Pengfei Yan

Heilongjiang University, Charbin, Heilongjiang Sheng, China

Are you Pengfei Yan?

Claim your profile

Publications (70)275.82 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A series of three salen-type lanthanide complexes, e.g., [Dy4(L)2(HL)2Cl2(μ3-OH)2]2Cl2(OH)2·3CH3CH2OH·H2O (1) and [Ln4(L)2(HL)2Cl2(μ3-OH)2]Cl2·5CH3OH·4CH2Cl2 (Ln = Tb(III), 2; Ho(III), 3) have been isolated by the reactions of H2L (H2L = N,N'-bis(3-methoxysalicylidene)cyclohexane-1,2-diamine) with LnCl3·6H2O. X-ray crystallographic analysis reveals that all complexes 1-3 are isostructural, in which four Ln ions and eight O atoms form the distorted defective dicubane {Dy4O8} cores. Magnetic studies indicate that complex 1 exhibits two slow magnetic relaxation processes with effective energy barrier Ueff = 55.71 K under a zero direct-current field, which is attributed to the two coordination geometries of the Dy(III) ions with a salen-type ligand and coordination of a chloride counterion. It represents the highest energy barrier among the salen-type tetranuclear lanthanide single-molecule magnets.
    Inorganic Chemistry 03/2015; DOI:10.1021/acs.inorgchem.5b00061 · 4.79 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A series of four β-diketone mononuclear dysprosium complexes, namely, Dy(EIFD)3(H2O)·CH2Cl2 (1), Dy(EIFD)3(DMF)·CH2Cl2 (2), Dy(EIFD)3(DMSO) (3), and Dy(EIFD)3(TPPO) (4) (EIFD: 1-(1-ethyl-1H-indol-3-yl)-4,4,4-trifluorobutane-1,3-dione, TPPO: triphenylphosphine oxide) have been isolated by the reactions of a newly designed β-diketone EIFD, DyCl3·6H2O and DMF, DMSO, TPPO, respectively. X-ray crystallographic analysis reveals that complexes 1−4 are isomorphic mononuclear structure in which the Dy(III) ion is rarely seven-coordinated with C3v geometry. Magnetic studies indicate that all complexes 1−4 are single-molecule magnets. The correlations between magnetism and the distortion of the coordination symmetry around the Dy(III) ions have been investigated. Notably, the quantum tunneling of magnetization (QTM) which universally existed in the lanthanide complexes have been effectively suppressed in this system more related to the less deviation from the ideal C3v symmetry.
    03/2015; DOI:10.1039/C5TC00321K
  • [Show abstract] [Hide abstract]
    ABSTRACT: Self-assembly reaction of 2-aldehyde-8-hydroxyquinoline, tris(hydroxymethyl)aminomethane and LnCl(3)center dot 6H(2)O affords a series of mononuclear lanthanide complexes Ce(baho)(2)center dot Et2O (1) (H(2)baho = 2,8-bis(2-(8-hydroxylquinolinyl))-1-aza-5-hydroxymethyl-3,7-dioxabicyclo[3.3.0]octane), DY(nhm)(2)Cl center dot 0.5H(2)O (2) and Ln(nhm)(2)Cl center dot 0.5C(6)H(14) (Ln = Ho (3), Er (4), Yb (5) and Hnhm = N-(2-(8-hydroxylquinolinyl)methylene)(trishydroxymethyl)methylamine. The crystal structures have been determined by Xray crystallographic analysis, and the tetravalence of Ce in 1 has been proven by XPS. Interestingly, the positive charge of Ce4+ ion in 1 is neutralized by two deprotonated baho(2-) ligands, while two deprotonated nhm(-) ligands and one Cl- compensate the positive charge of Ln(3+) ions in 2-5. Complex 5 exhibit essential NIR luminescence of Yb3+ ion with lifetime of 17.64 mu s in solid and 9.96 mu s in CH3OH solution.
