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A series of mononuclear aryl-substituted cyclopentadienyl complexes [CpPh3LnCl2(Me3tach)] (Ln = Tb (4), Ln = Nd (5)), [CpPh2ArTbCl2(Me3tach)] (6), and [CpPh3LnCl2(Me3tacn)] (Ln = Tb (7), Ln = Nd (8...

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 n-C8F17 by adding CF2 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. Despite the presence of low-lying ligand-to-metal charge transfer states, the fluorinated Eu3+ complexes proved to be bright luminophores capable of delivering ca. 50% quantum yield under UV radiation. The role of fluorination and carbon chain length was examined by using experimental spectroscopic methods and the results obtained were largely in good agreement with theoretical calculations (Judd–Ofelt theory analysis, and semiempirical quantum chemistry calculations) supporting our key experimental findings.

The use of dicyanamide and chelating phenanthroline ligands resulted in the synthesis of organometallic europium and neodymium coordination polymers [Ln(Phen)2{N(CN)2}3–xClx(CH3OH)](CH3OH)y]∞ (Ln = Eu (I), Nd (II)) in which the dicyanamide ligand forms 1D chains, while the phenanthroline ligand provides packing of the 1D polymer in the crystal lattice. Under similar conditions, the binuclear complex [Gd(Phen)2(μ-OH){N(CN)2}(H2O)]2Cl2 (III) was obtained for gadolinium, with the dicyanamide ligands being coordinated to only one gadolinium ion without forming a polymer chain (CCDC CIF files nos. 1936378 (I), 1936379 (II), 1936377 (III)).

The mononuclear title complex, [Eu(C24H34O4P)3(CH4O)5]·CH4O, (1), has been obtained as a minor product in the reaction between EuCl3(H2O)6 and lithium bis(2,6-diisopropylphenyl) phosphate in a 1:3 molar ratio in a methanol medium. Its structure exhibits monoclinic (P21/c) symmetry at 120 K and is isostructural with the La, Ce and Nd analogs reported previously [Minyaev et al. (2018a). Acta Cryst. C74, 590–598]. In (1), all three bis(2,6-diisopropylphenyl) phosphate ligands display the terminal κ1 O-coordination mode. All of the hydroxy H atoms are involved in O—H...O hydrogen bonding, exhibiting four intramolecular and two intermolecular hydrogen bonds. Photophysical studies have demonstrated luminescence of (1) with a low quantum yield.

In recent years the electro-optic polymers emerged as an important branch of material science. This growth and interest is fundamentally motivated by practical application of these materials in sec...

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

Complexes [(1,2,4-Ph3C5H2)2NdCl2K(THF)2]2 (Nd1), {[1,2-Ph2-4-(4-MeOC6H4)C5H2]2NdCl2K(THF)2}2 (Nd2), {[1,2-Ph2-4-(2-MeOC6H4)C5H2]2NdCl2[K(THF)4]}(THF)0.5 (Nd3), and [(1,2,4-Ph3C5H2)2TbCl2K]2 (Tb1) h...

Novel mononuclear lanthanide thiocyanates with 2,2′;6′,2″-terpyridine (terpy), namely isomorphic complexes [Ln(terpy)2(NCS)3] (Ln = Y, Eu, Tb and Dy) were prepared and studied. The effective luminescence sensitization of the Eu, Tb and Dy ions owing to the terpy ligands was observed and corresponding values of the absolute quantum yields were determined. The influence of structural features of the complexes studied on their luminescent properties was analyzed. Slow magnetic relaxation indicating SMM behavior was found for Dy complex.

The crystal structure of the complex {Eu[O2P(O-2,6-iPr2C6H3)2]3(CH3OH)5}·CH3OH, which exhibits intra- and inter­molecular O—H⋯O hydrogen bonding, and its luminescent properties have been studied., The mononuclear title complex, [Eu(C24H34O4P)3(CH4O)5]·CH4O, (1), has been obtained as a minor product in the reaction between EuCl3(H2O)6 and lithium bis­(2,6-diiso­propyl­phen­yl) phosphate in a 1:3 molar ratio in a methanol medium. Its structure exhibits monoclinic (P21/c) symmetry at 120 K and is isostructural with the La, Ce and Nd analogs reported previously [Minyaev et al. (2018a ▸). Acta Cryst. C74, 590–598]. In (1), all three bis­(2,6-diiso­propyl­phen­yl) phosphate ligands display the terminal κ1 O-coordination mode. All of the hy­droxy H atoms are involved in O—H⋯O hydrogen bonding, exhibiting four intra­molecular and two inter­molecular hydrogen bonds. Photophysical studies have demonstrated luminescence of (1) with a low quantum yield.

