Bimetallic Metal-Organic Frameworks: Probing the Lewis Acid Site for CO2 Conversion.

A highly porous metal-organic framework (MOF) incorporating two kinds of second building units (SBUs), i.e., dimeric paddlewheel (Zn2 (COO)4 ) and tetrameric (Zn4 (O)(CO2 )6 ), is successfully assembled by the reaction of a tricarboxylate ligand with Zn(II) ion. Subsequently, single-crystal-to-single-crystal metal cation exchange using the constructed MOF is investigated, and the results show that Cu(II) and Co(II) ions can selectively be introduced into the MOF without compromising the crystallinity of the pristine framework. This metal cation-exchangeable MOF provides a useful platform for studying the metal effect on both gas adsorption and catalytic activity of the resulted MOFs. While the gas adsorption experiments reveal that Cu(II) and Co(II) exchanged samples exhibit comparable CO2 adsorption capability to the pristine Zn(II) -based MOF under the same conditions, catalytic investigations for the cycloaddition reaction of CO2 with epoxides into related carbonates demonstrate that Zn(II) -based MOF affords the highest catalytic activity as compared with Cu(II) and Co(II) exchanged ones. Molecular dynamic simulations are carried out to further confirm the catalytic performance of these constructed MOFs on chemical fixation of CO2 to carbonates. This research sheds light on how metal exchange can influence intrinsic properties of MOFs.

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.

Single-molecule-magnet behavior in a Fe(12)Sm(4) 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).

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.

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.

New 3D coordination polymers constructed from pillared metal-formate Kagomé layers exhibiting spin canting only in the nickel(II) complex.

Sparked by the strategy of pillared-layer MOFs, three formate coordination polymers, {[Ni(2)(HCO(2))(3)(L)(2)](NO(3)).2H(2)O}(infinity) (1), {[Co(2)(HCO(2))(3)(L)(2)](HCO(2)).2H(2)O}(infinity) (2), and {[Cu(2)(HCO(2))(3)(L)(2)](HCO(2)).2H(2)O}(infinity) (3), have been synthesized by employing the rodlike ligand 4,4'-bis(imidazol-1-yl)biphenyl (L) as the pillar. Structural analysis indicates that the title complexes 1-3 are isostructural compounds, which possess metal-formate 2D layers perpendicularly pillared by the ligand L to afford a 3D open framework. This is an interesting example of a Kagome lattice based on the formate mediator. Moreover, the formate anion of this 2D Kagome layer exhibits various bridging modes: anti-anti, syn-anti, and 3.21 modes. Their magnetic measurements reveals that only complex 1 presents the spin canting phenomenon, while its isostructural Co(II) and Cu(II) complexes are simply paramagnets with antiferromagnetic coupling.

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.

[Study of LI Gao's native place].

Li Gao, a famous doctor in Jin and Yuan Periods, was born in Zhengding County, Hebei Province according to History of the Ming Dynasty. But his tomb in Adang Village, Huangling County, Shanxi Province, the epitaph of tombstone (set up in 1828, the 8th year of the Daoguang Period) and the Li's Genealogica Tree held by the villagers show that LI Gao was the 4th generation of local Li's family. Literatures of the Republic of China period, like Huangling County Annals, also recorded that Huangling county as LI Gao's native place. All of the historical relics, oral historical materials and literatures are of historical value and LI Gao's native place needs to be further investigated.

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.

An unprecedented double-bridging interpenetrating α-Po network based on a new heterometallic cluster {Cu4Mo6}.

A new coordination polymer of polyoxomolybdate, {[Cu(4)(bbp)(5)Mo(6)O(22)]·(H(2)O)(4)}(∞) (bbp = 1,4-bis(benzoimidazol-1-yl)phenyl), has been synthesized under solvothermal reaction, which represents a double-bridging interpenetrating α-Po network based on the bimetallic cluster {Cu(4)Mo(6)}. The thermogravimetric and electrochemical behaviors have also been studied.

Homospin single-chain magnet with 1D ferromagnetic azido-cobalt Ising-type chain.

