Near-Infrared Emission of Lanthanide(III) Texaphyrin Complexes

Lanthanide texaphyrin derivatives containing Er³⁺, Nd³⁺, and Yb³⁺ ions exhibit near-IR emission from the f–f transition of the lanthanide ions. Both the triplet transient difference absorption spectral measurement and singlet oxygen generation measurement suggest energy transfer from the macrocyclic ligand to the lanthanide ions. Electron-transfer mechanism could also play a role in the NIR emission of Yb–Tex complex.     

Salen-Type Lanthanide Complexes with Luminescence and Near-Infrared (NIR) Properties

Two type lanthanide complexes obtained by salen-type ligand N,N’-ethylenebis(salicylideneimine) (H₂L^a) and N,N’-ethylene-bis(3-methoxysalicylideneimine) (H₂L^b) have been isolated. They are 2D coordination polymer [Yb(H₂L^a)_1.5(NO₃)₃] _n (1), mononuclear Ln(H₂L^b)(NO₃)₃ [Ln = Sm (2), Ho (3)]. The structures of 1–3 were determined by single crystal X-ray crystallographic studies and their photophysical properties were investigated.     

Crystal Structures and Luminescent Properties of Two Lanthanide(III) Complexes Featuring Double-Stranded Helical Chains of Based on 2-Sulfoterephthalate

Hydrothermal reaction of Eu³⁺ and Dy³⁺ salts with monosodium 2-sulfoterephthalate (NaH₂stp) gives two 2D lanthanide coordination polymers, [Ln(stp)(H₂O)₂] _n (Ln = Eu (1) and Dy (2)). Single-crystal X-ray diffraction of the complexes reveal that both 1 and 2 crystallize in the triclinic crystal system of Pī space group. For 1, each Eu³⁺ ion lies in a 9-coordinated slightly distorted tri-capped triangle pyramidal configuration. The stp ligands adopt a μ ₄-type link to the metal ions to form a 2D layer-like structure, of which there exist the left- and right-handed double-stranded helical chains. For 2, each Dy³⁺ ion is in a 8-coordinated distorted bi-capped triangle pyramidal geometry. The double-stranded helical chains in 2 differ from those in 1. The thermal stabilities of the two compounds are studied by TGA. The solid state photoluminescence of 1 and 2 are reported. The fluorescent decay curves of the ligand and compounds indicate that 1 has the lifetime of 286.7 μs, τ ₁ = 0.51 ns and τ ₂ = 3.07 ns for the ligand, and for 2, τ ₁ = 0.53 ns and τ ₂ = 2.71 ns.     

Preparation and Properties of Monodispersed Colloidal Particles of Lanthanide Compounds: III, Yttrium(III) and Mixed Yttrium(III)/Cerium(III) Systems

Colloidal dispersions of uniform spherical particles of yttrium basic carbonate and rodlike particles of yttrium ammine carbonate were prepared by aging at elevated temperatures yttrium salt solutions in the presence of urea. Different composition and morphology were achieved by altering the aging temperature and time. Coprecipitation in mixed solutions of yttrium(III) and cerium(III) salts under similar experimental conditions yielded composite spherical particles of basic carbonate. The content of the two metals in the solids followed closely the initial composition of the reacting solutions. On calcination all prepared solids converted to their corresponding oxides while retaining their particle morphology. The so-prepared powders were characterized by various techniques.     

Water-Soluble Ruthenium(III)-Dimethyl Sulfoxide Complexes: Chemical Behaviour and Pharmaceutical Properties

In this paper we report a review of the results obtained in the last few years by our group in the development of ruthenium(III) complexes characterized by the presence of sulfoxide ligands and endowed with antitumor properties. In particular, we will focus on ruthenates of general formula Na[trans-RuCl(4)(R(1)R(2)SO)(L)], where R(1)R(2)SO = dimethylsulfoxide (DMSO) or tetramethylenesulfoxide (TMSO) and L = nitrogen donor ligand. The chemical behavior of these complexes has been studied by means of spectroscopic techniques both in slightly acidic distilled water and in phosphate buffered solution at physiological pH. The influence of biological reductants on the chemical behavior is also described. The antitumor properties have been investigated on a number of experimental tumors. Out of the effects observed, notheworthy appears the capability of the tested ruthenates to control the metastatic dissemination of solid metastasizing tumors. The analysis of the antimetastatic action, made in particular on the MCa mammary carcinoma of CBA mouse, has demonstrated a therapeutic value for these complexes which are able to significantly prolong the survival time of the treated animals. The antimetastatic effect is not attributable to a specific cytotoxicity for metastatic tumor cells although in vitro experiments on pBR322 double stranded DNA has shown that the test ruthenates bind to the macromolecule, causing breaks corresponding to almost all bases, except than thymine, and are able to cause interstrand bonds, depending on the nature of the complex being tested, some of which results active as cisplatin itself.     

