Fluorescence and DNA-binding properties of neodymium(III) and praseodymium(III) complexes containing 1,10-phenanthroline

The binding of neodymium(III) and praseodymium(III) complexes containing 1,10-phenanthroline, [M(phen)2Cl3·OH2] (M=Nd (1), Pr (2)), to DNA has been investigated by absorption, emission, and viscosity measurements. The complexes show absorption decreasing in charge transfer band, fluorescence decrement when bound to DNA. The binding constant Kb has been determined by absorption measurement for both complexes and found to be (6.76±0.12)×10(4) for 1 and (1.83±0.15)×10(4)M(-1), for 2. The fluorescence of [M(phen)2Cl3·OH2] (M=Nd (1), Pr (2)) has been studied in detail. The results of fluorescence titration reveal that DNA has the strong ability to quenching the intrinsic fluorescence of Nd(III) and Pr(III) complexes through the static quenching procedure. The binding site number n, apparent binding constant Kb and the Stern-Volmer constant kSV are determined. Thermodynamic parameters, enthalpy change (ΔH°) and entropy change (ΔS°), are calculated according to relevant fluorescent data and Van't Hoff equation. The experimental data suggest that the complexes bind to DNA by non-intercalative mode. Major groove binding is the preferred mode of interaction for [M(phen)2Cl3·OH2] (M=Nd (1), Pr (2)) with DNA.     

IR luminescence of neodymium(III) and ytterbium(III) ions in complexes with N-alkyl-substituted 2-aminobenzoic acids

The luminescence of neodymium(III) and ytterbium(III) ions in complexes with N-alkyl-substituted 2-aminobenzoic acids has been studied. The luminescence spectra of the Nd(III) complexes show two bands with maxima at 875 and 904 and 1060 nm, and the spectra of the Yb(III) complexes show one band at 980 nm. The introduction of an additional ligand or some surfactants into the Nd(III) and Yb(III) coordination sphere leads to an increase in the luminescence intensity. A correlation between the luminescence intensity of Nd(III) and Yb(III) 2(N-alkylamino)benzoates and the length of the hydrocarbon radical bound to the nitrogen atom has been studied.     

氯冉酸阴离子桥联的Nd(III)-Nd(III), Dy(III)-Dy(III)和 Ho(III)-Ho(III)双 核配合物的合成与磁性

本文合成了三个以氯冉酸阴离子为桥基的稀土双核配合物,Ln~2(Phen)~4(CA)(NCS)~4(Ln=Nd,Dy,Ho;Phen=菲咯啉;CA=氯冉酸二价阴离子)。通过元素分析,红外光谱,电导,电子吸收光谱及变温(4-300K)磁化率表征了配合物,并由变温磁化率观察到的数据和理论方程通过最小二乘法拟合,得出分子内稀土离子间的相互作用参数:Z'J'=-0.79(Nd),-0.67(Dy),-0.63cm^-^1(Ho);表明稀土离子间存在极弱的反铁磁性交换相互作用。零场分裂参数Δ=-0.16(Nd),-0.76(Dy),-2.55cm^-^1(Ho);g=0.618(Nd),1.739(Dy),1.601(Ho),拟合因子≈10^-^4。     

Cerium(III) and neodymium(III) amides derived from a chelating 2-pyridyl amido ligand

Homoleptic Ce(III) and Nd(III) triamides [LnL(3)] [Ln = Ce(1) or Nd(2)] and the heterobimetallic amide-alkoxide derivatives [LnL(2)(mu-OBu(t))2M(tmeda)] [Ln = Ce, M = Na (3); Ln = Nd, M = Na (4); Ln = Nd, M = K (5)] supported by the bulky [N(SiBu(t)Me2)(2-C(5)H(3)N-6-Me)]- ligand (L-) have been successfully synthesized and characterized. Complexes 1-3 and 5 show a high activity toward the ring-opening polymerization of epsilon-caprolactone.     

