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1.
Sayed FN Grover V Dubey KA Sudarsan V Tyagi AK 《Journal of colloid and interface science》2011,353(2):445-453
A series of doped CeF(3): RE(3+) (RE(3+): Tb(3+), Eu(3+) and Dy(3+)) nanoparticles were synthesized, with the aim of obtaining a white light emitting composition, by a simple polyol route at 160°C and characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR) and photoluminescence. Uniformly distributed and highly water-dispersible rectangular nanoparticles (length ~15-20 nm, breadth ~5-10 nm) were obtained. The steady state and time resolved luminescence studies confirmed efficient energy transfer from the host to activator ions. Lifetime studies revealed that optimum luminescence is observed for 2.5 mol% Dy(3+) and 7.5 mol% Tb(3+). The energy transfer efficiencies (Ce(3+) to activators) were found to be 89% for CeF(3): Tb(3+) (7.5 mol%) nanoparticles and 60% for CeF(3): Dy(3+) (2.5 mol%) nanoparticles. Different concentrations of Tb(3+), Eu(3+) and Dy(3+) were doped to achieve a white light emitting phosphor for UV-based LEDs (light emitting diodes). Finally CeF(3), triply doped with 2.0 mol%Tb(3+), 4.5 mol% Eu(3+) and 3.5 mol% Dy(3+), was found to have impressive chromaticity co-ordinates, close to broad day light. The colloidal solutions of doped CeF(3) nanoparticles emitted bright green (Tb(3+)), blue (Dy(3+)) and white (triply doped) luminescence upon host excitation. Composites of poly methyl methacrylate (PMMA) and poly vinyl alcohol (PVA) were made with CeF(3): 5.0 mol%Tb(3+), CeF(3): 5.0 mol% Dy(3+) and triply doped white light emitting composition. The CeF(3)/PMMA (PVA) nanocomposite films, so obtained, are highly transparent (in the visible spectral range) and exhibit strong photoluminescence upon UV excitation. 相似文献
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Mariyam Thomas M. Deepa M.R. Chandran Peter Koshy 《Journal of solid state chemistry》2009,182(1):203-4002
We report the photoluminescence properties of a novel powellite-based red-emitting phosphor material: CaLa1−xNbMoO8:xEu3+ (0.01, 0.03, 0.05, 0.1) for the first time. The photoluminescence investigations indicated that CaLa1−xNbMoO8:xEu3+ emits strong red light at 615 nm originating from 5D0→7F2 (electric dipole transition) under excitation either into the 5L0 state with 394 nm or the 5D2 state with 464 nm, that correspond to the two popular emission lines from near-UV and blue LED chips, respectively. When compared with emission intensity from a CaMoO4:Eu3+, the emission from CaLaNbMoO8:Eu3+ showed greater intensity values under the same excitation wavelength (394 nm). The enhanced red emission is attributed to the enhanced f-f absorption of Eu3+. These materials could be promising red phosphors for use in generating white light in phosphor-converted white light emitting diodes (WLEDs). 相似文献
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Q. Wang L. C. Kong Y. Wang E. C. Yang X. J. Zhao 《Russian Journal of Coordination Chemistry》2014,40(10):773-780
Two novel lead(II) coordination polymers with the same mixed ligands, [Pb(AAP)(NIP)] n (I) and {[Pb(AAP)(NIP)] · 2H2O} n (II) (AAP = 4-aminoantipyrine and NIP2? = 5-nitroisophthalate), were prepared by controlling the pH value of the reaction mixture. Complexes I and II were characterized by X-ray single-crystal diffraction analyses (CIF files CCDC nos. 936101 (I) and 936102 (II)). Complex I with terminal AAP molecule displays a linear chain with hemidirected Pb2+ ions connected by bis-bidentate chelating-NIP2? anions. By contrast, complex II exhibits a dimeric {Pb2(AAP)2}-based coplanar layer extended by bidentate chelating-bidentate chelating and bridging-NIP2? anions. Obviously, the pH-directed structural difference is dominated by the competitive binding modes of the AAP and carboxylate groups of NIP2? ligands. Both complexes display different thermal stability due to structural difference and similar emissions originated from the intra- and/or inter-ligand electron transfer, suggesting their potential application as luminescent materials. 相似文献
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The hydrothermal reactions of LnCl3·6H2O (Ln=Eu, Tb), pyridine-3,4-dicarboxylic acid (3,4-pydaH2), 1,10-phenthroline (phen) and NaOH in aqueous medium yield two metal-organic hybrid materials, [Eu2(3,4-pyda)3(phen)(H2O)·H2O]n (1) and [Tb2(3,4-pyda)3(phen)(H2O)·H2O]n (2), respectively. Both compounds have similar topology structure containing one-dimensional nano-chain, which is further assembled into a three-dimensional supramolecular network via π-π stacking interactions and hydrogen bonds. To the best of our knowledge, they represent the first example of nano-chain coordination polymers constructed by 3,4-pydaH2 and chelate heterocylic ligand. Interestingly, the 3,4-pyda anion exhibits three kinds of coordination modes in these complexes. The coordination modes of 3,4-pyda in complexes 1 and 2 have not been observed in other coordination polymers containing 3,4-pyda ligands. Compounds 1 and 2 exhibit strong fluorescent emission bands in the solid state at room temperature. Their magnetic analyses show that they exhibit different magnetic interactions. 相似文献
5.
