Synthesis and magnetism of μ-isophthalato dinuclear lanthanide(III) complexes

Seven new μ-isophthalato dinuclear lanthanide(III) complexes, namely [Ln₂(IPHTA)(Me₂-phen)₄-(ClO₄)₂](ClO₄)₂ (Ln=La, Nd, Sm, Eu, Gd, Ho, Er), where Me₂-phen denotes 2,9-dimethyl-1,10-phenanthroline (Me₂-phen), IPHTA represents isophthalate dianion, have been synthesized and characterized by elemental analyses, molar conductance measurements, IR, ESR and electronic spectra. The variable-temperature magnetic susceptibilities of [ Gd₂ (IPHTA) (Me₂-phen)₄ ( ClO₄ )₂ ] ((ClO₄ )₂ complex were measured in the temperature range of 4–300 K and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, H = -2JS₁. J₂. giving the exchange parameter J = -0.19 cm^?1. This result is commensurate with a weak antiferromagnetic spin-exchange interaction between Gd(III)-Gd(III) im within the complex.     

系列双核Ln(III)配合物的晶体结构和磁性

合成了分子式为[Ln~2(phen)~2L],phen=C~1~2H~8N~2[ALn=Nd,L=(CH~3COO)~4(ONO~2)~2,BLn=Sm,L=(C~6H~5COO)~6,CLn=Eu,L=(C~6H~5COO)~6]3种同双核配合物。用X射线四圆衍射仪测定了3种化合物的结构。在化合物A分子中,2个Nd(III)原子由4个CH~3COO^-基团桥联,以phen和ONO~2^-为端基,构成了一个具有C~2对称性的双核分子。配合物B和C具有完全相同的结构,它们是以4个苯甲酸根为桥,2个phen和2个C~6H~5COO^-为端基的中心对称双核分子,其中6个苯甲酸根的成键状态可分为3种状况。在3种化合物中,每个Ln均为9配位,呈不规则多面体。Ln-Ln距离,A为0.397nm,B和C均为0.405nm。测定了各配合物的变温磁化率,通过对磁性质研究,发现化合物A在低温下具有反铁磁物质行为,并由理论拟合,求得了磁参数g,J值。     

Structures and fluorescence of two new hetero-dinuclear lanthanide(III) complexes derived from a Schiff-base ligand

Two isostructural dinuclear lanthanide(III)/Schiff-base complexes [{Ce_1.5Eu_0.5(clapi)}₂]·2CH₃CN (1) and [{La_1.5Eu_0.5(clapi)}₂]·2CH₃CN (2) {H₃clapi = 2-(5-chloride-2-hydroxyphenyl)-1,3-bis[4-(5-chloride-2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine} have been prepared by template procedure and characterized by elemental analyses, ICP, IR, and single-crystal X-ray diffraction analyses. Lanthanide ions Ce(III) and Eu(III) in 1, and La(III) and Eu(III) in 2 are disordered with occupancies 0.75 for Ce and 0.25 for Eu in 1; 0.75 for La and 0.25 for Eu in 2. In the compounds, each lanthanide is coordinated to four N and four O atoms from two clapi^3? ligands, forming a distorted square antiprism. Two phenol oxygen atoms from the middle arms of the two heptadentate μ₂-bridging ligands connect the two Ce(Eu) atoms in 1, and La(Eu) in 2. The solution of the two complexes in CH₂Cl₂ exhibits red fluorescence from Eu³⁺ ions at 77 K, very weak at room temperature.     

The coupled TG-MS investigations of lanthanide(III) nitrate complexes with hexamethylenetetramine

New transition metal compounds of the general formula Ln(NO₃)₃·2[N₄(CH₂)₆]·nH₂O, where Ln = La, Nd, Sm, Gd, Tb, Dy, Er, Lu, and n = 7-12, were obtained. The compounds and the gases evolved in the course of their thermal decomposition were characterised by thermogravimetric analysis. The measurements were carried out in air and argon environment in order to compare the intermediate products, final products and the mechanism of the thermal decomposition. The combined TG-MS system was used to identify the main volatile products of thermal decomposition and fragmentation processes of the obtained compounds. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal properties of lanthanide(III) complexes with 2-aminoterephthalic ACID

The complexes of yttrium(III) and lanthanides(III) with 2-aminoterephthalic acid form the isostructural series of triclinic compounds with a space group P from La to Lu and they have the general formula of Ln₂(C₈H₅O₄N)₃·8H₂O. On heating in air or inert gas atmosphere they lose all water molecules in the temperature range 50–200°C in one or two steps. The anhydrous compounds are stable from 360 to 435°C and then decompose to oxides.     

