Spectra Of Cu Research Articles

Structural analysis of Cu–As–Te glasses: Results from Raman and 65Cu NMR spectroscopy

The structure of Cu–As–Te glasses is investigated using a combination of 65Cu Nuclear Magnetic Resonance (NMR) and Raman spectroscopy. A comparison of 65Cu NMR spectra from a series of glasses and two reference crystalline phases CuInTe2 and CuGaTe2 reveals that Cu in all glasses invariably adopts a tetrahedral coordination with Te. This assignment is consistent with the presence of a sharp CuTe4 tetrahedral mode in all Cu–As–Te Raman spectra. The Raman spectra of Cu–As–Te and Ge–As–Te glasses of identical compositions suggest that the short range order of As and Te is the same in both systems. 125Te NMR results corroborate this hypothesis. However, the breach in chemical order commonly observed in Ge–As–Te does not appear to occur in Cu–As–Te. The variation in glass transition temperature with composition shows identical trends for Cu–As–Te and Ge–As–Te glasses, however, the density trends for these two systems show dramatic differences. Such trends are partly controlled by the difference in chemical order in these telluride glasses.

Angle resolved photoemission from Cu single crystals: Known facts and a few surprises about the photoemission process

We present angle resolved photoemission spectra for Cu(100) and Cu(111) singly crystals in normal emission geometry, taken at tightly spaced intervals for photon energies between 8eV and 150eV. This systematic collection of spectra gives unprecedented insight into the influence of the final states to the photoemission process as well as the band structure and lifetimes of highly excited electrons in Cu.

Vibrational Spectroscopy Reveals Varying Structural Motifs in Cu(+)(CH4)(n) and Ag(+)(CH4)(n) (n = 1-6).

Vibrational spectra are measured for Cu(+)(CH4)(Ar)2, Cu(+)(CH4)2(Ar), Cu(+)(CH4)n (n = 3-6), and Ag(+)(CH4)n (n = 1-6) in the C-H stretching region (2500-3100 cm(-1)) using photofragment spectroscopy. Spectra are obtained by monitoring loss of Ar or CH4. Interaction with the metal ion produces substantial red shifts in the C-H stretches of proximate hydrogens. The magnitude of the shift reflects the metal-methane distance and the coordination to the metal ion of the methane hydrogens (η(2) or η(3)). The structures of the complexes are determined by comparing the measured spectra with spectra calculated for candidate geometries using the B3LYP and CAM-B3LYP density functionals with 6-311++G(3df,3pd) and aug-cc-pVTZ-PP basis sets. Because of the d(10) electronic configuration of the metal ions, the complexes are expected to adopt symmetric structures, which is confirmed by the experiments. All of the complexes have η(2) hydrogen coordination in the first shell, in accord with theoretical predictions; second-shell ligands sometimes show η(3) hydrogen coordination. The vibrational spectrum of Cu(+)(CH4)(Ar)2 shows extensive structure due to Fermi resonance between the lowest-frequency C-H stretch and overtones of the H-C-H bends. The Cu(+)(CH4) cluster has a smaller red shift in the lowest-frequency C-H stretch than M(+)(CH4), M(+) = Co(+) (d(8)) and Ni(+) (d(9)). Although all three ions have similar binding energies, the metal-ligand electrostatic interaction is largest for Cu(+), while the contribution from covalent interactions is largest for Co(+). The larger ionic radius of Ag(+) leads to a larger metal-ligand distance and weaker interaction, resulting in substantially smaller red shifts than in the Cu(+) complexes. The Cu(+)(CH4)2 and Ag(+)(CH4)2 clusters have symmetrical structures, with the methanes on opposite sides of the metal, while Cu(+)(CH4)3 and Ag(+)(CH4)3 adopt symmetrical, trigonal planar structures with all M-C distances equal. For Cu(+)(CH4)4, the tetrahedral structure dominates the observed spectrum, although a trigonal pyramidal structure may contribute; however, only the tetrahedral structure is observed for Ag(+)(CH4)4. The structures of Cu(+)(CH4)n and Ag(+)(CH4)n differ for clusters with n > 4. For copper complexes, these are primarily formed by adding outer-shell methane ligand(s) to the tetrahedral n = 4 core. The observed spectra of the larger Ag(+) clusters are dominated by symmetrical structures in which all of the Ag-C distances are similar: Ag(+)(CH4)5 has a trigonal bipyramidal geometry and Ag(+)(CH4)6 is octahedral.

