Synthesis,density functional theory calculations and luminescence of lanthanide complexes with 2,6‐bis[(3‐methoxybenzylidene)hydrazinocarbonyl] pyridine Schiff base ligand

A pyridine‐diacylhydrazone Schiff base ligand, L = 2,6‐bis[(3‐methoxy benzylidene)hydrazinocarbonyl]pyridine was prepared and characterized by single crystal X‐ray diffraction. Lanthanide complexes, Ln–L, {[LnL(NO₃)₂]NO₃.xH₂O (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Er)} were prepared and characterized by elemental analysis, molar conductance, thermal analysis (TGA/DTGA), mass spectrometry (MS), Fourier transform infra‐red (FT‐IR) and nuclear magnetic resonance (NMR) spectroscopy. Ln–L complexes are isostructural with four binding sites provided by two nitro groups along with four coordination sites for L. Density functional theory (DFT) calculations on L and its cationic [LnL(NO₃)₂]⁺ complexes were carried out at the B3LYP/6–31G(d) level of theory. The FT‐IR vibrational wavenumbers were computed and compared with the experimentally values. The luminescence investigations of L and Ln–L indicated that Tb–L and Eu–L complexes showed the characteristic luminescence of Tb(III) and Eu(III) ions. Ln–L complexes show higher antioxidant activity than the parent L ligand.     

Synthesis and luminescence properties of polymer–rare earth complexes containing salicylaldehyde‐type bidentate Schiff base ligand

Using molecular design and polymer reactions, two types of bidentate Schiff base ligands, salicylaldehyde–aniline (SAN) and salicylaldehyde–cyclohexylamine (SCA), were synchronously synthesized and bonded onto the side chain of polysulfone (PSF), giving two bidentate Schiff base ligand‐functionalized PSFs, PSF–SAN and PSF–SCA, referred to as macromolecular ligands. Following coordination reactions between the macromolecular ligands and Eu(III) and Tb(III) ions (the reaction occurred between the bonded ligands SAN or SCA and the lanthanide ion), two series of luminescent polymer–rare earth complexes, PSF–SAN–Eu(III) and PSF–SCA–Tb(III), were obtained. The two macromolecular ligands were fully characterized by Fourier transform infrared (FTIR), ¹H NMR and UV absorption spectroscopy, and the prepared complexes were also characterized by FTIR, UV absorption spectroscopy and thermo‐gravity analysis. On this basis, the photoluminescence properties of these complexes and the relationships between their structure and luminescence were investigated in depth. The results show that the bonded bidentate Schiff base ligands, SAN and SCA, can effectively sensitize the fluorescence emission of Eu(III) and Tb(III) ions, respectively. PSF–SAN–Eu(III) series complexes, namely the binary complex PSF–(SAN)₃–Eu(III) and the ternary complex PSF–(SAN)₃–Eu(III)–(Phen)₁ (Phen is the small‐molecule ligand 1,10‐phenanthroline), produce strong red luminescence, suggesting that the triplet state energy level of SAN is lower and well matched with the resonant energy level of the Eu(III) ion. By contrast, PSF–SAN–Eu(III) series complexes, namely the binary complex PSF–(SCA)₃–Tb(III) and the ternary complex PSF–(SCA)₃–Tb(III)–(Phen)₁, display strong green luminescence, suggesting that the triplet state energy level of SCA is higher and is well matched with the resonant energy level of Tb(III).     

Synthesis and luminescence properties of two novel lanthanide (III) complexes of acetophenonylcarboxymethyl sulphoxide

