A bridge between pillared-layer and helical structures: a series of three-dimensional pillared coordination polymers with multiform helical chains

Rational self-assembly of a long V-shaped 3,3',4,4'-benzophenonetetracarboxylate (bptc) ligand and metal salts in the presence of linear bidentate ligand yield a series of novel pillared helical-layer complexes, namely, [Cu2(bptc)(bpy)2] (1), [M3(Hbptc)2(bpy)3(H2O)4].2 H2O (M = Fe(2) and Ni(3)), [Co2(bptc)(bpy)(H2O)].0.5 bpy (4), [Cd2(bptc)(bpy)(H2O)2].H2O (5), [Mn2(bptc)(bpy)1.5(H2O)3] (6) and [M2(bptc)(bpy)0.5(H2O)5].0.5 bpy (M = Mn(7), Mg(8) and Co(9), bpy=4,4'-bipyridine). Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric (TG) analyses. The structure of 1 consists of two types of chiral layers, one left-handed and the other right-handed, which are connected by bpy pillars to generate a novel 3D open framework featuring four distinct helical chains. Compounds 2 and 3 are isostructural and feature 3D structures formed from the interconnection of arm-shaped helical layers with bpy pillars. Compound 4 is a pillared helical double-layer complex containing four different types of helices, among which the nine-fold interwoven helices constructed from triple-stranded helical motifs are unprecedented. Compound 5 exhibits a novel 3D covalent framework which features nanosized tubular channels. These channels are built from helical layers pillared by bptc ligands. The structure of 6 is constructed from {Mn(bptc)(H2O)}n2n- layers, which consist of left- and right-handed helical chains, pillared by [Mn2(bpy)3(H2O)4]4+ complexes into a 3D framework. To the best of our knowledge, compounds 1-6 are the first examples of pillared helical-layer coordination polymers. Compounds 7-9 are isostructural and exhibit interesting 2D helical double-layer structures, which are constructed from {M(bptc)(H2O)2}n2n- ribbons cross-linked by [M2(bpy)(H2O)6]4+ complexes. Furthermore, the 3D supramolecular structures of 7-9 are similar to the 3D structure of 6, and the 2D structure of 7 can be transformed into the 3D structure of 6 at higher reaction temperature. By inspection of the structures of 1-9, it is believed that the V-shaped bptc ligand and V-shaped phthalic group of the bptc ligand are important for the formation of the helical structures. The magnetic behavior of compounds 1, 2, 4, 6, and 9 was studied and indicated the existence of antiferromagnetic interactions. Moreover, compound 5 shows intense photoluminescence at room temperature.     

Four Zn(II)/Cd(II) coordination polymers derived from isomeric benzenedicarboxylates and 1,6-bis(triazol)hexane ligand: synthesis,crystal structure,and luminescent properties

Four coordination polymers, [Zn(o-bdc)(bth)_0.5(H₂O)] _n (1), [Cd(o-bdc)(bth)_0.5(H₂O)] _n (2), [Zn(m-bdc)(bth)] _n (3), and [Cd(p-bdc)(bth)?·?(H₂O)₂] _n (4) (where o-bdc?=?1,2-benzenedicarboxylate, m-bdc?=?1,3-benzenedicarboxylate, p-bdc?=?1,4-benzenedicarboxylate, and bth?=?1,6-bis(triazol)hexane), have been hydrothermally synthesized and structurally characterized. Both 1 and 2 are isostructural, featuring two binodal architectures: (6³)(6⁵·8) topology in terms of o-bdc and Zn^II/Cd^II as three- and four-connected nodes. Complex 3 shows a 2-D (4,4) network with the Zn?···?Zn?···?Zn angle of 57.84°, whereas 4 exhibits planar 2-D (4,4) network. These 2-D networks of 3 and 4 are extended by supramolecular interactions, such as CH?···?π/π–π stacking and hydrogen-bonding into 3-D architecture. A structural comparison of these complexes demonstrates that the dicarboxylate building blocks with different dispositions of the carboxyl site play a key role in governing the coordination motifs as well as 3-D supramolecular lattices. Solid-state properties such as photoluminescence and thermal stabilities of 1–4 have also been studied.     

