed to the role of high core region tensile residual stresses in the rolled Cu – Ni alloy specimens in accordance with the Bauschinger effect. The distance between the apexes of the dead metal cones during compression plays a significant role in electromagnetic radiation parameters. The dissociation of edge dislocations into partials and increase in internal stresses with increase in solute percentage in Cu – Ni alloys under compression considerably influences the electromagnetic radiation frequency.

Temperature and Composition Dependent Structural Evolution: Thermodynamics of CunAg135-n (n = 0-135) Nanoalloys during Cooling.

Molecular dynamics simulations are performed to investigate the changes of packing structures, and thermodynamic quantities including internal energy, entropy, and free energy are used to determine temperature regime and transition time of atomic packing structures. The simulation results show different packing structures as the component composition changes, and there are different packing patterns during cooling. For these Cu-Ag alloy clusters containing only a small number of atoms of Cu, they present FCC packing structures in different parts at high temperatures, and then there are transformations to icosahedral structures. With the increase in content of Cu atoms, there is a transition mechanism from molten state to icosahedron. When the content of Cu atoms is appropriate, core-shell structures can be formed at room temperature.

A binuclear copper(II) complex based on hydrazone ligand: Characterization, molecular docking, and theoretical and antimicrobial investigation

AbstractA new binuclear copper(II) complex [Cu2L2(μ‐SO4)(dmf)] with the 2‐acetylpyridinebenzoylhydrazone (HL) ligand was synthesized and characterized by elemental analysis, Fourier transform infrared (FT‐IR), ultraviolet–visible (UV–Vis), single‐crystal X‐ray diffraction, density functional theory (DFT), and molecular docking studies. The crystal structure revealed each copper(II) atom coordinated to the NNO chelating system of the anionic hydrazone ligand and a sulfate bridged. The copper ions are connected by a sulfate bridge, which keeps a distance of 3.292(3) Å between the two copper(II) centers. Additionally, only one of the copper(II) atoms is coordinated to the oxygen atom of the N,N‐dimethylformamide (dmf) solvent molecule, resulting in two different geometry to each metal center. Cu···O interactions are observed for the secondary coordination sphere of Cu1 and Cu2 atoms with distances of 2.545(2) and 2.821(3) Å, respectively. Theoretical studies with DFT were performed to optimize the geometry of the complex and investigate its spectroscopic properties supporting the experimental results. Two different approaches were used in computational calculations, the plane wave using Perdew–Burke–Ernzerhof (PBE) functional and the localized basis set using the following functionals: B3LYP, B3PW91, CAM‐B3LYP, LC‐wPBE, M06‐2X, ωB97‐XD, PBE1PBE, and HSEH1PBE. The in vitro antibacterial potential of the new complex was evaluated against pathogenic bacteria and fungi and compared with the free ligand. The molecular docking was used to predict the inhibitory activity of the ligand and complex against one Gram‐positive bacteria (Enterococcus faecalis), one Gram‐negative bacteria (Enterobacter aerogenes), and one fungi (Candida albicans) species.

Two-Dimensional Pd Rafts Confined in Copper Nanosheets for Selective Semihydrogenation of Acetylene.

The development of highly selective and active catalysts to catalyze an industrially important semihydrogenation reaction remains an open challenge. Here, we report the design of a bimetallic Pd/Cu(111) catalyst with Pd rafts confined in a Cu nanosheet, which exhibits desirable catalytic performance for acetylene semihydrogenation to ethylene with the selectivity of >90%. Theory calculations show that Pd atoms replacing neighboring Cu atoms in Cu(111) can improve the catalytic activity by reducing the energy barrier of the semihydrogenation reaction, as compared to unsubstituted Cu(111), and can improve the selectivity by weakening the adsorption of C2H4, as compared to a Pd(111) surface. The presence of Pd rafts confined in Cu nanosheets effectively turns on Cu nanosheets for semihydrogenation of acetylene with high activity and selectivity under mild reaction conditions. This work offers a well-defined nanostructured Pd/Cu(111) model catalyst that bridges the pressure and materials' gap between surface-science catalysis and practical catalysis.

Generating Short‐Chain Sulfur Suitable for Efficient Sodium–Sulfur Batteries via Atomic Copper Sites on a N,O‐Codoped Carbon Composite

AbstractSodium–sulfur batteries have attracted attention due to their high energy capacities and low costs, but the dissolution of sodium polysulfides still severely affects their cycle life, limiting their real‐world applications. Herein, a stable sulfur host is reported, based on a N,O‐codoped carbon composite derived from a bimetallic Cu–Zn metal‐organic framework, which ensures high sulfur loading (67 wt%). Most importantly, this composite also includes single‐atom copper catalysts, with a high Cu loading of 8.03 wt%. Solid‐state nuclear magnetic resonance, synchrotron X‐ray absorption spectroscopy, and single‐crystal X‐ray diffraction analysis show that single atoms of Cu are coordinated with two N and two O atoms within the produced composite material. Those copper sites can weaken SS bonds in the S8 ring structure, and thus are able to catalyze the formation of short‐chain sulfur molecules in even larger‐size pores. In addition, Cu atoms facilitate the conversion between the short‐chain sulfur and Na2S. As a result, when the produced sulfur‐loaded carbon framework containing the atomic Cu catalyst is used as a cathode for sodium–sulfur batteries, it exhibits superior capacity of 776 mAh g–1 with a high sulfur utilization (1158 mAh gs–1 normalized with sulfur content) after 100 cycles at 0.1 A g–1, and an excellent rate performance of 483 mAh g–1 (720 mAh gs–1) at 5 A g–1.