Xia Li Wei Liu Hong-Yun Zhang Ben-Lai Wu 《Journal of organometallic chemistry》2008,693(20):3295-3302
A new ferrocene-containing dicarboxylate ligand, L = 5-ferrocene-1,3-benzenedicarboxylic acid, has been prepared. Self-assembly of L, M(II) salts (M = Co and Zn) and chelating ligands dpa or phen (dpa = 2,2′-dipyridylamine and phen = 1,10-phen) gave rise to four new coordination polymers {[Co(L)(dpa)] · 2MeOH}n (1), {[Zn(L)(dpa)] · 2MeOH}n (2), {[Co(L)(phen)(H2O)] · MeOH} (3), [Zn(L)(phen)(H2O)] · MeOH (4). The isostructural complexes 1 and 2 possess 1D helical chain structures with 21 screw axes along the b-direction, and the right- and left-handed helical chains are alternate arrayed into 2D layer structures through hydrogen-bonding interactions; while isostructural complexes 3 and 4 are 1D linear chain structures with phen and ferrocene groups of L as pendants hanging on the different sides of the main chain. A structural comparison of complexes 1–4 demonstrated that the characteristics of subsidiary ligands and slight difference in coordination models of L play very important role in the construction of the complexes. In addition, the redox properties of complexes 1–4, as well as the magnetic properties of complexes 1 and 3 are also investigated. 相似文献
6.
Carmen Coya Rafael Juárez Rafael Gómez Alicia de Andrés Carlos Zaldo Alejandro de la Peña José L. Segura 《European Polymer Journal》2010,46(8):1778-1789
New luminescent polymers containing two individual emission species-poly(fluorene-alt-phenylene) as a blue host and variable amounts of 1,8-naphthalimide as red dopant have been designed and synthesized. Optical studies (optical absorption (OA) and steady-state photoluminescence emission (PL)) in diluted solutions and thin solid films reveal that the emission spectrum can be tuned by varying the content of 1,8-naphthalimide moieties. Although no significant interaction can be observed between both moieties in the ground state, after photoexcitation an efficient energy transfer takes place from the PFP backbone to the red chromophore, indeed, by adjusting the polymer/naphthalimide ratio it is possible to obtain single polymers which emit white light to the human eye in solid state. Energy transfer is more effective in the co-polymers than in physical mixtures of the two chromophores. We prepared single-layer electroluminescent simple devices with structure: ITO/poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT:PSS)/active layer/Ba/Al. With this single layer-single component device structure, white light with Commission Internationale de l’Eclairage (CIE) color coordinates (0.3, 0.42) is obtained for the electroluminescence (EL) emission with an efficiency of 22.62 Cd/A. 相似文献
7.
Two Co(II) coordination polymers (CPs), namely [Co(L1)(DCTP)]n (1) and [Co(L2)(DCTP)]n (2) [L1?=?1,4-bis(5,6-dimethylbenzimidazol-1-yl)butane, L2?=?1,5-bis(5,6-dimethylbenzimidazol-1-yl)pentane, H2DCTP?=?2,5-dichloroterephthalic acid] were synthesized and characterized by single-crystal X-ray diffraction analysis, elemental analysis, powder X-ray diffraction (PXRD) and infrared spectroscopy. CP 1 has a 2D (4,4) corrugated sheet structure, which is further extended into a 2D double layer by C–H···O weak hydrogen bonding interactions, while CP 2 displays a 2D layer with hcb network, which is assembled into a 3D supramolecular framework through C–H···O hydrogen bonding. Both CPs exhibited promising photocatalytic activities for the degradation of methylene blue under UV irradiation. In addition, the thermal stabilities and the luminescence properties of both CPs have been investigated. 相似文献
8.
