Synthesis and photoluminescence properties of single-crystal ZnO hexagonal pyramids by PEG400-assisted thermal decomposition route

Large-scale synthesis of ZnO hexagonal pyramids was achieved by a simple thermal decomposition route of precursor at 240 oC in the presence of PEG400. The precursor was obtained by room-temperature solid-state grinding reaction between Zn（CH3COO）2-2H2O and Na2CO3. Crystal structure and morphology of the products were analyzed and characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and high-resolution transmission electron microscopy （HRTEM）. The results of further experiments show that PEG400 has an important role in the formation of ZnO hexagonal pyramids. Difference between the single and double hexagonal pyramid structure may come from the special thermal decomposition reaction. The photoluminescence （PL） spectra of ZnO hexagonal pyramids exhibit strong near-band-edge emission at about 386 nm and weak green emission at about 550 nm. The Raman-active vibration at about 435 cm-1 suggests that the ZnO hexagonal pyramids have high crystallinity.

Two Cd(Ⅱ) Coordination Polymers Based on a Flexible Tricarboxylate Ligand: Syntheses, Structures, and Photoluminescence and Catalytic Properties

Studies on the synthesis and design of coordination polymers(CPs) with flexible ligands are of great interest owing to their dynamic structures and promising applications. The title coordination polymers, {[Cd·(HTTTA)·(phen)]·2HO}n(1) and [Cd·(HTTTA)·(phen)]n(2)(H3 TTTA = 2,2’,2’’-[1,3,5-triazine-2,4,6-triyltris(thio)] tris-acetic acid, phen = 1,10-phenanthroline) have been synthesized and characterized by elemental analysis, IR, powder XRD and single-crystal X-ray diffraction. Complex 1 consists of one CdII ion, one HTTTA2-ligand and one phen co-ligand. The Cd(Ⅱ) metal clusters were bridged by the tridentate HTTTA2-ligands into infinite 1D chains, which are further connected into the 3D architecture by abundant hydrogen bonds. In 2, three carboxyl groups of HTTTA2-ligand show different coordination directions because of the C–S–C flexible bond angle, which leads to different 1D chains of 2. The strong π-π stacking interaction and four C–H···O hydrogen bonds connect the 1D chains into a 3D framework. The solid-state photoluminescence and catalytic properties were studied as well.

Synthesis,Structure,Photoluminescence and Photocatalytic Properties of a New Cd(Ⅱ)Metal-organic Framework Based on 1,4-Di(2,6-dimethyl-3,5-dicarboxypyridyl)benzene

A new 3D coordination polymer, [Cd2（L）（bpb）2]n（1, H4L = 1,4-di（2,6-dimethyl-3,5-dicarboxypyridyl） benzene, bpb = 1,4-bis（4-pyridyl） benzene, has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis, elemental analysis, TGA, IR spectroscopy and UV-Vis spectrum. Complex 1 crystallizes in orthorhombic, space group C2221, with a = 10.9393（12）, b = 20.900（3）, c = 20.027（2） A, β = 90°, V = 4578.9（9） A^3, Dc = 41.668 Mg/cm^3, Mr = 1149.74, F（000） = 2312.0, μ = 0.996 mm^（–1）, Z = 4, the final R = 0.0316 and wR = 0.0786 for 4271 observed reflections with I 〉 2σ（I）. Structural analysis shows that 1 possesses a 3D network based on the 2D layer bridged by L^4-ligands, while the 2D layers are composed of the adjacent 1D chains joined by L^4-ligand. The photoluminescent investigation indicates that one broad emission band with the maximum of 445 nm can be observed in 1. Moreover, compound 1 has high photocatalytic degradation effects on methylene blue under UV irradiation.

