Heterometallic Compounds Research Articles

Synthesis, crystal structure, and luminescent property of a new heterometallic compound based on a large π-conjugated dicarboxylate ligand

Presented here is a new heterometallic compound with the formula of [CdCa(L)2(H2O)(DMF)]n (1, H2L = 5-(1-oxoisoindolin-2-yl)isophthalic acid, DMF = N,N’-dimethylformamide), which was synthesized under solvothermal conditions. Compound 1 crystallized in the orthorhombic Pna21 space group, and the unit cell parameters of 1 are a = 18.3689(11) Å, b = 14.2830(11) Å, c = 13.9233(11) Å, and α = 90°, β = 90°, γ = 90°, Z = 4. The heterometallic dinuclear [CdCa(COO)3] building subunits are connected by the L2- ligands into a 3D framework. Topological simplification for 1 represents a binodal (3,5)-connected topological network. The result of luminescence test revealed that compound 1 may be good candidate of blue luminescent material.

A spectroscopic, structural, and computational study of Ag-oxo interactions in Ag+/UO22+ complexes.

Twelve novel Ag+/UO22+ heterometallic complexes have been prepared and characterized via structural, spectroscopic, and computational methods to probe the effects of Ag-oxo interactions on bonding and photophysical properties of the uranyl cation. Structural characterization reveals Ag-oxo interaction distances ranging from 2.475(3) Å to 4.287(4) Å. These interactions were probed using luminescence and Raman spectroscopy which displayed little effect on the luminescence intensity and the energy of the Raman active UO symmetric stretch peak as compared to previously reported Pb-oxo interactions. Computational efforts via density functional theory-based natural bond orbital analysis revealed that the highest stabilization energy associated with the Ag-oxo interaction had a value of only 11.03 kcal mol-1 and that all other energy values fell at 7.05 kcal mol-1 or below indicating weaker interactions relative to those previously reported for Pb2+/UO22+ heterometallic compounds. In contrast, quantum theory of atoms in molecules analysis of bond critical point electron density values indicated higher electron density in Ag-oxo interactions as compared to Pb-oxo interactions which suggests more covalent character with the Ag+. Overall, this data indicates that Ag+ has a less significant effect on UO22+ bonding and photophysical properties as compared to other Pb2+, likely due to the high polarizability of the cation.

Nanoarchitectonics of heterometallic compound Al4Bi4 for optical limiting

Presented herein are the synthesis, structure, and optical properties of a novel aluminum-bismuth heterometallic coordination compound. [Al4Bi4(L)10(μ4-O)2(sal)4(Hsal)2] (L = benzyl alcohol, H2sal = salicylic acid) represents the highest nuclearity of AlBi based cluster compound. This compound is fully characterized. In addition, the optical limiting mechanism was investigated using the open-aperture and closed-aperture techniques. The results show it exhibits obvious reverse saturation absorption (RSA) response.

A series of heterometallic 3d-4f hydroxyl sulfate-fluoride compound Ln2Cu(SO4)2(OH)3F·H2O (Ln = Gd, Ho, Yb)

A series of heterometallic 3d-4f hydroxyl sulfate-fluoride compound Ln2Cu(SO4)2(OH)3F·H2O (Ln = Gd, Ho, Yb) are synthesized by a conventional hydrothermal method. All of Ln2Cu(SO4)2(OH)3F·H2O family crystallize in the monoclinic system with a space group of P21/c, where the [CuO6]∞ and [Ln2O12F2]∞ chains are perpendicular to each other, featuring a three-dimensional framework. Magnetic measurements confirm that all of Ln2Cu(SO4)2(OH)3F·H2O family (Ln = Gd, Ho, Yb) exhibit a paramagnetic behavior down to 2 K, where the Weiss temperature θ of near zero, positive, and negative values is observed for Gd, Ho, and Yb-analogues, respectively, due to possibly different 3d-4f spin-orbital couplings.

Discrete versus 1D Compounds based on Pentagonal Bipyramid Coordination Geometries: A Matter of Solubility?