Study of Cu(II) Chemisorption Mechanisms on Modified Carbon Nanotubes Based on Isotherms, Column Experiments, and FTIR First Derivative Analysis

The objective of this study was to investigate the chemisorption mechanisms of Cu(II) on alcohol functionalized carbon nanotubes (OH-CNT) compared to granulated activated carbon (F-400). Two different sizes of OH-CNT were used on both adsorption isotherm experiments and continuous-flow fixed-bed columns. The experiments were conducted as a function of adsorbent type with fixed bed height (5 cm), fixed flow rate (0.035 mL/min), and one initial Cu(II) concentration (10 mg/L) at pH 5.1 and room temperature. Isotherm curves follow Freundlich model with better adsorption capacity for OH-CNT (6.3 and 15.7 mg/g) compared to F-400 (6.0 mg/g). Breakthrough curves for all adsorbents were typical, while OH-CNT showed higher capacity to treat water per amount of adsorbent than F-400. After 5 days of desorption, there was very little Cu(II) leached from the OH-CNT column as compared to F-400 that slowly desorbed 85 % of Cu(II). These results indicated chemisorption process on OH-CNT with low residual release of Cu(II) from adsorbent after reaching saturation. A systematic correlation method using converted FTIR absorbance curves (first derivative analysis) of as-received and hybrid OH-CNT identified new peaks on the spectra for Cu(II) chemisorbed on CNT surface, showing that Cu(II) target acidic functional groups during adsorption.

Structure and optical properties of copper impurity in LiF and NaF crystals from ab initio calculations

This letter reports the results of ab initio calculations of absorption spectra of Cu+ ion embedded in LiF and NaF matrices. The calculations have been performed in embedded cluster approach at hybrid density functional theory (DFT) level. We propose the model of oscillator strength and absorption intensity calculations for forbidden 3d10→3d94s transitions based on the linear dependence between transitions dipole matrix elements and copper ion displacements. For LiF:Cu+ crystal one should expect two bands in absorption spectra at 5.32 and 5.88eV with different intensity ratios: the low energy band is more intense than the high energy band.

The influence of La-substituted Cu0.5Co0.5Fe2O4 nanoparticles on its structural and magnetic properties

Abstract Lanthanum substituted cobalt ferrite Cu 0.5 Co 0.5 Fe 2 − x La x O 4 ( x = 0, 0.01, 0.03, 0.05) powders have been prepared by a sol–gel method. X-ray diffraction (XRD) results indicate the production of a single phase cubic-spinel structure. Both the lattice parameter and grain size decrease with the substitution of La 3+ ions. Scanning electron microscope (SEM) shows that the ferrite powers are nanoparticles. Room temperature Mossbauer spectra of Cu 0.5 Co 0.5 Fe 2 − x La x O 4 are two normal Zeeman-split sextets, which display ferrimagnetic behavior. The saturation magnetization, coercivity and residual magnetization increase at first and then decrease with the incorporation of La 3+ .

Elaborated spectral analysis and modeling calculations on Co(II), Ni(II), Cu(II), Pd(II), Pt(II), and Pt(IV) nanoparticles complexes with simple thiourea derivative

A series of metal complexes was synthesized using a simple thiourea derivative. The prepared complexes were characterized using different techniques (FTIR, ESR, X-ray diffraction [XRD], TG/DTA, and TEM). The FTIR spectrum of the ligand shows the presence of its tautomer forms (keto–enol). The ligand coordinates as a neutral bidentate in the Pt(IV), Pd(II), and Pt(II) complexes. In the case of Co(II) and Ni(II) complexes, the ligand is mono-negative bidentate. The proposed complexes are four to six coordinate. The geometries are proposed based on electronic spectral data and magnetic measurements and were verified using other tools. The XRD patterns reflect the nanocrystalline structures except for the Cu(II) complex, which is amorphous. The TEM images for platinum complexes show nanosize particles and homogeneous metal ion distribution on the complex surface. The EPR spectrum of Cu(II) complex verified the octahedral geometry of the complex. Molecular modeling was performed to assign the structural formula proposed for the ligand based on the characterization results.

