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Using reactive molecular dynamic simulation, the diffusion behavior of oxygen ions is studied during the oxidation of Fe (1 0 0) under applied tensile strains at room temperature. We find that the strain induced changes of the oxide structure lead to the change of the oxygen diffusion coefficient. This is supported by the comparative analysis of diffusion energy barrier in the corresponding oxide structure. Compared with the effect of the diffusant concentration (composition) and oxidation growth stresses, the evolution of oxide structure plays a dominant role on the change of diffusion coefficient in the strain-reaction engineering. [ABSTRACT FROM AUTHOR]

Two uracil derivatives of methyl 3-(5-fluoro-2,4-dioxo-3,4-dihydropyrimidin-1(2 H)-yl)propanoate ( 1) and methyl 3-(5-chloro-2,4-dioxo-3,4-dihydropyrimidin-1(2 H)-yl)propanoate ( 2) were synthesized and characterized by elementary analyses, MS, IR and NMR. The crystal structures of 1 and 2 were determined by means of X-ray diffraction. Compound 1 crystallized in the monoclinic P21/ c space group with a = 7.4213(9), b = 5.8480(7), c = 23.248(3) Å, and β = 108.184(4)°. Compound 2 crystallized in the monoclinic P21/ c space group with a = 12.5754(12), b = 4.9363(5), c = 16.5352(15) Å, and β = 97.455(3)°. The thermal stabilities of 1 and 2 were studied by DSC-TGA techniques. The UV spectra indicated that the two compounds interacted with DNA by electrostatic binding. Graphical Abstract: The X-ray diffraction revealed that the N-H···O inter-molecular hydrogen bond in solid state of the two title compounds resulted in antiparallel β-sheet arrangement.[Figure not available: see fulltext.][Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Reactions of piperazine hexahydrate with triazol and paraformaldehyde afford a new piperazine-containing ligand: (N,N′-bis(1-H-1,2,4-triazole-1-yl)piperazine) (btp). X-ray crystal diffraction reveals that btp is an overall linear structure. Its Hg2+ polymer displays a zigzag chain in which piperazine is held in the chair conformation. In addition, the spectra properties of the btp and 1 are investigated, the strong luminescence characteristics of btp and 1 are found. [ABSTRACT FROM AUTHOR]

Two new binuclear complexes, Cd2(HL)2(NO3)4 · (CH3OH)2 (1) and Cu2(L)2(ClO4)2 (2), based on N'-(pyridin-2-ylmethylene)-2-(1H-1,2,4-triazol-1-yl)acetohydrazide (HL) and Cd(II) and Cu(II) salts have been synthesized and characterized by single crystal X-ray diffraction. Hydrogen bonds and π-π interactions extend both binuclear molecules, a 3-D supramolecular framework for 1 and 1-D staggered chains for 2. Fluorescence of both complexes is discussed. [ABSTRACT FROM AUTHOR]

A 3D complex [Cd(L)(4,4-bipy)].2H2O (1) has been synthesized by hydrothermal reaction of Cd(NO3)2, 4,4'-bipyridine and 1,2-bis[3-(1,2,4-triazolyl)-4-amino-5-carboxylmethylthio]ethane (H2L). X-ray crystal diffraction reveals that 1 belongs to triclinic system, [image omitted] space group. The crystallographic data are: a = 10.103(2) Å, b = 11.786(2) Å, c = 12.005(2) Å, α = 93.58(3)°, β = 98.66(3)°, γ = 105.47(3)°. In 1, Cd2+ ions are seven-coordinated and carboxylate groups adopt two coordination modes (bidentate chelate, bidentate chelate bridging) to connect Cd2+ ions forming a 2D layer. The auxiliary ligand 4,4'-bipy further link these 2D layers leading to a 3D network structure. Besides, the spectrum properties of 1 are investigated. [ABSTRACT FROM AUTHOR]

A coordination polymer, [Cu2(SCN)4(BPX)]n(BPX = 1,4-bis(pyridinium) xylol) was synthesized and characterized by IR spectrum, fluorescence spectrum and single crystal X-ray diffraction. Crystal structure revealed that the title compound crystallized in monoclinic system with space group P2(1)/c, a = 5.7540(7)Å, b = 12.7203(15) Å, c = 17.598(2) Å, β = 94.9940(10)°. Two SCN-ions served as bridging ligands to link two Cu(I) ions, giving rise to an eight-member ring. Furthermore, copper atom and sulfur atom of the eight-member ring bonded sulfur atom and copper atom of adjacent eight-member ring through the formation of Cu-S to form a small four-member ring. Thus, innumerable eight-member rings alternately linked four-member rings each other to form an infinite one-dimensional ladder-shaped structure. [ABSTRACT FROM AUTHOR]

