Search

International audience; Solid solution of Hydrogen bonded networks of formula ((1-2H +)3x(2-2H +)3(1-x)([Fe(CN)6] 3-2)). nH2O, where (1-2H +) and (1-2H +) are bisamidinium H bond donor entities, have been synthetized and structurally analysed. The H bonded systems display a honeycomb-like structure, and depending on the x value, three different pavages of the (6,3) system are observed, leading to three different phases. The precise location of the H bond donor cations (2-2H +) have been performed, evidencing H bonding between adjacent cations. Thermal properties of the solid solutions have been performed.

Different ways of anions introduction were applied to construct cluster-based frameworks, owning to the versatile coordination ability of the formate anion and its sensitivity to the pH value of the reaction system. Three tetra-, penta-, and hexanuclear cluster-based cobalt-organic frameworks, [Co2(L)3(HCO2)·MeOH]n (1), [Co5(L)6(OH)2(NO3)2·2H2O]n (2), and [CoL(HCO2)]n (3) [L = (E)-3-(pyridin-3-yl)acrylate], have been successfully synthesized. In these complexes, each CoII cluster is linked by twelve L ligands with different connectivities to generate unique topological nets. In 1, two formate anions link four CoII ions forming a tetranuclear cluster, and each of the tetranuclear clusters is connected to eight neighbors by L ligands, giving an 8-connected 36418536 net. In 2, the pentanuclear cluster is formed by five CoII ions linked through two OH– and six carboxylate groups, which are further connected by L ligands to afford a pcu (primitive cubic lattice) net. Different from 1 and 2, complex 3 is a 2-fo...

Three new CoII–azido complexes, [Co3(L)2(o-BDC)2(N3)2]n (1), [Co3(L)2(m-BDC)2(N3)2]n·nH2O (2), and [Co2(L)2(p-BDC)(N3)2]n·2nMeOH (3) [o-BDC = 1,2-benzenedicarboxylate, m-BDC = 1,3-benzenedicarboxylate, p-BDC = 1,4-benzenedicarboxylate, and L = di(1H-imidazol-1-yl)methane], have been constructed from di(1H-imidazol-1-yl)methane, azido, and different aromatic dicarboxylates under hydrothermal conditions. Complex 1 takes a dia topology with the Co3 units as connecting nodes, and complex 2 is a two-dimensional sql layer that further extends to a three-dimensional (3D) supramolecular network via π···π interaction between m-BDC ligands, while complex 3 forms a 3D pcu network based on Co2 units as nodes. The investigaton of magnetic properties of complexes 1–3 demonstrates that they all display ferromagnetic coupling between CoII ions but antiferromagnetic interaction between Co3 or Co2 units.

This paper reports two new coordination polymers formed by carboxylate-substituted benzoimidazole and formate ligands: [Mn(L)·(HCO2)] n (1) and [Co(L)·(HCO2)] n (2) (L = benzoimidazol-1-yl-acetate). Complexes 1 and 2 are isomorphous and adopt a new 3,6-connected three-nodal topology showing interesting magnetic properties: spin canted antiferromagnetism for MnII complex 1, but simple antiferromagnetic coupling for CoII complex 2.

The investigation of magnetic materials with fascinating structures and unusual magnetic behavior has witnessed flourishing development. Transition-metal hydroxides are of particular significance because of their potential application in magnetic devices (as substitutes for traditional ferrite or nanometric magnetic memory units), and have been extensively explored. Even so, it is still a tremendous challenge for researchers to rationally design, precisely control, artfully modulate, and effectively re-assemble new transition-metal/hydroxide species (hydroxide-bridged clusters, chains, and layers). In the hydroxyl inorganic layers (such as Cu(OH)2, FeO(OH), Mg(OH)2, etc.), the hydroxide groups are present in m2 and m3 modes. To replace some of the hydroxide ligands with other bridging groups in order to alter the magnetic properties is still a challenge to chemists today. As we know, azide is one of the most studied ligands in magnetochemistry, and its complexes display exciting magnetic properties ranging from long-range ordering to SMM (single-molecule magnet) and SCM (single-chain magnet) behavior. Additionally, the magnetic interaction through an azide bridge can be easily predicted based on its bridging mode and the M-N-M angles. The most typical bridging modes are end-to-end (EE, m2-1,3) and end-on (EO, m2-1,1), usually resulting in antiferromagnetic and ferromagnetic coupling, respectively, but this greatly depends on the Cu-N-Cu angle for end-on azides. Azides can also bridge more than two ions in their EO mode; for instance, it can bridge three metal ions in a pyramidal fashion analogous to that of a m3-OH group. In view of azides being able to take both m2-1,1 and m3-1,1,1 bridging modes, it may replace some OH positions in the 2D inorganic layer, which could lead to different magnetic behavior. To avoid the inorganic layer collapsing or aggregating into a 3D solid, a second ligand is usually introduced into the system. Herein, phthalic acid (H2-pta) is our second ligand of choice. A Cu / N3 /OH /pta network could have a high negative charge and counterion will then be needed. Herein we report the synthesis of an unusual 2D N3-Cu -OH complex, [CuACHTUNGTRENNUNG(H2O)6]ACHTUNGTRENNUNG[{Cu2(N3)4/3-(OH) ACHTUNGTRENNUNG(pta)}6] (1). Indeed, our results show that the [Cu ACHTUNGTRENNUNG(H2O)6] 2+ complex ion from the CuACHTUNGTRENNUNG(NO3)2 aqueous solution may serve as a template for the [Cu24] macrocycles. The crystal structure of complex 1 (Figure 1) consists of a new anionic 2D layer network containing two Cu ions, one phthalic anion (in m4-O,O’,O’’,O’’’ bridging mode), one m3 hydroxyl anion, and =3 azide anions, which take m2-1,1 and m3-1,1,1 bridging modes (Figure S1). As can be seen in Figure 1 (top), Cu1 is five-coordinate with a distorted square-based pyramid CuN2O3 geometry formed by the coordination of two nitrogen atoms, from the m2-1,1and m31,1,1-azide anions (apical position) (Cu1 N1=2.000(5), Cu1 N4=2.287(3) ;), and three oxygen atoms, one from the m3 hydroxyl anion and two from phthalic anions (Cu1 O5=1.969(4), Cu1 O1=1.983(4), Cu1 O4=2.018(4) ;). The square-based pyramidal coordination sphere of Cu2 is CuNO4, in which the N atom is from a m2-1,1 azide anion (Cu2 N1A=1.972(5) ;), and the four oxygen atoms are from two m3 hydroxyl anions and two phthalic anions (one occupied the apical position) (Cu2 O5=1.954(4), Cu2 O5A=1.979(4), Cu2 O2=2.646, Cu2 O3=1.934(4) ;). Two hydroxyl anions in the m3 mode (Cu1-O5-Cu2=100.74, Cu1-O5-Cu2A=118.24, Cu2-O5-Cu2A=100.308) bridge [a] Y.-F. Zeng, X. Hu, J.-P. Zhao, B.-W. Hu, Dr. F.-C. Liu, Prof. X.-H. Bu Department of Chemistry Nankai University Tianjin 300071 (China) Fax: (+86)22-2350-2458 E-mail : buxh@nankai.edu.cn [b] Dr. E. C. SaCudo Departament de QuJmica InorgKnica Universitat de Barcelona Diagonal, 647, Barcelona (Spain) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.200800068.