《Journal of Coordination Chemistry》2012,65(12):2079-2087
Two lead coordination compounds [Pb2(nta)]NO3 (1) and [Pb(oda)] (2) have been synthesized by slow evaporation or hydrothermal conditions using nitrilotriacetic acid (nta) and 2,2′-oxydiacetic acid (oda) as ligands, respectively. Their structures were determined by single-crystal X-ray diffraction and further characterized by X-ray powder diffraction, infrared absorption spectrum, and thermogravimetric analysis. Compound 1 is a 2-D honeycomb-like layer structure with (6,3) topology. When the bonding limit of Pb–O extends from 2.76 to 2.90 Å, potential weak Pb–O bonds can be found in 1, and the 2-D layer structure can be further linked to generate a 3-D 4-connected supramolecular sra net with the (42.63.8) Schläfli symbol. Compound 2 contains a 1-D infinite Pb–O chain which is connected through µ3-, µ4-, and µ5-coordination modes of oda to form a new 3-D structure. 相似文献
9.
《Journal of Coordination Chemistry》2012,65(6):995-1005
Two complexes constructed from aromatic acid and N-heterocyclic ligands have been synthesized by hydrothermal reaction: [Pb(cipt)(NDC)]n (1) [cipt?=?2-(3-chlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, NDC?=?naphthalene-1,4-dicarboxylic acid] and [Pb(ipm)(BDC)2]n (2) [BDC?=?terephthalic acid, ipm?=?5-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-2-methoxyphenol]. Single-crystal X-ray analysis shows that 1 exhibits an interesting arm-shaped chain structure. 1-D ladder chain structure is formed by N–H···O bonding interactions and further into a 2-D network by N–H···O hydrogen bonds and interchain π–π stacking interactions. Complex 2 shows a 2-D butterfly wings structure, which has been rarely reported. The structure in 2 has intermolecular N–H···O interactions, which help in construction of the 3-D framework. In 1, the coordination sphere of Pb(II) is hemi-directed, whereas the Pb(II) geometry in 2 is holo-directed. The solid-state fluorescence spectra of 1 and 2 are also investigated, as well as the ligands cipt and ipm. 相似文献
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Three novel coordination polymers, {[Co(L)(SO4)(H2O)](CH3OH)}∞ (1), {[Cd(L)2(SiF6)](H2O)}∞ (2) and [Zn(L)(NO3)2]∞ (3), synthesized from 1,4-di(benzimidazole-1-yl)benzene (L), have been characterized by infrared spectroscopy, elemental analysis and single crystal X-ray diffraction. Compounds 1–3 exhibit different structures. Complex 1 has a 3-D diamond network containing 1-D CoII chains connected by SO 4 2? · anions; 2 has a 3-D-Po framework with 1-D porous channels along the c axis; and 3 has a 1-D zig-zag chain structure with a 2-D supramolecular network based on π-π interactions. The magnetic properties of 1 and the solid state fluorescence spectra of 2 and 3 have also been explored. 相似文献
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Five novel Cd(II) coordination polymers with three structurally related flexible disulfoxide ligands, [[Cd(L1)3](ClO4)2]n (1), [[Cd(L2)3](ClO4)2(CHCl3)]n (2), [Cd(L2)(NO3)2(H2O)]n (3), [Cd2(L3)2(NO3)4]n (4) and [[Cd(L3)3](ClO4)2]n (5), where L1= 1,3-bis(phenylsulfinyl)propane, L2= 1,4-bis(phenylsulfinyl)butane and L3= 1,4-bis(ethylsulfinyl)butane, were synthesized and structurally determined by X-ray diffraction. Complex 1 has a 2D layer structure, in which part of the L1 ligands bridge the Cd(II) ions to form double-bridging chains and the other part of ligands link such chains to form a 2D framework. Complexes 2 and 5 are isomorphous, showing unusual 2D (3,6) network structures containing triangular grids. Complex 3 adopts a 2D (4,4) network formed by L2 linking the NO3- bridged (Cd-O-N-O-)n 1D zigzag chains. By contrast, is a 1D chain, in which two Cd(II) centers are bridged by mu2-O of sulfoxide groups to form a dinuclear unit, and L3 ligands link such dinuclear units to form a 1D double-bridging chain. The structural differences among such complexes show that the ligand nature and counter anions have important influences on the complex structures, which may provide a rational method for controlling the framework formation in metal-organic coordination polymers. 相似文献
