Synthesis, Characterization, DNA-Binding Properties of the Ln(III) Complexes with 6-Hydroxy Chromone-3-Carbaldehyde-(4′-Hydroxy) Benzoyl Hydrazone

6-Hydroxy chromone-3-carbaldehyde-(4′-hydroxy) benzoyl hydrazone (L) and its Ln (III) complexes, [Ln = La, Nd, Eu and Tb] have been prepared and characterized on the basis of elemental analyses, molar conductivities, mass spectra, ¹H NMR, thermogravimety/differential thermal analysis (TG-DTA), UV-vis spectra, fluorescence spectra and IR spectra. The formula of the complex is [Ln L·(NO₃)₂]·NO₃. Spectrometric titration, ethidium bromide displacement experiments and viscosity measurements indicate that Eu (III) complex bind with calf-thymus DNA, presumably via an intercalation mechanism. The intrinsic binding constant of Eu (III) with DNA was 2.48 × 10⁵ M⁻¹ through fluorescence titration data.     

Angular optical characteristics of light scattered by double-layer metal–oxide nanoparticles

The interaction of Tb(III)-2-{[(4-methoxy benzoyl) oxy]} methyl benzoic acid binary complex with nucleosides (adenosine, cytidine, guanosine and inosine) was investigated using UV and fluorescence methods. The reaction of Tb-complex with cytidine, guanosine and adenosine is accompanied by shift to longer wavelength in the absorption band, while there is a blue shift in the absorption band with an enhancement in the molar absorptivity upon the reaction with inosine. The fluorescence intensity of Tb(III)-2-{[(4- methoxy benzoyl) oxy]} methyl benzoic acid binary complex at λ = 545 nm (5D4 → 7F5) was decreased with the addition of the nucleoside molecule following the order: cytidine > inosine > guanosine > adenosine.     

Synthesis of Novel Eu(III) Luminescent Probe Based on 9- Acridinecarboxylic Acid Skelton for Sensing of ds-DNA

Eu(III)-9-acridinecarboxylate (9-ACA) complex was synthesized and characterized by elemental analysis, conductivity measurement, IR spectroscopy, thermal analysis, mass spectroscopy, ¹H-NMR, fluorescence and ultraviolet spectra. The results indicated that the composition of this complex is [Eu(III)-(9-ACA)₂(NCS)(C₂H₅OH)₂] 2.5 H₂O and the oxygen of the carbonyl group coordinated to Eu(III). The interaction between the complex with nucleotides guanosine 5′- monophosphate (5′-GMP), adenosine 5′-diphosphates (5′-ADP), inosine (5′-IMP) and CT-DNA was studied by fluorescence spectroscopy. The fluorescence intensity of Eu(III)-9-acridinecarboxylate complex was enhanced with the addition of CT-DNA. The effect of pH values on the fluorescence intensity of Eu(III) complex was investigated. Under experimental conditions, the linear range was 9–50 ng mL⁻¹ for calf thymus DNA (CT- DNA) and the corresponding detection limit was 5 ng mL⁻¹. The results showed that Eu(III)-(9-ACA)₂ complex binds to CT-DNA with stability constant of 2.41 × 10⁴ M .     

Synthesis and Luminescence Properties of Two Novel Lanthanide (III) Perchlorate Complexes with Bis(benzoylmethyl) Sulfoxide and Benzoic Acid

