Yaguang Sun

Solvothermal synthesis, crystal structure, and properties of lanthanide-organic frameworks based on thiophene-2,5-dicarboxylic acid

A series of lanthanide-organic framework coordination polymers, {[La(2)(TDC)(2)(NO(3))(H(2)O)(4)](OH)·5H(2)O}(n) (1) and [Ln(TDC)(NO(3))(H(2)O)](n) (TDC = thiophene- 2, 5- dicarboxylic acid; Ln = Nd(2), Sm(3), Eu(4), Gd(5), Tb(6), Dy(7), Ho(8), Er(9), Yb(10)) have been synthesized by solvothermal reaction and characterized by elemental analysis, FT-IR, TG analysis, single-crystal X-ray diffraction and power X-ray diffraction. The single-crystal X-ray diffraction analysis results show that 1 displays a 3-D porous framework with (3,7)-connected {4(10).6(11)}{4(3)} topology. The compounds 2-10 crystallized in the same P2(1)/c space group and exhibits a (3,6)-connected {4.6(2)}(2){4(2).6(10).8(3)} topology, Right-handed and left-handed helical chains coexist in the 2-D layer structure. The luminescence properties of 2-10 and the magnetic properties of 5,7,8,9 were investigated.

Hydrothermal synthesis, structure, and photoluminescence of four complexes based on 1H-imidazole-4,5-dicarboxylate or 1H-imidazole-2-carboxylate ligands

Four complexes, [Ag4(bipy)2(Himdc)2(H2O)2] n (1), [Ag(H2imdc)] n (2), [K(H3imdc)(H2imdc)(H2O)2] n (3), and [Cu(Himc)2] (4) (H3imdc = 1H-imidazole-4,5-dicarboxylic acid, H2imc = 1H-imidazole-2-carboxylic acid, and bipy = 4,4′-bipyridine), were hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis and elemental analysis. The obtained complexes exhibit different coordination structures; 1 contains a 2-D supramolecular layer based on two chains arraying uniformly in an ABAB manner. Compound 2 displays sawtooth-shaped 1-D chains extending to 2-D layers via hydrogen bond interactions. Compound 3 possesses a 3-D framework structure based on a 1-D chain via hydrogen bonding interactions. Compound 4 has a 3-D framework structure bearing a pcu-type topology. In addition, the photoluminescence for 1 has been investigated.

Hydrothermal synthesis, crystal structure and properties of Ni(II)–4f complexes based on 1H-benzimidazole-5,6-dicarboxylic acid

Nine novel heterometallic coordination polymers [Ln(2)Ni(Hbidc)(2)(SO(4))(2)(H(2)O)(8)](n) (Ln = Pr (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6), Ho (7), Er (8), Yb (9), H(3)bidc = 1H-benzimidazole-5,6-dicarboxylic acid) have been synthesized under hydrothermal conditions and characterized by elemental analysis, FT-IR, TG analysis and single crystal X-ray diffraction. X-ray analysis revealed that all complexes present almost identical three-dimensional (3D) structures with PtS-type topology. Complexes 1-7 are all isomorphous, and the structure variation of polymers 8 and 9 is induced by the lanthanide contraction effect. In additional, the luminescence properties of complexes 2, 3 and 5-7, and the magnetic properties of complexes 4 and 6-8 were investigated.

Uniform and well-dispersed GdVO4 hierarchical architectures: hydrothermal synthesis, morphology evolution, and luminescence properties

GdVO4 nano/microcrystals with different morphologies were successfully synthesized via an efficient and facile hydrothermal process using trisodium citrate (Na3Cit) as the chelating ligand. X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectra (XPS), fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) and cathodoluminescence (CL) spectra were employed to characterize the samples. By tuning the reaction time, vanadium sources, and Na3Cit content, GdVO4 samples with different morphologies and sizes have been successfully synthesised. The possible formation mechanism for these diverse architectures is proposed on the basis of time-dependent experiments. Under ultraviolet (UV) and low-voltage electron beam excitation, GdVO4 : Ln3+ (Ln3+ = Eu, Dy, and Sm) phosphors show strong light emissions with different colors coming from various Ln3+ ions due to an efficient energy transfer from vanadate groups to the dopants. The ability to generate GdVO4 nano/microstructures with diverse shapes, and multicolor emission provides a great opportunity for systematically evaluating their luminescence properties, as well as fully exploring their applications in light emitting phosphors, advanced flat panel display, field emission display devices or biological labeling.

Ruthenium Complexes Containing Bidentate Schiff Base Ligands as Precursors of Homogeneous and Immobilized Catalysts

The paper presents recent work conducted in our group on the synthesis of a novel class of homogeneous and immobilized Ru- complexes containing Schiff bases as O,N-bidentate ligands benefiting from a versatile, quite general and thoroughly exemplified two- step procedure. The new Ru-complexes with improved stability incorporate a variety of Schiff bases, associated with traditional inorganic and organic ligands such as chloride, phosphanes, arenes, cyclodienes, NHC etc., and different carbenes (alkylidene, vinylidene, allenylidene and indenylidene). By a proper choice of the Schiff base, useful physical and chemical properties of the derived Ru- complexes could be induced resulting in tunable catalytic activity for metathesis and related processes. A pertinent example is the latency of selected Schiff base Ru catalysts which by becoming active only under specific conditions (heat or acid activation) are ideal for industrial applications, e.g. reaction injection molding processes. The synthetic approaches that are critically discussed in this artcile have led to a diversity of Ru-complexes of which several members have risen to the rank of commercial catalysts.