A new approach to design “antenna-ligands” to enhance the photoluminescence of lanthanide coordination compounds has been developed based on a π-type ligand—the polyphenyl-substituted cyclopentadienyl. The complexes of di-, tri-, and tetraphenyl cyclopentadienyl ligands with Tb and Gd have been synthesized and all the possible structural types from mononuclear to di- and tetranuclear complexes, as well as a coordination polymer were obtained. All types of the complexes have been studied by single-crystal X-ray diffraction and optical spectroscopy. All terbium complexes are luminescent at ambient temperature and two of them have relatively high quantum yields (50 and 60%). Analysis of energy transfer process has been performed and supported by quantum chemical calculations. The role of a low-lying intraligand charge transfer state formed by extra coordination with K+ in the Tb3+ ion luminescence sensitization is discussed. New aspects for design of lanthanide complexes containing π-type ligands with desire...

Nonlinear optical properties of 24 derivatives of [2.2]paracyclophane (pCp) have been analyzed. The set of the compounds studied include such classes as β-diketones, formyl-metoxy and formyl-hydrox...

Luminescent composite materials based on linear polyethylene doped by a well dispersed tetrakis dibenzoylmethanate europium complex have been developed. The anion of the latter serves as an efficient light harvesting antenna and possesses the desired photophysical properties. The targeted modification of the Eu complex, namely introduction of a long hydrocarbon chain into the tetraalkylammonium cation [RNEt3]+, has ensured the compatibility of the complex with the polyethylene matrix. The [RNEt3]+ cation has been obtained by using long-chained 1-iodoalkanes synthesized via the Nd-catalyzed ethylene oligomerization process. The photophysical properties and the homogeneity of the obtained composites have been controlled by optical spectroscopy, luminescence intensity mapping as well as scanning electron microscopy.

Novel deoxyribonucleic acid (DNA) based materials, functionalized with hexadecyltrimethylammonium chloride (CTMA) and europium – (1.10 – phenanthroline) triazotate complex [Eu(NO 3 ) 3 phen] were synthesized and characterized for their linear and nonlinear optical properties. The obtained complexes were processed into good optical quality thin films by spin coating method. The measured absorption spectra and fluorescence bands of studied solutions indicated the incorporation of Eu(NO 3 ) 3 phen into DNA-CTMA matrix. The third-order nonlinear optical (NLO) properties of thin films were determined by the optical third-harmonic generation technique at 1 064.2 nm fundamental wavelength. A large cubic susceptibility of Eu complex is observed.

The synthesis and electroluminescent (EL) properties of two europium complexes with unsymmetrical β-diketonates and 1,10-phenanthroline are reported. The molecules are substituted by functional groups with different donor–acceptor properties and contain [2.2]paracyclophane moiety. They were used to fabricate the organic light emitting diodes (OLEDs). A large emission wavelength tunability by the applied electric field is observed for OLED containing europium β-diketonate substituted by phenyl group, with the maximum of luminance of 8 cd/m 2 . Such tunability disappears for OLED based on europium β-diketonate substituted by CH 3 group, for which the luminance decreases to ca 2.5 cd/m 2 . Also in that case an emission band in UV disappears. The OLED stability is lower in the latter case too, showing the importance of the substitution on the OLED operation. It shows also a high potential for the electroluminescent properties control and improvement of these Eu based macromolecules through a simple β-diketonate ligand chemical structure modification.