Two novel ternary rare earth complexes of Tb(III) and Dy(III) perchlorates with bis(benzoylmethyl) sulfoxide (L) and benzoic acid (L′) had been synthesized and characterized by elemental analysis, coordination titration analysis, molar conductivity, IR, TG-DSC, ¹HNMR and UV spectra. The results indicated that the composition of these complexes was REL₅L′(ClO₄)₂·nH₂O (RE= Tb(III), Dy(III); L=C₆H₅COCH₂SOCH₂COC₆H₅, L′=C₆H₅COO; n = 6,8). The fluorescence spectra illustrated that the ternary rare earth complexes presented stronger fluorescence intensities, longer lifetimes and higher fluorescence quantum efficiencies than the binary rare earth complexes REL₅·(ClO₄)₃·2H₂O. After the introduction of the second ligand benzoic acid group, the relative fluorescence emission intensities and fluorescence lifetimes of the ternary complexes REL₅L′(ClO₄)₂·nH₂O (RE= Tb(III), Dy(III)) enhanced more obviously than the binary complexes. This indicated that the presence of both organic ligands bis(benzoylmethyl) sulfoxide and the second ligand benzoic acid could sensitize fluorescence intensities of rare earth ions, and the introduction of benzoic acid group was resulted in the enhancement of the fluorescence properties of the ternary rare earth complexes. The phosphorescence spectra were also discussed.     

Synthesis, Characterization, Antioxidant Activity and DNA-Binding Studies of Three Rare Earth (III) Complexes with 1-(4-Aminoantipyrine)-3-tosylurea Ligand

1-(4-Aminoantipyrine)-3-tosylurea (H₂L) and its three lanthanide (III) complexes, M(H₂L)₃ 3NO₃ [where M = Nd(III), Sm(III) and Eu(III)], have been synthesized and characterized. In addition, the DNA-binding properties of the three complexes have been investigated by UV–vis (ultraviolet and visible) absorption spectroscopy, fluorescence spectroscopy, circular dichroism (CD) spectroscopy, cyclic voltammetry, and viscosity measurements. Results suggest that the three complexes bind to DNA via a groove binding mode. Furthermore, the antioxidant activity (superoxide and hydroxyl radical) of the metal complexes was determined by using spectrophotometer methods in vitro. These complexes were found to possess potent antioxidant activity and be better than standard antioxidants like vitamin C and mannitol. Absorption spectra of the complex 3 inTris-HCl buffer upon addition of calf-thymus DNA. [complex]=1×10^-5 M, [DNA]=(0-1) ×10^-5 M. Arrow shows the absorbance changing upon increasing DNA concentrations. Inset: plots of [DNA]/(ε_a – ε_f) versus [DNA] for the titration of DNA with the complex.     

Fluorescence and electrochemical recognition of nucleosides and DNA by a novel luminescent bioprobe Eu(III)-TNB

The luminescence arising from lanthanide cations offers several advantages over organic fluorescent molecules: sharp, distinctive emission bands allow for easy resolution between multiple lanthanide signals; long emission lifetimes (μs –ms) make them excellent candidates for time-resolved measurements; and high resistance to photo bleaching allow for long or repeated experiments. A method is presented for determination of nucleosides using the effect of enhancement of fluorescence of the easily accessible europium(III)-TNB in presence of different nucleosides. The latter coordinates to Eu(III) -TNB and enhances its luminescence intensity as a result of the displacement of water from the inner coordination sphere of the central metal. A similar method for the determination of DNA based on the quenching of Eu(III)-TNB has been established. The interaction of Eu(III)-4,4,4 trifluoro-1-(2-naphthyl)1,3-butanedione (TNB) complex with nucleosides (NS) (guanosine, adenosine, cytidine , inosine) and DNA has been studied using normal and time-resolved luminescence techniques. Binding constants were determined at 293 K, 298 K, 303 K, 308 K and 313 K by using Benesi-Hildebrand equation. A thermodynamic analysis showed that the reaction is spontaneous with ΔG being negative. The enthalpy ΔH and the entropy ΔS of reactions were all determined. The formation of binary and ternary complexes of Eu (III) with nucleosides and TNB has been studied potentiometrically at (25.0 ± 0.1) °C and ionic strength I = 0.1 mol.dm⁻³ (KNO₃) . The formation of the 1:1 binary and 1:1:1 ternary complexes are inferred from the corresponding titration curves. Initial estimates of the formation constants of the resulting species and the protonation constants of the different ligands used have been refined with the HYPERQUAD computer program. Electrochemical investigations for the systems under investigations have been carried out using cyclic voltammetry (CV), differential pulse polarography (DPP), and square wave voltammetry (SWV) on a glassy carbon electrode in I = 0.1 mol/L p-toluenesulfonate as supporting electrolyte.     

