Heteronuclear Complexes Research Articles

Electrochemical Doping of Zinc Coatings with Chromium and Nickel Coatings with Phosphorus

The electrochemical doping of coatings with metals and nonmetals is discussed. Using the examples of the electrodeposition of zinc–chromium and nickel–phosphorus coatings, it has been shown that the presence of donors of the electrodeposited coating components in the inner sphere of a heteronuclear or heteroligand complex contributes to their coreduction and the formation of an alloy. The composition, morphology, and properties of the coatings have been characterized. It has been shown that the corrosion resistance of the zinc–chromium coatings is two times higher than that of the zinc coatings. After storage, the nickel–phosphorus coatings preserve their solderability with low-temperature solders.

Cu II -Na I heteronuclear complex as anticancer entity against human breast cancer cell lines: DNA binding, cleavage, and Computational studies

Abstract Herein, we report the synthesis and structural investigation of CuII-NaI heterobimetallic complex 1, which comprises of the compartmental Schiff-base ligand (H2L) derived from DACH (1,2-Diaminocyclohexane) and o-vanillin. B3LYP/TZVP DFT calculation was performed to get a deeper insight of the ground state electronic structure, and quantitative analysis of non-covalent interactions was carried out using Hirshfeld surface analysis to explore H-bonding, C-H···π, Cu···C-H and Cu···H-C interactions. Furthermore, in vitro DNA binding studies with Complex 1 demonstrated the electrostatic mode of interaction at the major groove of the DNA. Complex 1 showed the oxidative damage of pBR322 DNA via ROS generation. Additionally, in vitro cytotoxicity and genotoxicity of complex 1 were investigated on human breast cancer cells (MCF-7), revealed concentration-dependent cell viability at micromolar concentration level. Flow cytometric analysis confirmed the cytotoxic potential of complex 1 as the percentage of apoptotic cells were increased in the treatment group. Genotoxicity was evident in the induction of micronucleus and DNA fragmentation.

Carbohydrate-based heteronuclear complexes as topoisomerase Iα inhibitor: approach toward anticancer chemotherapeutics

Due to the critical role of cellular enzymes necessary for cell proliferation by deciphering topological hurdles in the process of DNA replication, topoisomerases have been one of the major targets in the anticancer drug development area. A need, therefore, arises for new metallodrugs that specifically recognizes DNA and inhibits the activity of topoisomerase enzymes, herein, we report the synthesis and characterization of new metal-based glycoconjugate entities containing heterobimetallic core CuII–SnIV (1) and NiII–SnIV (2) derived from N-glycoside ligand (L). The optimized structure of complex 1 and other significant vibrational modes have been explained using dispersion corrected B3LYP/DFT calculations. In vitro DNA binding profile of the L and both the complexes 1 and 2 were done by various biophysical studies. Complex 1 breaks pBR322 DNA via a hydrolytic means which was validated by T4 DNA enzymatic assay. To get a mechanistic insight of mode of action topoisomerase I (Topo I) inhibition assay was carried out. Also, we have taken the help of molecular modeling studies in accordance with experimental findings. In vitro cytotoxicity of the complex 1 was evaluated against a panel of cancer cells which exhibited remarkably good anticancer activity (GI50 values <10 μg/ml). Moreover, intracellular localization of the complex 1 was visualized by confocal microscopy against HeLa cells.

Chemical assembly of the heteronuclear pivalate complex with the LiI and FeIII ions

The heteronuclear complex [Fe4Li2(O)2(Piv)10(H2O)2] (1, Piv is the pivalic acid anion) was obtained by refluxing FeIII pivalates with LiI pivalates in toluene and isolated as the 1•PhCH3 solvate with a toluene molecule. According to X-ray diffraction data, complex 1 contains the {Fe4Li2O2} core. The Mossbauer spectroscopy data indicate that the core comprises para magnetic FeIII ions in the high-spin state located in the symmetric octahedral environment of oxygen atoms. Thermolysis of 1 studied by simultaneous thermal analysis demonstrated thermal stability of the complex up to 225 °С. The main end product of thermolysis at 600 °С is the mixed oxide LiFe5O8.

