cis-Dicyanoosmium(II) diimine complexes bearing phosphine or sulfoxide ligands: spectroscopic and luminescent studies

A series of cis-dicyanoosmium(II) complexes [Os(PPh3)2(CN)2(N intersectionN)] (N intersectionN = Ph2phen (2a), bpy (2b), phen (2c), Ph2bpy (2d), tBu2bpy (2e)) and [Os(DMSO)2(CN)2(N intersectionN)] (3a-3e, N intersectionN = Br2phen (3f), Clphen (3g)), were synthesized and their spectroscopic and photophysical properties were examined, and [Os(PMe3)2(CN)2(phen)] (4) with axial PMe3 ligands was similarly prepared. The molecular structures of 2a, 2c, [2c.Zn(NO3)2]infinity, 2d, 2e, 3b, 3d, 3e, and 4 were determined by X-ray crystallographic analyses. The two CN ligands are cis to each other with mean Os-C bond distance of 2.0 A. The two PR3 (R = Ph, Me) or DMSO ligands are trans to each other with P/S-Os-P/S angles of approximately 177 degrees . The UV-vis absorption spectra of 2a-2e display an intense absorption band at 268-315 nm (epsilon = approximately (1.54-4.82) x 104 M-1 cm-1) that are attributed to pi --> pi*(N intersection N) and/or pi --> pi*(PPh3) transitions. The moderately intense absorption bands with lambdamax at 387-460 nm (epsilon = approximately (2.4-11.3) x 103 M(-1) cm(-1)) are attributed to a 1MLCT transition. A weak, broad absorption at 487-600 nm (epsilon = approximately 390-1900 M(-1) cm(-1)) is assigned to a 3MLCT transition. Excitation of 2a-2e in dichloromethane at 420 nm gives an emission with peak maximum at 654-703 nm and lifetime of 0.16-0.67 micros. The emission energies, lifetimes, and quantum yields show solvatochromic responses, and plots of numax, tau, and Phi, respectively, versus ET (solvent polarity parameter) show linear correlations, indicating that the emission is sensitive to the local environment. The broad structureless solid-state emission of 2a-2e at 298 (lambdamax 622-707 nm) and 77 (lambdamax 602-675 nm) K are assigned to 3MLCT excited states. The 77 K MeOH/EtOH (1:4) glassy solutions of 2a-2e also exhibit 3MLCT emissions with lambdamax = 560-585 nm. The 1MLCT absorption and 3MLCT emission of 3a-3g occur at lambdamax = 332-390 nm and 553-644 nm, respectively. In the presence of Zn(NO3)2, both the 1MLCT absorption and 3MLCT emission of 2c in acetonitrile blue-shift from 397 to 341 nm and 651 to 531 nm, respectively. The enhancement of emission intensity (I/Io) of 2e at 531 nm reached a maximum of approximately 810 upon the addition of two equivs of Zn(NO3)2. The crystallographic and spectroscopic evidence suggests that 2c undergoes binding of Zn2+ ions via the cyano moieties.     

Highly luminescent Eu(3+) and Tb(3+) macrocyclic complexes bearing an appended phenanthroline chromophore

A two-component ligand system (1) containing 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A) as the hosting unit for the lanthanide cations and an appended asymmetrically functionalized 1,10-phenanthroline (phen) as the chromophore was synthesized. The 1:1 complexes with Eu(3+), Gd(3+), Tb(3+), and Yb(3+) have been prepared and studied in aqueous solution. For Gd.1, a relaxivity value of 2.4 mM(-1) s(-1) has been measured at 20 MHz and 25 degrees C, which indicates that there are no water molecules in the first coordination sphere of the metal ion. The analysis of high resolution (1)H NMR spectra of Yb.1 supports this view and suggests the direct involvement of the phen moiety in the coordination of the metal ion. For Eu.1 and Tb.1, the absorption and luminescence spectra, the overall luminescence efficiencies, and the metal-centered (MC) lifetimes were obtained; coordination features were also determined by comparing luminescence properties in water and deuterated water. For Eu.1 and Tb.1, the overall emission sensitization (se) process in air-equilibrated water was found to be notably effective with phi(se) = 0.21 and 0.11, respectively. A detailed study of the steps originating from light absorption at the phen unit and leading to MC sensitized emission was performed.     