AbstractA series of heterometallic compounds based on the association of trans‐dicyanido Cr(III) complex [Cr(L)(CN)2]K ⋅ 2H2O and several divalent [MnII(H2Ln)Cl2] heptacoordinated complexes, where Ln stands for pentadentate ligands featuring a planar N3O2 coordination pocket and various substituents (NH2, cyclohexyl, S,S‐mandelic), is described. A dinuclear compound [Cr(L)(CN)2M(H2L2)] and 1D coordination polymers of general formula [Cr(L)(CN)2M(H2Ln)]X (X=PF6− or [Cr(L)(CN)2]−) were rationally prepared by a simple adjustment of the Cr : M stoichiometry for R=NH2 or tuning the solvent mixtures to promote the crystallization of discrete complexes or chains. The crystal structures, phase purities and magnetic properties of all the compounds are reported.

A New (3, 6)-Connected Heterometallic Coordination Polymer: Therapeutic and Protective Effect on Ischemic Cerebral Infarction

Solvothermal reaction of 4,4’,4’-nitrilotribenzoic acid (H3TCA) with Ca(NO3)2·4H2O and Cd(NO3)2·4H2O successfully afforded a heterometallic compound, that is, [Cd2Ca(TCA)2(DMA)2(H2O)3]n·2n(DMA) (1, DMA = N,N’-dimethylacetamide). The structure of 1 was further characterized through EA, diffraction of single crystal X-ray, and thermogravimetric analysis (TGA) together with powder X-ray diffraction (PXRD). Moreover, complex 1’s luminescent performance in solid state was also discussed at environmental temperature. The applications on the ischemic cerebral infarction therapy were evaluated, and the specific mechanism was investigated at the same time. Firstly, the hypersensitivity C-reactive protein (hs-CRP) content in human brain microvascular endothelial cell (HBMEC) was measured with real-time reverse transcription-polymerase chain reaction (RT-PCR). Then, interleukin-18 and interleukin-1β content released through the HBMEC was detected with enzyme-linked immunosorbent assay (ELISA).

Anion-Dependent Structure and Luminescence Diversity in ZnII-LnIII Heterometallic Architectures Supported by a Salicylamide-Imine Ligand.

To advance the structural development and fully explore the application potential, it is highly desirable but challenging to elucidate the relationship between the structures and properties of ZnII-LnIII heterometallic species. Herein, three types of ZnII-LnIII heterometallic compounds (LnIII = GdIII, TbIII) formulated as [Zn16Ln4L12(μ3-O)4(NO3)12]·8CH3CN (ZnLn-1), [Zn2Ln2L2(NO3)6(H2O)2]·3CH3CN (ZnLn-2), and [Zn4Ln2L8(OAc)12]·xCH3CN (ZnLn-3: for Ln = Gd, x = 5; for Ln = Tb, x = 4) were dictated by common inorganic anions, NO3- and OAc-, with the aid of the multidentate ligand H2L with propane as the central skeleton and 3-methoxysalicylamide and 3-methoxysalicylaldimine as terminal groups. ZnLn-1 features cubic cages with four {Zn4L3} tetrahedral subunits and four Ln3+ centers positioned at the eight vertices alternately when NO3- was introduced into the reaction system exclusively. An attempt to replace NO3- in ZnLn-1 with OAc- partially led to the formation of {Zn2Ln2L2} heterometallic wheels. Meanwhile, ZnLn-3 featuring double-hairpin-like {Zn4Ln2L4} hemicycles that are orthogonal to each other assisted by intermolecular hydrogen bonds was constructed when NO3- in ZnLn-1 was completely replaced by OAc-. Their structural integrity in solution were ascertained by both emission and 1H NMR spectroscopy. Ascribed to the different Zn2+-containing antenna, ZnTb-2 possesses a relatively strong emission characteristic of Tb3+; ZnTb-1 has moderate Tb3+ luminescence, yet an absence of Tb3+ emission is found in ZnTb-3. Such an emission difference could be mainly attributed to the antenna effect directed by distinct structural characteristics induced by anions. The anion-dictated self-assembly strategy presented herein not only offers a facile approach to regulate the coordination mode of H2L to such an extent to obtain diverse structures of ZnII-LnIII heterometallic species but also provides an understanding of how common inorganic anions tune coordination-driven self-assemblies as well as the subsequent luminescence properties.

