Daofeng Sun

Diverse Ni(II) MOFs constructed from asymmetric semi-rigid V-shaped multicarboxylate ligands: structures and magnetic properties

Novel nickel(II) coordination polymers have been constructed from asymmetric semi-rigid V-shaped multicarboxylate ligands with the help of 4,4′-bipyridine (4,4′-bpy) ligand. The hydrothermal reaction between 3-(4-carboxy-phenoxy)-phthalic acid (H3L1) and Ni(OAc)2·4H2O led to the formation of [Ni3(L1)2(μ-4,4′-bpy)3(H2O)2]n·(4,4′-bpy)n·(H2O)5n (1). In contrast, the same reaction using 3-(2-carboxy-phenoxy)-phthalic acid (H3L2) as a starting material instead of H3L1 resulted in [Ni3(L2)2(H2O)4(μ-4,4′-bpy)3]n·(H2O)2n (2) and [Ni3(L2)2(H2O)4(μ-4,4′-bpy)4]n·(H2O)2n (3) at 120 and 150 °C, respectively, revealing the effect of reaction temperature on the structure of the coordination polymer formed from the semi-rigid V-shaped ligand of L2. Single-crystal X-ray diffraction analysis reveals that complex 1 shows a 3D framework structure assembled from right- and left-handed helices together with isolated tubes. This compound represents the first metal–organic hybrid tube constructed from an asymmetric semi-rigid V-shaped multicarboxylate ligand. Compound 2 also exhibits a 3D network composed of discontiguous trinuclear Ni(II) clusters, while the 3D architecture of 3 consisting of isolated Ni(II) ions separated in a long distance is constructed by two kinds of 2D (6,3) networks. Magnetic studies reveal the overall antiferromagnetic interaction between the neighbouring Ni(II) ions in 1–3.

Eight Zn(II) coordination networks based on flexible 1,4-di(1H-imidazol-1-yl)butane and different dicarboxylates: crystal structures, water clusters, and topologies

Eight new Zn(II) coordination polymers based on flexible 1,4-di(1H-imidazol-1-yl)butane and different dicarboxylates, [Zn(dimb)(suc)·2DMF]n (1), [Zn(dimb)(mbda)·3H2O]n (2), [Zn(dimb)(adip)·DMF·2H2O]n (3), [Zn(dimb)(pma)·2.5H2O]n (4), [Zn2(dimb)(tha)2(H2O)]n (5), [Zn(dimb)(chda)·2H2O]n (6), [Zn(dimb)(obda)·DMF]n (7), [Zn(dimb)(tdga)·CH3OH]n (8) (dimb = 1,4-di(1H-imidazol-1-yl)butane, H2suc = succinic acid, H2mbda = m-benzenediacetic acid, H2adip = adipic acid, H2pma = pimelic acid, H2tha = thiophene-2,5-dicarboxylic acid, H2chda = 1,4-cyclohexanedicarboxylic acid, H2obda = o-benzenediacetic acid, H2tdga = thiodiglycolic acid; DMF = N,N-dimethylformamide), have been synthesized and structurally characterized by single-crystal X-ray diffraction analyses, and further characterized by infrared spectra (IR), elemental analyses, powder X-ray diffractions (PXRD) and thermogravimetric analyses (TGA). Single-crystal X-ray diffraction analysis reveals that 1, 2, 4, 7 and 8 are 2D wavy 4(4)-sql networks with different dimensions of quadrilateral window units, depending on the conformation and length of dimb and dicarboxylates. Complex 3 is a 2D a 6(3)-hcb network incorporating a [Zn2(dimb)2] cyclic subunit. In complex 5, Zn(II) centers as 3-connected node are linked by dimb and tha to form a 3D 8-fold interpenetrating ThSi2 network. Complex 6 is a 4-connected noninterpenetrating cds network. Interestingly, an infinite T4(2)6(2) water tape and a D2h cyclic water tetramer are also found in complexes 2 and 3, respectively. In 1-8, all Zn(II) centers are located in a four-coordinated environment, and dimb and dicarboxylates are 2-connected linkers, but networks with diverse topologies are built, which indicates the linkage of central metal ion, the conformation of dimb and dicarboxylate have important influences on the resulting structures. Furthermore, the solid-state photoluminescence properties of the 1-8 were investigated at 298 and 77 K.

A 3D porous metal–organic framework constructed of 1D zigzag and helical chains exhibiting selective anion exchange

Slow diffusion of AgClO44 with Me2Si [(4-(Im-1-yl)Ph]2 (BIPS) yields the crystalline complex 1 with a 3D-braided porous metal–organic framework via self-assembly of two series of 1D polymer chains through both braiding and interpenetrating. Complex 1 consists of two distinct kinds of channels with different sizes and shapes along a and b directions occupied by perchlorate anions and water molecules.

Two novel entangled metal–organic networks constructed from 4,4′-bis(2-methylimidazol-1-ylmethyl)biphenyl and dicarboxylates: From polycatenated 2D + 2D → 3D framework to polyrotaxane-like 2D + 2D → 2D layer

Two novel entangled metal–organic networks, namely [Cd(bmimbp)(bdc)]n (1) and [Zn(bmimbp)(tbtpa)]n (2) (bmimbp = 4,4′-bis(2-methylimidazol-1-ylmethyl)biphenyl, H2bdc = 1,3-benzenedicarboxylic acid, H2tbtpa = tetrabromoterephthalic acid), exhibit a polycatenated 2D + 2D → 3D framework and a polyrotaxane-like 2D + 2D → 2D layer, respectively. Moreover, the thermal stabilities and photoluminescent properties are also discussed.