Synthesis and spectroscopic characterization of new metal(II) complexes with methionine sulfoxide

Methionine sulfoxide complexes of iron(II) and copper(II) were synthesized and characterized by chemical and spectroscopic techniques. Elemental and atomic absorption analyses fit the compositions K₂[Fe(metSO)₂]SO₄·H₂O and [Cu(metSO)₂]·H₂O. Electronic absorption spectra of the complexes are typical of octahedral geometries. Infrared spectroscopy suggests coordination of the ligand to the metal through the carboxylate and sulfoxide groups. An EPR spectrum of the Cu(II) complex indicates tetragonal distortion of its octahedral symmetry. ⁵⁷Fe Mössbauer parameters are also consistent with octahedral stereochemistry for the iron(II) complex. The complexes are very soluble in water.     

Synthesis and photovoltaic properties of new europium complex Eu（DBM）3（CPyBM）

A new europium（Ⅲ） complex, tris（dibertzoylmethanate）{ 1-[9-hexyl-9-carbazole]-2-（2-pyridyl）-bertzimidazole}europium（Ⅲ） [Eu（DBM）a（CPyBM）] was synthesized and used as an electron-acceptor and electron-transport layer in organic photovoltaic （PV） device. Power conversion efficiency achieved from the device was 1.04% under illumination with 365 nm UV light at 1.6 mW/cm^2. Compared with the previous reported devices based on Eu（Ⅲ） complexes, the PV performances were improved. The working mechanism of the organic PV device was discussed.     

Eu(DBM)3qp和Eu(DBM)3pp的晶体结构及荧光性质对比研究

两种新型铕配合物Eu(DBM)₃qp(DBM=二苯甲酰甲烷,qp=喹喔啉并[2,3-i]-1,10-邻二氮杂菲)和Eu(DBM)_3pp(DBM=二苯甲酰甲烷,pp=吡嗪并[2,3-i]-1,10-邻二氮杂菲)的晶体结构均属单斜晶系,P2(1)/c空间群.中心铕离子分别与DBM配体的六个氧原子及第二配体的两个鳌合氮原子配位,形成八配位的扭曲四方反棱柱构型.两种配合物晶体中,每四个配合物分子的第二配体共轭平面相互平行,形成一种特殊的"块"状π-π堆积单元.在紫外光激发下两种配合物均表现为Eu³⁺的特征发射,由于第二配体能级的不同,Eu(DBM)_3pp的发射强度比Eu(DBM)_3qp高十几倍.     

Synthesis and Photoluminescence of New Europium Complex Eu(DBM)3 (DPPZ) with Dipyridophenazine Ligand

Dipyrido[3,2-a:2′,3′-c] phenazine moiety has been introduced as neutral lignad in europium complex.Therefore a new europium complex with saturate emission,strong fluorescnet intensity and good solubility was designed and synthesized for the first time.Its photoluminescence and UV properties were examined.The experimental results showed that this new Eu-complex could be used as red electroluminescnet materials.     

2,2'-bipyridine lariat calixcrowns: a new class of encapsulating ligands forming highly luminescent Eu3+ and Tb3+ complexes

A new class of calix[4]arene crown ethers with one or two bipyridines appended to the polyether ring (lariat calixcrowns) have been designed and synthesized; the luminescence properties of their Eu3+ and Tb3+ complexes have been studied in acetonitrile. In this solvent, long lifetimes for the metal emitting states and high metal-luminescence intensities obtained upon ligand excitation have been observed in both Eu3+ and Tb3+ complexes. The association constants in methanol have been determined for some of the complexes studied.     

