Yong-Fei Zeng

Tuning the structure and magnetism of azido-mediated Cu(II) systems by coligand modifications.

Through the use of a series of structurally related benzoates bearing different substituents as coligands, three new azido-copper compounds, [Cu(benzoate)(N(3))](n) (1), [Cu(2-methyl-benzoate)(N(3))](n) (2), and [Cu(1-naphthoate)(N(3))](n) (3), have been successfully obtained and structurally and magnetically characterized. Single-crystal structure analyses indicated that the uncoordinating substituents in the benzoates greatly affect the structure of the complexes. Complex 1 displays isolated ferromagnetic chains with the largest Cu-N-Cu angle in known carboxylate/end-on-azido mixed-bridged copper systems, while complexes 2 and 3 were 2D coordination polymers, containing mu-(1,1,3,3) and mu-(1,1,3) bridging azides and exhibiting new azido-copper networks with (4(4)) and (4.8(2)) topologies, respectively. Furthermore, 2 was a chiral complex obtained through spontaneous resolution. In the low-temperature range, both 2 and 3 showed spontaneous magnetization with characteristics of soft ferromagnetic magnetism with phase transition temperatures of 13 and 10 K, respectively.

An azido–metal–isonicotinate complex showing long-range ordered ferromagnetic interaction: synthesis, structure and magnetic properties

A new 3D Cu(II) complex [Cu1.5(N3)2(isonicotinate)]n [1], which features two types of bridging modes for azide (mu(1,1) and the rare asymmetric mu(1,1,3)) where the three bonds of the mu(1,1,3)-N3(-) group to Cu exhibit three different distances, has been synthesized and characterized, and magnetic measurements indicate that [1] experiences long-range ferromagnetic ordering at approximately 6 K.

Single-Molecule-Magnet Behavior in a Fe12Sm4 Cluster

Through the combination of Sm(III) spin carriers with a Fe(III) system, the largest Fe-Ln cluster so far has been synthesized. To our knowledge, the new complex, Fe(12)Sm(4), is the first Sm(III) single-molecule magnet. Furthermore, Fe(12)La(4) and Fe(12)Gd(4) have also been synthesized to help understand the magnetic exchange interactions and origin of magnetic anisotropy in Fe(12)Sm(4).

Tuning silver(I) coordination architectures by ligands design: from dinuclear, trinuclear, to 1D and 3D frameworks

In our efforts to tune the structures of AgI complexes by ligand modification, six structurally related ligands: 1,2-bis(triazol-1-ylmethyl)benzene (L1), 1,3-bis(triazol-1-ylmethyl)benzene (L2), 1,4-bis(triazol-1-ylmethyl)benzene (L3), 1,3,5-tri(triazol-1-ylmethyl)-2,4,6-trimethylbenzene (L4), 1,4-bis[3-(2-pyridyl)-pyrazol-1-ylmethyl]naphthalene (L5), and 9,10-bis(benzimidazol-1-ylmethyl)anthracene (L6) have been designed and used to react with AgI salts to form six new complexes: {[Ag2(L1)2](BF4)2(H2O)} (1), [Ag2(L2)(NO3)2]n (2), [Ag(L3)(NO3)]n (3), {[Ag3(L4)2](SiF6)1.5(H2O)3.5} (4), {[Ag2(L5)2](NO3)2(H2O)} (5), and {[Ag2(L6)2](NO3)2(CH3OH)2} (6). All the complexes have been structurally characterized by IR and X-ray diffraction. Structural analyses show that complexes 1, 5, and 6 possess dinuclear structures, which extend to infinite coordination networks linked by Ag⋯N, C–H⋯O, or π–π weak interactions. 2 is a 3D chiral coordination polymer with (10,3)-a topology, and 4 forms a trinuclear cage structure, which further connected by Ag⋯Ag weak interactions to form a 1D supramolecule, while 3 exhibits an infinite 1D chain structure. The structures of complexes 1–6 span from dinuclear, trinuclear, 1D, to 3D network, which indicates that ligands play important roles in the formation of such coordination architectures. Furthermore, the CD spectrum, thermal, and fluorescent properties of the chiral complex 2 have been investigated in the solid state.