A new 2D coordination polymer with an azide-bridged 1D homospin chain is synthesized, which shows slow magnetic relaxation and step hysteresis loop, and is ascribed to be a typical Ising-type single-chain magnet.

Two unprecedented 10-connected bct topological metal-organic frameworks constructed from cadmium clusters.

By simply modifying the expansion of ligand tether length, two Cd(ii) metal-organic frameworks have been constructed from linear tetranuclear and trinuclear cadmium clusters, respectively, which present an unprecedented 10-connected uninodal bct net.

One-dimensional metal-azido complex constructed by a double EO azido bridged trinuclear nickel(II) unit: synthesis, structure and magnetic properties.

The hydrothermal reaction of Ni(NO(3))(2).6H(2)O, NaN(3) phenanthroline and nicotinic acid yielded a one-dimensional (1D) complex, [Ni(1.5)(N(3))(2)(phen)(nic)](n) (1) (phen = phenanthroline, nic = nicotinate), which is a new example of the named orbital countercomplementarity-like complex. In 1, the nicotinate shows mu(3)-nic-N,O,O coordination mode, and the azide groups adopt mu(1,1) bridging mode linking Ni(II) ions to form a rare trinuclear Ni(II) unit bridged by a double mu(1,1) azido.

Azido-mediated systems showing different magnetic behaviors.

Azido has been one of the well used bridging ligands in the construction of magnetic molecule materials, which has stimulated considerable interest in magnetochemistry. This tutorial review is concentrated on the study of azido metal compounds with their magnetochemistry and consists of eight main sections. The first section offers an introduction to azido complexes and some important results obtained from magneto-structural correlation in azido complexes which will be referred to in the following sections. The next six sections give overviews of azido-mediated ferromagnets, ferrimagnets, canted (weak) ferromagnets, antiferromagnets, single molecule magnets (SMMs) and single chain magnets (SCMs), and metamagnets. The last section is the conclusion and gives a perspective of azido-mediated magnets.

Novel lanthanide-azido complexes: hydrothermal syntheses, structures and magnetic properties.

Three new 1D lanthanide-azido complexes, [Ln(2)(N(3))(isonic)(2)-(OH)(3)(Hisonic)(H(2)O)](n) (Ln = Gd(III), Eu(III) and Sm(III)), were synthesized by hydrothermal reaction and their magnetic properties were studied.

Nickel(II)-azido ferromagnetic chains in a 3D porous metal-organic framework with breathing guest molecules.

A new 3D porous Ni(II)-azido complex has been synthesized and characterized and exhibits guest sorption properties explored by single-crystal to single-crystal transformations and linear ferromagnetic chains held together by a Ni-isonicotinate framework.

Two new copper azido polymorphs: structures, magnetic properties, and effects of "noninnocent" reagents in hydrothermal methods.

Two new 3D copper(II) azido isomers, [Cu(N3)(nic)]infinity (1 and 2) (nic = nicotinate), have been synthesized and characterized. To the best of our knowledge, 1 is the first metal azido complex showing rutile-type topology, while 2 is a chiral compound obtained by spontaneous resolution upon crystallization.

An unusual 1D manganese azido complex with novel EO/EO/EO/EE coordination mode: synthesis, structure, and magnetic properties.

A novel one-dimensional manganese(II) azido complex, [Mn2(N3)4(phen)2]n (1), in which the azido bridging ligands take on an unusual new type of combination with the metal center as the sign of [-EO-EO-EO-EE-]n, has been hydrothermally synthesized, and its magnetic properties have been studied.

Structures with tunable strong ferromagnetic coupling: from unordered (1D) to ordered (Discrete).

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.

First metal azide complex with isonicotinate as a bridging ligand showing new net topology: hydrothermal synthesis, structure, and magnetic properties.

A new 3D azido-bridged coordination polymer, [Co1.5(N3)(OH)(Isonic)]n (1), has been synthesized and characterized and its magnetic properties studied. Isonicotinate acts as a bridging coligand in this complex. In 1, all of the ligands take tridentate bridging coordination modes, and the overall structure of 1 exhibits a new 3,6-connected net topology.