Photoluminescence and magnetic properties of isostructural europium(III), gadolinium(III) and terbium(III) oxamate-based coordination polymers.

Developing and investigating advanced multifunctional materials with magnetic properties as candidates for assembling spin qubits for quantum computing is imperative. A new polytopic ligand based on oxamate and aniline was used to promote the synthesis of three neutral homometallic lanthanide-coordinated polymers. New complexes with the formula {Ln(phox)(DMSO)(HO)}, where Ln = Eu (1), Gd (2), and Tb (3) [phox = -(phenyl)oxamate and DMSO = dimethylsulfoxide], were synthesized and well characterized by spectroscopic methods as well as X-ray crystallographic analysis.

Luminescent Supramolecular Metallogels: Drug Loading and Eu(III) as Structural Probe.

Supramolecular metallogels combine the rheological properties of gels with the color, magnetism, and other properties of metal ions. Lanthanide ions such as Eu(III) can be valuable components of metallogels due to their fascinating luminescence. In this work, we combine Eu(III) and iminodiacetic acid (IDA) into luminescent hydrogels.

Consequences of thimerosal on human erythrocyte hemoglobin: Assessing functional and structural protein changes induced by an organic mercury compound.

Background: Thimerosal (TM) is an organic mercury compound used as a preservative in many pharmacological inputs. Mercury toxicity is related to structural and functional changes in macromolecules such as hemoglobin (Hb) in erythrocytes (Ery).

Method: Human Hb and Ery were used to evaluate O uptake based on the TM concentration, incubation time, and temperature.

Tuning the luminescence efficiency by perfluorination of side chains in Eu complexes with β-diketones of the thiophene series.

A series of europium and gadolinium complexes comprising a β-diketone moiety modified with a fluorinated side-group and thiophene ring have been designed and synthesized and a comparative study of their luminescence properties has been carried out. In this study, when the methyl side group was modified by sequential addition of fluorine substituents and then the perfluorinated carbon chain was extended up to -CF by adding CF fragments, it transpired that the non-radiative energy processes are significantly suppressed in structurally more rigid polyfluorinated β-diketonate compounds of the series as C-H oscillators are replaced with low-energy C-F oscillators. The impact of other electron-withdrawing and electron-donating substituents on the spectroscopic and photophysical properties of the complexes in the present study has also been observed.

Experimental and Theoretical Studies of Glyphosate Detection in Water by an Europium Luminescent Complex and Effective Adsorption by HKUST-1 and IRMOF-3.

Designing an effective and simple detection method to quantify glyphosate (GLY) herbicide is desirable. Current chromatography-mass spectrometry and electrochemical methods can be used for this purpose, but these methods are difficult to be made portable and need high-cost equipment. Here, we evaluate a luminescent β-diketonate-Eu-ethylenediaminetetraacetic acid complex for GLY quantification in aqueous media on the basis of the luminescent quenching process.

Mononuclear lanthanide(III)-oxamate complexes as new photoluminescent field-induced single-molecule magnets: solid-state photophysical and magnetic properties.

Implementing additional optical (luminescent) properties into the well-known class of single-molecule magnets (SMMs) is considered as a promising route toward obtaining the next generation of optomagnetic materials for quantum information storage and computing. Herein, we report a joint optical and magneto-structural study for the two novel series of lanthanide(iii) complexes of general formula Bu4N[LnIII(HL)4(dmso)]·nH2O where H2L = N-(4-Xphenyl)oxamic acid with X = Cl and n = 2 [Ln = Eu (1_Cl), Gd (2_Cl), Dy (3_Cl), and Tb (4_Cl)] and X = F and n = 3 [Ln = Eu (1_F), Gd (2_F), Dy (3_F), and Tb (4_F)]. All these compounds are mononuclear species with each lanthanide(iii) cation in a low-symmetry nine-coordinate environment (LnO9) which is constituted by four didentate monoprotonated oxamate groups and one dmso molecule.

Lanthanide Contraction in Lanthanide Organic Frameworks: A Theoretical and Experimental Study.

In this work, the lanthanide (Ln) contraction phenomenon has been analyzed for three-dimensional structures in the solid state. We chose to study an isostructural series of lanthanide organic frameworks (LOFs) of formula [Ln(CHO)(HO)]·HO and 14 crystallographic structures (except promethium complex). The analysis of Ln contraction was made by analyzing the sum of all Ln-O bond lengths and the sum of all O-O distances, for the oxygen atoms of the coordination polyhedra, calculated with different semiempirical quantum mechanical models.

Are the Absorption Spectra of Doxorubicin Properly Described by Considering Different Tautomers?

The elucidation of the action of doxorubicin (DOX) has been considered a challenge for cancer therapy. Using theoretical approaches, we investigated the structure and electronic properties of DOX as a function of pH, which we thought likely to be related to the influence of its tautomers. Regarding the relative stabilities among the tautomers, the results obtained from PM6 were the most similar to those obtained from DFT.

Estimating the Individual Spectroscopic Properties of Three Unique Eu Sites in a Coordination Polymer.