Thermal behavior of the highly luminescent poly(3-hydroxybutyrate):Eu(tta)3(H2O)2 red-emissive complex

The aim of this study has been to gain a fundamental understanding of the mechanisms governing thermal degradation of luminescent poly(3-hydroxybutyrate) (PHB). PHB was doped with diaquatris(thenoyltrifluoroacetonate) europium(III) complex, [Eu(tta)₃(H₂O)₂], and different luminescent systems were obtained. The thermal-stability of the luminescent films was discussed and the products of decomposition were analyzed. Thermal degradation of PHB:Eu(tta)₃ x % systems (x = 0, 1, 5, 10, and 15 %) was elucidated by means of thermogravimetric analysis (TG), the thermal-stability decreases with the increase of europium complex concentration. The PHB polymer decomposed with evolution of carbon dioxide and 2-butenoic acid molecules. The TG–FTIR results, of the gaseous degradation products of PHB in nitrogen atmosphere, indicated that the polymer is stable at temperatures up to 200 °C. Polymer matrix at concentrations above 5 % decomposed with evolution of water molecules among the other gaseous products, which implied the presence of a hydrated complex in the system. The luminescent films showed more flexibility due to a loss in crystallinity, which suggested a potential usefulness in technical applications.     

Enhanced luminescence of Eu(3+) by Y(3+) in ternary complexes Eu(X)Y(1-X)(TTA)3Dipy

Rare-earth ternary complexes Eu(X)Y(1-X)(TTA)3Dipy {X=0, 0.1, 0.25, 0.5, 0.75, 0.9, 1.0, using thenoyltrifluoroacetone (TTA) as ligand and 2,2'-dipyridyl (Dipy) as synergic agent} were synthesized. Characterization with X-ray diffraction (XRD), IR and elemental analysis had also been carried out. The photophysical properties of these complexes were studied in detail with ultraviolet absorption spectra and fluorescent spectra. It is found that the enhanced luminescence of Eu(3+) ions by Y(3+) ions occurs in ternary complexes. And we monitored the spectra of Eu(X)Y(1-X)(TTA)3Dipy (PVK:Eu/BCP/AlQ/Al) at the different rate (rpm). The results showed that the Y(3+) ion acts as an energy transfer bridge that helps energy transfer from PVK to Eu(3+).     

链状Eu(BO2)3的合成与发光性能研究

采用固相反应合成出链状结构的稀土硼酸盐Eu(BO2)3发光材料。分别利用XRD、TEM、SAED、EDS和PL等测试技术对产物进行了研究,结果表明:链状结构的Eu(BO2)3属于单斜晶系,空间群为I2/a,直径约10～15nm,长度达几个微米,探讨了链状Eu(BO2)3的生长机理。在395nm紫外光激发下,Eu(BO2)3能发出Eu3+的特征红色荧光,发射主峰位于591nm,归属于5D0→7F1磁偶极跃迁。     

Self-assembly of highly luminescent lanthanide complexes promoted by pyridine-tetrazolate ligands

Two tridentate pyridine-tetrazolate ligands (H(2)pytz and H(2)pytzc), analogues of the well-known dipicolinate (H(2)dpa) ligand, have been synthesized in a straightforward manner and used for lanthanide(III) coordination. The structures of the resulting tris-ligand complexes were determined in solution ((1)H-NMR), where they remain undissociated, as well as in the solid state (X-ray diffraction). The solubility of these anionic complexes can be easily tuned by changing the countercation. The bis-tetrazolate-pyridine ligand H(2)pytz sensitizes very efficiently both the visible and near-IR emission of the lanthanides, with unusually high luminescence quantum yields in solid state (61% and 65% for Eu and Tb, respectively, and 0.21% for Nd) and in water (63% for Tb and 18% for Eu). Furthermore, the absorption window of the complexes is significantly extended towards the visible region up to 330 nm. The results show that the bis-tetrazolate-pyridine ligand provides a very attractive alternative to the classic dipicolinate ligand.     

Synthesis and spectroscopic studies of dinuclear copper(II) complexes with new pendant-armed macrocyclic ligands

Three dinuclear Cu^II perchlorate complexes of macrocyclic ligands derived from the condensation of sodium 4-X-2,6-diformylphenolate (X=Me, Cl or Bu^t) with 1,5-diamino-3-(8-methylquinolyl)azapentane were prepared by in situ transmetallation with Cu(ClO₄)₂ and characterized by physicochemical, spectroscopic and electrochemical methods.     