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The reactions of meso-1,2-bis(ethylsulfinyl)ethane (meso-L) with Ln(ClO(4))(3) [Ln(NO(3))(3) or Ln(NCS)(3)] in MeOH and CHCl(3) gave a series of new lanthanide coordination polymers, [[Ln(micro-meso-L)(rac-L)(2)(CH(3)OH)(2)](ClO(4))(3)](n) [Ln: La (1), Nd (2), Eu (3), Gd (4), Tb (5), Dy (6), and Yb (7)], [Yb(micro-meso-L)(1.5)(NO(3))(3)](n) (8), and [La(micro-meso-L)(2.5)(NCS)(3)](n) (9). All the structures were established by single-crystal X-ray diffraction. Complexes 1-7 are isostructural with infinite single micro-chain structure, in which the L ligands take two kinds of coordination modes: bidentate chelating and bis-monodentate bridging. Six sulfur atoms of the sulfoxide groups around each Ln(III) center adopt alternatively the same R or S configuration in the chain. In addition, the configuration change of partial ligands occurred from the meso to the rac form when reacting with Ln(ClO(4))(3). To our knowledge, this is the first example of disulfoxide complexes with two kinds of coordination modes and three kinds of configurations (R,R, S,S, and R,S) occurring simultaneously in the same complex. 8 exhibits single-double bridging chain structure, in which dinuclear macrometallacycles formed through bridging two Yb(III) by two meso-L ligands are further linked by another meso-L ligand. In 9 each La(III) ion is linked to five other La(III) ions by five meso-L ligands to form a 5-connected 2-D (3/4,5) network containing two types of macrometallacyclic arrays: quadrilateral and triangle grids. The structural differences among 1-7, 8, and 9 show that counteranions play important roles in the framework formation of such coordination polymers. In addition, the luminescent properties of 3 and 5 were also investigated. 相似文献
19.
Harold B. Tanh Jeazet Jens Mizera Thomas Doert Kerstin Gloe Axel Heine Gert Bernhard Karsten Gloe 《Journal of inclusion phenomena and macrocyclic chemistry》2011,71(3-4):343-352
Reaction of equimolar amounts of AgClO4 and bis[4-(2-pyridylmethyleneamino)phenyl] methane (L1) or bis[4-(2-pyridylmethyleneamino)phenyl] ether (L2) in a 1:1 solvent mixture of CH3CN and CH2Cl2 leads to the formation of two infinite coordination polymers of the composition {[Ag(L1)]ClO4·CH3CN}n (1) and {[Ag(L2)]ClO4·CH2Cl2}n (2). Whereas 1 represents a homochiral single-stranded helicate the related complex 2 shows a typical zigzag chain arrangement. Both structures are characterized by a distorted tetrahedral coordination environment of the Ag(I) centres each based on a N4 coordination pattern of two ligand molecules. The resulting strands are connected by a hydrogen bonding network including ClO4 ? anions and solvent molecules forming 2-D layers. Additional ?ШC?? and CH?C?? interactions between the aromatic parts of the ligand molecules give a 3-D arrangement of the packing. In contrast, a discrete dinuclear metallocycle, [Ag2(L2)2](ClO4)2·CH3OH (3), has been formed by reaction of AgClO4 with L2 when CH2Cl2 in the solvent mixture was replaced by CH3OH. Again each Ag(I) has a distorted tetrahedral geometry and is coordinated to two pyridylimine units of two ligand molecules. Additional weak hydrogen bonds involving perchlorate and solvent molecules as well as edge-to-face and face-to-face ?ШC?? interactions allow a 3-D packing arrangement. 相似文献
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Five new eclipsed two-dimensional (2D) coordination polymers, [[Cd(2)(TPT)(2)L(2)](GM(1))(3/2)(H(2)O)](infinity) (1) (TPT = terephthalate, L = 3-(2-pyridyl)pyrazole, GM(1) = terephthalic acid), [[Cd(TPT)L](GM(2))(H(2)O)(2)]( infinity) (2) (GM(2) = L = 3-(2-pyridyl)pyrazole), [[Cd(TPT)L](GM(3))(1/2)(H(2)O)](infinity) (3) (GM(3) = mesitylene), [[Cd(4)(TPT)(4)L(4)](GM(4))(7/2)](infinity) (4) (GM(4) = tetramethylbenzene), and [[Cd(TPT)L](GM(5))(1/2)](infinity) (5) (GM(5) = naphthalene), have been synthesized and characterized by X-ray diffraction. All the five complexes take the similar eclipsed 2D open-channel framework with different guest molecules included in the cavities of their channels. TGA analysis indicates that the eclipsed open-channel frameworks are thermally stable up to 300 degrees C. The porous property of the 2D framework of 5 was also investigated by the XRPD technique, which indicated that the guest molecules included in the open-channel frameworks are removable and the framework is maintained after the removal of the guest molecules. Moreover, complexes 1-5 also display strong blue emission in the solid state. 相似文献