A novel ligand containing multiple coordinating groups (sulfinyl, carboxyl and carbonyl groups), acetophenonylcarboxymethyl sulphoxide, was synthesized. Its corresponding two lanthanide (III) binary complexes were synthesized and characterized by element analysis, molar conductivity, FT‐IR, TG‐DTA and UV spectroscopy. Results showed that the composition of these complexes was REL₃L^‐ (ClO₄)₂·3H₂O (RE = Eu (III), Tb (III); L = C₆H₅COCH₂SOCH₂COOH; L^‐ = C₆H₅COCH₂SOCH₂COO^‐). FT‐IR results indicated that acetophenonylcarboxymethyl sulphoxide was bonded with an RE (III) ion by an oxygen atom of the sulfinyl and carboxyl groups and not by an oxygen atom of the carbonyl group due to high steric hinderance. Fluorescent spectra showed that the Tb (III) complex had excellent luminescence as a result of a transfer of energy from the ligand to the excitation state energy level (⁵D₄) of Tb (III). The Eu (III) complex displayed weak luminescence, attributed to low energy transfer efficiency between the triplet state energy level of its ligand and the excited state (⁵D₀) of Eu (III). As a result, the Tb (III) complex displayed a good antenna effect for luminescence. The fluorescence decay curves of Eu (III) and Tb (III) complexes were also measured. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis,characterization and luminescence of europium perchlorate with MABA‐Si complex and coating structure SiO2@Eu(MABA‐Si) luminescence nanoparticles

This article reports a novel category of coating structure SiO₂@Eu(MABA‐Si) luminescence nanoparticles (NPs) consisting of a unique organic shell, composed of perchlorate europium(III) complex, and an inorganic core, composed of silica. The binary complex Eu(MABA‐Si)₃·(ClO₄)₃·5H₂O was synthesized using HOOCC₆H₄N(CONH(CH₂)₃Si(OCH₂CH₃)₃)₂ (MABA‐Si) and was used as a ligand. Furthermore, the as‐prepared silica NPs were successfully coated with the ‐Si(OCH₂CH₃)₃ group of MABA‐Si to form Si–O–Si chemical bonds by means of the hydrolyzation of MABA‐Si. The binary complexes were characterized by elemental analysis, molar conductivity and coordination titration analysis. The results indicated that the composition of the binary complex was Eu(MABA‐Si)₃·(ClO₄)₃·5H₂O. Coating structure SiO₂@Eu(MABA‐Si) NPs were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and infrared (IR) spectra. Based on the SEM and TEM measurements, the diameter of core‐SiO₂ particles was ~400 and 600 nm, and the thickness of the cladding layer Eu(MABA‐Si) was ~20 nm. In the binary complex Eu(MABA‐Si)₃·(ClO₄)₃·5H₂O, the fluorescence spectra illustrated that the energy of the ligand MABA‐Si transferred to the energy level for the excitation state of europium(III) ion. Coating structure SiO₂@Eu(MABA‐Si) NPs exhibited intense red luminescence compared with the binary complex. The fluorescence lifetime and fluorescence quantum efficiency of the binary complex and of the coating structure NPs were also calculated. The way in which the size of core‐SiO₂ spheres influences the luminescence was also studied. Moreover, the luminescent mechanisms of the complex were studied and explained.     

Synthesis and photophysical studies of tetrazolate‐based Eu(III) photoluminescent ternary complexes containing N‐heterocyclic phosphine oxides auxiliary co‐ligands

Two new ternary tetrazolate Eu(III) complexes with phosphine oxide co‐ligands Eu(PTO)₃·(P1/P2) [PTO = 5‐(2‐pyridyl‐1‐oxide)tetrazole, P1 = diphenylphosphorylamino‐phenylphosphoryl‐benzene, P2 = diphenylphosphorylpyridine)‐bis‐isobutyricphosphoryl] were synthesized and characterized using UV, fluorescence, IR and ¹H NMR spectroscopic techniques. The analytical data prove that the complexes are mononuclear in nature and the central Eu(III) ion is coordinated by three N and three O atoms of tetrazolate, and two O atoms of the corresponding bidentate phosphine oxide ligands. The ancillary ligand increased the photoluminescence efficiency of Eu(PTO)₃·P1 (complex 3) by twofold compared with our previously reported Eu(PTO)₃ complex (complex 1). Copyright © 2015 John Wiley & Sons, Ltd.     

