Lanthanide perchlorate complexes of 4-cyano pyridine-N-oxide, 4-chloro 2-picoline-N-oxide and 4-dimethyl amino-2-picoline-N-oxide

Complexes of lanthanide perchlorates with 4-cyano pyridine-1-oxide, 4-chloro 2-picoline-1-oxide and 4-dimethyl-amino 2-picoline-1-oxide have been isolated for the first time and characterized by analysis, conductance, infrared, NMR and electronic spectra. The complexes of 4-cyano pyridine-1-oxides have the composition Ln(CyPO)₆(ClO₄)₃. 2H₂O (Ln=La, Sm, Dy and Ho); Ln(CyPO)₇ (ClO₄)₃. 2H₂O (Ln=Pr, Nd, Er and Yb); and Ln(CyPO)₅ (ClO₄)₃. 2H₂O (Ln=Gd and Tb). The complexes of 4-chloro 2-picoline-1-oxide analyse for the formulae Ln(CpicO)₆ (ClO₄)₃ (Ln=La, Pr, Nd and Ho); and Ln (CpicO)₅ (ClO₄)₃ (Ln=Er and Yb), and those of 4-dimethylamino 2-picoline-1-oxide for Ln(DMPicO)₆ (ClO₄)₃ (Ln=La and Nd); Ln(DMPicO)₇ (ClO₄)₃ (Ln=Gd, Er and Yb); and Ln(DMPicO)₈ (ClO₄)₃ (Ln=Dy and Ho).     

2,4-Lutidine-1-oxide complexes of lanthanide perchlorates

2,4-Lutidine-1-oxide (2,4-LutO) complexes of lanthanide perchlorates of the formulae Ln₂(2,4-LutO)₁₃(ClO₄)₆ (Ln = Pr and Nd) and Ln₂(2,4-LutO)₁₅ (ClO₄)₆ (Ln = La, Tb, Dy, Ho and Yb) have been prepared and characterised by chemical analysis, IR, NMR, conductance and electronic spectral data. Proton NMR data along with the IR data show that the ligand coordinates to the metal ion through the oxygen. Conductance data of the complexes in acetone and nitrobenzene indicate that the perchlorate is not coordinated to the metal ion.     

Photoactive Eu(III) and Tb(III) complexes of calix[4]arenes with pyridine-N-oxide pendant groups

Two calix[4]arenes with four 2-pyridyhnethyl-l-oxide pendant groups at the lower rim have been synthesized, and their Tb(III) and Eu(III) complexes are fluorescent upon UV light excitation at 312 nm. The complexes are not stable in aqueous solution, completely losing their luminescent properties.     

Lanthanide perchlorate complexes of 4-nitroquinoline-1-oxide and 5-nitroisoquinoline-2-oxide

Novel complexes of lanthanide perchlorates with 4-nitroquinoline-1-oxide (NQNO) and 5-nitroisoquinoline-2-oxide (NIQNO) have been prepared and characterized. The complexes have the general formulaeLn(NQNO)₈(ClO₄)₃ (whereLn=La-Nd), Ln(NQNO)₇(ClO₄)₃ (whereLn=Gd-Yb),Ln(NIQNO)₉(ClO₄)₃ (whereLn=La-Nd), andLn(NIQNO)₇(ClO₄)₃ (whereLn=Gd-Yb). The IR, proton NMR spectral data indicate the coordination of the N—O group of the ligands to he lanthanide ions.de|Es wurden neue Komplexe von Lanthanidperchloraten mit 4-Nitrochinolin-1-oxid (NQNO) und 5-Nitroisochinolin-2-oxid (NIQNO) dargestellt und charakterisiert. Die Komplexe haben die allgemeinen FormelnLn(NQNO)₈(ClO₄)₃ (mitLn=La-Nd),Ln(NQNO)₇(ClO₄)₃ (mitLn=Gd-Yb),Ln(NIQNO)₉(ClO₄)₃ (mitLn=La-Nd) undLn(NIQNO)₇(ClO₄)₃ (mitLn=Gd-Yb). Die IR- und NMR-Daten zeigen die Koordination der N—O-Gruppe der Liganden zum Lanthanidenion an.