Electron interactions with the heteronuclear carbonyl precursor H2FeRu3(CO)13 and comparison with HFeCo3(CO)12: from fundamental gas phase and surface science studies to focused electron beam induced deposition.

In the current contribution we present a comprehensive study on the heteronuclear carbonyl complex H2FeRu3(CO)13 covering its low energy electron induced fragmentation in the gas phase through dissociative electron attachment (DEA) and dissociative ionization (DI), its decomposition when adsorbed on a surface under controlled ultrahigh vacuum (UHV) conditions and exposed to irradiation with 500 eV electrons, and its performance in focused electron beam induced deposition (FEBID) at room temperature under HV conditions. The performance of this precursor in FEBID is poor, resulting in maximum metal content of 26 atom % under optimized conditions. Furthermore, the Ru/Fe ratio in the FEBID deposit (≈3.5) is higher than the 3:1 ratio predicted. This is somewhat surprising as in recent FEBID studies on a structurally similar bimetallic precursor, HFeCo3(CO)12, metal contents of about 80 atom % is achievable on a routine basis and the deposits are found to maintain the initial Co/Fe ratio. Low temperature (≈213 K) surface science studies on thin films of H2FeRu3(CO)13 demonstrate that electron stimulated decomposition leads to significant CO desorption (average of 8–9 CO groups per molecule) to form partially decarbonylated intermediates. However, once formed these intermediates are largely unaffected by either further electron irradiation or annealing to room temperature, with a predicted metal content similar to what is observed in FEBID. Furthermore, gas phase experiments indicate formation of Fe(CO)4 from H2FeRu3(CO)13 upon low energy electron interaction. This fragment could desorb at room temperature under high vacuum conditions, which may explain the slight increase in the Ru/Fe ratio of deposits in FEBID. With the combination of gas phase experiments, surface science studies and actual FEBID experiments, we can offer new insights into the low energy electron induced decomposition of this precursor and how this is reflected in the relatively poor performance of H2FeRu3(CO)13 as compared to the structurally similar HFeCo3(CO)12.

Co-fluorescence effect of rare earth complexes with 4-aminobenzoic acid in a silica matrix

ABSTRACTTerbium(III), yttrium(III), and neodymium(III) complexes with 4-aminobenzoic acid have been co-doped into silica matrix. For the samples, the characteristic emissions of terbium(III) increase obviously with the addition of yttrium(III) complex, while the reverse is true with the addition of neodymium(III) complex. Compared with terbium(III) complex doped silica sample, the photoacoustic signal of the ligand decreases for terbium(III)–yttrium(III) complexes co-doped sample, and increases for terbium(III)-neodymium(III) complexes co-doped sample. The fluorescence quantum yields and lifetimes of the samples have been determined. The co-fluorescence mechanism has been discussed from radiative and nonradiative relaxations. The nephelauxetic parameters and photoacoustic branching vectors of neodymium(III) in the silica samples have also been calculated. The spectral result indicates that heteronuclear complexes may form in the silica matrix upon a suitable heat treatment. The co-fluorescence effect found in the inorganic matrix can contribute to the better design and application of rare earths containing fluorescent materials.

NiII-LnIII complexes with o-vanillin as the main ligand: syntheses, structures, magnetic and magnetocaloric properties.

ortho-Vanillin in the presence of nickel and lanthanide ions yields three types of heteronuclear NiII-GdIII complexes, ranging from dinuclear to tetranuclear defect dicubane complexes, as demonstrated by their structural determinations. These complexes are dependent on the solvents used during the reaction processes and on the retained lanthanide ions, as characterized by an increase in their Lewis acid character on moving from lighter to heavier lanthanide ions. Intramolecular ferromagnetic NiII-GdIII interactions are present in the heterodinuclear NiII-GdIII entities, whereas ferromagnetic NiII-NiII and NiII-GdIII interactions dominate above 2 K in the tetranuclear Ni-Gd compounds, devoid of any GdIII-GdIII interaction. The effect of a magnetic field on the magnetic entropy and adiabatic temperature changes is maximum near the liquid-helium boiling temperature, mainly determined by the relative weakness of the magnetic interactions.

