Crystal structures and luminescence properties of two new terbium complexes with aromatic carboxylic acid

Two new terbium complexes with aromatic carboxylic acids, [(Tb)₂(L₁)₆(H₂O)₄] (1) and [(Tb)₂(L₂)₆(H₂O)₂(DMF)₂] (2) (HL₁: nicotinic acid; HL₂: 4-hydroxybenzoic acid), with different coordination geometries have been synthesized and their crystal structures determined. The luminescence properties of the two complexes, including the phosphorescence lifetime, have been investigated. The effect of a secondary ligand on luminescence of the ternary terbium complex with carboxylic acid and the relationship between luminescence properties and crystal structure, including coordination mode of the carboxyl groups from HL₁ and HL₂ and coordination mode of a secondary ligand, are discussed.     

Crystal structures and luminescence of two zinc(II) complexes with benzimidazole ligands

Two new zinc(II) complexes have been synthesized and studied by single crystal X-ray diffraction method: [Zn(L1)Cl₂]·2DMF (1) and [Zn(L2)Cl₂]·DMF (2) (L1 = 3,3′-bis(2-benzimidazolyl)-2,2′-dipyridine, L2 = 3,3′-bis[2-bis(2-ethylbenzimidazolyl)]-2,2′-dipyridine). Compound 1 is monoclinic, C2/c, a = 23.142(3) ?, b = 11.845(1) ?, c = 14.735(3) ?; compound 2 is orthorhombic, C222₁, a = 12.140(7) ?, b = 16.283(9) ?, c = 16.51(1) ?. In both compounds, Zn(II) cations are coordinated by two chlorine atoms and two benzimidazole nitrogen atoms in a slightly distorted tetrahedron fashion. Structural features responsible for fluorescent properties of the complexes are discussed.     

Crystal structures and luminescence of a series of cadmium(II) complexes based on isophorone derivative containing imidazolyl

Three new complexes, [CdL₂(CH₃COO)₂(H₂O)₂] (I), CdL₂Br₂ (II), CdL₂I₂ (III), have been successfully synthesized by self-assembly of corresponding metal salts with (E)-2-(3-(4-(1H-imidazole-1-yl)styryl)-5,5-dimethylcyclohex-2-enylidene)malononitrile (L). The structures of the complexes were determined by single crystal X-ray diffraction analysis (CIF file CCDC nos. 957831 (I), 957792 (II), 957832 (III)). In complex I, central metal is six-coordinated and the crystal packing shows a 3D supramolecular framework. Complexes II and III display the similar 2D supramolecular structures in which the central metals are four-coordination. The luminescent properties were investigated.     

Crystal structures of two dinuclear cadmium(II) complexes with Schiff bases as ligands

Two new cadmium(II) complexes, Cd₂(L1)₂(NCS)₂ (1) and Cd₂(L2)₂(NCS)₂ (2), where L1 and L2 are the deprotonated forms of 2-[(3-dimethylaminopropylimino)methyl]-6-ethoxyphenol and 2-methoxy-6-[(pyridin-2-ylmethylimino)methyl]phenol, respectively, have been isolated as crystalline products and characterized by elemental analysis, IR spectroscopy, and single crystal X-ray diffraction method. Both compounds are structurally similar and are phenolate-O-bridged dinuclear cadmium(II) complexes. Each Cd(II) cation in the complexes is octahedrally coordinated. The Cd Cd distances in (1) and (2) are 3.618(2) d 3.571(2)     

Crystal structure and luminescence property of ternary terbium p-aminobenzoic acid complexes with different second ligands

Ternary terbium complexes with p-aminobenzoic acid (HL), [TbL₃(DMSO)(H₂O)]₂ (1), [TbL₃(DMF)(H₂O)]₂ (2) and [TbL₃(Bpy)(H₂O)]₂·2H₂O (3) (DMSO=dimethyl sulfoxide, DMF=N, N- dimethylformamide, Bpy=2, 2′- bipyridyl) have been synthesized, and their crystal structures determined. The luminescence properties of these complexes, including both the emission quantum yield and the fluorescence lifetime, have been investigated. The effect of a second ligand on the crystal structure and luminescence property of the ternary terbium p-aminobenzoic acid complexes, and the relationship between luminescence properties and crystal structure, including coordination mode of the L⁻ ligand and the characteristics of a second ligand, are discussed.     