Synthesis and properties of lanthanide(III) complexes with 4-hydroxy-3,5-dimethoxybenzoic acid

Complexes of yttrium(III) and lanthanides(III) with 4-hydroxy-3,5-dimethoxybenzoic (syringic) acid were obtained as solids with metal to ligand mole ratio of 1: 3. The compounds were characterized by elemental analysis, IR spectroscopy, X-ray diffraction patterns, solubility, and thermal studies. The complexes are sparingly soluble in water and stable at room temperature. Compounds of light lanthanides (from La to Nd) are hydrated and they crystallize in a triclinic system. When heated, they lose water molecules in one step and in the next step they decompose to oxides. Complexes of yttrium and other lanthanides are anhydrous and crystallize in a monoclinic system. They are stable up to 300°C and then decompose to oxides. As the coordination number of lanthanide ions is usually equal to 9 or 8, one can suppose that hydroxy or methoxy groups take part in the coordination of these metal ions.     

Synthesis, characterization and magnetism of μ-chloranilato bi-nuclear chromium (III) complexes

Five new chloranilato-bridged binuclear chromium (III) complexes have been synthesized and identified as [Cr2(CA)L4]-(ClO4)4[L denotes 5-methyl-1,10-phenanthroline (Me-phen); 2,9-dimethyl-1, 10-phenanthroline ( Me2-phen); 5-chloro-1,10-phenanthroline(Cl-phen); diaminoethane (en) or 1,3-diaminopropane (pn)], where CA represents the dianion of chloranilic acid. Based on elemental analyses, molar conductivity and magnetic moment of room-temperature measurements, and IR and electronic spectral studies, it is proposed that these complexes have CA-bridged structures and consist of two chromium (III) ions, each in an octahedral environment. The complexes [Cr2(CA)(Me-phen)4](ClO4)4(1) and [Cr2(CA)(Me2-phen)4](ClO4)4(2) were further characterized by variable temperature (4.2-300 K) magnetic susceptibility measurements and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, , giving the exchange parameter J = -7.8 cm-1 for (1) and J= -6.5 cm*1 for (2). This result     

X-ray studies of lanthanide(III) complexes with 4-hydroxy-3-methoxybenzoate anion

Polycrystalline complexes of lanthanide(III) with 4-hydroxy-3-methoxybenzoic acid were obtained as hydrated compounds of general formula Ln(C₈H₇O₄)₃?·?nH₂O. After slow recrystallization we obtained single crystals of complexes and determined their structures. Praseodymium(III) and neodymium(III) form isostructural dihydrated complexes [Ln(C₈H₇O₄)₃(H₂O)₂], which crystallize in the triclinic system, space group P 1. Sm(III), Eu(III), Gd(III), Ho(III) and Tb(III) compounds are hexahydrates and also crystallize in the triclinic system, space group P 1. Dihydrated compounds form polymeric chains with metal centres linked by oxygen atoms of bridging carboxylates. Each metal ion is coordinated by chelating carboxylic group and two water molecules. Complexes of the second isostructural group form dinuclear units [Ln₂(C₈H₇O₄)₆(H₂O)₄]?·?8H₂O. Lanthanide(III) ions are linked by oxygen atoms of two chelating–bridging carboxylate groups. In the dimeric structure each metal ion coordinates additionally two chelating carboxylic groups and two water molecules.     