Metal-organic frameworks based on trigonal prismatic building blocks and the new "acs" topology

Cationic and mixed-valent forms of Fe3O(CO2)6 trigonal prismatic clusters have been linked by ditopic links, namely, 1,4-benzenedicarboxylate (1,4-BDC) and 1,3-benzenedicarboxylate (1,3-BDC), to produce two 3-periodic metal-organic frameworks (MOFs), [Fe3O(1,4-BDC)3 (DMF)3][FeCl4] x (DMF)3 (MOF-235) and Fe3O(1,3-BDC)3 (py)3 x (py)0.5(H2O)1.5 (MOF-236) (DMF = N,N-dimethylformamide, py = pyridine), respectively. These MOFs exemplify a new, high-symmetry topology termed acs which we identify here as the default arrangement for linking trigonal prisms together.     

Hydrothermal synthesis, structures, and physical properties of four new flexible multicarboxylate ligands-based compounds

Four new compounds of partially or wholly deprotonated 5,5'-(1,4-phenylenebis(methylene))bis(oxy)diisophthalic acid (H4L1) and 5,5'-(1,3-phenylenebis(methylene))bis(oxy)diisophthalic acid (H4L2), namely {[Co(L1)0.5] x (H2O)2}n (1), {[Mn(L1)0.5] x (H2O)2}n (2), {[Cu(H2L1)](mu2-bipy)}n (bipy = 4, 4'-bipyridyl) (3), and {[Zn2(L2)] x H2O}n (4) were synthesized in the presence or absence of auxiliary bipy ligand. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra, and thermogravimetric analysis. Compounds 1 and 2 are isostructural and possess three-dimensional (3D) networks. In compound 3, multicarboxylate ligands and bipy ligands link Cu centers to generate a two-dimensional (2D) sheet structure which is further connected by intermolecular hydrogen bonds to form a 3D supramolecular structure. In compound 4, the Zn centers are connected by L2(4-) anions to generate a 3D framework. Magnetic susceptibility measurements indicate that compounds 1 and 2 exhibit antiferromagnetic coupling between adjacent Co(II) ions and Mn(II) ions. The photoluminescent properties of the free 4L1 and H4L2 ligands and compound 4 have been studied in the solid state at room temperature. Both ligands and compound 4 exhibit strong violet emissions. Compared with the fluorescent emission of the ligand, the emission of 4 is red-shifted and enhanced.     

Hydrogen storage in the dehydrated prussian blue analogues M3[Co(CN)6]2 (M = Mn, Fe, Co, Ni, Cu, Zn)

The porosity and hydrogen storage properties for the dehydrated Prussian blue analogues M3[Co(CN)6]2 (M = Mn, Fe, Co, Ni, Cu, Zn) are reported. Argon sorption isotherms measured at 87 K afford BET surface areas ranging from 560 m2/g for Ni3[Co(CN)6]2 to 870 m2/g for Mn3[Co(CN)6]2; the latter value is comparable to the highest surface area reported for any known zeolite. All six compounds show significant hydrogen sorption at 77 K and 890 Torr, varying from 1.4 wt % and 0.018 kg H2/L for Zn3[Co(CN)6]2 to 1.8 wt % and 0.025 kg H2/L for Cu3[Co(CN)6]2. Fits to the sorption data employing the Langmuir-Freundlich equation give maximum uptake quantities, resulting in a predicted storage capacity of 2.1 wt % and 0.029 kg H2/L for Cu3[Co(CN)6]2 at saturation. Enthalpies of adsorption for the frameworks were calculated from hydrogen isotherms measured at 77 and 87 K and found to increase with M varying in the order Mn < Zn < Fe < Co < Cu < Ni. In all cases, the binding enthalpies, which lie in the range of 5.3-7.4 kJ/mol, are higher than the 4.7-5.2 kJ/mol measured for Zn4O(1,4-benzenedicarboxylate)3.     