Separation of Americium (III) and Lanthanide (III) Ions using TPEN Analogs

Abstract

N,N,N′,N′-tetrakis(2-pyridylmethyl)-1,2-ethylenediamine (TPEN) has been shown previously to exhibit a high separation factor for the separation of americium (III) and europium (III). Application of TPEN is limited due to the solubility of the material under acidic conditions (pH < 4). A variety of analogs were synthesized in this study to examine effects caused by various structural modifications in an effort to retain the selectivity of the parent compound while decreasing solubility in acidic media. Results indicate that the substitution at the ethylene linker of TPEN eliminates the ability of the compound to separate americium (III) over europium (III).     

Lanthanide(III) Coordination Polymers with Longer-Spanning Flexible Ligand: Synthesis,Crystal Structure and Luminescence Property

Two new two-dimensional (2D) lanthanide-organic frameworks [Ln (C₁₀H₁₆O₄)_1.5(H₂O)₂][Ln = Tb(1), Eu(2)] have been synthesized and characterized by elemental analyses, IR, XRD, and the X-ray diffraction. And the X-ray diffraction result shows that complex 1 is nine-coordinate and connected through the carboxylate groups of sebacate ligands to generate an extended 2D layer structure. Furthermore, the thermogravimetric analyses of complex 1 and the luminescent properties of all the complexes were carried out.     

Stoichiometry and Structure of the Complexes Between Lanthanide Ions and Macrocyclic Crown Ethers Containing from Four to Seven Coordinating Sites

The factors influencing the stoichiometry and the structure of the complexes between trivalent lanthanide perchlorates, hexafluorophosphates, nitrates, trifluoroacetates, chlorides, bromides, isothiocyanates and the polyethers 12-crown-4, 15-crown-5, 18-crown-6, dibenzo-18-crown-6 and 21-crown-7 are reviewed. The properties of divalent lanthanide and Ce(IV) complexes with crown ethers are presented and discussed.     

Separation of Cobalt(III) Amine Complexes by Thin-Layer Chromatography: II. The Separation of Higher-Charged Cobalt(III) Complexes

Abstract

A solvent system of formamide-methanol-glacial acetic acid has been found to be particularly useful in the separation of the geometrical isomers of di- and tripositive cobalt(III) amine complexes from each other. Best separations are obtained for the various aquo complexes, so that this method may be of value in the study of hydrolysis or solvolysis reactions of these complexes.     

Spectroscopic and Thermal Studies of Mn(II), Fe(III), Cr(III) and Zn(II) Complexes Derived from the Ligand Resulted by the Reaction Between 4-Acetyl Pyridine and Thiosemicarbazide

Transition metal complexes of Mn(II), Fe(III), Cr(III) and Zn(II) metal ions with a general formulas [Mn(L)₂(Cl)₂]·4H₂O (I), [Fe(L)₂(Cl)₂]·Cl·6H₂O (II), [Cr(L)₂(Cl)₂]·Cl·6H₂O (III) and [Zn(L)₂(Cl)₂]·2H₂O (IV) where L = 4-acetylpyridine thiosemicarbazone, have been synthesized and interpreted using CHN elemental analysis, magnetic susceptibility measurements, molar conductance, thermal analysis and spectroscopic techniques; i.e., infrared, electronic UV/vis, ¹H-NMR and mass. The manganese(II), ferric(III), chromium(III) and zinc(II) complexes have octahedral geometry. The molar conductance measurements reveal that the Mn(II) and Zn(II) chelates are non-electrolytes but Fe(III) and Cr(III) have an electrolytic behavior. The IR spectra show that the 4-acetylpyridine thiosemicarbazone free ligand is coordinated to the metal(II) chlorides as a neutral bidentate ligand through both of the lone pair of electrons of the C=N azomethine group and C=S group. X-ray powder diffraction gives an impression that the resulting complexes are amorphous and different from the start materials. The thermogravimetric studies indicate that uncoordinated water molecules are lost in the first and second decomposition steps. The activation thermodynamic parameters E*, ΔH*, ΔS* and ΔG* are estimated from the differential thermogravimetric analysis (DTG) curves using Horowitz–Metzger (HM) and Coats–Redfern (CR) methods. The ligand and its complexes have been screened for antibacterial and antifungal activities against two bacteria; i.e., Escherichia coli (Gram −ve) and Bacillus subtilis (Gram +ve) and two fungi, i.e., tricoderma and penicillium activities).     

