Pengfei Yan

Heilongjiang University, Charbin, Heilongjiang Sheng, China

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Publications (77)297.75 Total impact

  • Rui Jia · Ting Gao · Yu Yang · Wenbin Sun · Ruoxi Chen · Pengfei Yan · Guangfeng Hou
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    ABSTRACT: The luminescence properties of the tetranuclear bimetallic lanthanide complexes Sm2Eu2 (1) and Eu2Tb2 (2), were compared with those of the analogous homometallic complexes [Sm4(μ3-OH)2(salen)2(acac)6(CH3OH)2]·CH3OH (3) and [Eu4(μ3-OH)2(salen)2(acac)6(CH3OH)2] (4) [H2salen = N, N′-ethylenebis(salicylideneimine), Hacac = acetylacetonate]. X-ray crystallographic analysis reveals that complexes 3 and 4 have planar tetranuclear structures. For the Eu2Tb2 configurational isomer, the TbIII ion in complex 2 mainly serves as a sensitizer. The quantum yields and lifetime measurements for 2 support the premise that Ln/Ln energy transfer occurs in such lanthanide bimetallic complexes, along with the usual ligand-to-metal triplet energy pathways. Complexes 3 and 4 exhibit the characteristic metal-centered emission.
    Zeitschrift für anorganische Chemie 07/2015; DOI:10.1002/zaac.201500138 · 1.25 Impact Factor
  • Yanping Dong · Pengfei Yan · Xiaoyan Zou · Guangming Li
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    ABSTRACT: A series of four β-diketone mononuclear dysprosium complexes, namely, Dy(DBM)3(bpy) (1), Dy(DBM)3(phen)·Tol (2), Dy(DBM)3(dpq)·Tol (3), and Dy(DBM)3(dppz) (4) (bpy = 2, 2'-bipyridine, phen = 1, 10-phenanthroline, dpq = dipyrazine [2, 3-f: 2´, 3´-h] quinoxaline, dppz = dipyrido [3, 2-a:2´, 3´-c] phenazine, Tol = toluene) have been isolated by the reactions of Dibenzoylmethane (DBM), azacyclo-auxiliary ligands and DyCl3·6H2O. X-ray crystallographic analysis reveals that complexes 1−4 are all eight-coordinated mononuclear structures. The azacyclo-auxiliary ligands have a dramatic effect on the structure and magnetic characteristics of complexes 1−4, originated from different degrees deviation from ideal coordination symmetry. Complexes 1 and 2 display a single relaxation mode under 0 Oe and complexes 3 and 4 display two single relaxation modes under 2000 Oe.
    06/2015; DOI:10.1039/C5QI00079C
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    ABSTRACT: Self-assembly of 2-aldehyde-8-hydroxyquinoline, histamine dichloride and LnX3•6H2O (X− = OAc−, NO3− and ClO4−) affords a series of lanthanide complexes Nd3(nma)2(OAc)7∙3CH3OH∙0.5H2O (1a), Ln3(nma)2(OAc)7∙2CH3OH [Ln = Tb (1b) and Dy (1c)], [Ln(nma)(NO3)2(DMSO)]∙CH3OH [Ln = Nd (2a), Tb (2b), Dy (2c) and Er (2d)] and [Dy(nma)2]∙ClO4∙0.5CH3OH (3) (Hnma = N-(2-(8-hydroxylquinolinyl)methane(2-(4-imidazolyl)ethanamine)). It is noted that the formation and structures of 1–3 are anion-dependent, where diverse coordination modes are detected for acetates in trinuclear 1 as compared to single coordination mode for nitrates in mononuclear 2. In the case of 3, the Dy3+ ion is completely encapsulated by two ligands with uncoordinated perchlorate anion balancing the charge. Magnetic measurement shows that the Dy complexes of 1c, 2c and 3 exhibit slow relaxations under zero dc field. It is noted that single molecular magnet behavior is obtained for 2c and 3 under an applied dc field of 2000 Oe.
    CrystEngComm 06/2015; 17(27). DOI:10.1039/C5CE00925A · 3.86 Impact Factor
  • Hongfeng Li · Tianyu Zhu · Peng Chen · Wenbin Sun · Ting Gao · Pengfei Yan
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    ABSTRACT: Two chemical structure similar ligands, mono-β-diketone (p-methoxylbenzoyl)trifluoroacetone (MBTF) and bis-β-diketone 1,2-bis(4,4'-bis(4,4,4-trifluoro-1,3-dioxobutyl))phenoxyl ethane (BTPE) have been designed and prepared for the purpose of building the relationships between the structures and luminescence properties of Eu(III) complexes. Structures of their Eu(III) complexes [Eu(MBTF)3(DMSO)(H2O)] and [Eu2(BTPE)3(DMSO)4] have been defined by single crystal X-ray crystallography. The mono-β-diketone complex [Eu(MBTF)3(DMSO)(H2O)] is a mononuclear structure, the central Eu(III) ion is coordinated by eight oxygen atoms from three ligands and two solvents, in an distorted trigonal-dodecahedral (8-TDH) geometry. Whereas, the bis-β-diketone complex [Eu2(BTPE)3(DMSO)4] adopts triple-stranded dinuclear structure in which the two Eu(III) are helically wrapped by three bis-bidentate ligands, and each Eu(III) ion is eight-coordinated by six oxygen atoms from the ligands and two oxygen atoms from the coordinated DMSO molecules, in a distorted square-antiprismatic (8-SAP) geometry. The photophysical properties related to the electronic transition are characterized by the absorbance spectra, the emission spectra, the emission quantum yields, the emission lifetimes, and the radiative (kr) and nonradiative rate constants (knr). The mono-β-diketone complex [Eu(MBTF)3(DMSO)(H2O)] offers a relatively high emission quantum yield (38%, in solid) compared to that observed in the bis-β-diketone complex [Eu2(BTPE)3(DMSO)4] (25%, in solid). This enhancement of emission quantum yield in mono-β-diketone complex can be attributed to its lower site symmetry around the Eu(III) ion, lower non-radiative rate constant and higher energy transfer efficiency from ligand to metal ion.
    Physical Chemistry Chemical Physics 05/2015; 17(24). DOI:10.1039/C5CP01392E · 4.20 Impact Factor