A new supramolecular complex [Ce2(bppt)3(NO3)12]·2H2O has been synthesized from 1,5-bis(pyridinium)pentane (bppt· Br2), and characterized by single-crystal X-ray diffraction and IR spectra. It consists of two [Ce(NO3)6]3- anions, three bppt2+ cations and a lattice water molecule. Both of Ce3+ are 12-coodination with oxygen atoms of nitrate, but one of them formed a distorted icosahedron. There existed weak π-π stacking interactions between the pyridine rings of organic cations. [ABSTRACT FROM AUTHOR]

Two new complexes [Ni(phen)(H2O)4] · (atda)(H2O)5 (1) and [Ni2(4,4' -bipy)2(H2O)8] · (atda)2 (2) (where H2atda = (4-amino-1,2,4-triazole-3,5-diyldithio)diacetic acid, phen = 1,10-phenanthroline, 4,4' -bipy = 4,4' -bipyridine) have been synthesized and characterized by elemental analysis, IR, UV, thermogravimetric analysis and X-ray diffraction technique. X-ray structural analyses reveal that the two complexes are both three-dimensional (3D) supramolecular structures and possess similar structural characters. The Ni(II) centers are both in distorted octahedral coordination environments, six-coordinated by four water molecules and two nitrogen atoms from a 1,10-phenanthroline molecule or two 4,4' -bipyridine molecules. The atda2 - ligands do not coordinate to the Ni(II) centers, but only exist as counter anions, forming hydrogen bonds with coordinated or uncoordinated water molecules. Various hydrogen-bonding interactions play an important role in the assembly of three-dimensional supramolecular architectures. [ABSTRACT FROM AUTHOR]

A novel 3D coordination polymer [Mn(tzda)(4,4'-bipy)(H2O)]n (1) of mixed ligands, (1,3,4-thiadiazole-2,5-diyldithio)diacetic acid (H2tzda) and 4,4'-bipyridine, has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction and IR spectra. Complex 1 crystallizes in the orthorhombic space group Pbca with a=18.1657(9)Å, b=9.0882(5)Å, c=22.9333(12)Å. In the structure, each Mn(II) ion is in a distorted octahedral coordination geometry, three among four coordination sites of the equatorial plane are occupied by the carboxylate oxygen atoms and the remaining site is occupied by the water molecule while the apical positions are occupied by two nitrogen atoms from two bipy molecules. The six-coordinated Mn ions are interlinked by flexible tzda ligands to form layers, which are sustained by rigid 4,4'-bipy ligands into a 3D open framework. The magnetic property of 1 was also investigated and the magnetic susceptibility data were rationally fitted with J=-0.103 cm-1, g=2.09, zJ'=-0.02 cm-1, showing weakly antiferromagnetic interactions among Mn(II) ions in 1. [ABSTRACT FROM AUTHOR]

A new coordination compound, [Pb(phen)(NO3)3(H2O)]n(1), has been synthesized by the reaction of Pb(NO3)2 with phenanthroline (phen) in water. The complex was crystallized using the solution diffusion method and structurally characterized by X-ray single crystal diffraction. The compound 1 crystallizes in the monoclinic space group P21/c. In the structure unit of the compound 1, the central Pb(II) ion is six-coordinated with two nitrogen atoms from the phen, three oxygen atoms from three nitrate groups and one oxygen atom from a water molecule. The [Pb(phen)(NO3)2(H2O)] units are linked together by O1, N3, and O3 bridge from nitrate groups, resulting in the formation of one-dimensional chain structures. It is further connected by hydrogen bonds and π-π interactions formed a complicated supramolecular compound. In addition, the spectral properties and TG analyses for the compound 1 are also discussed The IR, UV-Vis spectra of the title compound as well as its thermodecomposition behavior were also discussed in detail in this paper. [ABSTRACT FROM AUTHOR]