Synthesis, Characterization and DNA-binding Properties of Ln(III) Complexes with 6-Ethoxy Chromone-3-Carbaldehyde Benzoyl Hydrazone

A novel 6-ethoxy chromone-3-carbaldehyde benzoyl hydrazone (L) and its Ln(III) complexes, [Ln = Sm (1), Eu (2), Gd (3), Tb (4)], have been synthesized and characterized. The fluorescence properties of the Eu(III) and Sm(III) complexes in solid state and Eu(III) complex in different solutions (DMF, DMSO, methanol and acetonitrile) were investigated. At the same time, the DNA-binding properties of the two complexes are investigated using UV-Vis absorption spectroscopy, fluorescence spectroscopy, viscosity measurement. All the experimental evidences indicate that the two complexes can bind to CT-DNA via an intercalation mechanism. Furthermore, antioxidant activity tests in vitro showed that the complexes have significant antioxidative activity against hydroxyl free radicals from the Fenton reaction.     

Synthesis and Luminescent Properties of Lanthanide Complexes with Structurally Related Novel Multipodal Ligands

To explore the relationship between the structure of the ligands and the luminescent properties of the lanthanide complexes, a series of lanthanide nitrate complexes with two novel structurally related multipodal ligands, 1,3-bis{[(2’-(2-picolylaminoformyl))phenoxyl]methyl}benzene (L ^I ) and 1,2-bis{[(2’-(2-picolylaminoformyl))phenoxyl]methyl}benzene (L ^II ), have been synthesized and characterized by elemental analysis, infrared spectra and molar conductivity measurements. At the same time, the luminescent properties of the Eu(III) and Tb(III) nitrate complexes in solid state and the Tb(III) nitrate complexes in solvents were investigated at room temperature. Under the excitation of UV light, these complexes exhibited characteristic emissions of central metal ions. The lowest triplet state energy levels T₁ of these ligands both match better to the lowest resonance energy level of Tb(III) than to Eu(III) ion. The influence of the structure of the ligands on the luminescent intensity of the complexes was also discussed.     

Synthesis and Fluorescence Properties of Lanthanide (III) Perchlorate Complexes with Naphthyl-Naphthalinesulphonylpropyl Sulfoxide

A ligand with double sulfinyl groups, naphthyl-naphthalinesulphonylpropyl sulfoxide(dinaphthyl disulfoxide, L), was synthesized by a new method and its several lanthanide (III) complexes were synthesized and characterized by element analysis, molar conductivity, coordination titration analysis, IR, TG-DTA, ¹HNMR and UV spectra. The composition of these complexes, were RE₂(ClO₄)₆·(L)₅·nH₂O (RE = La, Nd, Eu, Tb, Yb, n = 2 ∼ 6, L = C₁₀H₇SOC₃H₆SOC₁₀H₇). The fluorescent spectra illustrated that the Eu (III) complex had an excellent luminescence. It was supposed that the ligand was benefited for transferring the energy from ligand to the excitation state energy level (⁵D₀) of Eu (III). The Tb (III) complex displayed weak luminescence, which attributed to low energy transferring efficiency between the average triplet state energy level of ligand and the excited state (⁵D₄) of Tb (III). So the Eu (III) complex displayed a good antenna effect for luminescence. The phosphorescence spectra and the relationship between fluorescence lifetime and fluorescence intensity were also discussed.     