Synthesis, characterization and thermogravimetric analysis of Co(II), Ni(II), Cu(II) and Zn(II) complexes supported by ONNO tetradentate Schiff base ligand derived from hydrazino benzoxazine

A new series of Co(II), Ni(II), Cu(II) and Zn(II) metal complexes of a novel ligand 3-(2-(1-(2,4-DihydroxyPhenyl)ethylidene)hydrazinyl)-2H-benzo[b][1,4]oxazin-2-one, (DPE-HBO) were prepared and characterized. Microwave synthesis of the ligand was also carried out which gave a high increase in its yield within very short time. 3D molecular modeling structure of the ligand is obtained by using ArgusLab software. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analysis, thermal, infrared, electronic spectra, magnetic moments and conductivity measurements. ESR spectrum of Cu(II) complex is studied. All the complexes show subnormal magnetic moments. ONNO donor atoms participate in coordination with Cu(II) and Zn(II) complexes exhibiting octahedral geometry. Co(II) and Ni(II) complexes behave differently with ONNO donor atoms showing two types of geometries i.e., octahedral and square planar within the same complex.

Copper sorption by the edge surfaces of synthetic birnessite nanoparticles

We investigated the sorption of Cu by δ-MnO2, an analog for natural birnessite (layer-type Mn oxide) that is characterized by randomly stacked and curled nanosheets, a low to moderate vacancy content, and variable amounts of layer and interlayer Mn3+. The synthetic δ-MnO2 used in this study had a Na:Mn molar ratio of 0.13, an average manganese oxidation number (AMON) of 3.85 after reaction, a specific surface area of 254m2g−1 and a particle size of 2–4nm in the ab plane. The maximum surface excess (qmax) value at pH6 estimated from sorption data of 0.72 (0.64–0.83, 95% confidence interval) molCumol−1 Mn far exceeded the nominal vacancy content for δ-MnO2 (ca. 6–11% molvacancymol−1 Mn), thus implicating multiple binding sites for Cu. The large values of qmax and specific surface area of the mineral suggest a major role for surface sites at the particle edges relative to vacancy sites. The extended X-ray absorption fine structure (EXAFS) spectra from δ-MnO2 samples differ with respect to the EXAFS spectra for Cu(OH)2, CuO, and Cu3(CO3)2(OH)2 and Cu-sorbed by biogenic MnO2. The Cu K-edge EXAFS spectra show two second-shell peaks that can be modeled with Mn and Cu near-neighbors. Copper appears to bind dominantly at particle edges of δ-MnO2 as dimers or polynuclear surface species. This sorption mechanism is consistent with the moderate vacancy content of δ-MnO2 and explains the similarity in the EXAFS spectra from samples having surface loadings of 0.01 to 0.26molCumol−1 Mn. The strong proclivity of Cu to bind on the edge surfaces of nanoparticulate birnessite leads to very large surface excesses of Cu without the formation of a discreet precipitate, making the surface sites at the particle edges the dominant sorption site for Cu.

A hybrid calibration-free/artificial neural networks approach to the quantitative analysis of LIBS spectra

A ‘hybrid’ method is proposed for the quantitative analysis of materials by LIBS, combining the precision of the calibration-free LIBS (CF-LIBS) algorithm with the quickness of artificial neural networks. The method allows the precise determination of the samples’ composition even in the presence of relatively large laser fluctuations and matrix effects. To show the strength and robustness of this approach, a number of synthetic LIBS spectra of Cu–Ni binary alloys with different composition were computer-simulated, in correspondence of different plasma temperatures, electron number densities and ablated mass. The CF-LIBS/ANN approach here proposed demonstrated to be capable, after appropriate training, of ‘learning’ the basic physical relations between the experimentally measured line intensities and the plasma parameters. Because of that the composition of the sample can be correctly determined, as in CF-LIBS measurements, but in a much shorter time.

PHOTOPHYSICAL AND PHYSICOCHEMICAL PROPERTIES OF Cu(II)CHLORIN e4 AND Cu(II)CHLORIN e6 AS A LEAD COMPOUND OF PHOTOSENSITIZER FOR PDT