Crystal structure and luminescence of europium(III) acrylate

The atomic structure of europium acrylate crystals [Eu₂(Acr)₅OH·3H₂O]·2(0.5H₂O) was studied by X-ray analysis (a = 24.360(3) Å, b = 18.466(2) Å, c = 8.5818(9) Å, β = 96.087(2)°, space group C2/c, Z = 6, ρ_calc = 2.036 g/cm³). The crystal structure involves chains of binuclear [Eu₂(C₃H₃O₂)₅OH·3H₂O] molecules, running infinitely in the [101] direction and having pairs of C₉H₉EuO₇H₂O molecules alternating with C₆H₆EuO₄OH·2H₂O molecules that link the pairs. The infinite chains are linked by hydrogen bonds and van der Waals interactions. The thermal behavior of luminescence of the europium(III) complex is discussed.     

Crystal structures and thermal decomposition kinetics of lanthanide complexes with 3,4,5-trimethoxybenzoic acid and 1,10-phenanthroline

A series of lanthanide complexes with the 3,4,5-trimethoxybenzoic acid(3,4,5-tmoba) and 1,10-phenanthroline(phen),[Ln(3,4,5-tmoba) 3 phen] 2(Ln = Pr(1),Nd(2) and Ho(3)),have been synthesized and characterized by a series of techniques including elemental analysis,IR spectra,X-ray crystallography and TG/DSC-FTIR technology.The three complexes have two kinds of coordination modes,in which the Pr 3+ and Nd 3+ cations are nine-coordinated and the Ho 3+ cation is eight-coordinated.The three-dimensional IR accumulation spectra of gaseous products for complexes 1-3 were analyzed and the gaseous products were identified by the typical IR spectra obtained from the 3D surface graphs.Meanwhile,we obtained the activation energy E of the first steps of complexes 1-3 by the integral isoconversional non-linear(NL-INT) method and discussed the non-isothermal kinetics of complexes 1-3 using the Malek method.Finally,SB(m,n) was defined as the kinetic method of the first-step thermal decomposition.The thermodynamic parameters △G≠,△H≠ and △S≠ of activation at the peak temperature were also calculated.     

Crystal structure and magnetic properties of two isomeric three-dimensional pyromellitate-containing cobalt(II) complexes

The hydrothermal preparation, crystal structure determination, and magnetic study of two isomers made up of 1,2,4,5-benzenetetracarboxylate and high-spin Co(II) ions of formula [Co2(bta)(H2O)4]n x 2n H2O (1 and 2; H4bta = 1,2,4,5-benzenetetracarboxylic acid) are reported. 1 and 2 are three-dimensional compounds whose structures can be described as (4,4) rectangular layers of trans-diaquacobalt(II) units with the bta(4-) anion acting as tetrakis-monodentate ligand through the four carboxylate groups, which are further connected through other trans-[Co(H2O)2](2+) (1) and planar [Co(H2O)4](2+) (2) entities, with the bridging units being a carboxylate group in either the anti-syn (1) or syn-syn (2) conformations and a water molecule (2). The study of the magnetic properties of 1 and 2 in the temperature range 1.9-300 K shows the occurrence of weak antiferromagnetic interactions between the high-spin Co(II) ions, with the strong decrease of chi(M)T upon cooling being mainly due to the depopulation of the higher energy Kramers doublets of the six-coordinated Co(II) ions. The computed values of the exchange coupling between the Co(II) ions across anti-syn carboxylate (1) and syn-syn carboxylate/water (2) bridges are J = -0.060 (1) and -1.90 (2) cm(-1) (with the Hamiltonian being defined as H = -Jsigma(i,j)S(i) x S(j)). These values follow the different conformations of the carboxylate bridge in 1 (anti-syn) and 2 (syn-syn) with the occurrence of a double bridge in 2 (water/carboxylate).     