Synthesis,characterization and cytotoxicity evaluation of new cerium(III), lanthanum(III) and neodymium(III) complexes

Complexes of cerium(III), lanthanum(III) and neodymium(III) with coumarin‐3‐carboxylic acid (HCCA) were synthesized by mixing of equimolar amounts of the respective metal nitrates and coumarin‐3‐carboxylic acid in ethanol. The complexes were characterized and identified by elemental analysis, IR and Raman spectroscopy. DTA and TGA were applied to study the compositions of the compounds. The vibrational study showed bidentate coordination of CCA^? to Ln(III) ions through the carbonyl oxygen and the carboxylic oxygen atoms. The newly synthesized compounds were assayed for cytotoxicity against SKW‐3, HL‐60 and Reh cells. The complexes of cerium(III) and lanthanum(III) showed marginal cytotoxic activity against SKW‐3 and Reh cells as compared with the inorganic salts at concentration 200 µM . The complex of neodymium(III) induced approximately 50% reduction of the survival HL‐60 and SKW‐3 cells at concentration 200 µM . Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis,characterization and magnetism of copper(II)‐lanthanide(III) heterobimetalic complexes with N,N'‐oxamidobis‐(benzoato)cuprate (II)

Seven new μ‐oxamido copper(II)‐lanthanide(III) heterobimetalic complexes described by the formula Cu(obbz) Ln‐(Ph‐phen)₂NO₃(Ln = La, Nd, Eu, Gd, Tb, Ho, Er), where obbz denotes the oxamidobis(benzoato) and Ph‐phen represents 5‐phenyl‐1, 10‐phenanthroline, have been synthesized and characterized by the elemental analyses, spectroscopic (IR, UV, ESR) studies, magnetic moments (at room temperature) and molar conductivity measurement. The temperature dependence of the magnetic susceptibility of Cu(obbz)Gd(Ph‐phen)₂NO₃ complex has been measured over the range 4.2–300 K. The least‐squares fit of the experimental susceptibilities based on the spin Hamiltonian operator, ? = ?2 J?₁·?₂, yielded J= +1.28 cm^?1, a weak ferromagnetic coupling, A plausible mechanism for a ferromagnetic coupling between Gd(III)‐Cu(II) is discussed in terms of spin‐polarization.     

Thermal properties of lanthanide(III) complexes with 5-amino-1,3-benzenedicarboxylic acid

The complexes of yttrium(III) and lanthanides(III) with 5-amino-1,3-benzenedicarboxylic acid form two isostructural series of compounds and have the general formula Ln₂(C₈H₅O₄N)₃·nH₂O, where n = 13 for Y, La-Er and n=9 for Tm, Yb, Lu. They are insoluble in water and stable at room temperature. On heating in air or inert gas atmosphere they lose all water molecules in several steps. The anhydrous compounds are stable to about 400°C and next decompose to oxides.     

Studies of "pinwheel-like" bis[1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninato] rare earth(III) double-decker complexes

Homoleptic bis(phthalocyaninato) rare-earth double-deckers complexes [M(III)[Pc(alpha-OC5H11)4]2] (M = Eu, Y, Lu; Pc(alpha-OC5H11)4 = 1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninate) have been prepared by treating the metal-free phthalocyanine H2Pc(alpha-OC5H11)4 with the corresponding M(acac)3.nH2O (acac = acetylacetonate) in refluxing n-octanol. Due to the C4h symmetry of the Pc(alpha-OC5H11)4 ligand and the double-decker structure, all the reactions give a mixture of two stereoisomers with C4h and D4 symmetry. The former isomer, which is a major product, can be partially separated by recrystallization due to its higher crystallinity. The molecular structure of the major isomer of the Y analogue has been determined by single-crystal X-ray diffraction analysis. The metal center is eight-coordinate bound to the isoindole nitrogen atoms of the two phthalocyaninato ligands, forming a distorted square antiprism. Such an arrangement leads to an interesting pinwheel structure when viewed along the C4 axis, which assumes a very unusual S8 symmetry. The major isomers of all these double-deckers have also been characterized with a wide range of spectroscopic methods. A systematic investigation of their electronic absorption and electrochemical data reveals that the pi-pi interaction between the two Pc(alpha-OC5H11)4 rings is weaker than that for the corresponding unsubstituted or beta-substituted bis(phthalocyaninato) analogues.     