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Lanthanid-Perchlorat-Komplexe von 4-Nitrochinolin-1-oxid und 5-Nitroisochinolin-2-oxid

     

Complexes of lanthanide nitrates with N,N-diethylantipyrine-4-carboxamide

New complexes of lanthanide nitrates with N, N-diethylantipyrine-4-carboxamide (DEAP), with the general formulae [Ln₂(DEAP)₃] [NO₃]₆ (where Ln = La, Pr, Nd, Sm, Tb, Ho, Er, Yb and Y) have been isolated and characterized by chemical analysis and various physical methods such as electrolytic conductance, IR and¹³C NMR spectral data. Electrolytic conductance values and infrared spectral studies indicate that the nitrate groups are coordinated. Infrared and¹³C NMR spectral analysis show that the ligand DEAP is coordinated to the tripositive metal ion through the diethylcarboxamide carbonyl and antipyrine carbonyl oxygens in a bidentate fashion.     

Synthesis, crystal structures and photoluminescent properties of lanthanide supramolecular complexes with 4-oxo-1(4H)-quinolineacetate

Five new lanthanide supramolecular complexes, namely, [Sm(oqa)₂(H₂O)₄]₂ (ClO₄)₂·(bpy)₂ (1), [Ln(oqa)₃]·2H₂O [Ln=Sm(2), Gd(3)] and [Ln(oqa)₂(NO₃)(H₂O)] [Ln=Pr(4), Eu(5)] (oqa=4-oxo-1(4H)-quinolineacetate, bpy=4,4′-bipyridine), have been synthesized under hydrothermal conditions. These complexes exhibit three typical structure features. Complex 1 possesses a dimeric structure, which is further connected together through hydrogen bonds and π-π attractions, forming a 3D supramolecular framework. Compounds 2-3 are isomorphous and contain 1D ring-like chains, which are further interconnected by the oqa ligands into 2D sheet-like structures. 4 and 5 exhibit eight-connected 3D network of 4²⁴·6⁴-bcu topology. The various coordination modes of carboxylate ligands and the selection of the counterions have clearly affected the topological structures. Furthermore, the solid-state luminescent properties of complexes 1, 2 and 5 were investigated at room temperature and they show intense, characteristic emissions in the visible region.     

Electrochemical Conversions of 2-Methyl-3-nitro-4-phenylquinoline, Its Quinolinium Salts, and Hydrogenated Derivatives

Classical polarography, cyclic voltammetry, and EPR spectroscopy was used to study electrochemical reduction and oxidation of 3-nitro derivatives of 2-methyl-4-phenylquinoline, the corresponding quinolinium perchlorates, and 1,2- and 1,4-dihydroquinolines. The nitro derivatives of quinoline and 1,2-dihydroquinoline are reduced in the first step at the nitro group; the quinolinium cations are reduced at the heterocycle followed by reduction of the nitro group; and in 1,4-dihydroquinolines, the nitro group is not reduced. Electrochemical reduction processes associated with electron transfer in the heterocycle mainly display the same behavior as established for pyridine derivatives. But important differences were observed in electrochemical oxidation: the N-methyl derivative of 1,4-dihydroquinoline is oxidized significantly more easily than the corresponding N-unsubstituted derivative of 1,4-dihydroquinoline (in the 1,4-dihydropyridine series, the difference in pot! enti als is fairly small), and even more easily than the corresponding N-methyl derivative of 1,2-dihydroquinoline.     

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.     

Two binuclear lanthanide complexes with 4-quinoline carboxylic acid: crystal structures and luminescent properties

Two isomorphic lanthanide complexes [Eu₂(L)₆(H₂O)₄] · 2H₂O (1) and [Tb₂(L)₆(H₂O)₄] · 2H₂O (2), (HL = 4-quinoline carboxylic acid) have been synthesized and structurally characterized by single-crystal X-ray diffraction. Both complexes are binuclear and each metal center adopts nine-coordination with nine oxygens from two H₂O molecules and carboxylates of three ligands; L exhibits three different coordination modes. Luminescent properties of 1 and 2 at room temperature indicate that the triplet-state level of this ligand matches better with the lowest excited state level of Eu(III) than with Tb(III).     