Synthesis,structure and luminescence properties of two novel lanthanide complexes with 2-fluorobenzoic acid and 1,10-phenanthroline

Two lanthanide complexes with 2-fluorobenzoate (2-FBA) and 1,10-phenanthroline (phen) were synthesized and characterized by X-ray diffraction. The structure of each complex contains two non-equivalent binuclear molecules, [Ln(2-FBA)₃?·?phen?·?CH₃CH₂OH]₂ and [Ln(2-FBA)₃?·?phen]₂ (Ln?=?Eu (1) and Sm (2)). In [Ln(2-FBA)₃?·?phen?·?CH₃CH₂OH]₂, the Ln³⁺ is surrounded by eight atoms, five O atoms from five 2-FBA groups, one O atom from ethanol and two N atoms from phen ligand; 2-FBA groups coordinate Ln³⁺ with monodentate and bridging coordination modes. The polyhedron around Ln³⁺ is a distorted square-antiprism. In [Ln(2-FBA)₃?·?phen]₂, the Ln³⁺ is coordinated by nine atoms, seven O atoms from five 2-FBA groups and two N atoms of phen ligand; 2-FBA groups coordinate Ln³⁺ ion with chelating, bridging and chelating-bridging three coordination modes. The polyhedron around Ln³⁺ ion is a distorted, monocapped square-antiprism. The europium complex exhibits strong red fluorescence from ⁵D₀?→?⁷F _j ( j?=?1–4) transition emission of Eu³⁺.     

Crystal structure,thermodynamic behavior,and luminescence properties of a new series of lanthanide halogenated aromatic carboxylic acid complexes

Five lanthanide complexes with polydentate coordination were successfully synthesized by volatilization of 2,4-difluorobenzoate and o-phenanthroline ligands. The structure general formula is [Ln(2,4-DFBA)₃(phen)]₂, (Ln = La(1), Gd(2), Tb(3), Dy(4), Ho(5); 2,4-DFBA = 2,4-difluorobenzoate, phen = o-phenanthroline). The crystal structures of five complexes were determined, and supramolecular structures were probed. Characterization was performed by elemental analysis, IR, Raman spectroscopy and XRD, followed by an examination of the fluorescence and heat capacity properties. The molar heat capacities of complexes 4 and 5 were determined in detail by the DSC apparatus, and the thermodynamic functions were calculated. Finally, the fluorescence properties of complexes 3 and 4 were investigated. Using DFT, the HOMO, LUMO energy levels of the ligands and their single and triplet state energy levels were calculated at the level of the valence layer cleavage 6-311G(d,p) basis group, and the fluorescence enhancement mechanism was explained from the energy transfer perspective.     

Crystal and molecular structure of 2a,3,4,5-tetrahydro-2,2a,3,4,5,6-hexabromoacenaphthene

Tiraspol' Branch, All Union Scientific Research Institute for Electrical Insulation Materials. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 3, pp. 184–187, May–June, 1989.     

Crystal and molecular structure of 2,2a,3,4,5,6,8-heptabromo-2a,3,4,5-tetrahydroacenaphthene

Tiraspol Branch, All-Union Scientific-Research Institute of Electromechanics, Odessa State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 3, pp. 100–102, May–June, 1991.     

Crystal and molecular structure of 2a,3,4,5-tetrahydro-2,2a,3,4,5,6-hexachloracenaphthene

Department of All-Union Scientific-Research and Planning-Technological Institute of Electrical Insulation Materials and Foiled Dielectrics. Translated from Zhurnal Strukturnoi Khimii, Vol. 28, No. 4, pp. 137–142, July–August, 1987.     