We isolated a coordination polymer with the formula [Eu(3,5-dcba)(HO)(dmf)]·2dmf, with three unique Eu coordination sites in the asymmetric unit, with the Eu ions bridged by 3,5-dichlorobenzoato (3,5-dcba) ligands. The coordination polymer crystallized in the triclinic space group P1̅ with unit cell dimensions a = 12.4899(15), b = 16.

Parameters for the RM1 Quantum Chemical Calculation of Complexes of the Trications of Thulium, Ytterbium and Lutetium.

The RM1 quantum chemical model for the calculation of complexes of Tm(III), Yb(III) and Lu(III) is advanced. Subsequently, we tested the models by fully optimizing the geometries of 126 complexes. We then compared the optimized structures with known crystallographic ones from the Cambridge Structural Database.

Chemical Partition of the Radiative Decay Rate of Luminescence of Europium Complexes.

The spontaneous emission coefficient, Arad, a global molecular property, is one of the most important quantities related to the luminescence of complexes of lanthanide ions. In this work, by suitable algebraic transformations of the matrices involved, we introduce a partition that allows us to compute, for the first time, the individual effects of each ligand on Arad, a property of the molecule as a whole. Such a chemical partition thus opens possibilities for the comprehension of the role of each of the ligands and their interactions on the luminescence of europium coordination compounds.

Europium Luminescence: Electronic Densities and Superdelocalizabilities for a Unique Adjustment of Theoretical Intensity Parameters.

We advance the concept that the charge factors of the simple overlap model and the polarizabilities of Judd-Ofelt theory for the luminescence of europium complexes can be effectively and uniquely modeled by perturbation theory on the semiempirical electronic wave function of the complex. With only three adjustable constants, we introduce expressions that relate: (i) the charge factors to electronic densities, and (ii) the polarizabilities to superdelocalizabilities that we derived specifically for this purpose. The three constants are then adjusted iteratively until the calculated intensity parameters, corresponding to the (5)D0→(7)F2 and (5)D0→(7)F4 transitions, converge to the experimentally determined ones.

RM1 Semiempirical Quantum Chemistry: Parameters for Trivalent Lanthanum, Cerium and Praseodymium.

The RM1 model for the lanthanides is parameterized for complexes of the trications of lanthanum, cerium, and praseodymium. The semiempirical quantum chemical model core stands for the [Xe]4fn electronic configuration, with n =0,1,2 for La(III), Ce(III), and Pr(III), respectively. In addition, the valence shell is described by three electrons in a set of 5d, 6s, and 6p orbitals.

Separation of glycosidic catiomers by TWIM-MS using CO2 as a drift gas.

Traveling wave ion mobility mass spectrometry (TWIM-MS) is shown to be able to separate and characterize several isomeric forms of diterpene glycosides stevioside (Stv) and rebaudioside A (RebA) that are cationized by Na(+) and K(+) at different sites. Determination and characterization of these coexisting isomeric species, herein termed catiomers, arising from cationization at different and highly competitive coordinating sites, is particularly challenging for glycosides. To achieve this goal, the advantage of using CO2 as a more massive and polarizable drift gas, over N2, was demonstrated.

RM1 Model for the Prediction of Geometries of Complexes of the Trications of Eu, Gd, and Tb.

All versions of our previous Sparkle Model were very accurate in predicting lanthanide-lanthanide distances in complexes where the two lanthanide ions directly face each other, and mainly lanthanide-oxygen, and lanthanide-nitrogen distances, which are by far the most common ones in lanthanide complexes. In this article, we are advancing for the first time the RM1 model for lanthanides. Designed to be a much more general NDDO model, the RM1 model for lanthanides is capable of predicting geometries of lanthanide complexes for the cases when the central lanthanide trication is directly coordinated to any other atoms, not only oxygen or nitrogen.

A Eu(III) tetrakis(β-diketonate) dimeric complex: photophysical properties, structural elucidation by Sparkle/AM1 calculations, and doping into PMMA films and nanowires.

Reaction of Ln(III) with a tetrakis(diketone) ligand H4L [1,1'-(4,4'-(2,2-bis((4-(4,4,4-trifluoro-3-oxobutanoyl) phenoxy)methyl)propane-1,3-diyl)bis(oxy)bis(4,1-phenylene))bis(4,4,4-trifluorobutane-1,3-dione)] gives new podates which, according to mass spectral data and Sparkle/AM1 calculations, can be described as dimers, (NBu4[LnL])2 (Ln = Eu, Tb, Gd:Eu), in both solid-state and dimethylformamide (DMF) solution. The photophysical properties of the Eu(III) podate are compared with those of the mononuclear diketonate (NBu4[Eu(BTFA)4], BTFA = benzoyltrifluoroacetonate), the crystal structure of which is also reported. The new Eu(III) dimeric complex displays bright red luminescence upon irradiation at the ligand-centered band in the range of 250-400 nm, irrespective of the medium.

Unusual photoluminescence properties of the 3D mixed-lanthanide-organic frameworks induced by dimeric structures: a theoretical and experimental approach.