New Sm (III) and Nd (III) complexes: Synthesis,structural characterization and fluorescent sensing of nitro‐aromatic compounds

In this work, four new Nd (III) and Sm (III) complexes of two pentadendate ligands (L¹ and L²) were prepared and their molecular structures were determined by single crystal X‐ray diffraction studies. X‐ray analysis showed that the Nd (III) and Sm (III) complexes of L¹ sits on a twofold crystallographic axis while the complexes of L² does not show crystallographically imposed symmetry. Absorption and photoluminescence properties of the complexes were studied both in the solid state and DMF solutions. The fluorescence sensing of nitro‐aromatic compounds [nitrobenzene (NB), 4‐nitrophenol (NP), 2,4‐dinitrophenol (DNP) and 2,4,6‐trinitrophenol (TNP)] were studied by photoluminescence spectroscopy. All four complexes showed better sensitivity towards nitrophenol (NP) with low LOD values.     

Synthesis and spectroscopic studies of novel mononuclear and binuclear ruthenium(III) complexes with bidentate and tridentate acyclic hydrazones

Nine novel acyclic hydrazone ligands, FINH?=?N-(furylidene)-N′-isonicotinoylhydrazine, FNH?=?N-(furylidene)-N′-nicotinoylhydrazine, PINH?=?N-(pyrienylidene)-N′-isonicotinoylhydrazine, PNH?=?N-(pyrienylidene)-N′-nicotinoylhydrazine, TINH?=?N-(thienylidene)-N′-isonicotinoylhydrazine, TNH?=?N-(thienylidene)-N′-nicotinoylhydrazine, FSH?=?N-(furylidene)-N′-salicyloylhydrazine, PSH?=?N-(pyrienylidene)-N′-salicyloylhydrazine and TSH?=?N-(thienylidene)-N′-salicyloylhydrazine, have been synthesized. Their corresponding mononuclear and binuclear ruthenium(III) complexes have been prepared by the reaction of the ligand with RuCl₃·3H₂O in 1?:?2 and 2?:?2 molar ratio and are characterized by elemental analyses, thermogravimetric analyses (TGA and DTG), IR, electronic, magnetic susceptibility and electrical conductance measurements. Electronic spectra and magnetic susceptibility measurements of the solid complexes (both mono- and binuclear) indicate an octahedral geometry around ruthenium(III). Particular emphasis is given to the binuclear complexes in which FSH, PSH and TSH behave as tridentate ligands and chloride bridges the Ru(III) ions. Conductance measurements show the mononuclear complexes are electrolytic and binuclear complexes are of non-electrolytic. The fungicidal activities of the ligands and metal complexes against Fusarium oxysporium and Aspergillus niger are described.     

IR luminescence of neodymium(III) and ytterbium(III) complexes with acylpyrazolones in solutions

Acylpyrazolones (L1–L5) have been synthesized and the conditions of their complexation with neodymium(III) and ytterbium(III) ions in aqueous solutions have been elucidated. The component ratio in the synthesized complexes is Nd(Yb): L = 1: 1. The conditions of excitation and luminescence of the ligands and complexes have been studied. The formation of mixed-ligand complexes upon the introduction of trioctyl- or triphenylphosphine oxide leads to a considerable rise of neodymium and ytterbium. In the presence of 1,10-phenanthroline and bathophenanthroline, competing complexation leads to a 20–70% decrease in luminescence intensity. The introduction of water-miscible organic solvents (30 vol %) decreases the Nd(III) and Yb(III) luminescence intensity by a factor of 9–20.     

Analytical application of poly[dibenzo-18-crown-6] for column chromatographic separation of Nd(III) from Ce(III), U(VI) and other elements

This research is dedicated to the study of analytical application of poly[dibenzo-18-crown-6] for separation of Nd(III) from possible lanthanides, actinides and other metal ions. A simple and efficient column chromatographic method has been developed using poly [dibenzo-18-crown-6] as stationary phase and hippuric acid as a counter ion. The capacity of crown polymer for Nd(III) was found to be 0.55 ± 0.01 mmol/g. Nd(III) was quantitatively separated from Ce(III), U(VI) and other elements in binary as well as multicomponent mixtures. Separation yields were good and reproducible (±2 %). This method has important application for separation of Nd(III) from Ce(III) rapidly and selectively.     

