Pengfei Yan

Heilongjiang University, Charbin, Heilongjiang Sheng, China

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Publications (57)240.16 Total impact

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    ABSTRACT: Five mononuclear lanthanide complexes were obtained.•Two distinct ligands were in-situ self-assembled.•Ce3+ ions were oxidized to Ce4+ ions in the reaction mixture.•NIR luminescence of Yb3+ ions was observed.
    Journal of Molecular Structure. 02/2015; 1081.
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    ABSTRACT: Variable-temperature dc magnetic susceptibility shows weak long-range order of chain of magnetization.•The dynamic susceptibility exhibits a typical of SMM behavior.•The Cole–Cole curves show the presence of at least two relaxation processes at a low temperature.•We report a Salen-type dysprosium complex that represents pure 4f SIMs with 1D ionic coordination network.
    Inorganic Chemistry Communications 01/2015; 51. · 2.02 Impact Factor
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    ABSTRACT: A series of short-conjugated zwitterionic cyanopyridinium chromophores were synthesized through a simple and versatile synthetic method. The charge-separated ground state of the zwitterions was confirmed by X-ray crystallography. Negative solvatochromism, fluorescence properties and nonlinear optical property of the new zwitterions were investigated.
    Dyes and Pigments 12/2014; 111:145–155. · 3.53 Impact Factor
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    ABSTRACT: Two polyoxometalates based coordination polymers (POMCPs) constructed form Keggin POMs and Ag+ with pyttz were synthesized, [Ag4(H2pyttz-I)(H2pyttz-II)(Hpyttz-II)][HSiW12O40]•4H2O (1) and [Ag4(H2pyttz-II)(Hpyttz-II)2][H2SiW12O40]•3H2O (2). (H2pyttz-I = 3-(pyrid-2-yl)-5-(1H-1,2,4-triazol-3-yl)-1,2,4-triazolyl; H2pyttz-II = 3-(pyrid-4-yl)-5-(1H-1,2,4-triazol-3-yl)-1,2,4-triazolyl). Both compounds have the similar building units, the similar stick-like units and the similar 1D inorganic chains, but finally obtain the different motifs of tunnels (tunnel A in 1 and tunnel A&B in 2). By careful inspection of structures of 1 and 2, it is believed that the isomerous pyttz molecules can precisely refine the structure of porous POMCPs without changing the underlying framework, which is favor of the study about the structure-activity relationship of POMCPs. Furthermore, the results of the photocatalytic activities show that compound 2 exhibits higher photocatalytic activity than that of compound 1, which is consistent with their structural characteration.
    Dalton Transactions 11/2014; · 4.10 Impact Factor
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    ABSTRACT: Three different fold interpenetrated metal-organic networks based on Keggin-type polyoxometalates have been hydrothermally synthesized by a simple change in organic ligand and structurally characterized. By changing the length and coordination mode of ligand, compound 1 represents the first example of three-fold interpenetrated POMOF architecture with pcu topology, and POMs occupy the vertex of pcu lattice. Compound 2 exhibits a POM-pillared metal-organic framework, which can be described overall as two-fold interpenetrated pcu frameworks, and POMs occupy the arris of pcu lattice. Different from 1 and 2, compound 3 can be described as a single pcu network and POMs occupy the face of pcu lattice. The influence of the organic ligand on the degree of interpenetration is also discussed. Furthermore, the results about the photocatalytic activities indicate that three compounds present good photocatalytic activities.
    CrystEngComm 10/2014; · 3.88 Impact Factor
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    ABSTRACT: The correspondence between triplet location effect and host-localized triplet-triplet annihilation and triplet-polaron quenching effects was performed on the basis of a series of naphthyldiphenylamine (DPNA)-modified phosphine oxide hosts. The number and ratio of DPNA and diphenylphosphine oxide was adjusted to afford symmetrical and unsymmetrical molecular structures and different electronic environments. As designed, the first triplet (T1 ) states were successfully localized on the specific DPNA chromophores. Owing to the meso- and multi-insulating linkages, identical optical properties and comparable electrical performance was observed, including the same first singlet (S1 ) and T1 energy levels to support the similar singlet and triplet energy transfer and the close frontier molecular orbital energy levels. This established the basis of rational investigation on T1 location effect without interference from other optoelectronic factors.