Synthesis,Crystal Structure and Photoluminescence Property of a Ni(Ⅱ) Coordination Polymer with One-dimensional Double-sinusoidal Structure

A new coordination polymer [Ni（3-bpo）（m-bdc）（C2H5OH） 2]n（1,3-bpo = 2,5-bis（3-pyridyl） -1,3,4-oxadiazole,m-H2bdc = 1,3-benzenedicarboxylic acid） was solvothermally synthesi-zed and characterized by IR,TGA and single-crystal X-ray diffraction. The title complex crystalli-zes in the orthorhombic system,space group Pnma with a = 7.786（3） ,b = 17.253（6） ,c = 18.478（6） ,V = 2481.9（14） A^3,Mr = 539.18,Dc = 1.443 g/cm^3,Z = 4,R = 0.0353 and wR = 0.0589. The m-bdc and 3-bpo bridge two Ni（Ⅱ） ions through two carboxylate groups and two pyridyl groups forming a 1D infinite double-sinusoidal chain along the c axis. The photoluminescence of 1 shows a large red shift compared to that of free ligands in the solid state.

A New Cd(Ⅱ)Coordination Compound Based on 4-(1,2,4-Triazol-4-yl)phenylacetic Acid:Synthesis,Structure and Photoluminescence Property

A new complex [Cd2（L）2（Cl）2（H2O）]n（1） was synthesized by reacting CdCl2·2.5 H2O with 4-（1,2,4-triazol-4-yl）phenylacetic acid（HL） ligand.The structure of the complex was characterized by single-crystal X-ray diffraction,IR spectroscopy,elemental analysis and PXRD.Complex 1 crystallizes in triclinic,space group P21/c with a = 11.4303（8）,b = 14.1792（10）,c = 14.6857（10） ？,β = 96.3780（10）o,V = 2365.4（3） A^3,Z = 4,C（20）H（16）Cl2N6O5Cd2,Mr = 716.09,Dc = 2.011 g/cm3,μ = 2.069 mm^-1,S = 1.051,F（000） = 1392,the final R = 0.0458 and wR = 0.0949 for 5402 observed reflections（I 〉 2σ（I））.Complex 1 is a two-dimensional（2D） layer structure and non-covalent bonding interactions such as C–H···π and π···π extend the 2D to form a three-dimensional supramolecular polymer.

A Cd(Ⅱ) Coordination Polymer Containing 4-(1-H-imidazol-2-yl) Benzoic Acid Ligand: Synthesis, Crystal Structure, and Photoluminescence Property

A new cadmium（II） polymer based on imidazole derivative, formulated as [Cd（Hiba）2]n 1, H2iba = 4-（1-H-imidazol-2-yl） benzoic acid）, has been synthesized under hydro- thermal conditions. The compound crystallizes in triclinic system, space group P1 with a = 7.062（4）, b = 10.840（7）, c = 13.099（8） A, a = 98.102（7）, fl = 101.524（7）, y = I07.961（7）°, V= 912.3（10） A3, Z = 2, Mr = 486.75, Dc = 1.772 Mg/m3,/t = 1.234 mm-1, F（000） = 484, the final R = 0.0735 and wR = 0.1739 for 2154 observed reflections with 1 〉 20（I）. Polymer 1 consists of （Cd-Hiba）2 zigzag chains, which are further linked by hydrogen bonding to extend into a two-dimensional （2D） corrugated-shape sheet structure. The 2D structures are further connected into a 3D supramolecular edifice through hydrogen bonding. The polymer exhibits exceptional high thermal stability. The bulk purity of the materials of 1 was confirmed through the powder X-ray diffraction （PXRD） patterns. The luminescent property of polymer I has also been investigated.

Topology and Photoluminescence Property of a Neodymium-carboxylate Coordination Polymer Based on a Tripodal Flexible Ligand

A new metal-organic coordination polymer {[Nd（tci）（H2O）2]·2H2O}n（1） has been synthesized based on the flexible tricarboxylate ligand tris（2-carboxyethyl）isocyanuric acid（H3tci） and structurally characterized by single-crystal X-ray diffraction analyses, elemental analysis, infrared spectra（IR）, powder X-ray diffraction（PXRD） and thermogravimetric analysis（TGA）. Complex 1 crystallizes in triclinic, space group P1 with a = 9.1648（11）, b = 9.3326（12）, c = 12.440（2） , C（12）H（20）N3O（13） Nd, Mr = 558.55, V = 886.9（2） 3, Z = 2, Dc = 2.092 g·cm-3, μ = 3.006 mm-1, F（000） = 554, 2.56〈θ〈25.00°, λ（Mo Kα） = 0.71073 , T = 293（2） K, the final R = 0.0662 and w R = 0.2071. X-ray diffraction analysis reveals that complex 1 is a two-dimensional layer, which is further assembled into a three-dimensional supramolecular architecture through hydrogen bonding interactions. The structure of complex 1 can be simplified as a rare 2-periodic uninodal {48·62} topology and a non-interpenetrating kgd topology. Furthermore, the thermal stability and photoluminescence property of 1 were investigated.