The results of high-resolution X-ray diffraction studies of the charge density distribution in crystals of three europium trinitrate complexes, including those with N-donor "antenna"-ligands are summarized. It is shown that the charge transfer between lanthanide ion and "antenna" correlates with the energy of interaction between the metal and nitrate anion, and the total stabilization energy of the metal polyhedron depends weakly on the coordination number of the metal and the nature of the ligands. The statistical treatment of the crystal structural data for similar complexes and the energies of the corresponding metal—ligand interactions allowed us to suggest the stability of mer-arrangement of the coordinated nitrate anions and to propose a semiempirical relationship to estimate the energy of Eu—O interactions. The influence of vibration processes on the electron density distribution in the EuO2NO fragment was additionally considered, and a feasibility to estimate the energy of interaction between the ligand and lanthanide ion at non-stationary points on the potential energy surface was validated.

Organophosphate-chloride complexes [{(2,6-iPr2C6H3-O)2POO}2LnCl(CH3OH)4]&middot, 2CH3OH, Ln = Nd (1), Eu (2), Gd (3), and Tb (4) have been obtained and structurally characterized. Their reaction with 2,2&prime, 6&prime, 2&Prime, terpyridine leads to the formation of 1:1 adducts ([{(2,6-iPr2C6H3-O)2POO}2LnCl(terpy)(H2O)2(CH3OH)], Ln = Eu (5), Gd (6), Tb (7) with exception of Nd, where tris-diisopropylphenylphosphate complex [{(2,6-iPr2C6H3-O)2POO}3Nd) (terpy)(H2O)(CH3OH)] (8) was obtained due to the ligand metathesis. A bright luminescence observed for the Eu and Tb organophosphate complexes is the first example of an application of organophosphate ligands for 4f-ions luminescence sensitization. Photophysical properties of all complexes were analyzed by optical spectroscopy and an energy transfer scheme was discussed. A combination of two types of ligands into the coordination sphere (phosphate and phenanthroline) allows designing the Eu surrounding with very high intrinsic quantum yield QEuEu (0.92) and highly luminescent Ln complexes for both visible and near-infrared (NIR) regions.

A series of lanthanide(III) complexes (Ln = La to Lu) with 2,2′-bipyridyl-6,6′-dicarboxamide ligands were obtained. The X-ray structure of the di(N-ethylanilide) of 2,2′-bipyridyl-6,6′-dicarboxylic acid is reported. The structures of the amides in the gas phase were modeled by DFT calculations. The global minima of the structures on the potential energy surface (PES) strongly depend on the nature of the substituents on the amidic nitrogen atom. The UV/Vis titration results of three diamides of 2,2′-bipyridyl-6,6′-dicarboxylic acid with lanthanide(III) metal nitrates show the composition of the complexes formed and allow us to determine the binding constants. Compounds with a 1:1 metal-to-ligand ratio are formed with the three diamide ligands under study. The binding constants are high, log β1 being higher than 5.5. The values of the constants decrease from LaIII to LuIII. The first structures, obtained by single-crystal X-ray diffraction, for GdIII and TbIII complexes of 2,2′-bipyridyl-6,6′-dicarboxamide ligands are described. Decacoordinated metal ions are bonded by the tetradentate ligand and three bidentate nitrate groups. 2D ROESY experiments with LaIII, LuIII, and EuIII complexes allow us to conclude that the structures of the complexes in solution are the same as those in the solid state. The photophysical properties of these Ln complexes were determined in the solid state at 77 and 300 K. Intense red and green luminescence was observed for both Eu and Tb complexes, and an intrinsic quantum yield of 90 % was determined for the europium complex.

In order to find eco-friendly materials for different applications an important research effort was devoted to the materials science in the last decade. A particular attention attracted the deoxyribonucleic acid (DNA). The interest is due to its versatility, biodegradability, abundance and their origin from renewable sources. DNA based new materials, functionalized with hexadecyltrimethylammonium chloride (CTMA) and aromatic compounds were prepared. Solutions with two different concentrations of aromatic compounds were obtained in butanol. The obtained, new complexes were processed into good optical quality thin films by spin coating method. Films were deposited on glass substrates and characterized for their spectroscopic, linear and nonlinear optical properties. The third-order nonlinear optical (NLO) properties of thin films were determined by the optical third-harmonic generation technique at 1 064.2 nm fundamental wavelength. The obtained materials, with improved fluorescence efficiency, present a potential interest for application in photonics.