Stability and donor-acceptor bond in dinuclear organometallics CpM1-M2Cl3 (M1, M2 = B, Al, Ga, In; Cp = η 5-C5H5).

The geometries and stabilities of the dinuclear organometallics CpM1-M2Cl3 (M1, M2 = B, Al, Ga, In; Cp = η 5-C5H5) have been investigated by density functional theory (DFT) at M06L/6-311G(d, p) levels. The nature of the donor-acceptor M1 → M2 bond was also studied based on the atoms in molecules (AIM) theory, energy decomposition analysis (EDA) and natural bond orbital (NBO) analysis. The results show that the electronegativity of the M atom determines the stability and covalent character of the dinuclear organometallics CpM1-M2Cl3. The compounds in which the M with larger electronegativity acts as the donor are more stable than in those in which it acts as the acceptor in the donor-acceptor bond, and the donor-acceptor bond has more covalent characteristics. The strength and polarity of the M1 → M2 donor-acceptor bond is determined by the periodicity of the M atom. When the period number of the M1 atom is smaller than that of M2, the strength of the M1 → M2 bond is larger than that of the M2 → M1 bond. For homonuclear dinuclear organometallics, the polarity of the M-M bond increases with increasing atomic number of the M atom. For heteronuclear complexes, the polarity of the M1-M2 bond for a given M1 also increases in the sequence of M2 = B, Al, Ga, and In. Graphic abstract Molecular graph and electron location function isosurfaces map of CpM 1 -M 2 Cl 3(small red spheres represent bond critical points).

Heteronuclear complexation in the system 1-hydroxyethylidenediphosphonic acid—manganese(ii)—gadolinium(iii) in aqueous solution

pH-Potentiometric method in combination with mathematical modeling was used to study the system manganese(ii)—gadolinium(iii)—1-hydroxyethylidenediphosphonic acid (HEDP, H4L). When both cations simultaneously are present in the solution, the accumulation of heteronuclear forms with the ratio of Gd: Mn: HEDP equal to 1: 1: 1, 1: 1: 2, and 1: 1: 3 was observed already in the strongly acidic pH region, while from homonuclear forms only five complexes were detected in the solution, namely, MnL26–, GdH4L2–, GdH2L+, KGd2HL2↓, and K3Gd2L2(OH)↓. It was concluded that heteronuclear complexes are much stronger and replace homonuclear forms in solution.

Zinc Tin Chalcogenide Complexes and Their Evaluation as Molecular Precursors for Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe).

A series of five heteronuclear zinc tin chalcogenide complexes with the general formula [(tmeda)Zn(SnR2)2E3] (1-R, E = S; R = Me, Ph, tBu; 2-R, E = Se; R = Ph, tBu) have been synthesized and characterized by X-ray crystal structure analysis. In all cases, the six-membered ZnSn2E3 rings exhibit twist boat conformation. The presence of the molecular structures in solution is confirmed by 119Sn and 77Se NMR spectroscopy. Cothermolysis experiments using a mixture of complexes 1-R or 2-R and [(iPr3PCu)2(EC2H4E)]2 as a copper source were monitored by thermogravimetry and temperature dependent X-ray powder diffraction to examine the thermolysis reaction. According to Rietveld refinement, the solid residue consists of Cu2ZnSnS4 (up to 78 wt %) or Cu2ZnSnSe4 (up to 43 wt %) as the main product, respectively.

The Missing Link in Ni(II)‐Ln(III) System: Design and Synthesis of a Dinuclear [Ni2] and Three Pentanuclear [Ni3Ln2] (Ln=La, Ce, Eu) Complexes of a Schiff Base Ligand