Construction of copper metal–organic systems based on paddlewheel SBU through altering the substituent positions of new flexible carboxylate ligands

Three flexible dicarboxylate ligands 2,2′-(1,2-phenylenebis(methylene))bis(sulfanediyl)dibenzoic acid (H2L6), 2,2′-(2,4,6-trimethyl-1,3-phenylene)bis(methylene)bis(oxy)dibenzoic acid (H2L7) and 2,2′-(1,4-phenylenebis(methylene))bis-(sulfanediyl)dinicotinic acid (H2L8), have been designed and synthesized. All ligands can adopt syn or anti conformations and the positions of the functional substituents in the central benzene ring change gradually from 1,2-, 1,3- to 1,4-position. By applying these flexible ligands to assemble with copper ions, four metal–organic complexes based on paddlewheel SBU have been isolated. Complexes 1 and 2 are discrete molecular chairs. Complex 3 is a 1D molecular-chair-based coordination polymer. The molecular chairs, similar to that found in 1 and 2, are infinitely connected by the bridging 4,4′-bipy ligands to result in the formation of the 1D chain structure. Complex 4 is a two-dimensional wavelike layer structure containing a 68-member ring. Both L6 and L7 in 1 and 2 adopt syn conformation, while L8 adopts anti conformation, which results in the formation of the 2D layer structure of complex 4.

Solvent-controlled Cd(II) metal–organic frameworks constructed from a tetrapodal silicon-based linker

Two solvent-modulated Cd(II) metal–organic frameworks (MOFs), [Cd4(TCS)2(DMF)2(EtOH)(H2O)7·4DMF]n (1) and [Cd2(TCS)(DMF)2·4H2O]n (2) (H4TCS = tetrakis(3-carboxyphenyl)silicon, DMF = N,N-dimethylformamide), were constructed from a novel tetrapodal silicon-based linker. In 1 and 2, the TCS ligands exhibit different coordination modes and link mononuclear [Cd(COO)4] and tetranuclear [Cd4(COO)8(DMF)4] SBUs (secondary building units) to give 1 and 2 2D 44-sql net and (4,8)-connected 3D framework with rare fluorite (flu) topology, respectively. Dissimilarities in the geometry of both SBUs are originated from the different solvent systems which result in the formation of different networks in each case. The photoluminescence behaviours of them were also discussed.

1D zigzag chain vs. 1D helical chain: the role of the supramolecular interactions on the formation of chiral architecture

Two 1D coordination polymers with a 1D zigzag and a helical chain, respectively, have been solvothermally synthesized. The different coordinated small molecules on the cadmium ion have significant influences on the formation of different architectures. Due to the existence of supramolecular interactions between the helices in complex 2, the same chirality is preserved, resulting in a chiral architecture. By introducing a chiral molecule as cosolute, the bulk homochiral crystallization from achiral precursors for 2 can be achieved.

A “Strongly” Self-Catenated Metal–Organic Framework with the Highest Topological Density among 3,4-Coordinated Nets

A new type of 3D strongly self-catenated metal-organic framework (SDU-9) has been constructed from [Cu2(COO)4] paddlewheel secondary building units and a tripodal carboxylate linker. SDU-9 ([Cu6(H2O)6L4]·24H2O, where [H3L = 4,4,4-(hydroxysilanetriyl)tris(triphenyl-4-carboxylic acid), represents a rare example of a highly symmetrical coordination network and extremely tight self-catenation. To the best of our knowledge, SDU-9 has the highest topological density among all known 3,4-coordinated nets.

Three novel 3D metal–organic frameworks with a 1D ladder, tube or chain as assembly units

Three novel metal–organic frameworks, Cu4(OH)2(SO4)(HBTC)2(bpy)·bpy (1), Cu1.5(H2O)(TMBTC)(bpy)·1/2H2O (2) and Cd2(H2O)5(TMBTC)(bpy)2·NO3·3H2O (3), constructed from mixed organic ligands, have been synthesized and characterized. Complex 1 crystallizes in monoclinic space groupC2/c and possesses a 3D three-fold interpenetrating framework. The copper ions were first connected by HBTC and SO42− to generate a 1D ladder, which was further linked by a 4,4′-bipyridine ligand to give rise to a 3D interpenetrating framework. Complex 2 crystallizes in monoclinic space groupP2/c and possesses a 3D two-fold interpenetrating framework. Similar to 1, the copper ions were first connected by TMBTC to generate a 1D tubular unit, which can be considered as the assembly block. The 1D tubular unit was further linked by 4,4′-bipyridine ligands to result in the formation of the 3D framework. Complex 3 crystallizes in monoclinic space groupCc and has a three-dimensional structure. Different from 1 and 2, the cadmium ions were first connected by a 4,4′-bipyridine ligand to form a 1D chain as the assembly unit, which was further linked by TMBTC ligand to generate the final 3D framework. The photoluminescence measurement of 3 in the solid state at room temperature showed that complex 3 exhibits luminescence, which can be assigned to an intraligand π → π* transition.

Stepwise Construction of a AgI9–CuII4 Heterometallic Cluster Incorporating Two Unusual Vertex-Shared Trigonal-Bipyramidal Silver Polyhedra

One step at a time: A novel tridecanuclear Ag(I)(9)-Cu(II)(4) heterometallic cluster comprising four [Cu(phen)(2)](2+) units on the periphery and one interior [Ag(9)(mna)(8)](7-) cluster was synthesized in a stepwise manner and characterized. The interior [Ag(9)(mna)(8)](7-) cluster contains two unusual vertex-shared trigonal-bipyramidal silver polyhedra.