Synthesis, characterization, antioxidant activity, and DNA-binding studies of 1-cyclohexyl-3-tosylurea and its Nd(III), Eu(III) complexes

A new ligand, 1-cyclohexyl-3-tosylurea (H(2)L), was prepared by condensation ethyl N-(3-tossulfonyl) carbamate and cyclohexanamine. Its two lanthanide(III) complexes, Ln(H(2)L)(3) . 3NO(3) [Ln=Nd (1), and Eu (2)], have been synthesized and characterized on the base of element analyses, ESI-MS, molar conductivities, IR spectra and thermogravimetry/differential thermal analysis (TG-DTA). In addition, the DNA-binding properties of the ligand and its complexes have been investigated by electronic absorption spectroscopy, fluorescence spectroscopy, circular dichroic (CD) spectroscopy and viscosity measurements. The experiment results suggest that the ligand and its two complexes bind to DNA via a groove binding mode, and the binding affinity of the complex 2 is higher than that of the complex 1 and the ligand. Furthermore, the antioxidant activity (superoxide and hydroxyl radical) of the ligand and its 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. In particular, complex 2 displayed excellent activity on the superoxide and hydroxyl radical.     

Investigation of the extraction complexes of light lanthanides(III) with bis(2,4,4-trimethylpentyl)dithiophosphinic acid by EXAFS,IR, and MS in comparison with the americium(III) complex

The structure of the extraction complexes of light lanthanides (La(III), Nd(III), Eu(III)) with bis(2,4,4-trimethylpentyl)dithiophosphinic acid (HBTMPDTP) have been characterized with extended X-ray absorption fine structure spectroscopy (EXAFS), IR, and MS; the IR spectrum of the extraction complex of (241)Am with HBTMPDTP has been studied too. The molecular formula of the extraction complexes of lanthanides is deduced to be HML(4).H(2)O (M = La, Nd, Eu; L = anion of HBTMPDTP). The coordination number of Ln(III) in the complexes is 8; the coordinated donor atoms are 7 sulfur atoms from 4 HBTMDTP molecules and 1 O atom from a hydrated water molecule. With the increase of the atomic number of Ln, the coordination bond lengths of Ln-O and Ln-S decrease in the complexes. For La(III), Nd(III), and Eu(III), the coordination bond lengths of Ln-O are 2.70, 2.56, and 2.50, respectively, the coordination bond lengths of Ln-S are 3.01, 2.91, and 2.84, respectively, and the average distances between Ln and P atoms are 3.60, 3.53, and 3.46, respectively. The structure of the extraction complexes of Ln(III) with HBTMDTP is different from that of the Am(III) extraction complex. The results of IR show that there is no water coordinated with Am in the extraction complex. The molecular formula of the complex of Am(III) is deduced as being HAmL(4), and there are 8 S atoms from 4 HBTMPDTP molecules coordinated with Am. Composition and structure differences of the extraction complexes may be one of the most most important factors affecting the excellent selectivity of HBTMPDTP for Am(III) over Ln(III).     

Highly efficient near-infrared-emitting lanthanide(III) complexes formed by heterogeneous self-assembly of Ag(I), Ln(III), and thiacalix[4]arene-p-tetrasulfonate in aqueous solution (Ln(III) = Nd(III), Yb(III))