Hydrogen storage properties of metal nitroprussides M[Fe(CN)5NO], (M = Co, Ni)

The volumetric hydrogen adsorption isotherms of two isostructural dehydrated cubic metal nitroprussides M[Fe(CN)5NO] (M = Co2+, Ni2+) have been measured up to a pressure of 760 Torr at 77 and 87 K. These materials are among the most efficient H2 sorbents based on porous coordination polymers reported to date. The H2 uptake in both materials is approximately 1.6 wt % at 77 K and 760 torr. These H2 capacities match those reported recently in the structurally related M3[Co(CN)6]2 compounds and are approximately 25% higher than those reported for Zn4O(1,4-benzenedicarboxylate)3 under the same conditions of temperature and pressure. The isosteric heats of H2 adsorption calculated from the 77 and 87 K isotherms for both materials were found to vary from approximately 7.5 kJ/mol at 0.40 wt % coverage to approximately 5.5 kJ/mol at 1.2 wt % coverage. The N2 BET surface areas were determined to be 634 m2/g and 523 m2/g for M = Ni and M = Co, respectively.     

Covalent metal-organic networks: pyridines induce 2-dimensional oligomerization of (mu-OC6H4O)2Mpy2 (M = Ti, V, Zr)

Treatment of M(OiPr)4 (M = Ti, V) and [Zr(OEt)4]4 with excess 1,4-HOC6H4OH in THF afforded [M(OC6H4O)a(OC6H4OH)3.34-1.83a(OiPr)0.66-0.17a(THF)0.2]n (M = Ti, 1-Ti; V, 1-V, 0.91 < or = a < or = 1.82) and [Zr(1,4-OC6H4O)2-x(OEt)2x]n (1-Zr, x = 0.9). The combination of of 1-M (M = Ti, V, Zr) or M(OiPr)4 (M = Ti, V), excess 1,4- or 1,3-HOC6H4OH, and pyridine or 4-phenylpyridine at 100 degrees C for 1 d to 2 weeks afforded various 2-dimensional covalent metal-organic networks: [cis-M(mu 1,4-OC6H4O)2py2] infinity (2-M, M = Ti, Zr), [trans-M(mu 1,4-OC6H4O)2py2.py] infinity (3-M, M = Ti, V), solid solutions [trans-TixV1-x(mu 1,4-OC6H4O)2py2.py] infinity (3-TixV1-x, x approximately 0.4, 0.6, 0.9), [trans-M(mu 1,4-OC6H4O)2(4-Ph-py)2] infinity (4-M, M = Ti, V), [trans-Ti(mu 1,3-OC6H4O)2py2] infinity (5-Ti), and [trans-Ti(mu 1,3-OC6H4O)2(4-Ph-py)2] infinity (6-Ti). Single-crystal X-ray diffraction experiments confirmed the pleated sheet structure of 2-Ti, the flat sheet structure of 3-Ti, and the rippled sheet structures of 4-Ti, 5-Ti, and 6-Ti. Through protolytic quenching studies and by correspondence of powder XRD patterns with known titanium species, the remaining complexes were structurally assigned. With py or 4-Ph-py present, aggregation of titanium centers is disrupted, relegating the building block to the cis- or trans-(ArO)4Tipy2 core. The sheet structure types are determined by the size of the metal and the interpenetration of the layers, which occurs primarily through the pyridine residues and inhibits intercalation chemistry.     