Biologically-Active Gold(III) Complexes

A review is given of the background to and results of the succesful pharmacological testing of [AuX(2)(damp)] (X = Cl, OAc; damp = 2-Me(2) NCH(2)C(6) H(4)) against a range of microbes, fungi and tumouts, culminating in in vivo xenografts of ZR-1-75. These are the first fully evaluated gold(III) complexes. The activity and reactions of the diacetato-complex bear a resemblance to cisplatin, and some of the relevant chemistry is discussed. Preliminary screening data for C,P-chelated tertiary phosphine derivatives of gold(III) are presented.     

Structural,Magnetic and Luminescent Properties of Lanthanide Complexes with N-Salicylideneglycine

A series of anionic heavy lanthanide complexes, involving the N-salicylideneglycinato(2-) Schiff base ligand (salgly) and having the general formula K[Ln(salgly)₂(H₂O)₂]∙H₂O (1–6), where Ln stands for Gd, Tb, Dy, Ho, Er and Tm, was prepared using the one-pot template synthesis. The complexes were thoroughly characterized by elemental and Thermogravimetric/Differential Thermal Analyses (TG/DTA), Fourier Transform Infrared Spectroscopy (FT-IR), and photoluminescence spectroscopies, electrospray-ionization mass spectrometry, and their magnetic properties were studied by temperature-dependent dc magnetic measurements using the superconducting quantum interference device (SQUID). The X-ray structure of the terbium(III) complex (2), representing the unique structure between the lanthanide complexes of N-salicylideneamino acids, was determined. The results of spectral and structural studies revealed the isostructural nature of the prepared complexes, in which the lanthanide ion is octacoordinated by two O,N,O-donor salgly ligands and two aqua ligands. The analysis of magnetic data confirmed that the complexes behave as paramagnets obeying the Curie law. The results of photoluminescence spectral studies of the complexes showed the different origin in their luminescent properties between the solid state and solution. An antenna effect of the Schiff base ligand was observed in a powder form of the complex only, while it acts as a fluorophore in a solution.     

Synthesis,Characterization and Fluorescence Properties of Poly(styrene-co-n-caprylamide maleic acid) and Its Europium(III) and Terbium(III) Complexes

Copolymer of poly(styrene-co-n-caprylamide maleic acid) (PSCMA, defined as HL) and its lanthanide complexes Ln(L)₃·6H₂O (Ln = Eu and Tb) had been synthesized and characterized by elemental analysis, X-ray diffraction, Fourier transform infrared spectra, UV-spectrophotometer and thermal analysis (TG–DTA). The fluorescence properties of the HL ligand and the Ln(L)₃·6H₂O complexes in the solid state were investigated. At room temperature, the HL ligand had a strong broad emission band at 410–575 nm (λmax = 458 nm) under excitation at 380 nm, while the respective characteristic emission of Eu(III) and Tb(III) ions was observed in Ln(L)₃·6H₂O complexes. This demonstrated that the HL ligand in the extra-framework channels succeeded in sensitizing Eu(III) and Tb(III) ions emission. Compared with the Eu(L)₃·6H₂O complex, the fluorescence intensity of the Tb(L)₃·6H₂O complex was much stronger. This indicated that the lowest excited triplet state energy level of HL matched well with the excited state energy level of Tb(III). With the increase of the Ln(III) ions content below 15 wt%, the fluorescence intensity increased monotonically. All the Ln(L)₃·6H₂O complexes exhibited high quantum yield, long fluorescence lifetime and good thermal stability.     

Copper(II) Complexes of Pyridazine-Based Azo-azomethine Ligands: Synthesis, Characterization Thermal and Absorption Properties

New copper(II) complexes with blue–violet light wavelength absorption were synthesized using direct reaction of acyclic azo-azomethine pyridazine-based ligands with copper ion. The prepared complexes were characterized using elemental analysis, spectroscopic methods and thermal analyses. The absorption properties of the prepared complexes in the region 200–800 nm and also the influence on the difference of absorption maximum of complexes were investigated. The thermogravimetric results show that the framework of all complexes is stable up to 270–320 °C.     