International audience; Nonlinear optical properties of [2.2]paracyclophane (pCp) derived beta-diketones containing functional groups with different donor-acceptor properties, bounded to the dicarbonyl fragment, have been studied. Two polymorphic modifications, one of which is characterized by the polar space group Pca2(1) while the other one is centrosymmetric (space group Pbca) were obtained for beta-diketone substituted by thiophene group depending on the crystal growth procedure. All molecules studied exhibit second harmonic generation ability, the efficiency of which was measured by the powder technique at 1064 nm fundamental wavelength. The NLO susceptibility for the compounds studied is analyzed taking into account the structural peculiarities and theoretical calculations.

International audience; The peculiarities of chemical bonding and nonlinear optical properties of the complex of Cr(CO)(3) with [2.2]paracyclophane (Cr-pCp) have been studied by a combined experimental-theoretical approach. The Cr-pCp complex exhibits second harmonic generation, the efficiency of which was measured by the powder technique at 1064.2 nm fundamental wavelength and estimated theoretically. The comparison of electronic structure of the Cr-pCp with benzene tricarbonyl chromium analogue has revealed an important role of intraligand charge transfer state in pCp moiety conditioned by a strong transannular interaction between aromatic rings which is responsible for the enhanced molecular hyperpolarizability of Cr-pCp.

The structures and one- and two-photon absorption properties of a series of phosphoryl substituted 3,5-bis(arylidene)piperid-4-ones bearing amino groups, nitro groups or fluorine atoms in the para-positions of the arene rings have been investigated. The measurable two-photon absorption cross sections and low fluorescence quantum yields have been observed for piperidone compounds with the general D–π–A–π–D structure. However, no fluorescence and, consequently, two-photon absorption cross sections (in the frame of the experimental method used) have been observed for the compounds containing the electron withdrawing substituents, such as nitro groups or fluorine atoms in the side aryl ligands. The X-ray diffraction analysis revealed the tendency of increasing of cytotoxic activity with the increase of planarity of the main backbone of phosphoryl substituted piperidone molecules. The results obtained furnish a link between structural features of these molecules and their photo- and cytotoxic activities to allow a design of new compounds of this class with the tuning of biological properties.

New dinuclear lanthanide pivalate complexes [Tb2(piv)6(Hpiv)6], [Tb2(piv)6(bpy)2], [Tb2(piv)6(phen)2], [Tb2(piv)6(bath)2]·1.5EtOH, and [Eu2(piv)6(bath)2]·2EtOH, as well as the coordination polymer {Tb(piv)3}n, in which piv = (CH3)3CCO2–, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, bath = 4,7-diphenyl-1,10-phenanthroline, and EtOH = ethanol, were synthesized and characterized by X-ray diffraction. For the terbium complexes, the magnetic properties and the solid-state thermolysis were investigated. The phase composition of the solid decomposition products was determined by X-ray powder diffraction. The photophysical properties of these complexes were analyzed by luminescence, excitation, and phosphorescence spectroscopy, and by lifetime measurements. A comparison of the photophysical data for bpy, phen, and bath complexes shows that the supramolecular organization affects the efficiency of the sensitization of Ln3+ luminescence. All the results obtained provide good prospects for the use of dinuclear lanthanide pivalate complexes as efficient light-conversion molecular devices (LCMD).

Lanthanide complexes with ortho- phosphorylated phenolate ligands LnL 3 (Ln = Eu, Tb, Lu; HL 1 = 2-di( p -tolyl)phosphorylphenol; HL 2 = 2-diphenylphosphoryl-4-ethylphenol) were synthesized for the first time and characterized by elemental analysis, FTIR, 1 H, 31 P NMR spectroscopy, LDI-TOF mass-spectrometry. The energy gap between the triplet energy level and the corresponding resonance level of a lanthanide ion ( 5 D 1 for Eu 3+ and 5 D 4 for Tb 3+ ) is optimal for luminescence sensitization of only terbium ions. Bright green photo- and electroluminescence of terbium complexes was demonstrated.