Intermediate neglect of differential overlap spectroscopic studies on lanthanide complexes

Summary The Intermediate Nelgect of Differential Overlap model for spectroscopy has been extended to lanthanide complexes by including spin-orbit coupling. The method uses atomic spectroscopy and model Dirac-Fock calculations on the lanthanide atoms and ions to obtain ionization potentials, Slater-Condon factors and basis sets. The spin-orbit interaction strength, (nl), is acquired from atomic spectroscopy, and only one-center terms are formally included. Calculation then proceeds using one open-shell operator for all sevenf-orbitals initially assumed degenerate to generate starting non-relativistic molecular orbitals for the subsequent configuration-interaction and spin-orbit calculation.Calculations are performed on the monoxides La, Ce, Gd, and Lu where there are ample experimental assignments. In general, the results are quite good, suggesting that the calculated energies, oscillator strengths and spin-orbit splittings can be used with success in assigning spectra, even in those cases wherejj-coupling is of intermediate strength.     

Near infrared study of aqueous lanthanide perchlorates

The near infrared spectra of water in aqueous solutions of La(ClO₄)₃, Pr(ClO₄)₃, Nd(ClO₄)₃, Gd(ClO₄)₃, Er(ClO₄)₃, Yb(ClO₄)₃, Lu(ClO₄)₃, and NaClO₄ have been measured in the concentration range from 0.3 to 2.5 mol-dm^–3, at 25°C. The relative contents of free OH groups in the 1.0, 1.6, and 2.2M solutions have been calculated from extinction coefficients for water at 1160 nm. They increase with increasing salt concentration and are greater in solutions of the lighter lanthanide perchlorates at any fixed molarity. The results are discussed in terms of the stoichiometry and structure of hydrated cations of trivalent lanthanides.     

Syntheses and characterization of novel lanthanide adamantine-dicarboxylate coordination complexes

Hydrothermal reactions of 1,10-phenanthroline (phen), 1,3-adamantanedicarboxylic acid (H₂L) and lanthanide chlorides yielded six compounds: [Ln(L)(HL)(phen)] (Ln=Pr, 1; Nd, 2), [Ln(L)(HL)(phen)(H₂O)] (Sm, 3; Eu, 4), [Tb(L)(HL)(phen)(H₂O)]₂·2H₂O (5), [Er₃(L)₄(OH)(phen)]₂ (6). Compounds 1-4 are structurally featured by one-dimensional polymeric chains; 5 hold binuclear structure constructed from eight-coordinated lanthanide center LnN₂O₆ of distorted bicapped trigonal prism bridged by dicarboxylate ligands; 6 shows that erbium ions are in mono and bicapped trigonal prismatic geometries, respectively, which are further connected by μ₃-OH to give rise to trinuclear structure. Thermogravimetric analyses of 1, 3 and 5 were performed. Fluorescent measurements of 4 and 5 were carried out, respectively.     

Correlations between electrochemical and spectral properties of alkyl-substituted diphthalocyanine lanthanide complexes

The electrochemical behavior and spectral properties of a series of symmetrical 2,3,9,10,16,17,23,24,2’,3’,9’, 10’,16’,17’,23’,24’-hexadecaalkyl-substituted lanthanide complexes (R₈Pc)₂Ln (R = H, Me, Et, Buⁿ; Ln = Eu, Dy, Lu) were studied. Regularities of changing the parameters under study were established, depending on the nature of lanthanide and substituents in the phthalocyanine macroligands. The position of the intervalence band of the complexes in the near-IR region depends on the effective distance between the macroligands and also on the electronic effect of the substituents. Correlations between the electrochemical and spectral properties of the complexes were found.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 184–189, January, 2005.     

Lanthanide perchlorate complexes of 2-acetamidopyridine-1-oxide

2-acetamidopyridine-1-oxide (AcAmPyO) complexes of six lanthanide perchlorates, with the general composition Ln(AcAmPyO)₅ (ClO₄)₃, have been synthesized and characterized by analysis, molar conductance, infrared, proton NMR and electronic spectral data. Infrared and conductance studies indicate the ionic nature of the anion. The coordination of the ligand through the N-O and C=O moieties is shown by the infrared and proton NMR spectral analysis.     