The present work describes a complementary experimental and theoretical investigation of the spectroscopic properties of the four isostructural 3D Ln-MOFs (wherein PDC = pyrazole-3,5-dicarboxylate, [La2(PDC)3(H2O)4]·2H2O (1), [(La0.9Eu0.1)2(PDC)3(H2O)4]·2H2O (2), [(La0.

LUMPAC lanthanide luminescence software: Efficient and user friendly.

In this study, we will be presenting LUMPAC (LUMinescence PACkage), which was developed with the objective of making possible the theoretical study of lanthanide-based luminescent systems. This is the first software that allows the study of luminescent properties of lanthanide-based systems. Besides being a computationally efficient software, LUMPAC is user friendly and can be used by researchers who have no previous experience in theoretical chemistry.

Semiempirical quantum chemistry model for the lanthanides: RM1 (Recife Model 1) parameters for dysprosium, holmium and erbium.

Complexes of dysprosium, holmium, and erbium find many applications as single-molecule magnets, as contrast agents for magnetic resonance imaging, as anti-cancer agents, in optical telecommunications, etc. Therefore, the development of tools that can be proven helpful to complex design is presently an active area of research. In this article, we advance a major improvement to the semiempirical description of lanthanide complexes: the Recife Model 1, RM1, model for the lanthanides, parameterized for the trications of Dy, Ho, and Er.

Theoretical methodologies for calculation of Judd-Ofelt intensity parameters of polyeuropium systems.

When Judd-Ofelt intensity parameters of polynuclear compounds with asymmetric centers are calculated using the current procedure, the results are inconsistent. The problem arises from the fact that the experimental intensity parameters cannot be determined for each asymmetric polyhedron, and this precludes the individual theoretical adjustment. In this study, we then propose three different methods for calculation of these parameters of polyeuropium systems.

Lanthanide complexes with aromatic o-phosphorylated ligands: synthesis, structure elucidation and photophysical properties.

Lanthanide complexes LnL3 (Ln = Sm, Eu, Tb, Dy, Tm, Yb, Lu) with aromatic o-phosphorylated ligands (HL(1) and HL(2)) have been synthesized and identified. Their molecular structure was proposed on the basis of a new complex approach, including DFT calculations, Sparkle/PM3 modelling, EXAFS spectroscopy and luminescent probing. The photophysical properties of all of the complexes were investigated in detail to obtain a deeper insight into the energy transfer processes.

Sparkle/PM7 Lanthanide Parameters for the Modeling of Complexes and Materials.

The recently published Parametric Method number 7, PM7, is the first semiempirical method to be successfully tested by modeling crystal structures and heats of formation of solids. PM7 is thus also capable of producing results of useful accuracy for materials science, and constitutes a great improvement over its predecessor, PM6. In this article, we present Sparkle Model parameters to be used with PM7 that allow the prediction of geometries of metal complexes and materials which contain lanthanide trications.

Water-soluble Tb3+ and Eu3+ complexes with ionophilic (ionically tagged) ligands as fluorescence imaging probes.

This article describes a straightforward and simple synthesis of ionically tagged water-soluble Eu(3+) and Tb(3+) complexes (with ionophilic ligands) applied for bioimaging of invasive mammal cancer cells (MDA-MB-231). Use of the task-specific ionic liquid 1-methyl-3-carboxymethyl-imidazolium chloride (MAI·Cl) as the ionophilic ligand (ionically tagged) proved to be a simple, elegant, and efficient strategy to obtain highly fluorescent water-soluble Eu(3+) (EuMAI) and Tb(3+) (TbMAI) complexes. TbMAI showed an intense bright green fluorescence emission selectively staining endoplasmic reticulum of MDA-MB-231 cells.

Synthesis and characterization of the europium(III) pentakis(picrate) complexes with imidazolium countercations: structural and photoluminescence study.

Six new lanthanide complexes of stoichiometric formula (C)(2)[Ln(Pic)(5)]--where (C) is a imidazolium cation coming from the ionic liquids 1-butyl-3-methylimidazolium picrate (BMIm-Pic), 1-butyl-3-ethylimidazolium picrate (BEIm-Pic), and 1,3-dibutylimidazolium picrate (BBIm-Pic), and Ln is Eu(III) or Gd(III) ions--have been prepared and characterized. To the best of our knowledge, these are the first cases of Ln(III) pentakis(picrate) complexes. The crystal structures of (BEIm)(2)[Eu(Pic)(5)] and (BBIm)(2)[Eu(Pic)(5)] compounds were determined by single-crystal X-ray diffraction.

Theoretical spectroscopic study of europium tris(bipyridine) cryptates.

A series of europium cryptates are studied, using semiempirical methods to predict electronic and spectroscopic properties. The results are compared with theoretical (DFT) and experimental results published by Guillaumont and co-workers (ChemPhysChem2007, 8, 480). Triplet energies calculated by semiempirical methods have errors similar to those obtained by TD-DFT methodology but hundreds of times faster.