Porphyrin derivatives are potential compounds for diagnostic agent and photosensitizer in photodynamic therapy. However, they have a weakness in molar absorptivity, especially in visible region of Q band which used to excite them. Due to incapabilities of porphyrin, other tetrapyrole derivatives, such as chlorophyllin can be alternative for a lead compound of photosensitizer. In the present research, two chlorin derivatives were isolated from commercial chlorophyllin product. Their photophysical and physicochemical properties, i.e. molar absorptivity, quantum yield of fluorescence and quantum yield of singlet oxygen were determined. Chlorophyllin carboxylic acid form, Cu(II)-chlorin e 4 and Cu(II)-chlorin e 6 ,were successfully isolated with recovery of 11.33% and 16.46%, respectively. The absorption spectrum of Cu(II)-chlorin e 4 showed an intense Soret band at 406 nm and two weaker Q bands at 628nm, 658nm. Fluorescence efficiency was 0.09 while efficiency for singlet oxygen at pH 6.3 and 7.4 were 0.0052±0.0017 and 0.0066±0.0012. Cu(II)-chlorin e 6 displayed soret band at 407nm and Q bands at 627nm, 663nm. Singlet oxygen at pH 6.3 was 0.0029±0.0007, while at pH 7.4 was 0.0034±0.0001. However, Cu(II)-chlorin e 6 did not show fluorescence. Key words: Chlorophyllin, Cu(II)-chlorin e 4 , Cu(II)-chlorin e 6 , singlet oxygen fluorescence

Synthesis, molecular structure, and spectral analysis of copper(II) complexes derived from pyridinediols

A series of mononuclear copper(II) complexes was synthesized by reaction of different 2,6-disubstituted pyridines with elemental Cu in a CCl4/DMSO solvent system. Physical properties were analyzed using IR, optical spectroscopy, mass spectrometry, and EPR. Single-crystal X-ray diffraction for complexes 2a and 4a revealed that the molecular structure of 2a is composed of a six-coordinate unit in which two ligands are linked to Cu(II) by oxygen and nitrogen donors. Conversely, in the molecular structure of 4a, the Cu(II) has a slightly distorted trigonal bipyramidal arrangement, where the coordination environment around the copper ion is five-coordinate. EPR spectra of Cu(II) complexes were illustrated elaborately and some theoretical data were abstracted from EPR curves to support the proposed structures.

Conformation, molecular structure, and vibrational assignment of bis(2,2,6,6-tetramethylheptane-3,5-dionato)copper(II)

Conformational analysis, molecular structure, relative stability, and complete vibrational assignment of bis(2,2,6,6-tetramethylheptane-3,5-dionato)copper(II), Cu(tmhd)2, were investigated by density functional theory (DFT), Natural Bond Orbital (NBO) theory and Atoms-in-Molecules (AIM) analysis. Fourier transform-Raman and IR spectra of this complex have been also recorded. The theoretical and experimental methods used to investigate the substitution effects of methyl groups by t-butyl (t-but) on the structure and stability of complex. To explore the substitution effects, the structure and vibrational spectra of Cu(tmhd)2 compared with copper(II) acetylacetonate, Cu(acac)2. A complete assignment of the observed band frequencies has been done. Comparing of observed and calculated vibrational spectra suggests coexisting of two conformers in the sample. All theoretical and vibrational spectroscopic results are consisting with a stronger metal–oxygen bond in Cu(tmhd)2 than in Cu(acac)2.

English

The Cu(II) complexes were synthesized by the addition of Cu(II) acetate  monohydrate to ligand in aqueous solution with 1,10-phenanthroline and 2,2'-bipyridyl which led to the precipitation of  complexes. The synthesized Cu(II) complexes [Cu(SAla)phen(H2O)].H2O, [Cu(SAla)bpy(H2O)].H2O were found to be soluble in water, ethanol, methanol and DMSO. The electronic spectra and the magnetic moment support the stereochemistry of the complexes. The electronic spectra of all the complexes display a broad band with maximum at 14765 to 15503 cm-1, which suggested an octahedral geometry of the metal ion. The magnetic moment at the room temperature lying in the range of 1.78 to 2.09 BM corresponds to one unpaired electron which are slightly greater than the spin only value of 1.73 BM, which was expected for one unpaired electron which offer possibility of the paramagnetic nature. The electronic spectra of free ligand shows band at 35651 cm-1 which are intra ligand charge transfer band (INCT). The electronic absorption spectra of the schiff base complexes were recorded using DMSO solvent. The spectrum of Cu(II) complexes display a broad band at 14765 cm-1, which attributed  to  2Egà2T2g  transition, which strongly favours the octahedral geometry around the central metal ion. The thermal gravimetric analysis (TGA), derivative thermogravimetric analysis (DTG), differential thermal analysis (DTA) experiments were carried out to explore the thermal stability of the complexes. The thermal behaviours of all the metal complexes were studied in the temperature range of 0 to 1400°C. The TGA, DTG and DTA studies of complexes reveal that the decomposition proceeds in three steps.   Key words: Copper(II) complexes, 2,2'-bipyridyl, 1,10-phenanthroline.