Organic-acid effect on the structures of a series of lead(II) complexes

An investigation into the dependence of coordination polymer architectures on organic-acid ligands is reported on the basis of the reaction of Pb(NO3)2 and eight structurally related organic-acid ligands in the presence or absence of N-donor chelating ligands. Eight novel lead(II)-organic architectures, [Pb(adip)(dpdp)]2 1, [Pb(glu)(dpdp)] 2, [Pb(suc)(dpdp)] 3, [Pb(fum)(dpdp)] . H2O 4, [Pb2(oba)(dpdp)2] . 2(dpdp).2(NO3).2H2O 5, [Pb2(1,4-bdc)2(dpdp)2] . H2O 6, [Pb(dpdc)(dpdp)] 7, and [Pb(1,3-bdc)(dpdp)] . H2O 8, where dpdp = dipyrido[3,2-a:2',3'-c]-phenazine, H2adip = adipic acid, H2glu = glutaric acid, H2suc = succinic acid, H2fum = fumaric acid, H2oba = 4,4'-oxybis(benzoic acid), 1,4-H2bdc = benzene-1,4-dicarboxylic acid, H2dpdc = 2,2'-diphenyldicarboxylic acid, and 1,3-H2bdc = benzene-1,3-dicarboxylic acid, were successfully synthesized under hydrothermal conditions through varying the organic-acid linkers and structurally characterized by X-ray crystallography. Compounds 1-8 crystallize in the presence of organic-acid linkers as well as secondary N-donor chelating ligands. Diverse structures were observed for these complexes. 1 and 5 have dinuclear structures, which are further stacked via strong pi-pi interactions to form 2D layers. 2-3 and 6-8 feature chain structures, which are connected by strong pi-pi interactions to result in 2D and 3D supramolecular architectures. Compound 4 contains 2D layers, which are further extended to a 3D structure by pi-pi interactions. A systematic structural comparison of these 8 complexes indicates that the organic-acid structures have essential roles in the framework formation of the Pb(II) complexes.     

四金属簇钨砷夹心型化合物[M4(H2O)2·(AsW9O34)2]10-(M=CuⅡ, CoⅡ, MnⅡ, NiⅡ, ZnⅡ)的合成、结构和磁特性研究

取代型杂多化合物可改变多酸化合物的酸碱性、氧化还原性和热稳定性,因而受到关注[1]. 夹心型化合物是一类新型化合物,具有大的摩尔质量,高的负电荷,且含有多个磁性中心,近年来已引起国内外的兴趣[2].     

Assembly of azido- or cyano-bridged binuclear complexes containing the bulky [Mn(phen)2]2+ building block: syntheses, crystal structures, and magnetic properties

Two new cyano-bridged heterobinuclear complexes, [Mn(II)(phen)2Cl][Fe(III)(bpb)(CN)2] x 0.5CH3CH2OH x 1.5H2O (1) and [Mn(II)(phen)2Cl][Cr(III)(bpb)(CN)2] x 2H2O (2) [phen = 1,10-phenanthroline; bpb(2-) = 1,2-bis(pyridine-2-carboxamido)benzenate], and four novel azido-bridged Mn(II) dimeric complexes, [Mn2(phen)4(mu(1,1)-N3)2][M(III)(bpb)(CN)2]2 x H2O [M = Fe (3), Cr (4), Co (5)] and [Mn2(phen)4(mu(1,3)-N3)(N3)2]BPh4 x 0.5H2O (6), have been synthesized and characterized by single-crystal X-ray diffraction analysis and magnetic studies. Complexes 1 and 2 comprise [Mn(phen)2Cl]+ and [M(bpb)(CN)2]- units connected by one cyano ligand of [M(bpb)(CN)2]-. Complexes 3-5 are doubly end-on (EO) azido-bridged Mn(II) binuclear complexes with two [M(bpb)(CN)2]- molecules acting as charge-compensating anions. However, the Mn(II) ions in complex 6 are linked by a single end-to-end (EE) azido bridging ligand with one large free BPh4(-) group as the charge-balancing anion. The magnetic coupling between Mn(II) and Fe(III) or Cr(III) in complexes 1 and 2 was found to be antiferromagnetic with J(MnFe) = -2.68(3) cm(-1) and J(MnCr) = -4.55(1) cm(-1) on the basis of the Hamiltonian H = -JS(Mn)S(M) (M = Fe or Cr). The magnetic interactions between two Mn(II) ions in 3-5 are ferromagnetic in nature with the magnetic coupling constants of 1.15(3), 1.05(2), and 1.27(2) cm(-1) (H = -JS(Mn1)S(Mn2)), respectively. The single EE azido-bridged dimeric complex 6 manifests antiferromagnetic interaction with J = -2.29(4) cm(-1) (H = -JS(Mn1)S(Mn2)). Magneto-structural correlationship on the EO azido-bridged Mn(II) dimers has been investigated.     