    Chemistry - A European Journal 10/2014; · 5.93 Impact Factor
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    ABSTRACT: A series of lanthanide (III) complexes constructed from Schiff base and β-diketonate ligands have been synthesized by the same method. They are mononuclear complex [Ln(hfac)3(L)] (Ln = Nd (1); Sm (2); Eu (3)); tetranuclear complex [Gd4(μ2-CH3COO)2L3(hfac)10] (4); dinuclear–mononuclear cocrystal [Dy(hfac)2(L)]2(μ2-CH3COO)·[Dy(hfac)4] (5); mononuclear–mononuclear cocrystal [Yb(hfac)2(L)]·[Yb(hfac)4] (6) (L = N,N'-bis(pyridine)-1,2-ethanediamine, hfac = hexafluoroacetylacetonate). The complexes 1–3 and 6 exhibit characteristic metal-centered emission not only in solid state but also in solvent. Lifetimes and quantum yields of luminescence are also determined.
    CrystEngComm 09/2014; · 3.88 Impact Factor
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    ABSTRACT: Highly efficient green and red electro-phosphorescence is achieved in devices with the host material DPESPODEF3. The multiple fluorenyl moieties of the host material are arranged such that it has an unsymmetrical molecular configuration, and its triplet-state location is tuned such that it has independent energy (ET) and charge transfer (CT) channels. As a result, DPESPODEF3 can suppress triplet-triplet annihilation and triplet-polaron quenching. In the resulting green and red phosphorescent devices, impressive external quantum efficiencies of ca. 20% and 16% and power efficiencies of ca. 75 and 20 lm W(-1) , respectively, are observed.
    Advanced Materials 09/2014; · 14.83 Impact Factor
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    ABSTRACT: A series of three β-diketone mononuclear dysprosium complexes, namely, Dy(TFI)3(H2O)2 (1), Dy(TFI)3(bpy) (2), and [Dy(TFI)3(Phen)]·0.02CHCl3 (3) (TFI = 2-(2,2,2-trifluoroethyl)-1-indone, bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline) have been designed and synthesized. Crystal structure analysis reveals that complexes 1-3 have haveisomorphic structures in which the central Dy(III) ion is eight-coordinated by six oxygen atoms from three TFI ligands and two O/N atoms from auxiliary ligands, forming a distorted bicapped trigonal prismatic geometry for 1, a distorted dodecahedral geometry for 2, and a distorted square antiprismatic geometry for 3, respectively. Magnetic studies indicate that complex 2 with D2d symmetry and 3 with D4d symmetry exhibit slow magnetic relaxation with barrier heights (Ueff/kB) of 48.8 K for 2 and 57.9 K for 3. Strikingly, the relaxation time (τ) of 0.0258 s for 3 is about 20 times that for 2, which is presumably associated with larger rotation of the SAP surroundings for 3. Further, complexes 2 and 3 exhibit essential magnetic hysteresis loops at 1.8 K. These extend the recent reports of the single-ion magnets (SIMs) of β-diketone mononuclear dysprosium complexes.
    Inorganic Chemistry 08/2014; · 4.59 Impact Factor
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    ABSTRACT: A series of solution-processible electroluminescent (EL) Eu3+ complexes were constructed with a self-host strategy, in which neutral ligands were employed as functionalized bidentate phosphine oxide (PO) ligands named DPEPOArn (DPEPO=bis(2-(diphenylphosphino)phenyl) ether oxide). The solubility of these complexes was dramatically improved owing to the increased ratios of organic components. This further enhanced the antenna effect of these ligands in both singlet and triplet energy-transfer processes to support high photoluminescent quantum yields (PLQYs) up to 86 % for their Eu3+ complexes, which is outstanding among conjugated Eu3+ complexes. Density function theory (DFT) simulations and electrochemical analysis further verified the contributions of DPEPOArn to the carrier injecting/transporting ability of the complexes. In this sense, these functionalized PO ligands served as hosts in optoelectronic processes, which rendered the self-host feature of their Eu3+ complexes. With the enhanced electrical properties, the spin-coated single-layer organic light-emitting diodes (OLEDs) of these complexes achieved improved low driving voltages, such as onset voltages about 6 V, compared to their Eu3+-contained red-emitting polymeric analogues. [Eu(DBM)3DPEPODPNA2] (DBM=1,3-diphenylpropane-1,3-dione, DPNA=diphenylnaphthylamine) with the most enhanced electrical properties and suitable frontier molecular orbital (FMO) and triplet state locations endowed its devices with the biggest maximum luminance of >90 cd m−2 and the highest EL efficiencies. This work verified the potential of small molecular EL Eu3+ complexes for solution-processed OLEDs through rational function integrations.