New cerium(III) and neodymium(III) complexes as cytotoxic agents

The cerium(III) and neodymium(III) complexes of 5‐aminoorotic acid were synthesized and characterized by means of spectral data (IR, Raman, ¹H NMR and ¹³C NMR) and elemental analysis. Significant differences in the IR spectra of the complexes were observed as compared with the spectrum of the ligand. A comparative analysis of the Raman spectra of the complexes with that of the free 5‐aminoorotic acid allowed a straightforward assignment of the vibrations of the ligand groups involved in coordination. ¹H NMR and ¹³C NMR spectra confirmed the formation of the complexes. The ligand and the complexes were tested for the cytotoxic activities on the chronic myeloid leukemia‐derived K‐562, overexpressing the BCR‐ABL fusion protein, and the non‐Hodgkin lymphoma‐derived DOHH‐2, characterized by a rexpression of the antiapoptotic protein bcl‐2 cell lines. The results obtained indicate that the tested compounds exerted a considerable cytotoxic activity upon the evaluated cell lines in a concentration‐dependent manner, which enabled the construction of dose–response curves and the calculation of the corresponding IC₅₀ values. Cytotoxicity towards tumor cells was determined for a broad concentration range. The inorganic salts exerted a very weak cytotoxic effect on these cells that is in contrast to the lanthanide complexes, which exhibited potent cytotoxic activity towards K‐562 and DOHH‐2 cell lines. Copyright © 2006 John Wiley & Sons, Ltd.     

Synthesis, characterization and luminescence properties of copper(I) complexes containing 2-phenyl-3-(benzylamino)-1,2-dihydroquinazolin-4(3H)-one and triphenylphosphine as ligands

Some copper(I) complexes of the formula [Cu(L)(PPh₃)₂]X (1-4) [where L = 2-phenyl-3-(benzylamino)-1,2-dihydroquinazolin-4(3H)-one; PPh₃ = triphenylphosphine; X = Cl⁻, NO₃⁻, ClO₄⁻ and BF₄⁻] have been prepared and characterized on the basis of elemental analysis, IR, UV-Vis and ¹H NMR spectral studies. The representative complex of the series 4 has been characterized by single crystal X-ray diffraction which reveal that in the complex the central copper(I) ion assumes the irregular distorted-tetrahedral geometry. Cyclic voltammetry of the complexes indicate a quasireversible redox behavior corresponding to Cu(II)/Cu(I) couple. All the complexes exhibit intraligand (π → π^∗) fluorescence with high quantum yield in dichloromethane solution.     

Dual-emissive complexes: Visible and near-infrared luminescence from bis-pyrenyl lanthanide(III) complexes

The syntheses and photophysical attributes of a range of dual-emissive lanthanide complexes are described. The simple ligand architecture is based upon a diethylenetriaminepentaacetic acid (DTPA) core and appended with two aminopyrenyl chromophores to yield the fluorescent free ligand L^pyr. Reaction of the ligand with Ln(tris-trifluoromethanosulfate) gave the mononuclear complexes Ln · L^pyr (Ln = Nd, Er, Yb). Luminescence studies revealed that the complexes were emissive in both the near-IR and UV–Vis, the latter resulting from pyrene localised emission (λ_em = 390 nm), the former from pyrene-sensitised emission of the lanthanide ion (λ_ex = 337 nm). Time-resolved measurements in the near-IR indicated that the number of coordinated solvent molecules for Nd and Yb was <1, confirming the proposed coordination mode of the octadentate L^pyr. The suitability of pyrene as a sensitiser for near-IR emitting lanthanides was further demonstrated in the rare observation of Er^III emission in a non-deuteriated protic medium.     

Dihalogen-halogenomethyl complexes of indium(III) X2InCH2X (X = Br, I): Simultaneous coordination of soft and hard ligands

Halogenomethyl-dihalogen-indium(III) compounds X₂InCH₂X (X = Br, I) obtained from indium monohalides and methylene dihalides were reacted with the soft donor ligands dialkylsulfides, R₂S (R = CH₃, CH₂Ph) to afford the corresponding dialkylsulfonium methylide complexes of InX₃, X₃InCH₂SR₂ (X = Br, R = CH₃, 1; X = I, R = CH₃, 2; X= I, R = CH₂Ph, 3). Compound 1 was reacted with the hard donor ligands dimethylsulfoxide or triphenylphosphine oxide to give the corresponding 1:1 adduct, Br₃(L)InCH₂S(CH₃)₂ (L = (CH₃)₂SO, 4; L = (C₆H₅)₃PO, 5). Compounds 1-5 were fully characterized in solution by NMR spectroscopy and in the solid state by X-ray methods.     