    Journal of Molecular Structure 02/2015; 1081. DOI:10.1016/j.molstruc.2014.10.033 · 1.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: One Ag+ homometallic complex [Ag4(pzdc)2]·H2O (1), and five Ln-Ag heterometallic complexes, namely, [Gd2Ag6(pzdc)6(H2O)9]·8H2O (2) and [LnAg(pzdc)2(H2O)2]·2H2O [Ln = Tb (3), Dy (4), Ho (5), Er (6)] based on pyrazine-2,3-dicarboxylate (pzdc2-) have been synthesized under room temperature. Complex 1 exhibits 3D metal-organic framework by Ag2 ions connecting 1D square columns consisting of Ag1 ions and pzdc2- ligands, possessing a unique trinodal net with {42·6}{43}{45·64·83·103} topology. Complex 2 displays a 3D heterometal-organic framework with a novel 12-nodal topological net constructed by Gd1 ions linking the adjacent Ag-pzdc2- anion layers. Complexes 3-6 are isostuctural 2D Ln-Ag heterometallic coordination frameworks featuring uninodal 4-connected net with {44·62} topology. Magnetic analyses suggest that complexes 4 and 6 exhibit field-dependent slow magnetic relaxation, and complex 6 represents the first slow magnetic relaxation behavior existing in Er3+-based 2D heterometallic coordination framework.
    Crystal Growth & Design 01/2015; DOI:10.1021/cg501644z · 4.56 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A new flexible Salen-type dysprosium coordination polymer, [Dy2(H2L)2(NO3)4(CH3O)2]n (1) (H2L = N,N'-bis(salicylidene)-1,4-butane-diamine), has been synthesized by a solvothermal method. The single-crystal X-ray diffraction studies reveal that complex 1 features a two dimension (2D) network structure with rare dinuclear units. Each Dy(III) ion is eight-coordinated where the μ2-(OCH3)2 bridged Dy2O2 cores are linked by four Salen-type ligands in bidentate fashion. Magnetic studies reveal that complex 1 presents antiferromagnetic interactions between Dy(III) centers and exhibits the frequency dependent peaks, a behavior characteristic of a single-molecule magnet.
    Inorganic Chemistry Communications 01/2015; 54. DOI:10.1016/j.inoche.2015.01.031 · 2.06 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Four isomorphic tetranuclear lanthanide complexes, namely [Ln4(L)2(HL)2(NO3)2(OH)2](NO3)2·4H2O (Ln = Dy (); Tb (); Ho (); Er ()), constructed using hexadentate salen-type ligand N,N'-bis(3-methoxy-salicylidene)cyclohexane-1,2-diamine, have been isolated. X-ray crystallographic analysis reveals that all of the complexes are of discrete tetranuclear structure with a unique {Ln4O8} core in which four lanthanide ions are coplanar in a rhombic frame. There are two crystallographically unequivalent lanthanide ions, that is the Ln1(III) ion which is nine-coordinated in a monocapped square-antiprismatic geometry of the C4v point group and the Ln2(III) ion which is eight-coordinated in a distorted bicapped trigonal-prismatic geometry of the C2v point group. Magnetic analysis reveals that complex exhibits two slow magnetic relaxations with the highest energy barrier among the reported tetranuclear salen-type dysprosium SMMs. This further extends the available SMMs of salen-type lanthanide complexes.
    Dalton Transactions 01/2015; 44(9). DOI:10.1039/c4dt02607a · 4.10 Impact Factor
  • [Show abstract] [Hide abstract]
    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. DOI:10.1016/j.inoche.2014.11.007 · 2.06 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Two novel bifunctional 1,8-naphthalimide-based ligands incorporating coordinated carboxyl group and blue emitting 1,8-naphthalimide, 3-(1,8-naphthalimido)ethanoic acid (HL1) and 3-(1,8-naphthalimido)propanoic acid (HL2), are designed for synthesis of white light emitting lanthanide complexes. Self-assembly of ligands with lanthanide ions formed two series of 1D coordination polymers {Ln(L1)3(CH3OH)(H2O)}n (Ln = Eu3+ (1), Gd3+ (2)) and {[Ln(L2)3(H2O)]•H2O}n (Ln = Eu3+ (3), Gd3+(4)). The single crystal X-ray crystallography analyses reveal the complexes feature 1D chain structure. In 1 and 3, partial energy transfer from the 1,8-naphthalimide moieties to the metal centres results in sensitized Eu(III)-based emission in addition to the ligand-based blue/green luminescence. Through changing the length of the linkers between the chromophore and the metal centre, energy transfer efficiency of ligands-to-Eu is effectively controlled. In 1, the emission spectrum is mainly dominated by the red light of the Eu(III) ions. However, the red light emission is suppressed in 3 due to the decrease of chromophore-to-Eu energy transfer efficiency. This effective adjustment realized the balance of three primary colours, and thus resulting in white light emission of 3. This result opens up a new synthetic strategy for white light emitting materials.