LnIII-NiII heterometallic compounds linked by nitronyl nitroxides: Structure and magnetism

Two Ln-Ni heterometallic complexes connected with nitronyl nitroxides [Ln(hfac)3Ni(hfac)2NIT-4py(H2O)2] (Ln = Gd (1), Tb (2); hfac = hexafluoroacetylacetonate; NIT-4py = 2-(4-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) have been synthesized as well as characterized. For two complexes, the NIT-4py radical is ligated to the Ln(III) ion and Ni(II) ion via its NO moiety and pyridine-N atom, respectively, resulting in rare radical bridged Ln-Ni heterobinuclear structure. Magnetic studies reveal that the magnetic exchanges arising from the uncoordinated NO groups dominate the system. Interestingly, the Tb compound displays a slow relaxation of magnetization.

Gd3 Triangles in a Polyoxometalate Matrix: Tuning Molecular Magnetocaloric Effects in {Gd30M8} Polyoxometalate/Cluster Hybrids Through Variation of M2+

Magnetocaloric Effects A family of nanoscale heterometallic 3d-GdIII compounds ligated by lacunary polyoxometalates (POMs) and featuring weakly antiferromagnetically coupled GdIII3 triangles dispersed within the diamagnetic POM matrix allows tuning of the magnetocaloric effect by variation of the 3d-cation. This provides a route for the development of low-temperature, energy-efficient and environmentally friendly sub-Kelvin magnetic cooling technologies. More details can be found in article number 2100052 by Masooma Ibrahim, Jürgen Schnack, Annie K. Powell, and co-workers.

Heterometallic Coii-Lii carboxylate complexes with N-heterocyclic carbene, triphenylphosphine and pyridine: a comparative study of magnetic properties

Heterometallic Coii-Lii compounds with N-heterocyclic carbene 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes), tri phenylphosphine (Ph3P) and pyridine (py), [Co2Li2(Piv)6(IMes)2] (Piv is the anion of pivalic acid), [Co2Li2(Piv)6(Ph3P)2] and [Co2Li2(Fur)6(py)2] (Fur is the anion of 2-furoic acid), respectively, have been prepared and structurally characterized by X-ray crystallography. Easy-plane magnetic anisotropy in Coii complexes with pseudo-tetrahedral cores CoO3X (X = C, P and N) was revealed by measuring the magnetic properties together with quantum-chemical calculations using the SA-CASSCF/NEVPT2 approach. The field-induced slow magnetic relaxation of the complexes was mainly attributed to the Raman and direct processes.

Heterometallic coordination polymers based on CuII/LnIII cations. Solid-state and magnetic characterization

Novel heterometallic three-dimensional coordination polymers {[CuII2LnIIICl2(HIA)4(NO3)(DMF)2]∙(2DMF)∙(H2O)}n based on Ce (1), Eu (2) or Gd (3) and imidazole-4-acrylic acid (H2IA), were successfully synthesized using the sonochemical method. All attempts to obtain the compound using other synthetic methods were unsuccessful. The heterometallic polymers are isostructural, crystallizing in the chiral P3221 trigonal space group. The crystal structures correspond to an intricated 3D framework where the Cu(HIA)2 fragments generate two interpenetrated copper (II) networks, [Cu(HIA)2]n. The LnIII cations that interact with these CuII-networks through the carboxylate group belonging to the organic ligand confer a higher complexity to the 3D network. Additionally, the coordination environment around the copper (II) cations is responsible for the chirality of the structures, making these even more exciting. The three-dimensional polymers were also characterized from a magnetic point of view, obtaining for (1) and (2) antiferromagnetic interactions, while for (3) a ferromagnetic interaction was observed. Furthermore, to the best of our knowledge, these coordination polymers are the first heterometallic compounds based on 3d/4f cations, assembled by the ligand imidazole-4-acrylate (HIA−).

Improving the Solubility of Hexanuclear Heterometallic Extended Metal Atom Chain Compounds in Nonpolar Solvents by Introducing Alkyl Amine Moieties.

The highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) interaction at the dz2 orbital between two kinds of metal complex is useful for obtaining heterometallic one-dimensional (1D) chains as well as heterometallic metal string compounds (HMSCs). Platinum dinuclear complexes, [Pt2(piam)2(NH2R)4]X2 (piam = pivalamidate, R = CH3, C2H5, C3H7, or C4H9, X = anion), comprising σ* as HOMO were mixed with [Rh2(O2CCH3)4] comprising σ* as LUMO in solvents to afford single crystals of [{Rh2(O2CCH3)4}{Pt2(piam)2(NH2R)4}2]X4 (2–5). Single-crystal X-ray analyses revealed that 2–5 are hexanuclear complexes that are one-dimensionally aligned as Pt–Pt–Rh–Rh–Pt–Pt with metal–metal bonds, where the alkyl moieties at end Pt atoms obstruct further 1D extension. Complexes 2–5 appear as if they are cut off from an infinite chain [{Rh2(O2CCH3)4}{Pt2(piam)2(NH3)4}2]n(PF6)4n·6nH2O (1) aligned as −{Pt–Pt–Rh–Rh–Pt–Pt}n–. The diffuse reflectance spectrum of 1 depicts broad shoulder bands, which are not present in the spectra of 2–5, proving that the infinite chain 1 forms a band structure. Compounds 4 and 5 with propyl or butyl moieties at amine ligands, respectively, are soluble in nonpolar solvents, such as CH2Cl2, without the dissociation of their hexanuclear structures. Taking advantage of their solubility, measurement of cyclic voltammetry in CH2Cl2 become possible, which shows the quasi-reversible oxidation and reduction waves at 4: Eox = 0.86 V and Ered = 0.69 V and 5: Eox = 0.87 V and Ered = 0.53 V.

Effect of the Alkaline Metal Ion on the Crystal Structure and Magnetic Properties of Heterometallic GdIII-VIV Complexes Based on Cyclobutane-1,1-Dicarboxylate Anions

A series of heterometallic GdIII-VIV compounds were synthesized by the reaction of VOSO4·3H2O with cyclobutane-1,1-dicarboxylic acid salts M2(cbdc) (M = Na, Rb, Cs). The new compounds were formed by [Gd(VO)2(cbdc)4(H2O)8]− trinuclear anionic units that were similar in composition but differed in structure, depending on the nature of the alkali metal cation incorporated in the crystal structure of the compound. In the case of Na+, the {GdV2}− units were characterized by identical V···Gd distances and were linked into the 1D-polymeric chain [NaGd(VO)2(cbdc)4(H2O)10]n (1). In the systems with Rb+ and Cs+, the V···Gd distances were different, and the {GdV2}− units were linked into the 3D-framework {[RbGd(VO)2(cbdc)4(H2O)10]·2.5H2O}n (2) and the octanuclear molecule {[CsGd(VO)2(cbdc)4(H2O)11]·5H2O}2 (3), respectively. According to dc-magnetic measurements, the VIV and GdIII ions were ferromagnetically coupled in compound 1 (JVGd = 0.163 ± 0.008 cm−1), while in compounds 2 and 3, ferro- and weak antiferromagnetic exchange interactions were observed (JVGd = 0.989 ± 0.028 and −0.089 ± 0.008 cm−1 for 2, 0.656 ± 0.009 and −0.050 ± 0.004 cm−1 for 3). Analysis of the EPR spectra of 1 revealed the presence of weak magnetic anisotropy of GdIII ions (D ~ 0.08 cm−1 and E/D ~ 0.1–0.15). Ac-susceptibility measurements showed an occurrence the field-induced slow relaxation of magnetization in 1–3.

Synthesis, Structure, and Spectroscopic Study of Redox-Active Heterometallic Cluster-Based Complexes [Re5MoSe8(CN)6]n.

The heterometallic cluster-based compound K5[Re5MoSe8(CN)6] was obtained by high-temperature reaction from a mixture of ReSe2 and MoSe2 in molten potassium cyanide. The redox behavior of the [Re5MoSe8(CN)6]5- cluster anion was studied by cyclic voltammetry in aqueous and organic media showing two reversible one-electron-redox transitions with E1/2 of -0.462 and 0.357 V versus Ag/AgCl in CH3CN. Aqueous media potentials were found to be noticeably shifted to higher values because of solvation. Chemically accessible potentials allowed us to structurally isolate and characterize the [Re5MoSe8(CN)6]n (n = 3-, 4-, and 5-) cluster complex in several charge states with corresponding cluster skeletal electron (CSE) numbers ranging from 24 to 22. The electronic absorption of the [Re5MoSe8(CN)6]n cluster complex varies significantly upon a change of the CSE number, especially in the visible and near-IR regions. The local cluster core distortion upon electron removal was confirmed by density functional theory calculation, while the overall geometry of the cluster anion remained practically unaltered.