AbstractA new Schiff base ligand N‐(2‐hydroxyphenyl‐3‐methoxy‐salicylideneamine)‐5‐nitrophenol (H2L) has been synthesized by the reaction of o‐vanillin with 2‐amino‐4‐nitrophenol. The ligand H2L has been employed to prepare homo‐ and heteronuclear metal complexes. For example, a dinuclear Ni(II) complex, [Ni2(L)2(H2O)3]⋅2DMF⋅3H2O (1) and a new family of three pentanuclear heterometallic [Ni3Ln2L6(H2O)4(DMF)2]⋅4DMF (Ln=La (2), Ce (3) and Eu (4) were prepared by the reaction of it with nickel nitrate hexahydrate and hydrated lanthanide nitrates. The solid state structures of ligand (H2L) and complexes 1–4 were determined by single crystal X‐ray diffraction analyses. Single crystal X‐ray diffraction and NMR data reveal that the ligand H2L exist as a keto‐enamine form in the solid state. Structure of complex 1 indicates formation of a dinuclear Ni(II) complex. Complexes 2–4 are isostructural and exhibits a butterfly‐like structure containing two Ln(III) ions and three Ni(II) ions. The Ni(II) and Ln(III) are bridged by phenoxo and aqua ligands resulting a pentanuclear chain with alternating Ni(II) and Ln(III) ions. Different coordination modes of ligand (H2L) have been explored. To the best of our knowledge, such pentanuclear complexes containing Ni−Ln and Schiff base ligand are hitherto unknown. The thermal stability and optical properties of all complexes are also investigated.

Catalytic N−N bond cleavage of hydrazine by thiolate-bridged iron-ruthenium heteronuclear complexes

The novel thiolate-bridged iron-ruthenium heteronuclear complex [(PPh3)(bdt)Ru(μ-η2:η4-bdt)FeCp*] (1, Cp*=η5-C5Me5, bdt=benzene-1,2-dithiolate) was prepared by one-electron reduction of complex [(PPh3)(bdt)Ru(μ-η2:η4-bdt)FeCp*][FeCl3] (1[FeCl3]) using CoCp2 as reducing agent. Meanwhile, complex 1 can also be one-electron oxidized by Fc·PF6 or HBF4 to regenerate the ionic complex 1[PF6] or 1[BF4]. Importantly, complex 1 shows good reactivity toward the catalytic N−N bond cleavage of hydrazine into ammonia.

Infrared Photodissociation Spectroscopy of Heterodinuclear Iron-Zinc and Cobalt-Zinc Carbonyl Cation Complexes.

Fe-Zn and Co-Zn heteronuclear carbonyl cation complexes are produced via a laser vaporization supersonic cluster source in the gas phase. The dinuclear FeZn(CO)5+ and CoZn(CO)7+ cation complexes are observed to be the most intense heterodinuclear carbonyl cation species in the mass spectra. The infrared spectra are obtained via mass selection and infrared photodissociation spectroscopy in the carbonyl stretching frequency region. Their geometric and electronic structures are assigned with the support of density functional calculations. The FeZn(CO)5+ complex is determined to have a (OC)5Fe-Zn structure with a Fe-Zn half bond. The CoZn(CO)7+ ion is established to have a staggered (OC)4Co-Zn(CO)3 structure involving a Co-Zn σ single bond.

The Analysis of Cu(II)/Zn(II) Cyclopeptide System as Potential Cu,ZnSOD Mimic Center

In this paper are presented the features of copper (II) and zinc (II) heteronuclear complexes of the cyclic peptide—c(HKHGPG)2. The coordination properties of ligand were studied by potentiometric, UV–Vis and CD spectroscopic methods. These experiments were carried out in aqueous solutions at 298 K depending on pH. It turned out that in a physiological pH dominates Cu(II)/Zn(II) complex ([CuZnL]4+) which could mimic the active center of superoxide dismutase (Cu,ZnSOD). In next step we performed in vitro research on Cu,ZnSOD activity for [CuZnL]4+ complex existing in 7.4 pH by the method of reduction of nitroblue tetrazolium (NBT). Also mono- and di-nuclear copper (II) complexes of this ligand were examined. The ability of inhibition free radical reaction were compared for all complexes. The results of these studies show that Cu(II) mono-, di-nuclear and Cu(II)/Zn(II) complexes becoming to new promising synthetic superoxide dismutase mimetics, and should be considered for further biological assays.