Linear and nonlinear optical properties of racemic and enantiomerically pure (R)-[1-(4-[2.2]paracyclophanyl)]-3-phenylpropane-1,3-diones, the first representatives of a novel class of noncentrosymmetric molecules, namely planar chiral [2.2] paracyclophane derived β-diketones, have been studied. Both molecules exhibit second harmonic generation ability, the efficiency of which was measured by the powder technique at 1064.2 nm fundamental wavelength and their average NLO susceptibility was found comparable with that of a such well known NLO crystal as PNP.

The 1-methyl-3-tetradecyl imidazolium ionic liquid (IL) with N(CN)2−, CF3SO3− and N(CF3SO2)2− anions doped with 1 mol% of [EuCl2Phen2(H2O)2]Cl·H2O complex were prepared and investigated. It was found that relatively large IL anion molecular volume promotes the formation of micro particles of europium complex. The influence of the IL anion nature on the optical properties of europium complex was studied by the analysis of the luminescence spectra and lifetime of europium excited states. The high coordinating ability of IL anions towards europium ion along with high temperature of obtaining of Eu-containing ILs produce the improvement of its luminance.

A low-temperature high-resolution luminescence study of the EuCl3bpy2(H2O) n isomers has been carried out. The Eu3+ luminescence spectra of all geometric isomers were recorded over the spectral range which includes transitions from the 5D0 excited state to the 7F0–4 ground state manifolds and from the 5D1 excited state to the 7F0–2 ground state manifolds. Analysis of the Eu3+ transitions observed in the luminescence spectra shows that the Eu3+ ion occupies a spectroscopic site symmetry that approaches a C2 v symmetry with distortion towards C2 or lower symmetry. The structural features and distortions of the Eu3+ coordination polyhedron in these geometric isomers were described based on the X-ray crystallographic data as well. The splitting patterns and energies found of the 7F0–4 manifolds have been used to calculate the crystal field parameters (CFPs) of the Eu3+ ions in these geometric isomers. In addition the mutual influence of the ligands as well as the relative stability of geometric isomers of the...

The europium complex [EuCl2(bpy)2(H2O)2]Cl⋅1.25 C2H6O⋅0.37 H2O, where bpy is 2,2′-bipyridine, was synthesized and investigated with the aim to relate its molecular geometry and crystal packing to the efficiency of energy-transfer processes. The presence of H-bonds between noncoordinated Cl− ions and coordinated H2O molecules leads to the formation of discrete trimers assembled by a number of CH⋅⋅⋅Cl and stacking interactions into ‘supramolecular balls’ which contain Cl− ions and solvate molecules (H2O and EtOH). The additional stabilization of the complex is due to intramolecular N⋅⋅⋅C interactions between two bpy ligands that causes some shortening of the EuN bonds. Deciphering the luminescence properties of the Eu complex was performed under consideration of both the composition of the inner coordination sphere and the peculiarities of the crystal packing. The influence of the latter and the bpy orientation on the energy of the ligand→Eu charge-transfer state (LMCT) was established, and an additional excited state induced by the π-stacking interaction (SICT) was identified.

Methods of synthesis of binuclear pivalate complexes L2Ln2(μ-O,η2-OOCCMe3)2(μ2-O,O′-OOCCMe3)2(η2-OOCCMe3)2, where Ln = Sm, Eu, Gd, or Er and L = 2,2′-dipyridyl (Bipy) or 1,10-phenanthroline (Phen), from the corresponding binuclear complexes Ln2(μ2-OOCCMe3)4(OOCCMe3)2(HOOCCMe3)6 · HOOCCMe3(I–IV), as well as of coordination polymers {Ln(OOCCMe3)3} n , were suggested. The compounds were characterized by X-ray crystallography and X-ray powder diffraction and their magnetic properties, solid-phase thermolysis, and the phase composition of solid decomposition products were studied. The structures of the metal carboxylate core and surrounding ligands were shown to have an effect on the thermal stability of the complexes. The luminescence properties of the Eu(III) complexes were analyzed.

Treatment of the 3-diphenylphosphorylbenzoic acid amides 3a,b with the Lawesson reagent resulted in 3-diphenylthiophosphorylbenzoic acid thioamides 4a,b, which easily underwent cyclopalladation at the C-2 position of the central benzene ring to give new hybrid pincer complexes 5a,b with κ3-SCS coordination. Molecular structures of the complexes were characterized by X-ray diffraction. The peculiarities of chemical bonding in 5a were investigated via topological analysis of charge density in the crystal. The palladium complexes 5a,b demonstrated high catalytic activity for the Suzuki cross-coupling reactions of aryl bromides with phenylboronic acid and exhibited luminescence at 77 and 300 K.