Crystal structure and thermal behavior of a new cadmium indium oxalate

A new mixed metal oxalate Cd₃In₂(C₂O₄)₆·9H₂O, with an open-framework structure, has been prepared from a precipitation method at room temperature. Its crystal structure has been solved from single-crystal diffraction data. The compound crystallizes with space group P6₄22 and the cell parameters are a=8.566(5)Å, c=37.811(5) Å, V=2403(2) Å³, and Z=3 (R₁=0.036). The three-dimensional structure is built from three types of MO₈ (M=Cd, In) polyhedra, i.e., triangular dodecahedra, bicapped trigonal prisms and an undefined distorted eight-fold cadmium polyhedron. Relationships with the structures of the related cadmium zirconium oxalates are discussed. The structure overview suggests the possibility to conceive new oxalate-based materials with open-framework structures. The thermal behavior of the new compound is described in details from temperature-dependent X-ray powder diffraction and thermogravimetry measurements. The dehydration process of the precursor is reversible in its stability temperature range. The final product consists of a mixture of nanocrystalline CdIn₂O₄ and the simple oxides.     

Crystal structure and luminescence of antimony(III) bromide with aniline

The atomic structure of antimony(III) bromide crystals with anilinium was determined by X-ray diffraction analysis of (C₆H₅NH₃)₂SbBr₅ (a = 19.704(3) Å, b = 7.914(1) Å, c = 25.556(4) Å; space group Pbca, Z = 8, ρ_calc = 2.365 g/cm³). The crystal structure consists of infinite chains of [SbBr₅]^2? complex anions formed by sharing six vertices and the anilinium (C₆H₅NH₃)⁺ cations, through which the chains are linked in layers by N-H...Br hydrogen bonds. The geometrical aspects that determine the luminescent spectral properties of the complex are discussed.     

偏硅酸镉的自激活发光

利用高温固相法合成了一种具有自激活发光行为的CdSiO3基质.对样品进行了X射线衍射分析和光谱分析.光谱分析结果表明,在偏硅酸镉的发射光谱中存在三个自激活发光峰,它们分别位于380,467和560nm处,另外,通过热释光谱技术讨论了偏硅酸镉中的缺陷及相关机理.在热释光谱中有两个明显的热释峰,分别位于448和563K,它们的陷阱深度分别为0 58和0 61eV,表明了在偏硅酸镉中存在着不同的陷阱,这些陷阱的存在导致了偏硅酸镉的自激活发光.     

Crystal architecture and thermal decomposition of two new organically templated cadmium sulfates

Two organic-inorganic hybrid compounds (C₅H₁₄N₂)[Cd(H₂O)₆](SO₄)₂ (I) and R-(C₅H₁₄N₂)×[Cd(H₂O)₆](SO₄)₂ (II) are synthesized by the slow evaporation method and characterized by single crystal X-ray diffraction, thermogravimetry, temperature-dependent X-ray diffraction, and infrared spectroscopy. The first compound crystallizes in the centrosymmetric space group P2₁/n with the following unit cell parameters: a = 6.6208(2) Å, b = 10.6963(3) Å, c = 12.9318(4) Å, V = 893.05(6) ų, and Z = 2. Its structure is solved by direct methods and refined by the least-squares analysis [R ₁ = 0.0389 and wR ₂ = 0.0821]. This compound shows a crystallographic disorder II destroys the inversion symmetry and leads to a fully ordered structure. Indeed, compound II crystallizes in the non-centrosymmetric space group P2₁ with the following unit cell parameters: a = 6.6306(1) Å, b = 10.7059(2) Å, c = 12.9186(1) Å, V = 894.67(2) ų, and Z = 2. The crystal structure of both compounds is built from isolated SO ₄ ^2? anions, disordered 2-methylpiperazinediium, (C₅H₁₄N₂)²⁺ in compound I or R-2-methylpiperazinediium R-(C₅H₁₄N₂)²⁺ in compound II, and divalent metal cations surrounded by six water molecules. These different entities are connected together only by a 3D hydrogen bond network. The thermodiffractometry and the thermogravimetric analyses indicate that the decomposition of the supramolecular precursors proceeds through several stages leading to cadmuim oxide.