A small copper carrier in blood plasma: purification, characterization, and metabolism

In mammals, concentrations of copper in tissues and fluids are kept very constant. The main mechanism underlying this constancy is the ability of the liver to modulate excretion of copper by varying the amounts entering the bile – which end up in the feces. When biliary excretion of copper is hindered, as occurs when one of the proteins involved is defective, copper accumulates in the liver and later in other organs, with fatal consequences if untreated. Major examples are the copper “pump”, ATP7B, defective in Wilson Disease, and COMMD1, which also aids biliary excretion. With copper overload, there is increased copper in the urine, which normally is very low. Studies by Gray et al.[1] with the mouse Atp7b knockout model of Wilson disease determined that the increase in urine is due to a small copper carrier (SCC) of about 2 kDa, which our laboratory then determined was also in the blood plasma of these mice. Moreover, canines with defective ATP7B also had large increases in SCC-Cu in their blood and urine. We have been researching ways of purifying significant amounts of SCC, using commercially available porcine plasma, so it can be further characterized. Based on size exclusion chromatography (SEC) of 3 kDa ultrafiltrates in small pore gels, we know that usually most of the Cu is in a single component (SCC), which by ESI-MS appears to have a mass/charge ratio of 845, one atom of Cu(II) – detected in EPR as bound to N and O ligands, and a pI in the range of 3-4. New ways of purifying SCC beyond the ultrafiltration stage have been developed, involving concentration by lyophilization and special forms of dialysis using very small pore membranes. Hydrophilic interaction chromatography and additional SEC are providing much purer SCC, with more reasonable yields. Meanwhile, we have also been investigating the secretion and uptake of SCC-Cu, using cultured cells. SCC is secreted by hepatic cells as well as those modeling intestinal and kidney epithelium, particularly when preloading with Cu(II)-diHis. Intestinal (Caco2) cell monolayers with tight junctions secreted SCC mainly across the apical membrane (representing the gut lumen), but this was dramatically reversed when albumin was present in the basal medium (which is more physiological). Kidney epithelial cells also secreted SCC-Cu and some additional copper components mainly into the apical fluid. Other studies, with 67Cu-labeled SCC from hepatic secretions, confirmed not only that SCC was secreted, but showed that it was also taken up by all cell types examined. These findings suggest that metabolism of SCC and its copper is very active, and that SCC may play an important role in mammalian copper homeostasis. [1]Gray et al. PLoS ONE 7(6): e38327.

An insight into molecular structures, fluorescent, and catalytic oxidase properties of novel heteromultinuclear [CuII4SmIII2] and [CuII2TbIII] bis (salamo)‐based complexes

Two newly designed heteromultinuclear [CuII4SmIII2] and [CuII2TbIII] bis (salamo)‐based complexes, [{Cu2(L)Sm (NO3)2(μ2‐NO3)(CH3OH)}2]·2CH3OH and [Cu2(L)Tb (NO3)2(μ2‐NO3)][Cu2(L)Tb (NO3)2(μ2‐NO3)(H2O)]·CH3OH, were synthesized and characterized by elemental analyses, Fourier transform infrared (FT‐IR) spectra, ultraviolet–visible (UV–vis) absorption spectra, and X‐ray crystallography. The ultraviolet titration experiments exhibited that the coordination ratio of the ligand, rare earth metal, and transition metal is 1:1:2. In the [CuII4SmIII2] complex, Cu1 atom has a distorted quadrilateral pyramid geometry, whereas Cu2 atom forms a slightly distorted octahedral geometry. The [CuII2TbIII] complex unit cell contains two crystallographically independent and chemically different heterotrinuclear complexes (Molecules A and B). In Molecule A, the Cu1 atom bears a four‐coordinated plane quadrilateral geometry, whereas the five‐coordinated Cu2 atom forms a slightly distorted tetragonal cone geometry. In Molecule B, the five‐coordinated Cu3 and Cu4 atoms possess slightly distorted tetragonal cone geometries. Noncovalent interactions like hydrogen bonding and π···π stacking interactions are operative in construction of supramolecular architectures. The [CuII2TbIII] complex behaves as a catalyst towards oxidative coupling of 2‐AP in MeCN medium. In addition, fluorescence properties of the ligand H4L and its [CuII4SmIII2] and [CuII2TbIII] complexes have also been discussed.

Theoretical Modification of Pheophytin Using Cu, Ni, and Zn Atoms as a Sensitizer for Dye Sentized Solar Cell (DSSC)

Theoretical studies of pheophytin compound modified with Cu, Ni, and Zn atoms as a sensitizer for dye solar cell compound (DSSC) have been carried out based on HOMO-LUMO energy parameters, LUMO electron localization, spectra, light absorption efficiency, coupling constant, and sensitizer bond length with TiO2. This study aims to determine the parameters of bond length, spectra, molecular density, HOMO-LUMO energy, LHE, and ΔG injection of pheophytin α and β complexes using the central atoms of Cu, Ni, and Zn; and formulating the effect of adding central atoms of Cu, Ni and Zn on the characteristics α and β pheophytin photoelectric and determine the best modification capable of producing the best characteristics for pheophytin as a dye compound on the DSSC based on parameters of bond length, spectra, molecular density, energy HOMO-LUMO, LHE, and ΔG injection. The theoretical modification that used is DFT/B3LYP, the accuracy of the method used amounted to 89.27% and 96.09%. Based on the above parameters the best modification sensitizer for DSSC is Zn Pheophytin β> Zn Pheophytin α> Pheophytin β> Pheophytin α> Cu Pheophytin β> Ni Pheophytin α> Ni Pheophytin β> Cu Pheophytin α.