Two series of lanthanide compounds, namely, chlorides containing different numbers of both 1,10-phenanthroline (Phen) molecules and chloride anions in the first coordination sphere, and Schiff Bases (SBs) derived from Pyridoxal (PL) and amino acids, were characterized by single crystal X-ray diffraction and luminescence techniques. The combined use of these techniques for the analysis of long-distance europium non-covalent interactions was performed for the first time. As a result, the correlation between supramolecular organization and the features of the Eu III electronic transitions was found for the compounds of the first series. Strong non-covalent interactions between pyridoxal rings of SBs (the second series of compound) led to the formation of 1:2 species and four-dentate coordination function of these SBs in aqueous solution.

Two families of lanthanide chlorides LnCl 3 L 2 (H 2 O) n and LnCl 3 L(H 2 O) m where L is 1,10-phenanthroline or 2,2′-bipyridine were synthesized. Their luminescence properties were investigated in the solid state and 1-dodecyl-3-methylimidazolium chloride solution. The structural peculiarities of lanthanide chlorides were elucidated by joint analysis of the X-ray, vibrational and luminescence data including the lifetime measurements. As a result the analysis of efficiency of energy transfer processes was performed and the correlation between the structure and the luminescence intensity was demonstrated in the systems studied.

The phosphinoyl-substituted macrocyclic receptor B8bL8, derived from p-tert-butylcalix[8]arene, was synthesized and its structure was studied in solution. According to temperaturedependent 1H and 31P NMR spectroscopic data, the calix[8]arene adopts a so-called in–out cone conformation. To investigate the influence of the narrow rim substitution, interaction with trivalent lanthanide ions, LnIII (Ln = La, Eu, Tb, Lu), was probed by MS, UV/Vis and NMR spectroscopic titrations. Although both 1:1 (in the presence of triflate) and 2:1 (in the presence of nitrate) Ln:B8bL8 complexes could be isolated in the solid state, the major species present in methanol is the 1:1 complex, irrespective of the anion. NMR spectroscopic data point to a common conformation for the 1:1 complexes in solution, the lanthanide ions being coordinated by four of the eight phosphinoyl arms, with a coordination sphere completed by methanol molecules or by nitrate ions, as ascertained by IR and MS spectra. The ligand displays a weak absorption at 360 nm that can be assigned to an intraligand charge-transfer (ILCT) state, which is very sensitive to coordination. Photophysical data of the EuIII 2:1 complex point to both metal ion sites providing a very similar chemical environment for the lanthanide ions, with no coordinated water, which is contrary to what is observed for the 1:1 complex. The use of optical electronegativity to predict the energy of the charge-transfer states in the lanthanide systems with inequivalent ligands is discussed and extensive analysis of the vibronic satellites of the Eu(5D0->7FJ) transitions ascertains conclusions drawn on the EuIII coordination.

The ionic liquid 1-dodecyl-3-methylimidazole chloride ([C12- mim]Cl) is doped with 1 mol-% of the lanthanide ternary complexes [Ln(tta)3(phen)] (tta = thenoyltrifluoroacetonate, phen = 1,10-phenanthroline, Ln = Nd, Eu, Er, Yb), resulting in luminescent mesogenic phases at room temperature. According to DSC and SAXS measurements, the temperature of the crystal liquid crystal transition is below 10 °C. Analysis of vibrational and luminescence data points to the inner co-ordination sphere of the EuIII ion being very similar in both the mesomorphic sample and the parent β-diketonate complex. The mesomorphic samples containing NdIII, ErIII, or YbIII display relatively intense near-infrared luminescence. This emission is enhanced in the liquid crystalline phases with respect to the initial compounds, as demonstrated for instance by the quantum yield of the [Yb(tta)3(phen)]-containing mesogenic sample which amounts to 2.1%, as compared to 1.6 and 1.1%for the powdered ternary complex and its solution in toluene, respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

The experimental electronic spectra of the Eu3+ ion in three groups of the Eu complexes (β-diketonates, acetates, and nitrates) with the 1,10-phenanthroline derivatives were used to calculate the crystal field parameters for the model of the nearest environment of this ion with the C2ν point group symmetry. It was shown that these parameters can be used for estimating the coordination number of the metal cation and establishing the structural peculiarities.