Synthesis of Y_2O_3:Eu^(3+) phosphors by surface diffusion and their photoluminescence properties

Y2O3:Eu3+ phosphors were synthesized by the surface diffusion method (SDM). X-ray diffractometry (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS) were used to characterize the structure, morphology and component of Y2O3:Eu3+ phosphors. The photoluminescent (PL) properties were also investigated. The results reveal that the PL intensity of Y2O3:Eu3+ phosphors prepared by the surface diffusion method (SDM) is much higher than that prepared by homogeneous co-precipitation. The luminescence efficiency of the sample (Y0.997, Eu0.003)2O3 prepared by the SDM is almost 1.9 times that by homogeneous co-precipitation. The concentration of Eu3+ in the phosphor Y2O3:Eu3+ prepared by the surface diffusion can be reduced greatly owing to the activator, Eu3+ ions, distributing mainly in the outer layer of the phosphors where the photon generation process occurs.

Solvothermal Synthesis,Crystal Structure and Photoluminescence Property of a 3D Lead(Ⅱ)Coordination Polymer Based on Terephthalic Acid

Solvothermal reaction of Pb（NO3）2·6H2O with rigid linear ligand terephthalic acid（H2pta） in N,N-dimethylformamide（DMF） produced a new three-dimensional（3D） lead（Ⅱ）coordination polymer[Pb2（pta）1.5（μ4-OH）（DMF）]n 1,and its structure was characterized by single-crystal X-ray diffraction analyses.In polymer 1,the μ4-OH bridges the nearby lead（Ⅱ） ions into an infinite one-dimensional（1D） chain,and then the organic ligand pta^2- joins the neighbored chains into a 3D structure by two similar connection modes in different configurations.The solid-state photoluminescent studies revealed that 1 exhibits a strong greenish emission mainly originating from ligand-to-metal charge transfer between the delocalized π bonds of the aromatic carboxylate ligand pta^2- and the p orbitals of the Pb^2＋ centers.

Correlation between the Low-Temperature Photoluminescence Spectra and Photovoltaic Properties of Thin Polycrystalline CdTe Films

A dominant intrinsic luminescence band, which is due to the surface potential barriers of crystalline grains, and an edge doublet, which arises as an LO-phonon repetition of the e-h band, has been revealed in the low-temperature photoluminescence spectra of fine-grained obliquely deposited films. Doping film with In impurity leads to quenching of the doublet band, while further thermal treatment causes activation of the intrinsic band, the half-width and the blue shift of the red edge of which correlates with the maximum value of anomalously high photovoltage generated by the film.

Frequency Up-conversion Luminescence Properties and Mechanism of Tm^(3+) /Er^(3+)/Yb^(3+) Co-doped Oxyfluorogermanate Glasses

Oxyfluoride glasses were developed with composition 60GeO 2 ·10AlF 3 ·25BaF 2 ·（1.95-x）GdF 3 · 3YbF 3 ·0.05TmF 3 ·xErF 3 （x=0.02,0.05,0.08,0.11,0.14,0.17）in mole percent.Intense blue（476 nm）,green（524 and 546 nm）and red（658 nm）emissions which identified from the 1G 4 →3H 6 transition of Tm3＋and the（2H 11/2 ,4S 3/2 ）→4I 15/2 ,4F 9/2 →4I 15/2 transitions of Er3＋,respectively,were simultaneously observed under 980 nm excitation at room temperature.The results show that multicolor luminescence including white light can be adjustably tuned by changing doping concentrations of Er3＋ion or the excitation power.In addition,the energy transfer processes among Tm3＋,Er3＋and Yb3＋ions,and up-conversion mechanisms are discussed.