Synthesis, interaction with double-helical DNA and biological activity of new Pt(II) and Pd(II) complexes with phenylglycine

The mononuclear palladium(II) (1) and platinum(II) (2) complexes containing phenylglycine have been synthesized and characterized by elemental analysis, IR spectra, and 1H NMR spectra. The structure of 1 was determined by X-ray diffractometry. The interaction between the complexes and fish sperm DNA (FS-DNA), adenosine-5′-triphosphate (ATP), and adenine (Ade) were investigated by UV absorption spectra, the interaction mode of the complex binding to DNA was studied by fluorescence spectra and viscometry. The results indicate that the two complexes have different binding affinities to DNA, complex 2 > complex 1. Gel electrophoresis assay demonstrates that the two complexes have the ability to cleave pBR322 plasmid DNA. Cytotoxicity experiments were carried out toward four different cancer cell lines, and 1 shows lower inhibitory efficiency than 2, consistent with the binding affinities towards DNA.

Synthesis, characterization, and interaction with DNA of Cu(II) and Zn(II) complexes with 2,2′-bipyridyl-6,6′-dicarboxylic acid

Two transition metal complexes, [Cu2(bpdc)2H2O]·2H2O (1) and Zn(bpdc)(H2O)2 (2) (H2bpdc = 2,2′-bipyridine-6,6′-dicarboxylic acid), were synthesized and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Complex 1 is dinuclear with two five-coordinate cupric ions and 2 is mononuclear with one six-coordinate zinc. Interactions of 1 and 2 with DNA have been investigated using UV–Vis absorption spectra. The cleavage reaction on DNA has been monitored by agarose gel electrophoresis.

Hydrothermally derived NaLuF4:Yb3+, Ln3+ (Ln3+ = Er3+, Tm3+ and Ho3+) microstructures with controllable synthesis, morphology evolution and multicolor luminescence properties

A series of NaLuF4:Yb3+, Ln3+ (Ln3+ = Er3+, Tm3+, and Ho3+) microstructures with diverse morphologies and sizes were successfully prepared via a designed hydrothermal route with the assistance of trisodium citrate (Na3Cit). The phases, morphologies, sizes and luminescent properties of the as-prepared products were fully characterized by means of X-ray diffraction (XRD), field scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and up-conversion (UC) photoluminescence spectroscopy, respectively. It can be found that the as-prepared microcrystals can be rationally modified in phase, size and morphology by tuning the pH value, Na3Cit content, and reaction time. Based on the experimental results, the possible formation mechanism of the crystal growth process was proposed. Moreover, a systematic study of the up-conversion (UC) luminescent properties of NaLuF4 has also been performed through doping different rare earth ions (Yb3+/Er3+, Yb3+/Tm3+ and Yb3+/Ho3+). It is found that under 980 nm NIR excitation, the emission intensity and the corresponding luminescent colors of Yb3+/Er3+, Yb3+/Tm3+, and Yb3+/Ho3+ co-doped NaLuF4 can be precisely modulated by changing the Yb3+ doping concentration. These merits of multicolor emissions in the visible region endow this kind of material with potential applications in the fields of light display systems, lasers, and optoelectronic devices.

Bis(imidazole) coordination polymers controlled by oxalate as an auxiliary ligand

Seven coordination polymers {[M(L)2(H2O)2]·(NO3)2}n (M = Co (1), Ni (2), Cd (3)) and [M(L)(ox)]n (M = Co (4), Ni (5), Zn (6), and Mn (7)) have been synthesized (L = 2,6-bis(imidazol-1-yl)pyridine, ox = oxalate) under hydrothermal conditions. Single-crystal X-ray diffraction analysis has revealed that 1–3 are isomorphous and possess 2-D networks, whereas 4–6 are isomorphous, but involve two kinds of oxalate chains. The structure of 7 is different from those of 4–6 due to various bridging modes of the oxalate ligand. Magnetic studies have revealed that 1, 2, 4, 5, and 7 exhibit strong antiferromagnetic coupling. Among these, 1 exhibits an interesting spin-canting phenomenon. Graphical Abstract In hydrothermal reactions, seven coordination polymers were synthesized. Single-crystal X-ray diffraction analysis revealed that compounds 1–3 possess 2-D networks, whereas compounds 4–6 involve two kinds of oxalate chains. The structure of 7 adopts a 3-D framework structure due to various bridging modes of the oxalate ligand. Magnetic studies have revealed that compounds 1, 2, 4, 5, and 7 exhibit strong antiferromagnetic coupling.

A family of 3D lanthanide–organic frameworks constructed from parallelogram secondary building units: synthesis, structures and properties

A family of lanthanide–organic frameworks, {Ln2(pyip)(ox)2.5(H2O)5}n (Ln = La (1), Pr (2), Sm (3), Eu (4), Gd (5), Tb (6), Dy (7)) has been synthesized based on mixed bridging ligands, H2pyip and oxalate anion (H2pyip = 5-(4-pyridyl)-isophthalic acid, H2ox = oxalic acid) and characterized by elemental analysis, Fourier transform infrared spectroscopy, steady state and time-resolved luminescence spectroscopy, thermogravimetric analysis, powder X-ray diffraction and single-crystal X-ray diffraction. The single-crystal X-ray diffraction analysis results show that complexes 1–7 are isostructural. They crystallize in the same P21/c space group and exhibit a (3,4)-connected {42·6·82·10}{82·10} topology, being a 2-nodal net topology. The luminescence properties of 3, 4, 6, and 7 were investigated and related to the structural properties. The magnetic studies reveal that strong ferromagnetic coupling exists in compound 6.