A novel 3D coordination polymer [Gd2(tzda)3(H2O)5]n (1) has been synthesized by hydrothermal reaction of Gd(NO3)3 with a flexible building unit - (1,3,4-thiadiazole-2,5-diyldithio)diacetic acid (H2tzda). X-ray single crystal diffraction analysis reveals that 1 belongs to triclinic system, P1¯ space group. The crystallographic data are: a=9.6769(7)Å, b=13.4539(9) Å, c=14.9369 (10)Å, α=65.9050(10)°, β=82.1290(10)°, γ=80.1210(10)°. In the structure, two Gd(III) ions are both nine-coordinated and in different coordination environments while the tzda2- anions display three different coordination modes to link Gd(III) ions and then form a complicate three-dimensional network structure. [ABSTRACT FROM AUTHOR]

A new planar aromatic tridentate terpyridine-like ligand, 2,4- bis (3,5-dimethylpyrazol-1-yl)-6-diethylamino-1,3,5-triazine ( L ), has been synthesized and the structures of its complexes [Y L (NO 3 ) 3 ] ( 1 ) and [Ln L (NO 3 ) 3 (H 2 O)] L [Ln = La ( 2 ), Ce ( 3 ), Pr ( 4 ), Nd ( 5 ), Eu ( 6 )] have been determined by X-ray crystal structural analysis. The structures of the five lanthanoid complexes are isomorphous and isostructural but different from the crystal structure of the yttrium complex [Y L (NO 3 ) 3 ]. The latter shows a nine-coordinate metal center whereas the crystal structure of the lanthanoid complexes [Ln L (NO 3 ) 3 (H 2 O)] L show a 10-coordinate metal center. The π-π stacking and hydrogen bonding between the coordinated and uncoordinated L molecules sensitized the Ln luminescence. The thermal behavior of the ligand and its complexes is discussed. [ABSTRACT FROM AUTHOR]

Abstract: Three Cu(II) coordination polymers [Cu(taa)2] n (1), [Cu(taa)2 ·(H2O)4 ·Na0.5 ·(ClO4)0.5] n (2) and [Cu(taa)2 ·(H2O)4 ·Na0.5 ·(BF4)0.5] n (3) have been synthesized by the reaction of 1H-1,2,4-triazol-1-acetic acid (Htaa) with different Cu(II) salts. Polymer 1 features a 2-D grid-like network structure constructed by crossed zigzag chains. In both of polymers 2 and 3, there exist rare four-fold 1-D helical chains, which are induced by or anions. Besides, trapped sodium chains are found to be nested in the channels formed by the intertwist of the helical chains of 2 and 3. [Copyright &y& Elsevier]

Abstract: Hydrothermal reactions of 1-aminoethylidenediphonic acid { CH3C(NH2)(PO3H2)2, H4aedp} with CaCl2, Sr(NO3)2 and Pb(AC)2·3H2O resulted in three new main group metal diphosphonate coordination polymers. Namely, Ca[CH3C(NH3)(PO3H)2]2[CH3C(NH3)(PO3H)(PO3H2)]2 (1), Sr[CH3C(NH2) (PO3H)2(H2O)]·H2O(2) and Pb[CH3C(NH3)(PO3H)(PO3)]·H2O(3). The calcium (II) ion in complex 1 is octahedrally coordinated by six phosphonate oxygen atoms from six diphosphonate ligands, four of them in a bidentate and two in a monodentate fashion. The neighboring calcium ions are linked by pairs of P–O–P bridges, resulting in a pseudo-one-dimensional chain along the c axis. Complex 2 is the first example of the strontium phosphonate which has not been synthesized and structurally characterized before. It features a layered structure, in which strontium(II) ions are eight coordinated by an aqua ligand and seven phosphonate oxygen atoms from four diphosphonate ligands, two SrO8 polyhedra are bridged into a demeric unit by a pair of oxygen atoms and two diphosphonate groups. And such dimers are interconnected by the P–O–P bridges and O bridges to form complicated layers parallel to the ab plane. Complex 3 also has a layered structure in which the lead (II) ions are six coordinated by six phosphonate oxygens from four equivalent diphosphonate ligands. Each pair of PbO6 octahedra forms a dimeric unit via O–O edge-sharing and such dimeric units are interconnected via O–O edge-sharing to form a one-dimensional chain along the b-axis. These 1D chains are further bridged by the phosphonate ligands to form a complicated layer parallel to the bc plane. This type of layered structure has not been reported in other lead phosphonates. [Copyright &y& Elsevier]

A series of 9,10-diarylphenanthrenes was prepared, and their structures and dynamic behaviors were both theoretically and experimentally investigated. A more twisted and crowded phenanthrene backbone was associated with a lower barrier to the rotation of an aryl group. [ABSTRACT FROM AUTHOR]