Syntheses,Crystal Structures and Photoluminescence Properties of Two Cadmium(Ⅱ)Coordination Polymers

The solvothermal reaction of CdCl2·2.5H2O with terephthalic acid yields two new three-dimensional(3D)cadmium(II)coordination polymers(CPs),namely{[Cd(C8H4O4)Cl]·C2H8N}n and[Cd(C8H4O4)]n,we use the abbreviations CP1 and CP2 to refer to them,respectively.The compounds are characterized in detail by single-crystal X-ray diffraction,powder X-ray diffraction,IR spectroscopy,elemental analysis and thermogravimetric analysis(TGA).The results indicate that compounds CP1 and CP2 are 3D frameworks,and both the compounds feature a uninodal 4-connected framework with a dia net.The empty spaces of such 3D framework are filed by the other two identical frameworks,leading to a 3-fold interpenetrated network.In addition,the photochemical properties of the frameworks are also investigated.The two frameworks show strong solid-state fluorescence emission at 463 and 503 nm,respectively,which are obvious red-shift compared to the emission of ligand.

Photoluminescence Properties of Si_(1-x)Ge_x/Si Strained Layer Structures

The investigation on optical properties of Si1-xGex/Si strained layer structures has been carried out actively in recent years. The photoluminescence has become a brisker subject in the studies of its various optical properties. A research development on photoluminescence properties of some new Si1-x Gex/Si strained layer structures is introduced.

Synthesis,Structure and Photoluminescent Property of a Cd-organic Complex [Cd(L)_2(pbda)]_n

A new complex,[Cd（L）2（pbda）]n（1,L = 3-（2-pyridyl）-4-（p-methoxyphenyl）-5-（2-thienyl）-1,2,4-triazole,H2pbda = 1,4-benzenedicarboxylic acid）,has been hydrothermally prepared and characterized by single-crystal X-ray diffraction,IR spectroscopy,elemental analysis and PXRD.The complex crystallizes in monoclinic,space group P21/c with a = 8.2929（9）,b = 21.668（2）,c = 10.9940（11） ,β = 90.242（2）o,V = 1975.5（4） 3,Z = 2,C44H32N8O6S2Cd,Mr = 945.30,Dc = 1.589 g/cm3,μ = 0.721 mm-1,S = 1.097,F（000） = 960,the final R = 0.0590 and wR = 0.1045 for 3846 observed reflections（I 2σ（I））.In the title complex,the rigid bridging pbda2-ligands utilize oxygen atoms of carboxylate groups to coordinate with Cd（II） atoms to form one-dimensional chains which are further interlinked into a three-dimension framework via the intermolecular weak interactions.Photoluminescence study revealed that complex 1 exhibits strong fluorescent emission band in the solid state at room temperature.

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 ligand in europium complex. Therefore, a new europium complex with saturated emission, strong fluorescent 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 electroluminescent materials.

Synthesis, Structure and Photoluminescent Property of a New 3D Cd(Ⅱ) Coordination Polymer with Terphenyl-2,2',4,4'-tetracarboxylic Acid and 1,10-Phenanthroline

A new 3D Cd（II） coordination polymer, [Cd2L（phen）（HzO）]n （1, HaL = terphenyl- 2,2＇,4,4＇-tetracarboxylic acid, phen = 1,10-phenanthroline）, has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis, elemental analysis, TGA and IR spectroscopy. Complex 1 crystallizes in the monoclinic system, space group P21/c with a = 8.196（2）, b = 18.348（5）, c = 19.036（5） A, β = 97.741（5）°, V= 2836.6（14） A3, Z = 4, Dc = 1.933 Mg.m-3, p = 1.565 mm1, F（000） = 1624, the final R = 0.0356 and wR = 0.0612 for 4990 observed reflections with 1 〉 2a（I）. Complex 1 has a 1D chain containing Cd4 structural units, which are linked by 2- and 2＇-carboxyl groups of L4- to result in a 3D framework. Additionally, the photoluminescent property of 1 was also studied in the solid state at room temperature.