Silver(I) complexes with (1-pyrazolyl)pyridazine ligands: Synthesis,crystal structures and luminescent properties

Four Ag(I) coordination complexes formulated as {[Ag(L¹)(ClO₄)]}_n (1), {[Ag(L¹)(NO₃)]}_n (2), {[Ag(L¹)(PF₆)]}₂ (3) and {[Ag(L²)](ClO₄)·CH₃OH}_n (4), (L¹ = 3,6-bis(1-pyrazolyl)pyridazine, L² = 3,6-bis(3,5-dimethyl-1-pyrazolyl)pyridazine) have been synthesized in the presence of different anions [ClO₄^? (1) and (4), NO₃^? (2), PF₆^? (3)] and structurally characterized by FT-IR spectra, elemental analysis and X-ray diffraction. Studies of X-ray diffraction reveal that complexes 1, 2 and 4 show infinite helical chains, which are the alternate left- and right-handed helical chains. Furthermore, helical chains are arranged to 2D sheet via C–H?O (from anion O atoms) hydrogen bonds. As the anion changed to PF₆^?, a dinuclear molecule is formed in complex 3, further constructing a 2D sheets by C–H?F hydrogen bonds. The photoluminescence properties of all the complexes 1–4 have been investigated in the solid state at room temperature.     

Synthesis,structure and spectroscopic study of Cu(II) polypyridine complexes with phenylcyanamide derivative ligands

Several new mononuclear copper(II) complexes, [Cu(phen)₂L]PF₆, where phen = 1,10-phenanthroline and L = monoanions of phenylcyanamide (pcyd), 2,5-dichlorophenylcyanamide (2,5-Cl₂pcyd), 2-dichlorophenylcyanamide (2-Clpcyd) and 4-methylphenylcyanamide (4-Mepcyd), have been prepared and characterized by elemental analysis, UV–Vis, IR and ¹H NMR spectroscopies and cyclic voltammetry. [Cu(phen)₂(2,5-Cl₂pcyd)]PF₆ crystallized with a molecule of acetone with empirical formula of C₃₁H₂₀N₆OF₆Cl₂PCu in a triclinic crystal system and space group P 1 with a = 9.2086(6) Å, b = 13.3117(9) Å, c = 15.5313(10) Å, α = 107.8210(10)°, β = 104.6180(10)°, γ = 104.1670(10)°, V = 1643.21(19) ų and Z = 2. The structure was refined using 7555 Mo-Kα reflections with I > 2σ(I) and R ₁ = 0.0276 and Rw = 0.0692. The results are consistent with a mostly σ bonding interaction between Cu(II) and cyanamide anion. The LMCT band intensity and electrochemical potentials are compared with ruthenium phenylcyanamide analogues.     

Lanthanide directed self-assembly formations of Tb(III) and Eu(III) luminescent complexes from tryptophan based pyridyl amide ligands

The formation of self-assembly complexes between the ligands 1 (SS) and 2 (RR) and terbium or europium was undertaken and shown (using various spectroscopic titrations) to give rise to the exclusive formation of 2:1 (L:Ln) stoichiometry and not the anticipated 3:1 stoichiometry.     

Eu(DBM)3超微粒子的光谱特性

The colloids of Eu(DBM)3 and ultrafine particles Eu(DBM)3 were perpared. The particle sizes determined by X-ray and by TEM measurements were in 7-30nm range. Their UV absorption and fluorescence spectra were compared with each other and with those of the solid sample. It was shown that the 5D1→7 F1,2 transition was observed in the colloids of Eu(DBM)3 at room temperature. The increase of the excited-state S1 and T1 energy, the peak positions of UV absorption shifted to shorter wavelength, the changes of the absoprtion coefficient with decreasing size were observed.     