The X-ray crystal structures, magnetic susceptibilities from 2 to 300 K, and theoretical analyses of the magnetism for 1D and trinuclear azido Cu(II) carboxylate complexes [Cu(1.5)(hnta)(N(3))(2)(H(2)O)](n) (1) and [Cu(3)(hnta)(4)(N(3))(2)(H(2)O)(3)] (2), respectively, where hnta is 6-hydroxynicotinate, are described. Although both exhibit strong ferromagnetic coupling, discrete complex 2 exhibits long-range ferromagnetic ordering, while the very similar 1D system 1 does not. Density functional calculations provided accurate J values and allowed rationalization of the ferromagnetic coupling in terms of the magnetic orbitals and spin densities.

A new azido-NiII complex constructed from nicotinate has been obtained by cation−anion pairs as templates under hydrothermal conditions, which exhibits three-dimensional Kagome topology and ferromagnetic coupling.

A magnetic isolated chain-based substituted cobalt-formate framework was obtained with isonicotine as a spacer. In the chain, canted antiferromagnetic interactions exist in between the Co(II) ions, and slow magnetic relaxation is detected at low temperature. For the block effects of the isonicotine ligands, the complex could be considered as a peculiar example of a weak ferromagnetic single-chain-magnet.

The molecular 1:1 complexation of cinchona alkaloids by mono(6-deoxy-6-{[(R)-1-(hydroxymethyl)propyl]amino})-beta-cyclodextrin (1) in aqueous solution has been investigated by 2D-NMR, fluorescence titration, and fluorescence-lifetime experiments. Generally, with 1 as the host, in contrast to beta-cyclodextrin proper, strong binding of quinine (2; Ka = 84,200 M(-1)) and quinidine (3; Ka = 27,300 M(-1)) at pH 6.8 was observed, as monitored by an increase in fluorescence intensity, with a fair degree of diastereoisomer discrimination (ca. 3:1). To rationalize these results, two possible cooperative complexation modes, including specific H-bonding interactions to the chiral tether of the cyclodextrin portion, are proposed.

Four novel AgI coordination complexes with azole heterocycle ligands bearing acetic acid group, [AgL1]n (1), [Ag(L2HL2)]n (2), [AgL3]n (3) and [Ag(L4)]n (4) (here, HL1 = 1H-imidazole-1-acetic acid, HL2 =1H-benzimidazole-1-acetic acid, HL3 =1H-1,2,4-triazole-1-acetic acid, HL4 =1H-benzotriazole-1-acetic acid), have been synthesized and structurally characterized by elemental analysis, IR and X-ray diffraction. Structural analyses show that complex 1 possesses a two-dimensional structure, which contains silver chains formed by weak Ag–Ag interactions, and 2 consists of neutral chains connected by weak bonds (O⋯H⋯O), while 3 and 4 have a three-dimensional network and a one-dimensional chain structure, respectively. It is interesting that in 1 there exist Ag–Ag interactions with a separation of 3.156 A, which play an important role in the formation of the complex. Furthermore, the conductivity of 1 was studied in the powder state.

The reaction of LnIII salts with 1,5-naphthalenedisulfonate (1,5-NDS) or 2,7-naphthalenedisulfonate (2,7-NDS), and phenanthroline (phen) under hydrothermal conditions gave a series of new 2-D complexes {[Ln(1,5-NDS)1.5(phen)2(H2O)2]·3H2O}n [Ln = EuIII (1), GdIII (2), NdIII (3), TbIII (4)] and dinuclear compounds [Ln2(2,7-NDS)2(μ2-OH)2(phen)4(H2O)2]·4H2O [Ln = EuIII (5), GdIII (6), TbIII (7)], respectively. 1–4 are puckered (6,3) networks with 1,5-NDS as a bridge and phen chelating to LnIII ions. 5–7 are hydroxyl bridged dinuclear entities, which extend to 2-D networks by H-bonds.