Europium-sensitized Chemiluminescence of System Tetracycline–H<Subscript>2</Subscript>O<Subscript>2</Subscript>–Fe(II)/(III) and Its Application to the Determination of Tetracycline

Chemiluminescence (CL) of the reaction system tetracycline–H₂O₂–Fe(II)/(III)–Eu(III) was used for the determination of tetracycline hydrochloride in water, pharmaceutical preparations, and honey. The CL spectrum registered for this system shows emission bands typical of Eu(III) ions, with a maximum at λ ∼ 600 nm, corresponding to the electronic transitions of ⁵D₀ → ⁷F₁ and ⁵D₀ → ⁷F₂. A strong chemiluminescence intensity characteristic of europium(III) ions in the system tetracycline–H₂O₂–Fe(II)/(III)–Eu(III), as contrasted to the emission of the system tetracycline–H₂O₂–Fe(II)/(III) without Eu(III), proves that the Eu(III) ion plays the role of a chemiluminescence sensitizer, accompanying tetracycline oxidation in the Fenton system (H₂O₂–Fe(II)/(III)). A linear dependence was observed for the integrated CL light intensity on the tetracycline concentration in the range of 2 × 10⁻⁷ to 3 × 10⁻⁵ mol l⁻¹ with the detection limit of 5 × 10⁻⁸ mol l⁻¹ in aqueous solution.     

Synthesis and Fluorescence Properties of Lanthanide (III) Perchlorate Complexes with Bis(benzoylmethyl) Sulfoxide

A ligand with two carbonyl groups and one sulfinyl group has been synthesized by a new method and its several lanthanide (III) complexes were synthesized and characterized by element analysis, molar conductivity, coordination titration analysis, IR, TG-DSC, ¹H NMR and UV spectra. The results indicated that the composition of these complexes is REL₅(ClO₄)₃·3H₂O (RE = La(III), Pr(III), Eu(III), Tb(III), Yb(III), L = C₆H₅COCH₂SOCH₂COC₆H₅). The fluorescent spectra illustrate that both the Tb (III) and Eu (III) complexes display characteristic metal-centered fluorescence in solid state, indicating the ligand favors energy transfer to the excitation state energy level of them. However, the Tb (III) complex displays more effective luminescence than the Eu (III) complex, which is attributed to especial effectively in transferring energy from the average triplet energy level of the ligands (T) onto the excited state (⁵D₄) of Tb (III) than that (⁵D₀) of Eu (III), showing a good antenna effect for Tb(III) luminescence. The phosphorescence spectra and the relationship between fluorescence lifetimes and fluorescence intensities were also discussed.     

Fluorescence and Biological Evaluation of the La(III) and Eu(III) Complexes with 7-methoxychromone-3-carbaldehyde Benzoyl Hydrazone Schiff Base

A novel Schiff base ligand (L = 7-methoxychromone-3-carbaldehyde benzoyl hydrazone) and its La(III) and Eu(III) complexes have been successfully prepared. The crystal structure of [LaL(2)(NO(3))(3)].H(2)O was characterized by X-ray crystallography. It crystallizes in monoclinic, space group C2/c with crystallographic data: a = 27.7173(17) A, b = 10.0002(6) A, c = 14.7884(9) A, beta = 102.6870(10) degrees and Z = 4. In the structure, the La(III) ion satisfies 12 coordination and three nitrate coordinate as bidentate ligand. The biological experiments show that the ligand and its two complexes can strongly bind to DNA through intercalation mode, and the three compounds also exhibit good antioxidant activities against OH(*) and O(2) (-*). Moreover, it is found that the Eu(III) complex exhibits characteristic fluorescence of europium ion in different organic solvent.     

Preparation and Time-Resolved Luminescence Bioassay Application of Multicolor Luminescent Lanthanide Nanoparticles

Because highly luminescent lanthanide compounds are limited to Eu³⁺ and Tb³⁺ compounds with red (Eu, ~615 nm) and green (Tb, ~545 nm) emission colors, the development and application of time-resolved luminescence bioassay technique using lanthanide-based multicolor luminescent biolabels have rarely been investigated. In this work, a series of lanthanide complexes covalently bound silica nanoparticles with an excitation maximum wavelength at 335 nm and red, orange, yellow and green emission colors has been prepared by co-binding different molar ratios of luminescent Eu³⁺–Tb³⁺ complexes with a ligand N,N,N¹,N¹-(4′-phenyl-2,2′:6′,2′′-terpyridine-6,6′′-diyl)bis(methylenenitrilo) tetrakis (acetic acid) inside the silica nanoparticles. The nanoparticles characterized by transmission electron microscopy and luminescence spectroscopy methods were used for streptavidin labeling, and time-resolved fluoroimmunoassay (TR-FIA) of human prostate-specific antigen (PSA) as well as time-resolved luminescence imaging detection of an environmental pathogen, Giardia lamblia. The results demonstrated the utility of the new multicolor luminescent lanthanide nanoparticles for time-resolved luminescence bioassays.     