Vacancy formation enthalpy of filledd-band noble metals by hybrid functionals

First-principles determination of the vacancy formation enthalpies has been long-term believed to be highly successful for metals. However, a widely known fact is that the various conventional density functional theory (DFT) calculations with the typical semilocal approximations show apparent failures to yield accurate enthalpies of Ag and Au. Recently, the previously commonly assumed linear Arrhenius extrapolation to determine the vacancy formation enthalpies at $T=0$ K from the high-temperature measured concentration of thermally created vacancies has been demonstrated to have to be replaced by the non-Arrhenius local Gr\"uneisen theory (LGT) [A. Glensk, B. Grabowski, T. Hickel, and J. Neugebauer, Phys. Rev. X 4, 011018 (2014)]. The large discrepancies between the conventional DFT-PBE data and the unrevised experimental vacancy formation enthalpies disappear for Cu and Al. Even by following the same LGT revisions for Ag, the large discrepancies still remain substantial at $T=0$ K. Here, we show that the hybrid functional (HSE), by including nonlocal exchange interactions to extend the conventional DFT method, can further correct these substantial failures. Upon a comparison of the experimental valence-band spectra for Cu, Ag, and Au, we have determined the HSE exchange-correlated mixing parameters $\ensuremath{\alpha}$ of 0.1, 0.25, and 0.4, and further derived the HSE enthalpies of vacancy formation of 1.09, 0.94, and 0.72 eV, respectively; in nice agreement with available LGT-revised experimental data. Our HSE results shed light on how to improve the theoretical predictions to accurately determine the defect formation energies and related thermodynamical properties.

A Series of Taurocholic Acid Complexes, Spectral, Kinetic, Molecular Modeling, and Antiviral Activity Studies

A series of taurocholic acid complexes was prepared with Cr(III), Fe(III), Co(II), Ni(II), and Cu(II) ions. The IR and Raman spectral data reveal the coordination of acid as mononegative bidentate. NH, and sulfonate (–O−). The bidentate mode of coordination is proposed toward all the metal ions. The electronic spectral data as well as the magnetic moment measurements proposed the octahedral geometry for all investigated complexes. The presence of water molecules was supported by thermal analysis study. ESR spectrum of Cu(II) complex was carried out and acting as a further supporting for the octahedral geometry. The molecular modeling was performed for all complexes to assert on the lower energy content for all isolated complexes in comparing with their free ligand. Such concludes the comparative stability of all isolated complexes. Scanning electron micrography for the Cu(II) complex reveals the particle size is presented in the nano range. An elaborated biological investigation was carried out for all complexes in comparison with their free ligand. The highest antiviral activity was observed with the free ligand and its Ni(II) and Co(II) complexes and moderate activity was observed with Cr(III) and Fe(III) complexes, but the lowest activity was observed with Cu(II) complex.

Synthesis, spectroscopic characterization, analgesic, and antimicrobial activities of Co(II), Ni(II), and Cu(II) complexes of 2-[N,N-bis-(3,5-dimethyl-pyrazolyl-1- methyl)]aminothiazole

Synthesis of new series of Cu(II), Co(II), and Ni(II) from the ligand 2-[N,N-bis-(3,5-dimethyl-pyrazolyl-1-methyl)]aminothiazole is described. The ligand and its complexes were characterized by various techniques such as elemental analysis, FT-IR, UV–Visible, 1H and 13C NMR spectra, mass spectrum, and conductometry. The electronic absorption spectra and magnetic susceptibility measurements suggest a square planar geometry for Cu(II) complex and distorted tetrahedral geometry for the other metal(II) complexes. The EPR spectrum of Cu(II) complex recorded at 77°K confirms the distorted square planar geometry. The antimicrobial activities of the ligand and metal complexes against the bacterial species such as Xanthomonas maltophilia, Chromobacterium violaceum, Acinetobacter,Staphylococci, Streptococci, and the fungus Candida albicans are carried out and the results indicated that all compounds exhibit more antibacterial activity than the standard drug. The synthesized compounds were investigated for analgesic activity and they act as potent analgesic drugs.