Bornane[2,3-b]pyrazino-fused [30]trithiadodecaazahexaphyrin. Synthesis, acid-base behavior and nickel(II) coordination ability

Polydentate ligand-bornane[2,3-b]pyrazino-fused [30]trithiadodecaazahexaphyrin has been synthesized by crossover condensation of the racemic mixture of (R/S)-bornane[2[Formula: see text],3[Formula: see text]-b]-2,3-dicyanopyrazine and 2,5-diamino-1,3,4-thiadiazole. Its coordination ability, acid-base behavior and stability were studied by chemical kinetics/thermodynamics, UV-vis spectrophotometry and quantum chemical DFT/B3LYP/6-31G(d,p) methods. The fourth-order kinetic equation with the kinetic constant of 3.38 × 108 s[Formula: see text].mol3.L[Formula: see text] and the association mechanism according to the Langford−Gray classification were established for the fused [30]trithiadodecaazahexaphyrin–nickel diacetate–DMF system. The stepwise protonation of macrocyclic ligand with p[Formula: see text] of -1.41 in CH2Cl2-CF3COOH mixtures at the Hammett acidity functions ([Formula: see text] changed from -2.0 to 2.0 and quantitative parameters of ligand stability in AcOH–H2SO4 mixtures was obtained. The chemical structure of protonated forms and ligand destruction mechanism have been proposed. The obtained results are of interest for development of technological regulations of complex formation and for the transition to the hetero nuclear complexes.

Dual function photocatalysis of cyano-bridged heteronuclear metal complexes for water oxidation and two-electron reduction of dioxygen to produce hydrogen peroxide as a solar fuel.

The photocatalytic production of hydrogen peroxide from water and dioxygen under visible light irradiation was made possible by using polymeric cyano-bridged heteronuclear metal complexes (MII[RuII(CN)4(bpy)]; MII = NiII, FeII and MnII), where the photocatalytic two-electron reduction of O2 and water oxidation were catalysed by the Ru and MII moieties, respectively.

Synthesis and characterization of a family of thioether-dithiolate-bridged heteronuclear iron complexes.

The thioether-dithiolate-bridged heterotrinuclear complexes [Cp*Fe(μ-1k3SSS':2k2SS-tpdt)M(μ-2k2SS:3k3SSS'-tpdt)FeCp*][PF6]2 (Cp* = η5-C5Me5; tpdt = S(CH2CH2S)2; 2, M = Co; 3, M = Ni; 4, M = Pd) have been prepared by a reaction of [Cp*Fe(η3-tpdt)] (1) with complexes CoCl2, NiCl2(PPh3)2, and PdCl2(PPh3)2, respectively. Similarly, treatment of complex 1 with CuCl(PPh3) or AgPF6 afforded two heterotrinuclear complexes, [Cp*Fe(μ-1k3SSS':2k2SS-tpdt)M(μ-2k2SS:3k3SSS'-tpdt)FeCp*][PF6] (5, M = Cu; 6, M = Ag), while reaction of 1 with the complex AuCl(PPh3) gave a heterobinuclear complex, [Cp*Fe(μ-1k3SSS':2k1S-tpdt)Au(PPh3)][PF6] (7). These complexes have been spectroscopically and crystallographically characterized. An X-ray diffraction analysis showed that complexes 2, 3, 5, and 6 feature a heterometal center binding four sulfur atoms of two tpdt ligands with a cis orientation. However, in the Pd-containing complex 4, two tpdt ligands are arranged in a trans configuration. The μeff data and EPR results indicate that complexes 2, 4, 5, 6, and 7 are paramagnetic and only complex 3 is diamagnetic. Electrochemical experiments on these heteronuclear clusters were performed at room temperature. Discrepancy of the redox couples in the CV plots of these complexes indicates different one-electron transfer processes.