Luminescent properties of europium complexes with bis(diphenylphosphino)alkane dioxides

Eu(NO₃)₃?5H₂O and EuCl₃?6H₂O were allowed to react with bis(diphenylphosphino)alkane dioxides Ph₂P(O)(CH₂)_nP(O)Ph₂ (n = 2, 4, 6) to obtain polymeric and binuclear complexes. The prepared compounds were structurally characterized by X‐ray diffraction. Luminescence measurements (emission and excitation spectra, quantum yields, lifetimes) were compared with crystallographic data in order to find a relationship between luminescent properties of the Eu(III) complexes and their structures. The Eu(III) polymers, especially [Eu(dpphO₂)₂Cl₂]⁺Cl^–}_n, have shown extremely long luminescence lifetimes, up to 3.73 ms, as a result of a highly protecting hydrophobic shield. Copyright © 2011 John Wiley & Sons, Ltd.     

Heterobinuclear Zn‐Ln (Ln = La,Nd, Eu,Gd, Tb,Er and Yb) complexes based on asymmetric Schiff‐base ligand: synthesis,characterization and photophysical properties

With a novel asymmetric Schiff‐base zinc complex ZnL (H₂L = N‐(3‐methoxysalicylidene)‐N′‐(5‐bromo‐3‐methoxysalicylidene)phenylene‐1,2‐diamine), obtained from phenylene‐1,2‐diamine, 3‐methoxysalicylaldehyde and 5‐bromo‐3‐methoxysalicylaldehyde, as the precursor, a series of heterobinuclear Zn‐Ln complexes [ZnLnL(NO₃)₃(CH₃CN)] (Ln = La, 1; Ln = Nd, 2; Ln = Eu, 3; Ln = Gd, 4; Ln = Tb, 5; Ln = Er, 6; Ln = Yb, 7) were synthesized by the further reaction with Ln(NO₃)₃·6H₂O, and characterized by Fourier transform‐infrared, fast atom bombardment mass spectroscopy and elemental analysis. Photophysical studies of these complexes show that the strong and characteristic near‐infrared luminescence of Nd³⁺, Yb³⁺and Er³⁺ with emissive lifetimes in the microsecond range has been sensitized from the excited state of the asymmetric Schiff‐base ligand due to effective intramolecular energy transfer; the other complexes do not show characteristic emission due to the energy gap between the chromophore and lanthanide ions. Copyright © 2012 John Wiley & Sons, Ltd.     

Structures and luminescent sensors of mixed‐counterions based salen‐type lanthanide coordination polymers

Reactions of N,N′‐bis (salicylidene)‐1,2‐cyclohexanediamine (H₂L) with mixed lanthanide counterions of LnCl₃·6H₂O and Ln (NO₃)₃·6H₂O afford six H₂L lanthanide coordination polymers, e.g. {[Pr(H₂L)₂(NO₃)₂Cl]·2CH₂Cl₂}_n ( 1 ); {[Ln(H₂L)_1.5(NO₃)₃]₂·5CHCl₃·mCH₃OH}_n [Ln = Sm ( 2 ), Eu ( 3 ), Gd ( 4 ), Tb ( 5 ) and Yb ( 6 ); m = 1 ( 2 – 5 ); m = 0 ( 6 )]. X‐ray crystallographic analysis reveals that complex 1 exhibits three‐dimensional diamondoid topologic structure and complexes 2 – 6 are of two‐dimensional structure. Luminescent spectra show that complexes 1 and 6 have characteristic near‐infrared (NIR) emission of praseodymium (III) and ytterbium (III) ions and complexes 2 – 5 emit luminescence in the visible region. Complexes 3 and 6 reveal sensitive luminescence responses to formaldehyde.     