Formyl-methoxy derivatives of [2.2]paracyclophane (pCp) have been synthesized and studied by optical spectroscopy as well as the X-ray diffraction method. These molecules crystallize in acentric space groups. The efficiency of SHG ability of these compounds was measured by the powder technique at 1064 nm fundamental wavelength and average NLO susceptibility for some of them was found comparable with such well-known NLO crystal as NPP. The calculations of molecular and crystalline nonlinearities within density functional theory using M052X/6-31+G* level of approximation were also conducted for the considered series of compounds.

A combined investigation of the structural, elec- tronic, and optical properties of three crystalline nonaaqualanthanoid(III) triflates, (Ln(H2O)9(CF3SO3)3), has pro- vided unambiguous experimental evidence for charge redis- tribution in the first coordination sphere of a lanthanide ion as a result of hydrogen bonds with outer-sphere anions. As well as resulting in charge transfer from the noncoordinated anions to the coordinated water molecules, these hydrogen bonds give rise to a new excited state, an hydrogen-bond- induced charge-transfer state, which is observed experimen- tally for the first time. This state was shown to be responsi- ble for the previously unknown negative aspect of hydrogen bonds with a lanthanide-bound water molecule: rather than increasing the luminescence efficiency of the complex, they can lead to additional quenching that is unfavorable for the task-specific design of optical materials.

Novel unsymmetrical SCS'-pincer ligands, 1-[PhNHC(S)]-3-[Ph(2)P(S)NH]-C(6)H(4) (3) and 1-[PhNHC(S)]-3-[Ph(2)P(S)O]C(6)H(4) (7), bearing a thiocarbamoyl moiety in combination with thiophosphorylamino- and thiophosphoryloxy-donating groups, respectively, were obtained via thiophosphorylation of 3-amino- and 3-hydroxy-benzoic acid (thio)anilides 1 and 6. Direct cyclometallation of the central benzene ring in the ligands 3 and 7 in reaction with (PhCN)(2)MCl(2) (M = Pd, Pt) as a metal precursor afforded κ(3)-SCS'-hybrid pincer complexes 8, 9 with 5- and 6-membered fused metallacycles in good to high yields (67-95%). The complexes 8 and 9 were characterized by multinuclear NMR ((31)P, (1)H, (13)C) and IR spectroscopy as well as single-crystal X-ray crystallography. Palladium complexes 8a and 9a were shown to be active catalysts for the Suzuki-Miyaura cross-coupling reaction. In the solid state the ligands 3 and 7 as well as their Pt(II) and Pd(II) complexes 8 and 9 are luminescent at 300 K. The emission of the complexes has the different origin depending on the metal nature.

The lanthanide compounds containing unsymmetrical β-diketone with [2.2]paracyclophane moiety in particular the europium complex with three [1-(4-[2.2]paracyclophanyl)]-3-phenylpropane-1,3-dione and 1,10-phenanthroline has been synthesized for the first time. The optical properties of [2.2]paracyclophane-derived ligands (symmetrical β-diketones and their respective N-phenylimines) as well as those of the europium complex were studied by UV-visible and luminescence spectroscopy. The diastereomers (racemic chiral, (R*,R*)- and achiral meso, (R,S)-) of the β-diketones and their respective N-phenylimines exhibit quite identical absorption spectra with intense broad band centered at 360 and 380 nm, respectively. The designed blue-emitting unsymmetrical β-diketone acts as a very efficient sensitizer of the EuIII emission and does so in the near-UV region. The introduction of [2.2]paracyclophane moiety in the β-diketones allows to expand the excitation wavelength of the lanthanide complex up to 500 nm and to obtain the relatively high overall quantum yield for the europium ion.