Fluorescence Quenching of a Novel Eu(Ⅲ) Coordination Compound for the Detection of Trace Amounts of Water： Synthesis, Structure and Photoluminescent Property

A novel luminescent coordination compound Eu（TTA）3（DEDAF）（1, TTA = 1,1,1-trifluoro-3-（2-thenoyl）acetone, DEDAF = 9,9-diethyl-4,5-diazafluoren） has been synthesized and fully characterized by infrared spectrum, elemental analysis, UV-vis spectrum, etc. X-ray single-crystal diffraction analysis reveals that compound 1 shows a mononuclear structure with the europium atom in coordinating to one DAF and three TTA ligands. The mononuclear structure units are assembled into a 3-D polymer by hydrogen bonds and π-π interactions. Photoluminescent property of 1 was investigated in detail at room temperature. Complex 1 emits strong red luminescence. However, it could be quenched even by small amount of water. The fluorescence intensity at 614 nm decreases linearly with the water content increasing（vol% in acetonitrile） in the range of 0.025~0.2% under 278 nm excitation. Thermogravimetric analysis has also been studied, which demonstrates good thermal stability of 1.

Synthesis, Structure and Photoluminescence of One Zinc-based Metal-metallosalen Framework

Dicarboxyl-functionalized salen ligand 1,2-phenylendiamine-N,N＇-bis（3-tert-butyl-5-（carboxyl）-salicylide-ene （HAL） was synthesized in good yield from 3-tert-butyl-5-formyl-4-hy- droxybenzoic acid and used to construct a 2D zinc complex, [（ZnL）Zn3/2（BDC）1/2（DMSO）2]·3DMSO （1, BDC = 1,4-benzenedicarboxylate）, under mild reaction conditions. 1 was characterized by IR, microanalysis, TGA and single-crystal X-ray crystallography. It crystallizes in triclinic space group P^-1 with a = 11.3860（4）, b = 13.2636（5）, c = 17.5503（7） A, α = 92.2240（10）, β = 94.5070（10）, γ = 96.0580（10）°, V= 2624.52（17） A^3, Z = 2, Mr = 1143.62, Dc = 1.448 g/cm^3, F（000） = 1186, g = 1.395 mm^-1, GOOF = 0.993, the final R = 0.0380 and wR = 0.1280 for 21752 observed reflections with I 〉 20（I）. The 2D coordination polymer 1 is further assembled into a 3D supramolecular network structure via π…π interactions between the aromatic rings of the ligands in adjacent layers. Thermal gravimetric analysis demonstrates that 1 is a thermally robust structure with network decomposition temperatures of 420 ℃ and it also exhibits strong photoluminescence in the visible region.

Synthesis,structure and photoluminescent property of a novel potassic compound

A novel 3D coordination compound of K（H2TDA）（H20） （1） （H3TDA = 1H-1,2,3-triazole-4,5-dicarboxylic acid） has been prepared and characterized by IR spectroscopy, elemental analysis, ICP and single-crystal X-ray diffraction. Compound 1 displays strong fluorescent emission at room temperature.

Synthesis, Crystal Structure and Photoluminescent Property of a Novel Disilver Complex with Pyrazinyl Oxime Ligand

A novel binuclear Ag（I） complex [Ag2（C6H6NaO）2（C6H7N3O）2]·2CH3CN （1） was synthesized by the evaporation reaction of silver nitrate and （E）-1-（pyrazin-2-yl）ethanone oxime （HL）. The complex was characterized by elemental analysis, IR spectrum and X-ray single-crystal diffraction analysis. It crystallizes in the monoclinic space group C2/c with a = 22.7089（3）, b = 11.5443（7）, c = 16.1468（4）/A, β = 127.7150（10）°, V= 3348.6（2） A^3, Dc = 1.675 g/cm^3, Mr = 844.42, Z = 4, F（000） = 1696.0,μ = 1.226 mm^-1, the final R =0.0250 and wR = 0.070. The coordination around the silver（I） atom is a distorted trigonal-bipyramidal geometry involving one protonated pyrazinyl oxime ligand （HL）, one deprotonated oxime ligand （L^-） and one CH3CN solvate molecule in the asymmetric unit of complex 1.