Thermodynamic parameters and stability constants of some tervalent lanthanide complexes of 1-(3-aryl-5-hydroxy 4-isoxazolylazo) 4-sulphonic acids

The stability constants of some tervalent lanthanide chelates of 1-(3-aryl-5-hydroxy 4-isoxazolylazo) 4-sulphonic acid (PHI-4S) and its substituents have been carried out by potentiometric and spectrophotometric methods. The results indicated the formation of 1:1 and 1:2 complexes with an order: Yb(III) > Y(III) > Gd(III) > Dy(III) > Tb(III) > Sm(III) > Nd(III) > Pr(III) > La(III). The stabilities increase with a decrease in the ionic or crystal radii [except a small break at Gd(III)], indicates the absence of extensive covalent bonding due to the non-availability of 4f-orbitals for bond formation. Structure-reactivity relationships of complex formation have been discussed by Hammett’s and Irving-Rossotti theories. Thermodynamic parameters have been discussed in terms of iso-equilibrium relationship.     

Highly efficient yellow-emitting iridium(III) complexes based on fluorinated 2-(biphenyl-4-yl)-2H-indazole ligands: Syntheses,structures, properties,and density functional theory calculations

Two new iridium (III) complexes ( Ir1-Ir2 ) bearing different fluorinated 2-(biphenyl-4-yl)-2H-indazole-based compounds as cyclometalated ligands and Xantphos as an ancillary ligand were synthesized and fully characterized. The ultraviolet (UV)–vis absorption, photoluminescence, and electrochemistry properties were studied. The single crystal structures of Ir1-Ir2 were determined by X-ray diffraction, showing each adopts the distorted octahedral coordination geometry. To gain insights into the lowest energy electron transitions and the lowest triplet excited states, density functional theory calculations were used to further investigate the origination. Two complexes emit yellow photoluminescence with quantum yields of 49.7–72.5% in solution at room temperature. Their Commission Internationale de L'Eclairage color coordinates are (0.42, 0.53) and (0.39, 0.47), respectively.     

Time-resolved luminescence of terbium complexes with poly(2- and 4-vinylpyridine N-oxide)s in aqueous solution

Terbium complexes with polymer ligands of poly(2- and 4-vinylpyridine N-oxide)s (P2VPNO, P4VPNO) in aqueous solution were prepared and characterized. Multi-exponential decays of the ⁵D₄ → ⁷F₅ terbium transition at 545 nm of [P2VPNO-Tb³⁺] and [P4VPNO-Tb³⁺] complexes were measured. The non-linearity of semi-logarithmic plots of time-resolved luminescence was more pronounced in [P4VPNO-Tb³⁺] than in [P2VPNO-Tb³⁺], being reduced by addition of salts such as sodium formate or acetate. We assume that multi-exponential decays of Tb³⁺ in the complexes are caused by a back metal-to-ligand energy transfer via triplet state of N-oxide polymer ligand. By carrying out separate experiments in water and deuterium oxide, the number of coordinated water molecules in the [P4VPNO-Tb³⁺] complex was estimated as 4-5, assuming that the Tb³⁺ aqua complex contains nine water molecules.     

Synthesis,characterization and antibacterial studies of Tm(III), Yb(III) and Lu(III) complexes of morin

New solid amorphous compounds of Tm(III), Yb(III) and Lu(III) with morin have been synthesized. Their composition and some physicochemical properties have been studied by elemental analysis, thermogravimetric analysis, IR spectroscopy as well as by conductivity, UV/Vis, MS, and NMR spectroscopies in solution. The spectroscopic studies have indicated that the 3-OH hydroxyl group and the carbonyl oxygen of morin were involved in the coordination of metal ion. The antibacterial activity of the synthesized compounds has been determined by the cylinder-plate diffusion and dilution methods (determination of minimum inhibitory concentration).