A highly selective fluorescent probe for pyrophosphate detection in aqueous solutions

A novel and simple fluorescence enhancement method is introduced for selective pyrophosphate (PPi) sensing in an aqueous solution. The method is based on a 1:1 metal complex formation between tris(8‐hydroxyquinoline‐5‐sulphonate) thulium(III) [Tm(QS)₃] and PPi ion. The linear response covers a concentration range of 1.6 × 10^?7–1.0 × 10^?5 mol/L PPi and the detection limit is 2.3 × 10^?8 mol/L. The association constant of Tm(QS)₃–PPi complex was calculated as 2.6 × 10⁵ mol/L. Tm(QS)₃ shows a selective and sensitive fluorescence enhancement toward PPi ion in comparion with I₃^?, NO₃^?, CN^?, CO₃^2?, Br^?, Cl^?, F^?, H₂PO₄^? and SO₄^2?, which is attributed to higher stability of the inorganic complex between pyrophosphate ion and Tm(QS)₃. Copyright © 2011 John Wiley & Sons, Ltd.     

Metal complexes with two tri-aza,tri-oxa pendant-armed macrocyclic ligands: Synthesis,characterization, crystal structures and fluorescence studies

Metal complexes of two new tri-aza, tri-oxa macrocycles containing ethyl acetate (L¹) or carboxymethyl (H₂L²) pendant arms with hydrated nitrate or perchlorate salts of alkaline earth, post-transition and lanthanide metal ions have been synthesized and characterized by microanalysis FAB MS, conductivity measurements, IR, UV–Vis spectroscopy and fluorescence emission studies. The synthesis and characterization of the Pb(II) complexes with the armless macrocyclic precursors L (Schiff base macrocycle) and L′ (diaminic reduced macrocycle) are also reported. The crystal structures of complexes [PbL(ClO₄)(H₂O)](ClO₄), [PbL′(ClO₄)](ClO₄) and ([Zn₂L²(Cl)(H₂O)](ClO₄))_∞ have been determined. In both lead(II) complexes, the metal ion is located inside the macrocyclic cavity and is coordinated by all N₃O₃ donor atoms in the complex with L′ but only by the nitrogen atoms present in the ligand in the complex with L. In both cases, the coordination sphere of the metal atom is completed with a perchlorate anion or a water molecule in the iminic complex of L. X-ray studies on the Zn(II) complex show the presence of a supramolecular structure that is consistent with a linear polymer formed alternately by an endomacrocyclic metal atom coordinated to a macrocyclic ligand and an exomacrocyclic metal ion in distorted octahedral and tetrahedral environments, respectively. UV–Vis and fluorescent emission studies were carried out on the ligands L¹ and H₂L² and their metal complexes, but only the luminescence spectra of the Eu(III) and Tb(III) complexes with L¹ in aqueous solution at ca. pH 7 show the characteristic visible emission of the metal. The value of the quantum yield determined for the Eu(III) complex is similar to that reported in the literature for other Eu(III) complexes.     

Synthesis and fluorescence properties of 1,2,4‐triazolo[3,4‐b]‐1,3,4‐thiadiazol derivatives and their terbium complexes

Eight novel 1,2,4‐triazolo[3,4‐b]‐1,3,4‐thiadiazol derivatives have been designed and synthesized, and their corresponding Tb³⁺ complexes were also prepared successfully. The fluorescence properties and fluorescence quantum yields of the target complexes were investigated, the results showed that the ligands were an efficient sensitizer for Tb³⁺ luminescence, and the target complexes exhibited characteristic fluorescence emissions of Tb³⁺ ion. The fluorescence intensity of the complex substituted by chlorine was stronger than that of other complexes. The substituents' nature has a great effect upon the electrochemical properties of the target complexes. The results showed that the introduction of the electron‐withdrawing groups tended to decrease the oxidation potential and highest occupied molecular orbital energy levels of the target Tb³⁺ complexes; however, introduction of the electron‐donating groups can increase the corresponding complexes' oxidation potential and highest occupied molecular orbital energy levels. Copyright © 2014 John Wiley & Sons, Ltd.     