Heterogeneous self-assembly of thiacalix[4]arene-p-tetrasulfonate (TCAS), Ag(I), and Ln(III) (= Nd(III), Yb(III)) in aqueous solutions conveniently afforded ternary complexes emitting Ln(III)-centered luminescence in the near-infrared (NIR) region. A solution-state study revealed that the Ag(I)-Nd(III)-TCAS system gave a complex Ag(I)(4)·Nd(III)·TCAS(2) in a wide pH range of 6-12. In contrast, the Ag(I)-Yb(III)-TCAS system gave Ag(I)(2)·Yb(III)(2)·TCAS(2) at a pH of around 6 and Ag(I)(2)·Yb(III)·TCAS(2) at a pH of approximately 9.5. The structures of the Yb(III) complexes were proposed based on comparison with known Ag(I)-Tb(III)-TCAS complexes that show the same self-assembly behavior. In Ag(I)(2)·Yb(III)(2)·TCAS(2), two TCAS ligands sandwiched a cyclic array of a Ag(I)-Ag(I)-Yb(III)-Yb(III) core. In Ag(I)(2)·Yb(III)·TCAS(2), Yb(III) was accommodated in an O(8) cube consisting of eight phenolate O(-) groups from two TCAS ligands linked by two S-Ag-S linkages. Crystallographic analysis of Ag(I)(4)·Nd(III)·TCAS(2) revealed that the structure was similar to Ag(I)(2)·Yb(III)·TCAS(2) but that it had four instead of two S-Ag-S linkages. The number of water molecules coordinating to Ln(III) (q) estimated on the basis of the luminescent lifetimes was as follows: Ag(I)(4)·Nd(III)·TCAS(2), 0; Ag(I)(2)·Yb(III)(2)·TCAS(2), 2.4; and Ag(I)(2)·Yb(III)·TCAS(2), 0. These findings were compatible with the solution-state structures. The luminescent quantum yield (Φ) for Ag(I)(4)·Nd(III)·TCAS(2) was 4.9 × 10(-4), which is the second largest value ever reported in H(2)O. These findings suggest that the O(8) cube is an ideal environment to circumvent deactivation via O-H oscillation of coordinating water. The Φ values for Ag(I)(2)·Yb(III)(2)·TCAS(2) and Ag(I)(2)·Yb(III)·TCAS(2) were found to be 3.8 × 10(-4) and 3.3 × 10(-3), respectively, reflecting the q value. Overall, these results indicate that the ternary systems have the potential for a noncovalent strategy via self-assembly of the multidentate ligand, Ln(III), and an auxiliary metal ion to obtain a highly efficient NIR-emissive Ln(III) complex that usually relies on elaborate covalent linkage of a chromophore and multidentate ligands to expel coordinating water.     

Synthesis and catalytic activity of Ln(III) complexes with an unsymmetrical Schiff base including multi()C = N-groups

A synthetic method for a new unsymmetrical Schiff base and its Ln (III) complexes including multi C == N- groups is reported. The complexes are characterized by elemental analysis, IR spectra, 1H and 13C NMR, especially 2D-COSY1H, 1H NMR spectra. The general formula of the obtained complexes is [Ln3(TBLY)(NO3)3]@nH2O (Ln = La, n = 3; Ln = Nd, n = 5; Ln = Gd, Dy, Yb, Y, n = 7), whereTBLY = tetraglycol aldehyde-2,4-dihydroxy benzaldehyde bis-lysine Schiff base. In addition, the evidence for existence of C == CH-NH- group is supported bythe AM1 method. The complexes obtained may be used as a catalyst. Conversion rate of 80% with the viscosity-average molecular weight 220000 for the polymerization of methyl methacrylate (MMA) without addition of any cocatalyst has been obtained.     

Complexation of lactate with neodymium(III) and europium(III) at variable temperatures: studies by potentiometry, microcalorimetry, optical absorption, and luminescence spectroscopy

The complexation of neodymium(III) and europium(III) with lactate was studied at variable temperatures by potentiometry, absorption spectrophotometry, luminescence spectroscopy, and microcalorimetry. The stability constants of three successive lactate complexes (ML(2+), ML(2)(+), and ML(3)(aq), where M stands for Nd and Eu and L stands for lactate) at 10, 25, 40, 55, and 70 °C were determined. The enthalpies of complexation at 25 °C were determined by microcalorimetry. Thermodynamic data show that the complexation of trivalent lanthanides (Nd(3+) and Eu(3+)) with lactate is exothermic and the complexation becomes weaker at higher temperatures. Results from optical absorption and luminescence spectroscopy suggest that the complexes are inner-sphere chelate complexes in which the protonated α-hydroxyl group of lactate participates in the complexation.     