New d10 metal–organic coordination polymers with 9,10-bis(triazol-1-ylmethyl)anthracene (L): Syntheses, crystal structures, and luminescent properties

In our continuous efforts to explore the effects of metal ions, ligand structures, counter-anions on the structure and properties of metal–organic complexes, six new d10 metal coordination polymers with an anthracene-triazole ligand, 9,10-bis(triazol-1-ylmethyl)anthracene (L), {[Cu(L)I]}∞ (1), {[Ag(L)(BF4)]}∞ (2), {[Zn(L)(NO3)2]}∞ (3), {[Zn(L)(CH3OH)2(ClO4)2(H2O)]}∞ (4), {[Cd(L)(CH3OH)2(ClO4)2(H2O)]}∞ (5) and {[Hg(L)(Br2)]}∞ (6), were synthesized and structurally characterized by elemental analyses, IR spectroscopy and single-crystal X-ray diffraction. 1–3 and 6 have similar one-dimensional (1-D) chain structures in which 1, 3 and 6 were further linked into infinite two-dimensional (2-D) sheets by inter-chain C–H⋯I, π⋯π or C–H⋯Br weak interactions, respectively, while 2 was extended into three-dimensional (3-D) supramolecular network by Ag⋯F and Ag⋯N weak interactions. 4 and 5 possess similar (4,4) 2-D sheet structure containing only one type of rhombic grid, and the Zn/Cd atoms are regarded as the four-connected nodes and the ligand as bridges. Obviously, the structural differences among them are attributable to the different metal ions and counter anions. In 1–6, L adopts a trans-gauche conformation with the shortest N⋯N distance between the two N donors. Furthermore, the fluorescent properties of 1–6 and ligand L have been investigated.

Three-Dimensional Porous Metal−Organic Frameworks Exhibiting Metamagnetic Behaviors: Synthesis, Structure, Adsorption, and Magnetic Properties

Two isomorphous 3D porous metamagnets, {[M(6)(N(3))(12)L(6)].(H(2)O)(13)}(infinity) (M = Ni(II), 1; Co(II), 2), have been constructed from 2-(1,3,4-thiadiazol-2-ylthio)acetic acid (HL), with azido as the auxiliary ligand. Single-crystal X-ray analysis indicates that the complexes possess hexagonal channels with dimensions of about 8.3 A x 8.3 A along the c axis and void space of about 25% per cell volume. Hydrogen adsorption measurements at 740 Torr and 77 K reveal that hydrogen uptakes of 0.68 and 0.83 wt % were observed in 1 and 2, respectively, with BET surface areas of 309 and 328 m(2)/g. Magnetic measurement reveals that both of them exhibit global metamagnetic behaviors resulted from strong intrachain ferromagnetic couplings and weak interchain antiferromagnetic interactions, with critical fields of 22 kOe and 6 kOe for 1 and 2, respectively.

Partial Substitution of Hydroxyl by Azide: An Unprecedented 2D Azido–Copper–Hydroxyl Compound with a [Cu24] Macrocycle in the Presence of [Cu(H2O)6]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.

Arenedisulfonate–lanthanide supramolecular architectures with phenanthroline as a co-ligand: syntheses and structures

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.

Isomorphous tetrazolate MnII and CoII compounds built on Δ-chain showing different magnetic behaviors.

As a continuation of the study on using the tetrazolate ligands to construct coordination polymers, two isomorphous 3D coordination polymers built on Δ-chain topological rod-shaped SBUs have been synthesized with formulae [M(2)(μ(3)-OH)L(1)L(2)](n) (5-amino-1H-tetrazole (HL(1)), 2,3-pyrazinedicarboxylic acid (H(2)L(2)) and different 3d spin carriers (M = Mn(II), 1 and Co(II), 2)). The SBU consists of corner-sharing [M(3)(μ(3)-OH)] isosceles triangle motifs with mixed multiple (μ(4)-tetrazolyl, μ(3)-OH, syn-syn carboxylate) bridges. The SBUs were further linked by syn-anti carboxylates to form the sra net. Spin-competing was observed in the Mn(II) compound, whereas the Co(II) compound exhibits spin-canting.

Fe20 Cluster Units Based Coordination Polymer from in Situ Ligand Conversion and Trapping of an Intermediate

A coordination polymer based on an unprecedented Fe(20) core has been constructed by in situ ligand conversion, including trapping of an intermediate.