Synthesis, X-ray crystal structures, and gas sorption properties of pillared square grid nets based on paddle-wheel motifs: implications for hydrogen storage in porous materials

A systematic modulation of organic ligands connecting dinuclear paddle-wheel motifs leads to a series of isomorphous metal-organic porous materials that have a three-dimensional connectivity and interconnected pores. Aromatic dicarboxylates such as 1,4-benzenedicarboxylate (1,4-bdc), tetramethylterephthalate (tmbdc), 1,4-naphthalenedicarboxylate (1,4-ndc), tetrafluoroterephthalate (tfbdc), or 2,6-naphthalenedicarboxylate (2,6-ndc) are linear linkers that form two-dimensional layers, and diamine ligands, 4-diazabicyclo[2.2.2]octane (dabco) or 4,4'-dipyridyl (bpy), coordinate at both sides of Zn(2) paddle-wheel units to bridge the layers vertically. The resulting open frameworks [Zn(2)(1,4-bdc)(2)(dabco)] (1), [Zn(2)(1,4-bdc)(tmbdc)(dabco)] (2), [Zn(2)(tmbdc)(2)(dabco)] (3), [Zn(2)(1,4-ndc)(2)(dabco)] (4), [Zn(2)(tfbdc)(2)(dabco)] (5), and [Zn(2)(tmbdc)(2)(bpy)] (8) possess varying size of pores and free apertures originating from the side groups of the 1,4-bdc derivatives. [Zn(2)(1,4-bdc)(2)(bpy)] (6) and [Zn(2)(2,6-ndc)(2)(bpy)] (7) have two- and threefold interpenetrating structures, respectively. The non-interpenetrating frameworks (1-5 and 8) possess surface areas in the range of 1450-2090 m(2)g(-1) and hydrogen sorption capacities of 1.7-2.1 wt % at 78 K and 1 atm. A detailed analysis of the sorption data in conjunction with structural similarities and differences concludes that porous materials with straight channels and large openings do not perform better than those with wavy channels and small openings in terms of hydrogen storage through physisorption.     

Design and synthesis of a near infra-red luminescent hexanuclear Zn-Nd prism

The use of the Schiff-base ligand N,N'-bis(5-bromo-3-methoxysalicylidene)propylene-1,3-diamine (H2L) and 1,4-benzenedicarboxylate (BDC) enables the construction of the hexanuclear luminescent Zn-Nd complex [Zn4Nd2L4(1,4-BDC)2].[Nd(NO3)5(H2O)].Et2O.2EtOH.3H2O.     

锌铝类水滑石的复原及表征(英)

本文采用焙烧复原法，在70 ℃以80%的乙醇溶液为分散介质，有机酸阴离子与煅烧后的锌铝类水滑石的物质的量之比为1∶9的条件下，实现了苯甲酸及苯二甲酸异构阴离子与锌铝类水滑石的插层反应，同时，还进行了等物质的量的两种酸与锌铝类水滑石（1∶1∶9）的插层反应。利用XRD和IR测试技术对样品结构进行表征，UV及HPLC对有机酸的反应量进行定量，并采用Gaussian-98软件包中ab initio分子轨道法（HF/6-31G）计算了各有机酸阴离子的分子结构，分析了其结构与插层行为的关系，并理论结合实验给出了各有机酸阴离子在锌铝类水滑石层间可能的空间构型。研究结果表明，苯甲酸及苯二甲酸异构阴离子在插层过程中表现出选择性，其优先进入锌铝类水滑石层间的顺序是：对苯二甲酸>邻苯二甲酸>间苯二甲酸>苯甲酸，且锌铝类水滑石对对苯二甲酸表现出较高的选择性，是环境友好的分离方法。     

Syntheses,Structures, and Properties of Five Coordination Polymers Involving Phthalic Acid

