Blue-emissions Modulated by Packing Forces in Alkaline-earth Metal OrganicFrameworks Based on Thiophene-2,5-dicarboxylic: Structures and Theoretical Calculations

Solvothermal reactions of Ca(NO), Sr(NO)with thiophene-2,5-dicarboxylic in DMF afforded two new inorganic-organic hybrid frameworks, [M(TDC)(DMF)]n(M = Ca(1), Sr(2), TDC = thiophene-2,5-dicarboxylic, DMF = N,N?-dimethylformamide), which have been characterized by single-crystal X-ray diffraction, powder X-ray diffraction, elemental analysis and IR spectra. Both compounds feature three-dimensional(3D) frameworks based on the versatile coordinated modes(μ-η~2:η~2, μ-η~2:η~1, μ-η~2:η~1) of carboxylic groups in tdc ligands. C–H···S hydrogen bonds and C–H···π interactions contribute to the stabilization of the structures. They exhibit weaker packing force compared with their literature isomers. Consequently, blue and blue/green luminescence of two compounds has been observed. Their luminescence mechanism can be ascribed to ligand-to-metal charge transfer(LMCT) compared with the ligand-centered luminescence in their isomers. Electronic structural calculations illustrate that under the condition of weaker packing forces, larger gaps can be achieved, which facilitate the LMCT. This work suggests that the introduction of S-heteroatom can result in more electrons rich in the metal centers, thus giving rise to metal-involved luminescence.

Structures and magnetic properties of several novel lanthanide coordination polymers based on thiophene-2,5-dicarboxylic acid

Eight novel lanthanide complexes： {Ln（TDA）I.5（H20）2 },, （Ln = Pr（la）, Nd（2a）） and { Ln（TDA）（Ac）（H2O）}n （Ln = Pr（1）, Nd（2） Eu（3）, Gd（4）, Tb（5）, Dy（6）; TDA = Thiophene-2,5-dicarboxylic acid anion） have been constructed by hydrothermal reaction. Structural analyses reveal that complexes Ia and 2a belong to the space group C2/c, exhibiting three-dimensional （3D） frame- works. Complexes 1-6 with P2t/c space group were prepared in the presence of excessive ammonium acetate, giving rise to interesting 3D frameworks different from those of la and 2a. Magnetic property studies of 4-6 reveal the weak antiferromag- netic interaction exists between adjacent Gd3＋ in 4. The complex 6 displays rather rare slow magnetization relaxation behavior in 3D frameworks.

Hydrothermal Synthesis and Crystal Structure of a New Three-dimensional Co(Ⅱ) Coordination Polymer Based on 2,3-Thiophenedicarboxylic Acid

A new Co（ll） polymer [Co（tdc）（l,4-bimb）]n 1 （H2tdc = thiophene-2,3-dicarboxy- lic acid, 1,4-bimb -- 1,4-bis（imidazol-1 ＇-yl）butane） was synthesized under hydrothermal conditions The compound crystallizes in the monoclinic system, space group C2/c with a = 15.643（9）, b = 8.839（5）, c=12.952（7） A, β = 105.964（6）°, V= 1721.8（16） A3, Z = 4, Mr = 419.32, Dc= 1.618 Mg/m3,μ = 1.149 mm-1, F（000） = 860, the final R = 0.0243 and wR =0.0613 for 1460 observed reflections with I 〉 2σ（I）. The compound presents a three-dimensional （3D） network extended by both tdc2- anions and 1,4-bimb ligands in which the tdc2- anions employ a chelating coordination mode. From the topology point of view, the structure could be described as a 3D 4-connected 65.8 CdSO4-type net. Infrared spectroscopy, elemental analyses, thermogravimetric analysis and powder X-ray diffraction properties of 1 are also investigated.

A Chain Structure Based on Homodinuclear Scandium Units: [Sc(μ-OH)(2,5-pydc)(H_2O)]_n

The reaction of pyridine-2,5-dicarboxylic acid with Sc2O3 under hydrothermal con- dition yields a new complex [Sc（μ-OH）（2,5-pydc）（H2O）]n 1 which has a chain structure based on homodinuclear scandium units. Crystal data for 1： space group P^-1, a = 6.7192（13）, b = 7.6131（13）, c = 8.9313（14） A, α = 95.976（6）, β = 101.663（6）, γ = 108.151（5）^o, V= 418.26（13） A^3, Z = 2, Dc = 1.946 g/cm^3, g = 0.889 mm^-1, F（000） = 248, C7H6NO6Sc, Mr = 245.09, the final R = 0.0429 and wR = 0.1086.

Synthesis,Crystal Structure,Thermal Stability and Luminescent Properties of a New 2D Zinc Complex

A new coordination polymer associated with zinc ion,[Zn（Tda）（bpp）] n （1,H 2 tda=thiophene-2,5-dicarboxylic acid,bpp=1,3-bis（4-pyridyl）propane）,was prepared under solvothermal conditions,and characterized by single-crystal X-ray diffraction,elemental analysis and IR spectra.The complex belongs to monoclinic,space group P2 1 /c with a=9.8799（4）,b=12.0430（6）,c=15.4269（9）,β=95.424（5） o,V=1827.33（16） 3,Z=4,D c=1.577 g/cm 3,S=1.074,μ=1.486 mm-1,F（000）=888,M r=433.80,R=0.0359 and wR=0.0968 for 2685 observed reflections （I 2σ（Ⅰ））.Complex 1 displays an interesting 2D lattice structure.In 1,four coordinated zinc ions were bridged by Tda and bpp ligands to generate a （4,4） two-dimensional layer.The thermogravimetric analysis,powder X-ray diffraction （XRD） and luminescent properties for 1 also have been explored.

Synthesis, Structure and Luminescent Properties of Three 1D Chain Rare Earth Complexes

Three 1 D chain coordination polymers [Ln(pydc)2(H2 O)2]n·n Him(Ln = Dy(1), Gd(2), Sm(3), H2 pydc = pyridine-2,5-dicarboxylic acid, Im = imidazole), were solvothermally synthesized by the reaction of pyridine-2,5-dicarboxylic acid(H2 pydc), Ln(Ⅲ) salts and imidazole. They have been characterized by X-ray single-crystal diffraction, IR spectra, TGA analysis and elemental analysis. Structural analyses revealed that complexes 1~3 have similar 1 D chain structures and belong to P1 space group. It is noteworthy that complexes 1~3 exhibited excellent thermal stability and no weightlessness below 117 ℃. Meanwhile, 1 and 3 show characteristic fluorescence of corresponding lanthanide metal ions in solid state at room temperature.