  • Guanghui An · Pengfei Yan · Jingwen Sun · Yuxin Li · Xu Yao · Guangming Li
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    ABSTRACT: The racemate-to-homochiral approach is a method to transform or separate a racemic mixture into homochiral compounds. This protocol, if without an external chiral source, is categorized into chiral symmetry breaking. The resolution processes without chiral induction are highly important for the investigation of the origin of homochirality in life, pharmaceutical synthesis, the chemical industry and materials science. Besides the studies on the models and mechanisms used to explain the racemate-to-homochiral approach which may give the probable origin of homochirality in life, recent developments in this field have been plotted towards the separation of enantiomers for the synthesis of pharmaceuticals and chiral chemicals. Direct synthesis of chiral metal–organic framework (MOF) coordination polymers has been achieved as well. In this highlight, we will disclose the comparison of spontaneous resolution and chiral symmetry breaking resolution, and describe the evolution of models and mechanisms for chiral symmetry breaking resolution and its applications in enantiomer resolution and materials science.
    CrystEngComm 04/2015; 17(24). DOI:10.1039/C5CE00402K · 3.86 Impact Factor
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    ABSTRACT: Three new Salen-type lanthanide coordination polymers, [Ln2(H2L)2(NO3)4(CH3O)2]n (Ln = Sm (1), Eu (2) and Lu (3); H2L = N,N’-bis(salicylidene)- 1,4-butanediamine), have been synthesized by a solvothermal method and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectra and thermogravimetric analysis. Single-crystal X-ray diffraction studies reveal that complexes 1-3 are isostructural 2D coordination polymers based on dinuclear units, where the μ2-(methoxy-O)2-bridged Ln2O2 cores are linked by four Salen-type ligands in a bidentate mode. Each lanthanide ion is eight-coordinated by eight oxygen atoms, forming a distorted dodecahedral geometry. Luminescence analysis in the solid state at room temperature indicates that complex 1 exhibits the co-luminescence of the ligand and SmIII ions and complex 2 shows the characteristic red luminescence of EuIII ions. Furthermore, the energy transfer mechanisms are described and discussed.
    Polyhedron 04/2015; 94. DOI:10.1016/j.poly.2015.04.018 · 2.05 Impact Factor
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    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; 54(7). DOI:10.1021/acs.inorgchem.5b00061 · 4.79 Impact Factor
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    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; 3(17). DOI:10.1039/C5TC00321K
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    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
  • Yumei Yue · Jingwen Sun · Pengfei Yan · Guangming Li
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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. DOI:10.1016/j.inoche.2014.11.007 · 2.06 Impact Factor
  • Yumei Yue · Pengfei Yan · Jingwen Sun · Guangming Li
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    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
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    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; 15(3):150129090917005. DOI:10.1021/cg501644z · 4.56 Impact Factor
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    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 · 4.20 Impact Factor
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    ABSTRACT: Poly(phenylene vinylene)/polyvinyl alcohol/Ag (PPV/PVA/Ag) composite nanofibers with excellent photoelectric properties were prepared by coaxial electrospinning using PPV/PVA as the shell and Ag nanoparticles (NPs) as the core, Ag NPs aqueous solution was prepared by the reduction method. The results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that Ag NPs are of a face-centered cubic structure, with an average diameter of 46 nm and the composite nanofibers have uniform and continuous morphology. With increasing Ag content, the diameters of the composite nanofibers decreased from 653 nm to 250 nm. The X-ray diffraction (XRD) patterns verified that in the composite nanofibers, the Ag NPs are not transformed. In the photoluminescence spectra, the PPV/PVA/Ag composite nanofibers presented red-shift compared with PPV/PVA nanofibers. Under illumination, the as-prepared PPV/PVA/Ag composite nanofibers exhibited relatively high photocurrent intensity.
    01/2015; DOI:10.1515/polyeng-2014-0251
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    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
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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 12/2014; 20(49). DOI:10.1002/chem.201404615 · 5.70 Impact Factor
  • Wen Hui Hao · Pengfei Yan · Guangming Li · Zhi Yuan Wang
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    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 · 3.97 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; 44(4). DOI:10.1039/C4DT02960G · 4.20 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; DOI:10.1039/C4CE01725K · 3.86 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; 16(45). DOI:10.1039/C4CE01556H · 3.86 Impact Factor