Five new coordination polymers Cu(phen)(H2O)(phth)·CH3OH(1), [Cu(2,2'-bipy)(H2O)](phth)·3.5H2O(2), Zn(phen)(phth)(H2O)·1.125H2O(3) and [M(4,4'-bipy)(H2O)2](phth)·2H2O[M=Zn(4), Mn(5)](H2phth=phthalic acid, bipy=bipyridine, phen=1,10-phenanthroline) have been synthesized from the amino acid derivatives(phthalyl-l- valine, H2L) and structurally characterized. H2L was hydrolyzed into phth2– group during the reaction, but the strucure feature was different from that of the complex directly synthesized from H2phth in the reported literature, revealing that H2L played an important role in composing the novel compounds. Compounds 1, 2 and 3 are all 1D chains, but the differences are that compound 1 is further hydrogen-bonded into 2D networks, and compound 2 is further extended into 3D supramolecular network through π-π stacking and hydrogen-bonding interactions. However, compound 3 is a 1D helix chain structure and further links into 2D networks through π-π stacking. Compounds 4 and 5 are isostructural and exhibit the same 2D layers, which are further connected by hydrogen-bonding interactions to form 3D supramolecular network. Antiferromagnetic superexchange was observed for compounds 1, 2 and 5.     

Cyanide-bridged Fe(III)-Co(II) bis double zigzag chains with a slow relaxation of the magnetisation

Reaction of [Fe(III)(bipy)(CN)4]- with fully solvated M(II) cations [M = Co (1) and Mn (2)] produces the isostructural bis double zigzag chains [[Fe(III)(bipy)(CN)4]2M(II)(H2O)] x MeCN x (1/2)H2O; 1 exhibits intrachain ferromagnetic and interchain antiferromagnetic couplings, slow magnetic relaxation and hysteresis effects.     

Design and construction of coordination polymers based on 2,2'-dinitro-4,4'-biphenyldicarboxylate and semi-rigid N-donor ligands: diverse structures and magnetic properties

Eight 2D and 3D coordination polymers, [Mn(NBPDC)(1,4-bimb)](n) (1), [Zn(NBPDC)(1,4-bimb)](n) (2), [Cd(NBPDC)(1,4-bimb)](n) (3), [Mn(2)(NBPDC)(2)(1,3-bimb)(H(2)O)](n) (4), {Zn(NBPDC)(1,3-bimb)}(n) (5), [Cd(2)(NBPDC)(2)(1,3-bimb)(2)(H(2)O)](n) (6), [Mn(NBPDC)(4,4'-bimbp)](n) (7), and [Cd(2)(NBPDC)(2)(4,4'-bimbp)(2)](n) (8), (NBPDC = 2,2'-dinitro-4,4'-biphenyldicarboxyl acid, 1,4-bimb = 1,4-bis(imidazol-1-ylmethyl) benzene, 1,3-bimb = 1,3-bis(imidazol-1-ylmethyl) benzene, and 4,4'-bimbp = 4,4'-(bis(imidazol-l-ylmethylene)) biphenyl), have been prepared and structurally characterized. In these coordination polymers, NBPDC and three N-donor ligands link different metal ions and SBUs to construct diverse architectures. Compounds 1 and 3 are isomorphic, showing a two-fold interpenetrating pcu topology. Compound 2 presents a 2D (4, 4) net. Compound 4 is a hex framework built by the linkage of ligands with infinite rod-shaped SBUs. Compound 5 presents a unprecedented eight-fold interpenetrating sra topology. Compound 6 exhibits a unique 2D {6(3)}{6(5).8} topology with four-fold interpenetrating structure. Compound 7 presents a 3D hex topology, and compound 8 shows a (4, 4) net. The magnetic properties of compounds 1, 4, and 7 have been characterized. Compound 1 displays interesting spin-canting antiferromagnetism and metamagnetism simultaneously. Compound 7 exhibits spin-canting antiferromagnetism.     