纳米MgBO_2(OH):Eu~(3+)的制备及发光性能研究

利用水热法,制备得到了纳米线组装的绒球状和纳米带聚集的絮状Mg BO2(OH):Eu3+,对它们进行了EDS、XRD、IR、SEM等表征及发光性能研究。研究发现两个产品的最高激发峰和发射峰分别都位于λ=250nm和λ=615nm处,为红色发光材料;且发现绒球状Mg BO2(OH):Eu3+的峰强度明显强于絮状Mg BO2(OH):Eu3+,但絮状Mg BO2(OH):Eu3+的红橙比(R/O)更高。     

Synthesis and fluorescence properties of rare earth (Eu3+ and Gd3+) complexes with alpha-naphthylacetic acid and 1,10-phenanthroline

Rare earth binary complex Eu(NNA)3 (NNA, alpha-naphthylacetic acid), ternary complex Eu(NNA)3.phen (phen, 1,10-phenanthroline) and a series of dinuclear complexes with different mole ratios of Eu3+ to Gd3+ were synthesized. Many advanced approaches, such as element analysis, FTIR spectra, TG and DTA analysis, were used to determine the composition and structure of binary and ternary complex. Moreover, their fluorescence properties were studied by fluorescent spectra and lifetimes. The fluorescence spectra and decay curves of dinuclear complexes indicated that the fluorescence emission intensity was enhanced and the fluorescence lifetime was prolonged by Gd3+. The dinuclear complexes show the best properties when the mole ratio of Eu3+ to Gd3+ is 6:4. A new parameter Y, which was used to evaluate the effect of Gd3+, was introduced. In addition, the relationship of Y value and mole fraction of Gd3+ was analyzed by mathematical software. The results showed that Y value decreased by single exponential mode when the content of Gd3+ decreased.     

Crystal Structure and Luminescence of Eu(DBM)_3TPPO Complex

The crystal structure of tris(dibenzoylmethanato)(triphenylphosphine oxide)europium (Ⅲ), C63H51O7PEu, has been determined by single crystal X-ray diffraction. The complex crystallizes in the tri-clinic space group P 1 with two molecules in a unit cell. The cell dimensions are a=12. 336 (3), b=18. 729 (5), c=11. 502 (3) A, α=95. 86 (2), β=103.14 (2), γ=87.89 (2)0. The total number of 6969 independent reflections was used for the structure determination. The final calculated R value is 0. 055. The central europium ion is hepta-coordinated by seven oxygen atoms. The polyhedron is a distorted capped trigonal prism with the Eu-O separation of 2. 305-2. 367 A. The high resolution excitation and emission spectra measured at 77 K indicate two Eu (Ⅲ) sites in the complex. The symmetries of the Eu (Ⅲ) sites are C2v and Cs respectively. The lower symmetrical Cs site predominates. A comparison of the emission spectra for Gd(DBM)3TPPO doped by 1% Eu(Ⅲ) with those for Eu(DBM)3TPPO complex shows no significant     

Tricarbonylrhenium(I) complexes of highly symmetric hexaazatrinaphthylene ligands (HATN): structural, electrochemical and spectroscopic properties

The new mononuclear and dinuclear tricarbonylrhenium(I) complexes [(HATN)Re(CO)(3)Cl] (1-Cl) and [(μ-Me(6)-HATN)[Re(CO)(3)Cl](2)] (2-Cl(2)) of highly symmetric ligands HATN and Me(6)-HATN were synthesized and structurally characterized. X-Ray crystal structures reveal identical strained aromatic systems and out of the plane fac-Re(CO)(3)Cl units for both complexes. The packing geometry in the unit cell of 1 suggests intermolecular π-π association. Infrared spectroelectrochemistry (SEC) experiments confirmed ligand-based reductions. To get more insight into the reduction mechanism the triflate salts, [(HATN)Re(CO)(3)](OTf) (1-OTf) and [(μ-Me(6)HATN){Re(CO)(3)}(2)](OTf)(2) (2-OTf(2)), were synthesized. Their electrochemical and spectroelectrochemical behavior also exhibits reduction of the aromatic systems. The electronic absorption spectral features of the one electron reduced species were studied by UV-vis-NIR spectroscopy, which shows a broad shoulder at 1500 nm, confirming intra-ligand charge transfer (ILCT). Density functional theory (DFT) calculations on the complexes 1-Cl and 2-Cl(2) for structural optimization show good agreement with experimental bond lengths and bond angles. The spin density plot shows a metal based HOMO and HATN ligand centered LUMO.