Fluorescence enhancement of europium (III) perchlorate by 1,10‐phenanthroline on the 1‐(naphthalen‐2‐yl)‐2‐(phenylsulthio)ethanone complex and luminescence mechanism

A novel ligand, 1‐(naphthalen‐2‐yl)‐2‐(phenylsulthio)ethanone was synthesized using a new method and its two europium (Eu) (III) complexes were synthesized. The compounds were characterized by elemental analysis, coordination titration analysis, molar conductivity, infrared, thermo gravimetric analyzer‐differential scanning calorimetry (TGA‐DSC), ¹H NMR and UV spectra. The composition was suggested as EuL₅ · (ClO₄)₃ · 2H₂O and EuL₄ · phen(ClO₄)₃ · 2H₂O (L = C₁₀H₇COCH₂SOC₆H₅). The fluorescence spectra showed that the Eu(III) displayed strong characteristic metal‐centered fluorescence in the solid state. The ternary rare earth complex showed stronger fluorescence intensity than the binary rare earth complex in such material. The strongest characteristic fluorescence emission intensity of the ternary system was 1.49 times as strong as that of the binary system. The phosphorescence spectra were also discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis and characterization of new lanthanide complexes with hexadentate hydrazonic ligands

In this paper, we report the synthesis and the characterization of a novel series of lanthanide (III) complexes with two potentially hexadentate ligands.The ligands contain a rigid phenanthroline moiety and two flexible hydrazonic arms with different donor atom sets (NNN′N′OO and NNN′N′N″N″, respectively for H₂L¹ (2,9-diformylphenanthroline)bis(benzoyl)hydrazone and H₂L² (2,9-diformylphenanthroline)bis(2-pyridyl)hydrazone).Both nitrate and acetate complexes of H₂L¹ with La, Eu, Gd, and Tb were prepared and fully characterized, and the X-ray crystal structure of the complex [Eu(HL¹)(CH₃ COO)₂] · 5H₂O is presented.The stability constants of the equilibria Ln³⁺ + H₂L¹ = [Ln(H₂L¹)]³⁺ and Ln³⁺ + (L¹)²⁻ = [Ln(L₁)]⁺ (Ln = La(III), Eu(III), Gd(III), and Tb(III)) are determined by UV spectrophotometric titrations in DMSO at t = 25 °C. The nitrate complexes of H₂L² with La, Eu, Gd and Tb were also synthesized, and the X-ray crystal structures of [La(H₂L²)(NO₃)₂(H₂O)](NO₃), [Eu(H₂L²)(NO₃)₂](NO₃) and [Tb(H₂ L²)(NO₃)₂](NO₃) are discussed.     

Complexes of lanthanoid salts with macrocyclic ligands. Part 32. Synthesis and characterization of the complexes between lanthanoid nitrates and a tetraoxadiaza macrocycle

Lanthanoid nitrates react with 1,7,10,16-tetraoxa- 4,13-diaza-N,N′-dimethylcyclooctadecane, Me₂(2,2), to give complexes with two different metal:ligand ratios, 1:1 (Ln = La, Ce, Tb) and 4:3 (Ln = Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho). The complexes were isolated from anhydrous solutions in acetonitrile and characterized by elemental analysis, X-ray diffraction, magnetic susceptibility measurements and vibrational analysis.The La and Ce 1:1 complexes are non-ionic and probably 12-coordinated, with the metal ion bound to the six donor atoms of the ligand and to three bidentate nitrate ions. The 4:3 complexes are ionic; they contain three bis(nitrato) complex cations [Ln(NO₃)₂·Me₂(2,2)]⁺ and one hexakis(nitrato) anion [Ln(NO₃)₆]³⁻. Spectroscopic data, including luminescence spectra, point to the 1:1 Tb-complex as being a 4:3 complex with an additional outer-sphere coordinated molecule of ligand.In solution, the 1:1 complexes remain essentially non-ionic, although some dissociation cannot be ruled out, whereas the 4:3 complexes behave as 2:1 (of even 3:1) electrolytes.     