Aqueous Ln(III) luminescence agents derived from a tasty precursor

The synthesis, characterization, and photophysical properties are reported for several Ln(III) complexes of a tetradentate chelate, 5LIO-MAM, derived from the common flavor enhancer "maltol". Eu(III), Yb(III), and Nd(III) form stable ML2 complexes in aqueous solution that emit in the red or near-infrared (NIR) upon excitation at ca. 330 nm. The synthesis, aqueous stability, and photophysical properties are reported for a novel tetradentate ligand derived from maltol, a commonly used flavor enhancer. In aqueous solution, this chelate forms stable complexes with Ln(III) cations, and sensitized emission was observed from Eu(III), Yb(III), and Nd(III). A comparison with recently reported and structurally analogous ligands reveals a slightly higher basicity but lower complex stability with Eu(III) [pEu = 14.7(1)]. A very poor metal-centered quantum yield with Eu(III) was observed (Phi(tot) = 0.04%), which can be rationalized by the similar energy of the ligand triplet state and the Eu(III) (5)D0 emissive level. Instead, sensitized emission from the Yb(III) and Nd(III) cations was observed, which emit in the NIR.     

Studies on synthesis, infrared and fluorescence spectra of new europium (III) and terbium (III) complexes with an beta-diketonate-type ligand

A new beta-diketonate-type ligand, N-(2-amino-6-methyl-pyridinyl)ketoacetamide (L) and its complexes with europium (III) and terbium (III) were synthesized. The complexes were characterized by elemental analysis, infrared spectra and conductivity. The europium (III) and terbium (III)-ions were found to coordinate to the CO oxygen atoms and pyridine nitrogen atoms. The fluorescence properties of these complexes in solid, DMF and CH3OH were studied. The solvent factors influencing the fluorescent intensity are discussed.     

Non-template synthesis and electrospray mass spectrometric study of some lanthanide(III) complexes

A new cryptand H₃L was synthesized by the direct condensation of tris(2-aminoethyl)amine (tren) with 2,6-diformyl-4-methoxyphenol (dmp) in the absence of a template ion. The complexes [M(H₃L)(NO₃)](NO₃)₂·xH₂O·yMeOH (M=Y, Sm, Nd; x=1–3, y=1,2) were characterized by several physical methods. The behaviours of the ligand and Nd(III) complex were investigated by electrospray mass spectrometry. The Nd(III) cryptate exhibits high thermodynamic and kinetic stability in solution for no cryptate fragmentation peaks were observed. A complex peak formed by the overlap of two species is also observed. The isotopic distributions of peak clusters in the mass spectrum of the Nd(III) cryptate were calculated.     

Complexation studies of iodides of trivalent uranium and lanthanides (Ce and Nd) with 2,2'-bipyridine in anhydrous pyridine solutions