Synthesis,Characterization Luminiscence Studies and Microbial Activity of Ethylenediamine Ruthenium (II) Complexes with Dipyridophenazine Ligands

Three symmetric ligands 7-methyl dipyrido-[3,2-a;2′,3′-c]phenazine (dppz-CH₃), 7-nitro dipyrido-[3,2-a;2′,3′-c]phenazine (dppz-NO₂) and benzo[i]dipyrido-[3,2-a;2′,3′-c]phenazine (dppn) and their ruthenium(II) complexes [Ru(en)₂(L)][ClO₄]₂ (en= ethylenediamine), L= dppz-CH₃, dppz-NO₂ and dppn have been synthesized and characterized by IR, ¹H, ¹³C NMR and Mass spectra. The interactions of these complexes with calf thymus DNA have been investigated by spectrophotometric, spectrofluorimetric, circular dichroism, viscosity and thermal denaturation studies. As the planar extension of the intercalative ligand increases, the interaction of the complex with DNA increases, indicating that the size and shape of the intercalalative ligand has a marked effect on the strength of interaction. The plot of log K versus log [Na⁺] yield a slope of -1.26, -1.53, -1.60 for the complexes 1, 2 and 3 respectively. These three complexes have been found to promote the cleavage of plasmid pBR 322 DNA upon irradiation.     

A europium(III) organic ternary complex applied in fabrication of?near UV-based white light-emitting diodes

A β-diketone, 2-acetylfluorene-4,4,4-trifluorobutane-1,3-dione (HAFTFBD), and its three europium(III) complexes, Eu(AFTFBD)₃⋅2H₂O, Eu(AFTFBD)₃(TPPO)₂ and Eu(AFTFBD)₃phen, were designed and synthesized, where TPPO was triphenylphosphine oxide and phen was 1,10-phenanthroline. The complexes were characterized by IR, UV-visible, photoluminescence (PL) spectroscopy and thermogravimetric analysis (TGA). The results show that the Eu(III) complexes exhibit a high thermal stability,and wide and strong excitation bands when monitored at 613 nm. Excited by ∼395 nm near UV light, the complexes emitted strong and characteristic red light due to f–f transitions of the central Eu³⁺ ion, and no emission from the ligands was found. The photoluminescence mechanism of the europium(III) complexes was investigated and proposed as a ligand-sensitized luminescence process. Among the three europium(III) complexes, Eu(AFTFBD)₃phen exhibits the highest thermal stability and the most excellent photoluminescence properties. A bright red light-emitting diode was fabricated by coating the Eu(AFTFBD)₃phen complex onto an ∼395 nm-emitting InGaN chip, and the LED showed appropriate CIE chromaticity coordinates (x=0.66, y=0.33). A white LED with CIE chromaticity coordinates (x=0.32, y=0.32) was prepared with Eu(AFTFBD)₃phen as red phosphor, indicating that Eu(AFTFBD)₃phen can be applied as a red component for fabrication of near ultraviolet-based white light-emitting diodes.     