Synthesis and photoluminescence properties of red emitting phosphor La2–xEuxLi0.5Al0.5O4 [x = 0.2–2] with K2NiF4 structure

Europium (Eu)³⁺‐substituted La₂Li_0.5Al_0.5O₄ red emitting phosphors were prepared by a conventional high‐temperature solid‐state reaction method. Powder X‐ray diffraction, diffuse reflectance spectra and spectrofluorometry were used as vital characterizing tools for the phosphors. The Eu concentration dependence luminescence properties and Judd–Ofelt intensity parameters were investigated and calculated, respectively. All compositions showed an orange red emission (due to the magnetic and electric dipole transitions of the Eu³⁺ ion) with the appropriate Commission Internationale de l'Eclairage (CIE) colour gamut under near ultraviolet or blue ray light excitation. The calculated critical distance showed that the energy transfer occured between Eu to Eu via an exchange mechanism. The Eu_1.4La_0.6Li_0.5Al_0.5O₄ composition showed the highest red emission intensity with CIE colour saturation compared with that of the commercial Eu‐activated yttrium oxysulfide red phosphor.     

Circularly polarized luminescence of Sm (III) and Eu (III) complexes with chiral ligand (R/S)‐BINAPO

Luminescent lanthanide (III) ions have been exploited for circularly polarized luminescence (CPL) for decades. However, very few of these studies have involved chiral samarium (III) complexes. Complexes are prepared by mixing axial chiral ligands (R/S))‐2,2’‐bis(diphenylphosphoryl)‐1,1′‐binaphthyl (BINAPO) with europium and samarium Tris (trifluoromethane sulfonate) (Eu (OTf)₃ and Sm (OTf)₃). Luminescence‐based titration shows that the complex formed is Ln((R/S)‐BINAPO)₂(OTf)₃, where Ln = Eu or Sm. The CPL spectra are reported for Eu((R/S)‐BINAPO)₂(OTf)₃ and Sm((R/S)‐BINAPO)₂(OTf)₃. The sign of the dissymmetry factors, g_em, was dependent upon the chirality of the BINAPO ligand, and the magnitudes were relatively large. Of all of the complexes in this study, Sm((S)‐BINAPO)₂(OTf)₃ has the largest g_em = 0.272, which is one of the largest recorded for a chiral Sm³⁺ complex. A theoretical three‐dimensional structural model of the complex that is consistent with the experimental observations is developed and refined. This report also shows that (R/S)‐BINAPO are the only reported ligands where g_em (Sm³⁺) > g_em (Eu³⁺).     

Spectroscopic investigation of europium(III) nitrato complexes in anhydrous and aqueous acetonitrile

Electronic absorption and emission spectra, along with lifetime measurements and vibrational spectra, are used to investigate the interaction between nitrate and trivalent europium ions in dilute solutions in anhydrous and aqueous acetonitrile. Upon addition of increasing quantities of nitrate, the complexes [Eu(NO₃)_n]^(3?n)+, with n = 1–5, form quantitatively in anhydrous acetonitrile. In solution, the pentanitrato species is not further solvated and its spectroscopic properties are similar to those of solid samples, indicating a similar structure with five bidentate nitrates bonded to the 10-coordinate Eu(III) ion. The lifetimes of the ⁵D₀ level are 1.35(5) and 1.25(5) ms for Eu(NO₃)₃ and (Me₄N)₂Eu(NO₃)₅ 0.05 M in CH₃CN. The quantum yield of Eu(NO₃)₃ in CH₃CN is 27.4%.The addition of small quantities of water to Eu(NO₃)₃ solutions does not result in the dissociation of the nitrate ions, provided R_w = [H₂O]_t/[Eu³⁺]_t is smaller than 8; the apparent equilibrium rations for [Eu(NO₃)₃(H₂O)_n] are K₃ = 40 ± 15 M^?1 and K₄ = 9 ± 3 M^?1; K₁ and K₂ are too large to be determined. The formation of nitrato complexes is studied in mixtures containing increasing amounts of water and nitrate. Deconvolution of the different components of the ⁵D₀ → ⁷F₀ transition allows a semi-quantitative estimate of the relative concentration of the nitrato complexes. The total number of coordinated nitrate ions per europium ion can be determined on the basis of fluorescence lifetime measurements. The apparent equilibrium ratios for the formation of the mono- and dinitrato species amount to K₁ = 23 ± 3, 15 ± 5 and 5 ± 1 for R_w = 44, 94 and 304, respectively, and to K₂ = 17 ± 8 for R_w = 44 and 94.     