A series of lanthanide complexes [LnCl(x)(bpy)(y)(H(2)O)(z)]Cl(3-x)(H(2)O)(n)(EtOH)(m) (Ln = Eu, Gd, Tb; x = 1, 2; y = 1, 2; z = 2-4) with different numbers of 2,2'-bipyridine (bpy), chloride ions, and water molecules in the inner coordination sphere were synthesized and investigated with the aim of relating their molecular geometry and crystal packing to the efficiency of ligand-to-metal energy transfer. In conjunction to the rotation of the pyridine rings upon coordination to the Ln ion, the high flexibility displayed by bpy ligands leads to rather unexpected bending of these rings with respect to the central bond, owing to intermolecular interactions such as Cl...pi and pi-stacking ones. Deciphering the luminescence properties of the Eu and Tb complexes needs to take into account both the composition of the inner coordination sphere and the peculiarities of the crystal packing. For instance, in addition to the classical ligand --Eu charge-transfer state (LMCT), another charge-transfer state induced by pi-stacking interactions (SICT) could be identified. These two states, located between the singlet and triplet states of the bpy ligand(s), provide relays facilitating the energy migration from the singlet to the triplet states and eventually to the excited Eu states, improving the overall ligand-to-Eu energy transfer. Another point is the involvement of the inner-sphere water molecules in H-bonding with chloride ions, which considerably lowers their luminescence quenching ability, so that the adducts remain highly luminescent. For instance, the terbium chloride with two bpy ligands is an efficient near-UV to green light converter, with an overall quantum yield equal to 37% despite the coordinated water molecules. The interpretations given are substantiated by DFT and TD-DFT theoretical calculations of the complexes and ligand assemblies.

A series of lanthanide adducts with different amounts of 1,10-phenanthroline, chloride ions, and water molecules in the inner and outer coordination spheres are investigated with the aim of relating the chemical bonding pattern in the crystals to the luminescence properties of the Eu ion: [LnCl1Phen2(H2O)3]Cl2(H2O) (Ln ) Eu, 1Eu; Gd, 1Gd; Tb, 1Tb), [EuCl2Phen2(H2O)2]Cl1(H2O) (2), and [EuCl2Phen1(H2O)4]Cl1(H2O) (3). The influence of inner- versus outersphere ligands on the Ln-X bond lengths and angles in the structure is examined. A detailed topological analysis of the electron density function derived from the X-ray diffraction data for 1Gd is performed within the frame of the “atoms in molecule” theory for the first time for a lanthanide complex. The chemical bonding pattern is interpreted in terms of net atomic charges, bond energies, and electron transfers from the ligands to the metal ion. A noteworthy finding is that the energy of extended noncovalent interactions occurring in the second coordination sphere (Hbonding and π-stacking interactions) is comparable to that of Ln-ligand bonds. The luminescence properties of the three Eu adducts are interpreted with the results of electron density distribution function topology. An intraligand charge transfer state is identified, and its contribution in the ligand-to-europium energy transfer process is analyzed. The outcome of this study is that specific interionic interactions which are usually not considered in theoretical calculations or in the interpretation of luminescence properties play an important role in the sensitization of the Eu luminescence.

Lanthanide complexes of Schiff bases (SBs) with 1:1 and 1:2 (M:Lig) stoichiometric ratios were prepared by condensation of pyridoxal (PL) and aspartic acid (Asp) or l-histidine (His), respectively, in the presence of the appropriate metal chloride as a templating agent. These complexes were studied by optical spectroscopy and single crystal X-ray diffraction techniques. Crystallographic studies of 1:1 ([Eu(PL-Asp)(H(2)O)(4)](H(2)O)) and 1:2 ([Eu(PL-His)(2)(H(2)O)(2)]Cl(H(2)O)(4)) complexes show that Eu(III) is eight-coordinate in both structures, in a distorted square antiprism environment formed by the phenolic oxygen of PL, the nitrogen atom of carbon-nitrogen double bond, oxygen atoms of the carboxylate groups of His or Asp, and oxygen atoms of the water molecules. The main species formed in aqueous solutions containing these SBs have been determined by analysis of the luminescence spectra, lifetimes of Eu(III) excited states and vibronic interaction as well as structural features of the Eu(III) coordination sphere. Possible tetradentate coordination function of SBs in aqueous solutions with relatively high concentrations as well as the potential application of the lanthanide SB complexes as new luminescence materials are discussed.