Synthesis,Characterization, DNA Binding Properties and Antioxidant Activity of Ln(III) Complexes with Schiff Base Ligand Derived from 3-Carbaldehyde Chromone and Aminophenazone

A novel Schiff base ligand, chromone-3-carbaldehyde-aminophenazone (L) and its Ln(III) (Ln = La, Yb) complexes were synthesized and characterized by physicochemical methods. The interaction between the ligand, Ln(III) complexes and calf thymus DNA in physiological buffer (pH = 7.10) was investigated by using UV–vis spectroscopy, fluorescence spectra, ethidium bromide experiments and viscosity measurements, indicating that the studied compounds can all bind to DNA via an intercalation binding mode and the complexes have stronger binding affinity than the free ligand alone. Furthermore, antioxidant activity of the ligand and its complexes was determined by superoxide and hydroxyl radical scavenging methods in vitro, suggesting that Ln(III) complexes inhibit stronger antioxidant activity than the ligand alone and some standard antioxidants, such as mannitol and vitamin C.     

Luminescence Characterisation of the Reaction System Histidine–KBrO3–Tb(III)–H2SO4

Chemiluminescence of the system containing Tb(III) ions, histidine and bromate ions in acid solution was studied. The kinetic curves and CL emission spectra of the system were discussed. The emission spectrum of the histidine–Tb(III)–KBrO₃–H₂SO₄ system revealed two emission maxima at ∼490 and 550 nm, characteristic of Tb(III) ions. Values of lifetimes of the Eu(III) excited states in Eu(III)–histidine system have shown that the histidine formed ML and ML₂ complexes in neutral solution and did not make them in acidic environment. On the basis of the results, a possible mechanism of reaction system: histidine–Tb(III)–KBrO₃–H₂SO₄ is presented.     

Chemiluminescence of the Reaction System Ce(IV) - Non-Steroidal Anti-Inflammatory Drugs Containing Europium(III) Ions and its Application to the Determination of Naproxen in Pharmaceutical Preparations and Urine

The chemiluminescence (CL) of oxidation of non-steroidal anti-inflammatory drugs (NSAIDs) by Ce(IV) ions, was recorded in the presence and absence europium(III) ions, in solution of pH ~ 4 of solution. Kinetic curves and CL emission spectra of the all studied systems were discussed. CL of measurable intensity was observed in the Ce(IV)–NP–Eu(III) reaction system only in acidic solutions. The CL spectrum rcegistered for this system shows emission bands, typical of Eu(III) ions, with maximum at λ ~ 600 nm. The chemiluminescent method, based on Eu(III) emission in reaction system of NP-Ce(IV)–Eu(III) in acid solution was therefore used for the determination of naproxen in mixture of non-steroidal anti-inflammatory drugs.     

Synthesis and Luminescent Properties of Lanthanide Complexes with a Novel Multipodal Ligand

Solid complexes of lanthanide nitrates, picrates and perchlorates with a novel multipodal ligand, 1,2,4,5-tetramethyl-3,6-bis{N,N-bis[((2′-benzylaminoformyl)phenoxyl)ethyl]-aminomethyl}-benzene (L) have been synthesized and characterized by elemental analysis, infrared spectra and molar conductivity measurements. At the same time, the luminescent properties of the Eu and Tb complexes in solid state were investigated. Under the excitation of UV light, these complexes exhibited characteristic emission of central metal ions. The lowest triplet state energy level T₁ of this ligand matches better to the lowest resonance energy level of Tb(III) than to Eu(III) ion. The influence of the counter anion on the luminescent intensity was also discussed.     

1,3-二苯基-4-酰基-5-吡唑酮Eu(Ⅲ)配合物的荧光性质

以四种1,3－二苯基－4－酰基－5－吡唑酮（酰基分别为苯甲酰基、苯乙酰基、丁酰基和氯乙酰基,化合物以DPBZP、DPPAP、DPBTP和DPCAP表示）为配体,合成了Eu(Ⅲ）的二元和三元配合物。通过化学分析和元素分析确定了配合物的组成,通过FTIR谱对配合物进行了表征。测定了配合物的荧光光谱,结果表明：配合物发射Eu(Ⅲ）的特征荧光;配合物荧光;配合物荧光强度与配体吡唑环4－位酰基上的取代基团密切相关,荧光强度随配体不同的变化顺序为DPBZP＜DPPAP＜DPCAP;第二配体邻菲罗啉具有较为明显的荧光增强作用。