    Chemistry - A European Journal 07/2014; · 5.93 Impact Factor
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    ABSTRACT: A series of pyrazine-2,3,5,6-tetracarboxylate alkali-lanthanide coordination frameworks, namely [NaLn(pztc)(H2O)3]·H2O [Ln = Ce (), Sm (), Eu (), Gd () and Tb (); H4pztc = pyrazine-2,3,5,6-tetracarboxylic acid], have been synthesized by reacting Ln(NO3)3·6H2O with H4pztc in the presence of NaOH at room temperature. X-ray crystallographic analysis reveals that complexes are isostructural, featuring three-dimensional (3D) networks with a unique (4(11)·6(8)·8(2))(4(3)·6(2)·8)(4(3)) topology in which the ligand displays a novel μ7-coordination mode. The photoluminescence (PL) spectra in the solid state reveal that complexes , and exhibit the characteristic luminescence of Sm(iii), Eu(iii) and Tb(iii) ions, respectively, while complex displays a broad band in the range of 400-650 nm (λmax = 505 nm) which exhibits about 103 nm red-shift and enhancement compared to the band of the free ligand. Further, the isostructural two-component Eu(iii)-doped Gd(iii) complexes realize color-tunable luminescence from red to yellow, white, green and blue by the variation of excitation wavelengths. They represent the first example of full-color-tunable emission in lanthanide coordination frameworks by the variation of excitation light.
    Dalton Transactions 07/2014; · 4.10 Impact Factor
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    ABSTRACT: Three chloride-bridged lanthanide compounds, [Ln4Cl6(CH3OH)12(OH)2]·4Cl·2CH3OH [Ln = Gd (), Dy () and Er ()], have been unexpectedly isolated by the reactions of LnCl3·6H2O and N,N'-bis(salicylidene)-1,2-(phenylene-diamine) (H2L). X-ray crystallographic analysis reveals a triclinic cell with a unique defect-dicubane {Ln4} core and the structure across this series is nominally isomorphic. Measurements of direct current magnetic susceptibility and isothermal magnetization give insight into the relevant cluster Hamiltonians for , , and , and alternating current susceptibility shows slow relaxation in , but not in or down to 2 K and up to 1 kHz.
    Dalton Transactions 06/2014; · 4.10 Impact Factor
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    ABSTRACT: Five N,N′-bis(salicylidene)-1,2-cyclohexanediamine (H2L) lanthanide coordination polymers featuring unique 1D liner and 1D spiral chain structures exhibit SHG active, NIR luminescence and red emission.
    Synthetic Metals 06/2014; 192:29–36. · 2.11 Impact Factor
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    ABSTRACT: A novel bis-β-diketone ligand, 4,4'-bis(4,4,4-trifluoro-1,3-dioxobutyl)(phenoxy)-1,1'-binaphthalene (BTPB), is designed for synthesis of a white light emissive lanthanide complex. The ligand bears two benzoyl β-diketonate sites linked by a 1,1'-binaphthoxy spacer. Reaction of the doubly negatively charged bis-bidentate ligand with lanthanide ions forms triple-stranded dinuclear complexes Sm2(BTPB)3(H2O)4 () and Gd2(BTPB)3(H2O)4 (), which have been fully characterized by various spectroscopic techniques. UV-Vis absorption and emission spectroscopic techniques are used to investigate photophysical properties of the ligand and its complexes in THF and CHCl3. In some cases aggregation of the ligand results in the appearance of a new luminescence band at about 510 nm in addition to the monomer fluorescence. In complex , partial energy transfer from BTPB results in Sm(iii)-based red light emission in addition to the BTPB-based blue/green emission. With the variation of the excited wavelength and concentration of the solution, complex shows a tunable white light emission with the balance of three primary colors. This is an unusual case of observation of white light emission from a single molecule Sm(iii) complex.