In anhydrous pyridine solution at 294 K, U(III) and Ce(III) triiodides were found to form both 1:1 (ML) and 1:2 (ML(2)) complexes with bipyridine (bipy = L) while Nd(III) triodide formed only a 1:2 complex. The 1:3 (ML(3)) complexes were identified at low temperature with a large excess of L. Conductometry measurements showed for U(III) a large increase in the conductivity when increasing the molar ratio L:U. The complex UL(2) was found to be a 1:1 electrolyte and the species UI(2)(+) was more reactive toward L in comparison with UI(3). For Ce(III) and Nd(III), MI(2)(+) and MI(3) present about the same affinity for L. The stability of the complexes is limited, and U(III) possesses a slightly higher affinity for bipy than the trivalent lanthanides. Interestingly, a preference for the formation of ML(2) complex was shown for all the studied M(III) ions. The driving force for complex formation was always the enthalpy, and, surprisingly for a bidendate ligand (bipy), no favorable entropy contribution to complex formation was observed. The X-ray crystal structures of [CeI(3)(bipy)(2)(py)](4).5py.bipy and UI(3)(bipy)(2)(py).2py were determined. The structures of the molecules MI(3)(bipy)(2)(py) are almost identical for U and Ce. The mean M(III)-N(bipy) bond distances are equal to 2.67(3) A for Ce(III) and 2.65(4) A for U(III). The slightly smaller M(III)-N(bipy) distances observed for U(III) would reflect a slightly more important covalent character of the U(III)-N(bipy) bonds, in agreement with the slightly better affinity of U(III) than Ce(III) or Nd(III) toward bipy observed in solution and with the fact that the enthalpy is the driving force for complex formation.     

Near-IR emission of Nd(III) encaged in nanosized zeolites

The near-IR emission of Nd(III) with the highest quantum yield (9.5%) in organic media was successfully observed for the first time by using bis-(perfluoromethylsulfonyl)amide (PMS) as a low vibrational ligand of the ion and TMA⁺-containing FAU zeolite nanocrystallites (TMA-nanoFAU) as a host matrix. Treatments such as deuteration and thermal treatments at high temperatures were ineffective for the strong emission of Nd(III) within TMA-nano-FAU. Judd-Ofelt analysis revealed that the ligation of PMS with the Nd(III) ion occurred easily, because the ions remained in the super cages without migrating into inner cages due to the hindrance of TMA⁺ ions occupying in the sodalite cages. The emission intensity of TMA-nano-FAU treated with PMS increased with the Nd(III)-loading level. The emission decays did not follow simple first-order kinetics and the average lifetime became longer with increasing Nd(III)-loading level. The short lifetimes at low loading levels and the long lifetimes at high loading level were attributed to Nd(PMS)₃ complexes formed with coordinating water molecules and [Nd(PMS)]-zeolite complexes without coordinating water molecules, respectively.     

Sensitized near-IR luminescence of Ln(III) complexes with benzothiazole derivatives

Lanthanide complexes with benzothiazole derivatives (Btz-R, R = OCH(3) and OH) and terpyridine (tpy) ligands were synthesized, and their photophysical properties were precisely investigated. The free Btz-OCH(3) ligand in toluene, excited with UV light, produced the normal emission bands around 410 nm, whereas Btz-OH produced a strong excited-state intramolecular proton transfer (ESIPT) band at 510 nm. The Ln(III) complexes (Ln = Nd, Er, and Yb) exhibited sensitized near-IR luminescence when the Btz-R ligands were excited. The sensitized luminescence quantum yields (Phi(Ln)) of the lanthanide complexes were markedly enhanced by ESIPT: for [Nd(Btz-R)(tpy)] in toluene solution, Phi(Ln) = 0.04% for Btz-OCH(3) and 0.39% for Btz-OH. The sensitized luminescence of the Er(III) complexes (Phi(Ln) = 0.002% for Btz-OCH(3) and 0.009% for Btz-OH) was less efficient than that of the Nd(III) complexes. This difference is due to the smaller energy gap between the emitting and ground levels of the Er(III) ion. The rate constants for the energy transfer from Btz-R to Ln(III) were about approximately 10(9) s(-1), as evaluated by the F?rster resonance energy transfer mechanism.     

稀土双苯并咪唑基乙二醇配合物的合成与荧光性能

合成了4种稀土（Ce（Ⅲ）、Nd（Ⅲ）、Dy（Ⅲ）、Er（Ⅲ）1,2-双（2-苯并咪唑基）-1,2-乙二醇配合物,采用元素分析、IR、UV光谱和摩尔电导率等方法对配合物的结构进行表征,测定了固体荧光光谱和荧光衰减曲线．研究结果表明,配合物都是1：3型电解质,它们发射很强的蓝色荧光,荧光寿命为1．95—2．34ns.