The Redox Chemistry of Manganese(III) and -(IV) Complexes

The oxidation-reduction thermodynamics for the manganese(III), -(IV), and -(II) ions, and their various complexes, are reviewed for both aqueous and aprotic media. In aqueous solutions the reduction potential for the manganese(III)/(II) couple has values that range from +1.51 V vs. NHE (hydrate at pH 0) to −0.95 V (glucarate complex at pH 13.5). The Mn(IV)/(III) couple has values that range from +1.0 V (solid Mn^IVO₃ at pH 0) to −0.04 V (tris gluconate complex at pH 13.5). With anhydrous media the propensity for the Mn(III) ion to disproportionate to solid Mn^IVO₂ and Mn(II) ion is avoided. For aprotic systems the range of redox potentials for various manganese complexes is from +2.01 V and +1.30 for the Mn(IV)/(III) and Mn(III)/(II) couples (bis terpyridyl tri-N-oxide complex in MeCN), respectively, to −0.96 V for the Mn(IV)/(III) couple (tris 3,5,-di-tert-butylcatecholate complex in Me₂SO). The redox reactions between manganese complexes and dioxygen species (O₂, O₂, and H₂O₂) also are reviewed.     

Structure and Nonlinear Optical Properties of Lanthanide Borate Glasses

The third–order nonlinear optical susceptibility, χ⁽³⁾, of lanthanide (lanthanum, praseodymium, neodymium, and samarium) borate glasses has been measured by the third harmonic generation method. The structure of the present glass system has been studied by infrared and Raman spectroscopic methods. The network structures of the present Ln₂O₃–B₂O₃ glasses have been confirmed to be basically similar to each other. Praseodymium, neodymium, and samarium borate glasses exhibit χ⁽³⁾ values that are larger than lanthanum borate glasses, because of the optical resonance effect, in accordance with the f – f transition. Especially, the χ⁽³⁾ value for 30Pr₂O₃·70B₂O₃ glass is 1.8 × 10⁻¹² esu, which is a factor of ∼60 larger than that of SiO₂ glass. This striking enhancement of χ⁽³⁾ is mainly attributed to the large transition moment to the first excitation state.     

Protein-binding Properties of two Antitumour Ru(III) Complexes to Human Apotransferrin and Apolactoferrin

The interaction of two ruthenium(III) complexes exhibiting high anticancer activity - namely trans-Indazolium(bisindazole) tetrachlororuthenate(III), Hlnd[RuInd(2)Cl(4)], and trans-Imidazolium (bisimidazole) tetrachlororuthenate(III), Hlm[RuIm(2)Cl(4)], - with human serum apotransferrin has been investigated through spectroscopic and chromatographic techniques with the ultimate goal of preparing adducts with good selectivity for cancer cells due to the fact that tumour cells express high amounts of transferrin receptors on their cell surface. Whereas the binding of Hlm[RuIm(2)Cl(4)] to human serum apotransferrin takes several hours, Hlnd[RuInd(2)Cl(4)], the less toxic complex, gives rise to a well defined 2:1 complex within a few minutes. Hlnd[RuInd(2)Cl(4)] will react with apotransferrin only in the presence of bicarbonate, this anion dictating the kinetic and mechanistic characteristics of protein-binding. Circular dichroism studies had previously indicated that binding of both Ru(III) complexes occurs around the unoccupied iron(III) binding sites; this result is now confirmed by preliminary X-ray data of Hlnd[RuInd(2)Cl(4)] and Hlm[RuIm(2)Cl(4)] bound to apolactoferrin, a related iron protein. The crystallograhic data reveals that binding of both complexes takes place at histidine residues, and that the ligand (indazole) remains bound in the case of Hlnd[RuInd(2)Cl(4)].     

Photoluminescent Polymer Composites Based on New Tb(III) and Eu(III): Maleimide Complexes

The paper reports the preparation of two photoluminescent polymer composites by embedding two newly prepared Tb(III) and Eu(III) complexes into poly(4-styrenesulfonic acid) matrices using maleimide as ligand. In the first step, the photoluminescent complexes were prepared at 1:3 metal-to-ligand ratio. Prior to the embedment into the polymer matrix the complexes were investigated by chemical and thermal analysis, FT-IR, powder X-ray diffraction and fluorescence spectroscopy. The prepared composites preserve the photoluminescent properties of the complexes and provide them with long-term stability. Thin films of the composites were spin–coated on glass slides and investigated by SEM and AFM techniques. The remarkable photoluminescent properties of the composites prepared in bulk or deposited in thin films on various substrates recommend them for applications in optical devices as photonic conversion mediums.