    Dalton Transactions 05/2014; · 4.10 Impact Factor
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    ABSTRACT: Three novel alkali–lanthanide heterometal–organic frameworks, namely, [K5Ln5(pztc)5(H2O)19]·7H2O [Ln = Dy (1), Ho (2), and Yb (3); H4pztc = pyrazine-2,3,5,6-tetracarboxylic acid], have been facilely synthesized. X-ray crystallographic analysis reveals that complexes 1–3 are isostructural, featuring unique 3D open frameworks, which possess a rare (4,8)-connected net with the Schläfli symbol of (415·612·8)(45·6)2. The 3D coordination framework involves a ladder-like square column structure by pztc4– ligands bridging metal ions, exhibiting 1D channels along the b axis. The magnetic analysis suggests that complexes 1 and 3 exhibit frequency-dependent out-of-phase signals in alternating current magnetic susceptibility measurements, indicating their slow magnetic relaxation characteristics. It is the first report of slow magnetic relaxation behavior existing in Yb3+-based HMOFs.
    Crystal Growth & Design 03/2014; 14(4):2014–2021. · 4.69 Impact Factor
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    ABSTRACT: Graphical abstract Two 7,7,8,8-tetracyanoquinodimethane (TCNQ) Pb2+ and Zn2+ complexes featuring unique 3D and 0D structure have been isolated and structurally determined.
    Inorganica Chimica Acta 03/2014; 413:32–37. · 1.69 Impact Factor
  • Journal of Luminescence 02/2014; · 2.14 Impact Factor
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    ABSTRACT: A series of phosphine oxide hosts were constructed to investigate the influence of the triplet state extension in hosts on electrophosphorescence, in which DPESPOPhCz with the carbazolyl-localized triplet state endowed its blue-emitting PHOLEDs with favourable performance, including an external quantum efficiency more than 13%.
    Chemical Communications 01/2014; · 6.38 Impact Factor
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    ABSTRACT: Two discrete salen type homo-multinuclear Yb3 and Yb4 complexes, namely, [Yb3L3(OAc)3]·3CH3OH·H2O (1) and [Yb4L2(OAc)4(μ3-OH)2(H2O)2](ZnCl4)·3CH3OH (2) (H2L = N,N′-bis(2-oxy-3-methoxybenzylidene)-1,2-phenylenediamine) have been synthesized by reactions of H2L and different ytterbium salts. X-ray crystallographic analysis reveals that complex 1 exhibits a triple-decker Yb3 sandwich structure with a ratio of H2L:Yb = 1:1, while complex 2 exhibits a defect-dicubane Yb4 core with a ratio of H2L:Yb = 1:2. The NIR luminescence of complexes 1 and 2 have been investigated and discussed.
    Journal of Inorganic and Organometallic Polymers and Materials 01/2014; · 1.17 Impact Factor
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    ABSTRACT: With the aim to rationally figure out the significance of charge and exciton capture in the electrophosphorescent processes in low-triplet-energy hosts involved doping systems, the frontier molecular orbital (FMO) energy levels of a series low-triplet-energy hosts with diphenylphosphine oxide (DPPO) and triphenylamine (TPA), collectively named DPExPOTPAn, were successfully and gradually tuned on the basis of their constant triplet energy levels (T1) of 2.63 eV to get rid of interference from host-dopant energy transfer. It was showed that device efficiencies were directly proportional to the depths of carrier traps formed on the dopants and inversely proportional to the exciton capture ability of the hosts, which were evidenced by the highest external quantum efficiency of 15% from FIrpic-based PHOLED of DPESPOTPA with the deepest hole and electron traps and the weakest exciton capture ability among DPExPOTPAn. This work not only demonstrated the great advantages and potential of this kind of host materials for low-driving-voltage application but also clarified the determinants of highly efficient low-triplet-energy hosts for blue PHOLEDs, which are consequentially referable for purposeful molecular design.
    Chemistry of Materials 12/2013; 25(24):4966–4976. · 8.24 Impact Factor