    12/2014; 3(8). DOI:10.1039/C4TC02512A
  • [Show abstract] [Hide abstract]
    ABSTRACT: A new class of short-conjugated zwitterionic cyanopyridinium chromophores with the absorption maxima less than 550 nm were designed and synthesized. These chromophores display a good solubility in organic solvents and exist in a charge-separated ground state, as confirmed by IR, X-ray crystallography, negative solvatochromism and fluorescence studies. They can be doped up to 10% by weight into poly(ether sulfone) and attached onto a methacrylate polymer by grafting. Without optimization of the poling conditions, a high electro-optic coefficient can be readily achieved using the chromophore-grafted nonlinear optical polymers.
    Dyes and Pigments 12/2014; 111:145–155. DOI:10.1016/j.dyepig.2014.06.005 · 3.47 Impact Factor
  • [Show abstract] [Hide abstract]
    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 12/2014; 20(49). DOI:10.1002/chem.201404615 · 5.70 Impact Factor
  • [Show abstract] [Hide abstract]
    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; 44(4). DOI:10.1039/C4DT02960G · 4.10 Impact Factor
  • [Show abstract] [Hide abstract]
    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; DOI:10.1039/C4CE01725K · 3.86 Impact Factor
  • [Show abstract] [Hide abstract]
    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; 16(45). DOI:10.1039/C4CE01556H · 3.86 Impact Factor
  • [Show abstract] [Hide abstract]
    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; 26(41). DOI:10.1002/adma.201400710 · 15.41 Impact Factor
  • [Show abstract] [Hide abstract]
    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 08/2014; 20(35). DOI:10.1002/chem.201403244 · 5.70 Impact Factor
  • [Show abstract] [Hide abstract]
    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; 53(17). DOI:10.1021/ic500501r · 4.79 Impact Factor
  • [Show abstract] [Hide abstract]
    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; 43(33). DOI:10.1039/c4dt00837e · 4.10 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: By introducing mixed organic ligands (pytz and 4,4′-bipy) into a Keggin POM system, a new Keggin POM-based supramolecular compound, [Cu3(bipy)4(pytz)2(H2O)6][HSiMo12O40]2·8H2O (1) (pytz = 5-(pyridyl)tetrazolate, bipy = 4,4′-bipy) was hydrothermally synthesized and characterized by routine methods. Crystal structure analysis reveals that the title compound contains both right- and left-helical chains, and these helical chains are further connected together forming an interesting mesh network via sharing the [Cu3(bipy)4(pytz)2(H2O)6] subunits. Finally, the 1D pillar-like chains link the mesh nets to construct a 3D supramolecular structure of 1. In addition, compound 1 shows good photocatalytic activity for the degradation of Rhodamine B dye.
    Journal of Inorganic and Organometallic Polymers and Materials 07/2014; 24(4):706-712. DOI:10.1007/s10904-014-0030-3 · 1.08 Impact Factor
  • [Show abstract] [Hide abstract]
    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; 43(31). DOI:10.1039/c4dt01329h · 4.10 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A series of five new N,N'-bis(salicylidene)-1,2-cyclohexanediamine (H2L) lanthanide coordination polymers, namely, [Nd((HL)-L-2)(NO3)(MeOH)-Me-3](n) (1), {[Sm(H2L)Cl-2(MeOH)(3)]Cl center dot 3MeOH}(n) (2), {[Ln(H2L)Cl-2(MeOH)(3)]Cl center dot 2MeOH}(n) [Ln =Gd (3) and Er (4)] and {[Lu(H2L)Cl-3(MeOH)].H2O}(n) (5) have been isolated by reactions of H2L with LnCl(3 center dot)6H(2)O and Ln(NO3)(3)center dot 6H(2)O, respectively. X-ray crystallographical analysis revealed that H2L effectively functions as a bridging ligand forming a series of 1D linear polymers 1 and 5 as well as ID spiral polymers 2-4. The luminescence of complexes I and 2 has been investigated. Complex 1 exhibits the NIR luminescence of Nd(III) ion and complex 2 exhibits co-luminescence of the ligand and the Sm(III) ions. The lowest triplet level of ligand H2L was calculated on the basis of the phosphorescence spectrum of complex 3. The energy transfer mechanism in the 2 were described and discussed. Strikingly, coordination polymers is SHG active, and the SHG efficiency is 0.4 times as much as that of urea.
    Synthetic Metals 06/2014; 192:29–36. DOI:10.1016/j.synthmet.2014.03.011 · 2.22 Impact Factor