Cu(II)-Na(I) heterometallic coordination compounds as photocatalyst for degradation of methylene blue

Two new Cu(II)/Na(I) coordination polymers, namely, {[(Cu(L1)Na)2(ox)(ClO4)2]∙dmf}n (1) and {[(Cu(L2)Na)2(nph)]∙H2O}n (2) were synthesized by using the Schiff base N-(2-hydroxyethoxy)ethyl-iminomethyl-phenol (H2L1) with oxalate (ox) and (3-methoxy-2-hydroxybenzylidene)propanoic acid (H2L2) with naphthalene-2,6-dicarboxylate anions (nph), respectively. Both the complexes were characterized using elemental analysis, FT-IR, UV–vis spectroscopic analyses. The solid state structures of complexes 1–2 were determined using single crystal X-ray crystallography that revealed for 1 the presence of dinuclear copper(II) species, [(L1)Cu(ox)Cu(L1)], while 2 consists of stair-like 1D -[CuL2]2-(nph)]n- polymers. Both these fragments are further connected by Na(I) cations to form 2D supramolecular assemblies. In both the compounds the copper and sodium atoms exhibit a square pyramidal and a distorted octahedral coordination geometry, respectively. The catalytic activity of complexes 1–2 for the degradation of methylene blue (MB) was investigated under UV irradiation and in the presence of very small amount of H2O2. Both the compounds were found to be photo-catalytically active, and the mechanism of photocatalysis has been discussed in detail.

Cavity Formation in Uranyl Ion Complexes with Kemp's Tricarboxylate: Grooved Diperiodic Nets and Polynuclear Cages.

Kemp's triacid (cis,cis-1,3,5-trimethylcyclohexane-1,3,5-tricarboxylic acid, H3kta) was reacted with uranyl nitrate under solvo-hydrothermal conditions in the presence of diverse counterions or additional metal cations to give eight zero- or diperiodic complexes. All the coordination polymers in the series, [PPh3Me][UO2(kta)]·0.5H2O (1), [PPh4][UO2(kta)] (2), [C(NH2)3][UO2(kta)] (3), [Cd(bipy)3][UO2(kta)]2 (4), and [Zn(phen)3][UO2(kta)]2·2H2O (5) (bipy = 2,2'-bipyridine, phen = 1,10-phenanthroline) crystallize as networks with the hcb topology, the ligand being in the chair conformation with the three carboxylate groups equatorial, except in 3, in which the axial/diequatorial boat conformation is present. Various degrees of corrugation and different arrangements of neighboring layers are observed depending on the counterion, with complexes 4 and 5, in particular, displaying cavities containing the bulky cations. [Co(en)3]2[(UO2)2(kta)(Hkta)2]2·2NMP·10H2O (6) (en = 1,2-ethanediamine; NMP = N-methyl-2-pyrrolidone) contains a metallatricyclic, tetranuclear anionic species, displaying two clefts in which the cations are held by extensive hydrogen bonding, and with the ligands in both triaxial chair and axial/diequatorial boat conformations. [(UO2)3Pb(kta)2(Hkta)(H2O)]2·1.5THF (7) (THF = tetrahydrofuran) and [(UO2)2Pb2(kta)2(Hkta)(NMP)]2 (8) are two heterometallic cage compounds containing only the convergent, triaxial chair form of the ligand, which have the same topology in spite of the different U/Pb ratio. These complexes are compared to previous ones also involving Kemp's triacid anions, and the roles of ligand conformation and of counterions in the formation of cavities, either in cage-like species or as grooves in diperiodic networks, is discussed.

Heterometallic Al6Zn12 nano-plate with π-conjugated ligand: synthesis and nonlinear absorption properties.