Three Cd(II) coordination polymers, namely, {[Cd 2 (bptp) 2 (H 2 O) 4 ]·3H 2 O} n ( 1 ), {[Cd 2 (Hbptp)(BTC)(H 2 O)]·4H 2 O} n ( 2 ) and {[Cd 2 (H 2 bptp)(BTEC)]·H 2 O} n ( 3 ) (1,3,5-H 3 BTC = 1,3,5-benzenetricarboxylic acid and H 4 BTEC = 1,2,4,5-benzenetetracarboxylic acid), have been successfully isolated by employing the rigid N-heterocyclic ligand 2,6-bis(3-(pyrid-3-yl)-1,2,4-triazolyl)pyridine (H 2 bptp) and different aromatic polycarboxylates. Complex 1 performs a helical chain structure, which is extended into 3D supermolecular framework due to its strong hydrogen bonding interactions. 2 demonstrates a binodal 3,4-connected 2D grid with the point symbol of (4 2 ·6 2 ·8)(4 2 ·6), while complex 3 features an interesting 2D structure with its 1D double chain looking like a folded paper lantern. The optical band gaps were analyzed by diffuse-reflectance UV–Vis spectra. The photocatalytic experiments for these complexes reflect well on their activities for the decomposition of MB under the irradiation of high-pressure mercury lamp. Complexes 1 and 2 present extremely good photocatalytic properties with their photocatalytic activities increasing from 17% (without any catalyst) to 87% for 1 and 96% for 2 after 2 h of irradiation. In addition, the luminescent properties of 1 – 3 have also been investigated. [ABSTRACT FROM AUTHOR]

Four new coordination polymers namely, [Zn(pddb)(H2O)] n (1), [Zn(pddb)] n (2), {[Cd2(pddb)2]·H2O} n (3) and [Cd(pddb)(H2O)2] n (4), have been solvothermally obtained. Among which, complexes 1 and 3 were prepared in presence of 4-nitrobenzoic acid, and complexes 2 and 4 not, respectively. Complex 1 shows a binodal 3,3-connected wavelike layer structure with the point symbol of (63)2. However, 2 performs a binodal 3,6-connected 3D coordination framework with the point symbol of (4·62)·(42·68·85). 3 exhibits a more complicated 3D periodic structure built on an infinite rod-shape secondary blocking units (SBUs), while 4 shows a double-chain structure, extended into 3D supramolecular framework through strong hydrogen bonding interactions. Furthermore, the study about photoluminescence properties of these four complexes and H2pddb ligand reveals that these diverse structures have significant influence on the photoluminescence signals. [ABSTRACT FROM AUTHOR]

Abstract: Five new 0D–2D Cd(II) complexes, [Cd2(Hbimt)2I4] (1), [Cd(bimt)(Hbimt)Br] n (2), [Cd(Hbimt)Cl2(H2O)] n (3), {[Cd(Hbimt)(SO4)(H2O)2]·1.5H2O} n (4) and [Cd(Hbimt)(SCN)2] n (5) (Hbimt=2-((benzoimidazol-yl)methyl)-1H-tetrazole) have been synthesized by the reactions of Hbimt with suitable cadmium salts. Employment of different anions can influence the coordination modes of the Hbimt ligand, and accordingly result in different structures ranging from 0D to infinite 1D and 2D networks. Complex 1 displays a dimeric structure in which two Cd(II) ions are bridged through two iodine atoms. Complex 2 was caused by deprotonation of the Hbimt ligand, resulting in a 1D helical chain. While in complexes 3 and 4, Hbimt acts as a bidentate bridging ligand which joins two Cd(II) ions, leading to 1D stair-like chains. Complex 5 exhibits a 2D network structure with infinite 1D [Cd2(SCN)2] n chains. The distinct structures of 1, 2, 3, 4 and 5 reveal that the anions and the versatile coordination modes of the ligand play an important role in the structures of the complexes. In addition, the luminescent properties of complexes 1–5 have been investigated in the solid state at room temperature. [Copyright &y& Elsevier]