Mid‐ and Far‐Infrared Marker Bands of the Metal Coordination Sites of the Histidine Side Chains in the Protein Cu,Zn‐Superoxide Dismutase

AbstractVibrational spectroscopy gives important information on the properties of ligand and metal–ligand bonds in metalloenzymes. Infrared spectroscopy is appealing for the study of metal active sites that are not amenable to Raman spectroscopy. We present a combined experimental and theoretical approach to analyze the mid‐ and far‐IR spectra of Cu,Zn‐superoxide dismutase (Cu,Zn‐SOD) as a probe of the histidine ligands. This metalloenzyme provides a unique model to identify specific IR signatures of metal–histidine coordination and to study their alterations as a function of the metal (copper/zinc), the copper valence state (+I/+II), the histidine coordination mode (Nτ and Nπ) and the histidine protonation state. DFT calculations combined with normal mode descriptions from potential energy distribution calculations were performed on two slightly different cluster models. Differences in the constraints at the side chain of one histidine Cu ligand sensibly modify the geometric parameters and vibrational properties. Electrochemically induced FTIR difference spectroscopy provided mid‐ and far‐IR fingerprint spectra of the Cu protein in aqueous media that are sensitive to the redox state of the Cu centre at the active site. Comparisons of the DFT predictions with the experimental IR modes of the histidine ligands at the Cu,Zn‐SOD active site showed that useful mid‐IR markers of histidine Nτ and Nπ coordination were predicted with good accuracy. The DFT analysis further demonstrated a link between the ν(C4–C5) mode frequency of His46 and the specific properties of the His46–Cu bond in Cu,Zn‐SOD. A combined theoretical and experimental approach on samples in H2O and 2H2O or 15N‐labelled samples identified the contributions from the histidine side chain modes in the 669–629 cm–1 region.

Developing predictive rules for coordination geometry from visible circular dichroism of copper(II) and nickel(II) ions in histidine and amide main-chain complexes.

Circular dichroism (CD) spectroscopy in the visible region (vis-CD) is a powerful technique to study metal-protein interactions. It can resolve individual d-d electronic transitions as separate bands and is particularly sensitive to the chiral environment of the transition metals. Modern quantum chemical methods enable CD spectra calculations from which, along with direct comparison with the experimental CD data, the conformations and the stereochemistry of the metal-protein complexes can be assigned. However, a clear understanding of the observed spectra and the molecular configuration is largely lacking. In this study, we compare the experimental and computed vis-CD spectra of Cu(2+)-loaded model peptides in square-planar complexes. We find that the spectra can readily discriminate the coordination pattern of Cu(2+) bound exclusively to main-chain amides from that involving both main-chain amides and a side-chain (i.e. histidine side-chain). Based on the results, we develop a set of empirical rules that relates the appearance of particular vis-CD spectral features to the conformation of the complex. These rules can be used to gain insight into coordination geometries of other Cu(2+)- or Ni(2+)-protein complexes.

Ab initiostudy of electronic, magnetic, and spectroscopic properties inA- andB-site-ordered perovskiteCaCu3Fe2Sb2O12

Electronic structure, magnetism, x-ray absorption spectroscopy (XAS), and x-ray magnetic circular dichroism (XMCD) spectra of $A$- and $B$-site-ordered quadruple perovskite $B$-site-ordered perovskite $\mathrm{Ca}{\mathrm{Cu}}_{3}{\mathrm{Fe}}_{2}{\mathrm{Sb}}_{2}{\mathrm{O}}_{12}$ (CCFSO) were studied using first-principles calculations with inclusion of spin-orbit coupling. The calculated XAS and XMCD spectra for Cu and Fe at the ${L}_{3,2}$ edges were consistent with a recent experiment and indicate ferrimagnetic ordering with antiparallel magnetic moments between Cu and Fe. The magnetic exchange coupling constants were also calculated to clarify the detailed mechanism of the ferrimagnetic ordering in CCFSO. The coupling constants for Cu-Cu, Fe-Fe, and Cu-Fe pairs were found to be moderate ferromagnetic, weak antiferromagnetic, and strong antiferromagnetic, respectively. From the analysis of the calculated density of states and magnetization density, the microscopic origin of the strong antiferromagnetic coupling between Cu and Fe was successfully elucidated by the superexchange mechanism via the $\mathrm{Cu}({d}_{{x}^{2}\ensuremath{-}{y}^{2}})\ensuremath{-}\mathrm{O}({p}_{x})\ensuremath{-}\mathrm{Fe}({t}_{2g})$ exchange path.