Fluorescence enhancement of rare earth Tb(III) by Tm(III) in benzyl benzoylmethyl sulphoxide complexes

A series of rare earth complexes [(Tb_xTm_y)L₅(ClO₄)₂](ClO₄)·3H₂O (x:y = 1.000:0.000, 0.999:0.001, 0.995:0.005, 0.990:0.010, 0.950:0.050, 0.900:0.100, 0.800:0.200, 0.700:0.300; L = C₆H₅CH₂SOCH₂COC₆H₅) (Tb(III) luminescence ion; Tm(III) doped inert ion) were synthesized and characterized by elemental analysis, infrared spectra (IR) and ¹H‐NMR. The photophysical properties of these complexes were studied in detail using ultraviolet absorption spectra, fluorescent spectra and lifetimes. The fluorescence spectra of complexes indicated that the fluorescence emission intensity was significantly enhanced by Tm(III). The complexes showed the best luminescence properties when the mole ratio Tb(III):Tm(III) was 0.990:0.010. The fluorescence intensity could be increased to 390%. Additionally, phosphorescence spectra and the luminescence mechanisms are discussed. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and properties of a new red luminescence europium complex containing a 2‐(benzimidazol‐2‐yl)‐8‐octyloxyquinoline as the second ligand

A new Eu(III) complex, Eu(III)(DBM)₃BIOQ, has been synthesized with dibenzoylmethane (DBM) as the first ligand and 2‐(benzimidazol‐2‐yl)‐8‐octyloxyquinoline (BIOQ) as the second ligand. The stability of the complex was analysed by DSC–TG. The results show that the Eu(III) complex has a relatively high thermal stability with a melting point of 235 °C and a decomposition temperature (onset) of 252 °C. The fluorescence properties of the compound were also investigated. The fluorescence results reveal that the as‐prepared complex shows the characteristic maximum emission spectra of Eu(III) at 611 nm (λ_ex = 350 nm). In addition, the photoluminescence spectrum of the complex in the solid state exhibits a single and symmetrical emission band at 611 nm, with a full width at half‐maximum of 4.7 nm, showing high colour purity. This finding indicates the possibility for the development of brighter red luminescent materials. Copyright © 2011 John Wiley & Sons, Ltd.     

Antioxidation and DNA‐Binding Properties of Binuclear Lanthanide(III) Complexes with a Schiff Base Ligand Derived from 8‐Hydroxyquinoline‐7‐carboxaldehyde and Benzoylhydrazine

8‐Hydroxyquinoline‐7‐carboxaldehyde (8‐HQ‐7‐CA), Schiff‐base ligand 8‐hydroxyquinoline‐7‐carboxaldehyde benzoylhydrazone, and binuclear complexes [LnL(NO₃)(H₂O)₂]₂ were prepared from the ligand and equivalent molar amounts of Ln(NO₃)?6 H₂O (Ln=La³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Dy³⁺, Ho³⁺, Er³⁺, Yb³⁺, resp.). Ligand acts as dibasic tetradentates, binding to Ln^III through the phenolate O‐atom, N‐atom of quinolinato unit, and C?N and ? O? C?N? groups of the benzoylhydrazine side chain. Dimerization of this monomeric unit occurs through the phenolate O‐atoms leading to a central four‐membered (LnO)₂ ring. Ligand and all of the Ln^III complexes can strongly bind to CT‐DNA through intercalation with the binding constants at 10⁵–10⁶ M ^?1. Moreover, ligand and all of the Ln^III complexes have strong abilities of scavenging effects for hydroxyl (HO^.) radicals. Both the antioxidation and DNA‐binding properties of Ln^III complexes are much better than that of ligand.