Abstract: Four novel lanthanide(III) coordination polymers [Ln(L)1.5(H2O)2]·5H2O [Ln=Sm (1), Eu (2), Tb (3), Dy (4)] have been hydrothermally synthesized by the reaction of 1,2-bis[4-amino-5-carboxylmethylthio-(1,2,4-triazol-3-yl)]ethane (H2L) with lanthanide(III) salts, and structurally characterized by single crystal X-ray diffraction. Polymers 1–4 are isostructural, in which all the LnIII atoms are nine-coordinated and the carboxylate groups adopt three different coordination modes (bidentate chelate, bidentate bridging, bidentate chelate bridging) to connect LnIII atoms. These polymers exhibit 3D network structures with 2-fold interpenetration, in which intriguing 1D channels are observed. Besides, the spectra properties of the title polymers are investigated, the strong luminescence characteristics of 2–3 are found. [Copyright &y& Elsevier]

Abstract: Four novel coordination polymers, one-dimensional chains [M(PTE)2(N3)2] n (M=Mn for 1 and Co for 2), and two-dimensional layers [M(PTE)2(dca)2] n (M=Mn for 3 and Co for 4) (PTE=1-(2,4-difluorophenyl-2-(1H-1,2,4-triazol-1-yl)ethanone, dca=dicyanamide anion, N(CN)2 −), have been synthesized under mild ambient conditions and structurally characterized by single crystal X-ray diffraction. In all four crystal structures, the metal atoms adopt octahedral coordination geometry with six nitrogen atoms from two monodentate PTE ligands and four azido (or dca) bridging ligands. The crystal structures of 1 and 2 are isostructural 1-D polymeric chains, alternatively linked by double end-on and double end-to-end azido bridges. However, the bent dca ligands as bidentate μ2-1,5 bridging ligands interlink the octahedral metal units to lead to 2-D (4,4) grid networks in 3 and 4. Temperature-dependent magnetic measurements in 2–300K have been performed for these four polymers, and suggest alternative ferro- and antiferromagnetic couplings for end-on and end-to-end azido bridges in 1, and the dominant ferromagnetic coupling in 2, respectively. Both polymers 3 and 4 show weak antiferromagnetic exchanges through the μ2-1,5-dca bridges. The effects of auxiliary coligands on the structure and the nature of these magnetic exchanges are discussed in the light of the crystal structures in detail. [Copyright &y& Elsevier]

Abstract: A novel tetranuclear silver(I) heterocyclic cluster, which is of nano-hole structure, based on 1,1′-bis[(2-hydroxybenzylidene)thiocarbonohydrazono-1-ethyl] ferrocene (FcL) has been prepared and structurally characterized by single-crystal X-ray diffractions. In addition, its electrochemical properties are also discussed. The results confirm that the receptor FcL is responsive to Ag+. [Copyright &y& Elsevier]

Abstract: Two Ag(I)-bridged metal-organic polymers: 2D double-crossed layer polymer {[Ag(bpfp)]·NO3 ·H2O)} n (bpfp= N,N′-bis(3-pyridylformyl)-piperazine) (1) and 1D zigzag chain polymer {[Ag(btx)]·NO3} n (btx=1,4-bis(triazol-1-ylmethyl)-benzene) (2) have been prepared and structurally characterized by single crystal diffraction. Their third-order nonlinear optical (NLO) properties and optical limiting (OL) effects were determined by Z-scan technique. The results show that both polymers possess strong optical nonlinear absorption and optical nonlinear refraction, and exhibit strong OL effect to nanosecond and picosecond incident pulsed laser. By comparing the optical nonlinearities of the polymers and purely bpfp and btx ligands, we find that the incorporation of Ag ion can largely enhance the optical nonlinearities of organic molecules attached. DFT calculation further confirms the corporate contributions of Ag ions and bridge ligands to the optical nonlinearities. [Copyright &y& Elsevier]

Abstract: A novel copper organodiphosphonate complex containing a second ligand 4,4′-bipyridine (4,4′-bpy) based on 1-aminoethylidenediphosphonic acid (H4aedp), Cu4(aedp)2(4,4′-bpy)(H2O)4 (1), has been synthesized under hydrothermal conditions. Complex 1 adopts a three-dimensional framework structure assembled from {Cu4(aedp)2(H2O)4} layers and 4,4′-bpy bridges. Each {Cu4(aedp)2(H2O)4} unit consists of three crystallographically distinct Cu atoms. The Cu(1) atom has a distorted square pyramidal geometry, whereas the Cu(2) and Cu(3) atoms have a distorted elongated tetragonal octahedral geometry. The magnetic studies indicate that complex 1 show typical antiferromagnetic behaviors at low temperature, which is attributed to the superexchange couplings between Cu(II) centers through –O bridge in the phosphonate layers. Crystal data for 1: triclinic, space group , , , , , , , , . [Copyright &y& Elsevier]