Polyoxometalate-based heteronuclear complexes [Fe2M2 (H2O)2 (FeW9O34)2]n− (M = MnII, MnIII, NiII) prepared by a pH-controllable degradation approach

Three new heteronuclear [FeW9O34]-based sandwich-type complexes [FeIII2MnII2(H2O)2(FeW9O34)2]12− (1), [FeIII2MnIII2(H2O)2(FeW9O34)2]10− (2) and [FeIII2NiII2(H2O)2(FeW9O34)2]12− (3) have been synthesized by an innovative method of pH-controllable degradation in aqueous solution, in which the [FeW12O40]5− precursor could be predominantly degraded into the trivacant [FeW9O34]11− anion. The active ligand of trivacant [FeW9O34]11− anion can catch in situ the mixed transition metal ions to conduce a directed coordination assembly reaction. These three heteronuclear complexes have been characterized by elemental analysis, single-crystal and powder X-ray diffraction analyses, IR spectra, UV–vis spectra, and thermal gravimetric analysis, cyclic voltammetry, magnetic properties, and thermal gravimetric analysis. Complexes 1 and 3 exhibit obvious catalytic activities for electrocatalytic reduction of nitrate. Compared with 1, the magnetic property of 2 shows a remarkable change by only a conversion of Mn(II) into Mn(III), so that a strong ferromagnetic interaction occurs in 2.

Organo Sn(IV) and Pd(II) complexes with various oxygen and sulphur donor ligands: Synthesis, spectroscopy and biological activity

Two Pd(II) complexes, (HL1CSS)2Pd (1) and (KL2CSS)2Pd (2), were synthesized by stirring 2-(1-piperazinyl)ethanol (HL1H)/l-lysine (HL2H) monohydrate in methanol with KOH, CS2 and PdCl2(aq). Homobimetallic (Sn, Sn) products, Ph3SnL3Sn(Cl)Bu2 (3) and Ph3SnL3SnBu3 (4) were produced by refluxing sodium but-2-ynedioate (Na2L3) with Ph3SnCl and Bu2SnCl2 or Ph3SnCl and Bu3SnCl in methanol. A heteronuclear (Sn,Pd) product, [(Bu3Sn)2L2CSS]2Pd (5) was synthesized by the reaction of 5-aminoisophthalic acid (H2L4H), KOH, CS2, PdCl2(aq) with Bu3SnCl. The products were characterized by elemental analysis, FT-IR, UV-Vis, 1H NMR and EIMS. A square planar geometry of Pd(II) and a penta-coordinated environment around Sn(IV) were verified in solid state. The complexes maintain their solid state geometries around Pd(II) even in solutions. Pd(II) complexes 1 and 2 exhibited a significant intercalating mode of binding with salmon sperm DNA. ALPs were inhibited in a concentration dependent manner. Sn(IV) complexes (3 and 4) were inactive against ALPs. Pd(II) complexes (1 and 2) were potent ALPs inhibitors, while the heteronuclear complex 5 was comparatively less active. Organotin(IV) products demonstrated significant antibacterial/ antifungal potential while Pd(II) products were inactive. The heteronuclear (Sn,Pd) product demonstrated moderate inhibition. Among all products, Pd(II) derivative 1 exhibited the highest hemolytic effect.

Four 3d–4f heteromultinuclear zinc(II)–lanthanide(III) complexes constructed from a distinct hexadentate N2O2-type ligand: syntheses, structures and luminescence properties

Four 3d–4f heteronuclear complexes, [(ZnL)2La(OAc)2]·ClO4·2CHCl3 (1), [(ZnL)2La(OAc)2]·CF3SO3·H2O (2), [ZnNd(L)(Py)(NO3)3] (3), and [ZnGd(L)(OAc)(NO3)2] (4) (Py = pyridine; H2L = 6,6′-dimethoxy-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol), have been prepared by one-pot reaction of H2L with zinc(II) acetate, lanthanide(III) ions and Py. Although the heterobinuclear complexes 1–4 are prepared in the same reaction condition, the Py does not coordinate to Zn(II) of 1, 2, and 4. Instead, the bridging μ-acetato ligand is present. The coordination of the Py in 3 leads to smaller distortion of square pyramidal coordination site of Zn(II), the higher coplanarity between the planes of ZnO(phenoxo)2 and LnO(phenoxo)2, and the longer Zn⋯Ln distance compared with 4. The luminescence properties of 1–4 have been discussed. The ligand (L2−) can sensitize NIR luminescence of Nd(III) ions.