Presented herein is the synthesis, structure, and optical properties of the aluminum(III)-zinc(II) heterometallic compound AlOC-57. This compound was found to form a large unit cell (approximately sixteen thousand atoms) and a three-shell nano-plate structure. Based on the Z-scan patterns, the third-order nonlinear optical response of the heterometallic nano-plate was mainly attributed to its nonlinear absorption (reverse saturable absorption).

QUANTUM CHEMICAL STUDY OF THE STABILITY OF COPPER-PALLADIUM COMPLEXES IN THE GAS PHASE

Heterometallic coordination compounds based on copper(II) and palladium(II) β-diketonates $$\text{ }\!\![\!\!\text{ Cu}{{\text{L}}_{\text{2}}}\cdot \,\text{Pd}{{\text{L}}_{\text{2}}}]$$ (L = 2-methoxy-2,6,6-trimethylheptane-3,5-dionato) and $$\text{ }\!\![\!\!\text{ Cu}{{(\text{hfa})}_{\text{2}}}\,\cdot \text{Pd}{{\text{L'}}_{\text{2}}}]$$ (hfa = hexafluoroacetylacetonate, L′ = 1,1,1-trifluoro-5-methoxy-5-methylhexane-2,4-dionato) with a polymeric chain-like crystal structure can be used to prepare Cu–Pd films by MOCVD. It was previously suggested that the Pd:Cu ratio in the films is related to the stability of binuclear complexes $$\text{Cu}{{\text{L}}_{\text{2}}}\cdot \,\text{Pd}{{\text{L}}_{\text{2}}}$$ and $$\text{Cu}{{(\text{hfa})}_{\text{2}}}\,\cdot \,\text{Pd}{{\text{L'}}_{\text{2}}}$$ (the forms these compound adopt in the gas phase). In the present work, the most probable structure of such binuclear complexes at 0 K is determined, their stability is studied, and interatomic interactions are analyzed by density functional theory calculations. The monometallic fragments of the complexes are connected by a network of weak non-covalent interactions, the Cu⋯O contact being the strongest one. When modeling such systems, empirical corrections are shown to be essential for the account of dispersion interactions.

The First Example of 3 d‐4 f‐Heterometallic Carboxylate Complex Containing Phosphine Ligand

AbstractThe interaction of heterometallic compounds [Co2La(Piv)6(NO3)(MeCN)2] (1) and [Co2La(Piv)6(NO3)(Py)2] (2) (Piv‐pivalate, Py‐pyridine) with triphenylphosphine was studied. It was shown that labile terminal molecules of MeCN in complex 1 were substituted by triphenylphosphine that led to the formation of complex [Co2La(Piv)6(NO3)(Ph3P)2] (3), whereas compound 2 in similar conditions did not undergo ligand substitution reaction. Molecular structure of compound 3 was determined by means single crystal X‐ray diffraction. The temperature dependence of the magnetic susceptibility of 3 was simulated with a model which implied only zero‐field splitting of Co(II) ions. It was found that ZFS parameters (D) for Co(II) ions in 3 were close to D value in 1. The field‐induced slow magnetic relaxation was observed for compound 3 on the result of magnetic susceptibility measurements in alternating current magnetic field.

A thermostable 3D heterometallic metal-organic framework based on bifunctional isonicotinic acid ligand: Luminescent and photocatalytic properties

Based on the solvothermal reaction of HIN linker, Ca(NO3)2·4H2O and CuI, a new heterometallic compound, formulated as [Ca4Cu5(IN)9(I)4(H2O)(DMF)3]n·x(solvent) (1, HIN = isonicotinic acid, DMF = N,N’-dimethylformamide, solvent = disordered solvent molecules that have been squeezed out from the framework by PLATON program), has been successfully synthesized and structurally characterized by single crystal X-ray diffraction analysis, elemental analysis, powder X-ray diffraction analysis (PXRD) and thermogravimetric analysis. Compound 1 features a 3D complicated framework based on 1D chain substructure constructed by the carboxylate groups of IN ligands and Ca(II) ions. Moreover, compound 1 not only shows intense luminescence at room temperature but also exhibits excellent photocatalytic activity for the degradation of methyl blue (MB) under xenon arc lamp irradiation.