Synthesis,characterization, and biological activity of some lanthanide ternary complexes

Five complexes have been synthesized by the reaction of lanthanide(III) nitrate with 2-thenoyltrifluoroacetone (HTTA) and p-hydroxybenzoic acid (L). The complexes have been characterized by elemental analysis, molar conductivity, FT-IR, UV-Vis, ¹H NMR, TG-DTA, XPS, and transmission electron microscope. The general formula of the complexes is Na[Ln(TTA)₃L] (Ln?=?La³⁺,?Ce³⁺,?Nd³⁺,?Eu³⁺,?Er³⁺). The antibacterial activities indicate that all five complexes exhibit antibacterial ability against Escherichia coli and Staphylococcus aureus with broad antimicrobial spectrums. The antitumor activity of the five complexes against K562 tumor cell in vitro is measured using methyl thiazolyl tetrazolium (MTT) colorimetry. The results show that the complexes induce K562 tumor cell apoptosis, and the complexes exhibit inhibitory effect on leukemia K562 cells.     

Vibrational and electronic absorption spectra of 4-chloro 2-methyl, 4-chloro 3-methyl and 6-chloro 3-methyl phenols

The infrared spectra of 4-Cl 2-Me, 4-Cl 3-Me and 6-Cl 3-Me phenols have been recorded. The vibrational spectrum has been analysed assuming that the molecules belong toC _s point group and a tentative assignment of the observed frequencies to various modes of vibration has been proposed. The near ultraviolet absorption spectrum of these compounds has also been recorded. Assuming the transition to be electronically allowed the strongest band on the longer wavelength side has been assigned as the (0, 0) band in each case. The spectrum has been analysed in terms of several excited state frequencies which have been correlated with the ground state frequencies observed in the infrared spectrum.     

Synthesis,characterization and fluorescence of lanthanide Schiff-base complexes

Six new lanthanide Schiff-base complexes were synthesized by reactions of hydrated lanthanide nitrates with H₂L (H₂L?=?N,N′-bis(salicylidene)-1,2-cyclohexanediamine) and characterized by elemental analysis, DTA–TG, IR, UV and luminescence spectra. The microanalyses and spectroscopic analyses indicate a 1D polymeric structure with the formula of [Ln(H₂L)(NO₃)₃(MeOH)₂] _n [Ln?=?La (1), Ce (2), Pr (3), Sm (4), Gd (5) & Dy (6)]. The fluorescence spectrum of complex 4 exhibited Sm³⁺ centered, Schiff-base sensitized orange fluorescence, indicating that energy levels of the triplet state of H₂L match closely to the lowest excited state (⁴G_5/2) of Sm³⁺ ion.     

Spectral and thermal studies of light lanthanide 4-chlorophthalates

Conditions for the preparation of light lanthanide 4-chlorophthalates were investigated and their composition, solubility in water at 295 K, IR spectra and thermal decomposition were determined. 4-Chlorophthalates of La–Nd(III) were prepared as complexes with general formula NaLn[ClC₆H₃(CO₂)₂]₂, whereas compounds of Sm and Eu have general formula Ln₂[ClC₆H₃(CO₂)₂]₃·6H₂O. During heating all complexes decompose to oxides with intermediate formation of oxochlorides. The carboxylate groups in the complexes studied are bidentate bridging (Sm, Eu) or bidentate chelating and bridging (La–Nd).     

镧系金属高氯酸盐与1.8-萘啶氮氧化物配合物的合成、性质和结构

本文合成了镧系金属高氯酸盐与1,8-萘啶氮氧化物形成的Ln(C8H6N2O)4(ClO4)3(Ln=Sm-Lu)的固体配合物. 进行了元素分析、红外光谱、差热-热重分析和摩尔电导测定, 并作了Eu(ClO4)2与1,8-萘啶氮氧化物配合物的X射线单晶结构分析. 结果表明Eu^3^+离子与4个配体的氧原子和氮原子配位, 配位数为8.