Synthesis and structures of polymeric Mn, Co, Cu, and Zn complexes of 3-diphenylamino-4-hydroxycyclobut-3-ene-1,2-dione (diphenylaminosquarate) and of the salt [Ni(H2O)6][(C6H5)2NC4O3]2.2H2O

Reaction of M(NO3)2.xH2O (M = Mn, Co, Ni, Cu, Zn) with 3-diphenylamino-4-hydroxycyclobut-3-ene-1,2-dione (diphenylaminosquarate) produces the neutral polymeric species (M[mu-(C6H5)2NC4O3]2[H2O]2)n [M = Mn (1), Cu (2)]; (M[mu-(C6H5)2NC4O3][(C6H5)2NC4O3][H2O]3)n [M = Co (3), Zn (4)]; and in the case of Ni, the salt [Ni(H2O)6][(C6H5)2NC4O3]2.2H2O (5). Complexes 1 and 2 are isomorphous and crystallize in the monoclinic space group P2(1)/c with, for 1, a = 13.138(1) A, b = 10.900(2) A, c = 9.269(2) A, beta = 96.07(1) degrees, and Z = 2. Complexes 3 and 4 are also isomorphous and crystallize in the space group P2(1)/c with, for 3, a = 13.211(1) A, b = 11.038(1) A, c = 18.748(1) A, beta = 97.75(1) degrees, and Z = 4. The nickel salt, 5, crystallizes in the triclinic space group P1 with a = 6.181(1) A, b = 9.417(1) A, c = 15.486(1) A, alpha = 101.37(1) degrees, beta = 95.51(1) degrees, gamma = 107.57(1) degrees, and Z = 1. In 1 and 2, the metal coordination is octahedral, comprising four mu-1,3-bridging diphenylaminosquarate ligands and two trans aqua ligands. In 3 and 4, the metal coordination is again octahedral, comprising two mu-1,3-bridging and one pendant diphenylaminosquarate ligands, the octahedron being completed by three aqua ligands in a meridional configuration. In 5, the hexaaquanickel(II) ion is linked by O-H...O hydrogen bonds to a pair of diphenylaminosquarate anions. These anion-cation units are linked via included water molecules to form hydrogen-bonded chains. The diphenylaminosquarate ligands in the polymeric complexes 1-4 display multiple-bond localization, a feature which is absent in 5. Complex 1 exhibits weak antiferromagnetic coupling, whereas 2 shows no significant magnetic interactions.     

Two independent, 1-D metal–organic nanotubes based on rings or helical chain units

Three coordination polymers {[Mn(bte)(NO₂-1,3-bdc)(H₂O)]·H₂O}_n (1), {[Mn(btp)(NO₂-1,3-bdc)(H₂O)]·2H₂O}_n (2), and {[Mn(btb)(NO₂-1,3-bdc)(H₂O)]·H₂O}_n (3) (bte, 1,2-bis(1,2,4-triazol-1-yl)ethane; btp, 1,3-bis(1,2,4-triazol-1-yl)propane; btb, 1,4-bis(1,2,4-triazol-1-yl)butane, NO₂-1,3- H₂bdc, 5-nitroisophthalic acid) were synthesized by combination of bte, btp, and btb, conformationally flexible ligands with different spacer lengths, and the rigid [NO₂-1,3-bdc]^2?. In 1, two [NO₂-1,3-bdc]^2? anions link adjacent [Mn₂(bte)₂] rings to give an independent, 1-D metal–organic nanotube (MONT). The structure of 2 is an undulating 2-D (4,4) network. In 3, the combination of a [Mn(btb)]_n single helical chain and two [Mn(NO₂-1,3-bdc)]_n linear chains assemble an intriguing independent, 1-D MONT. An interesting structural feature of 1 and 3 is that the nitro groups of each 1-D MONT interpenetrate into two adjacent 1-D MONTs to form a 1-D → 2-D interdigitated array. 3-D architectures in 1 and 3 are assembled via hydrogen bond interactions. The luminescent properties and thermal stabilities of 1, 2, and 3 were investigated.     

High-dimensional assembly depending on polyoxoanion templates, metal ion coordination geometries, and a flexible bis(imidazole) ligand

By introducing the flexible 1,1'-(1,4-butanediyl)bis(imidazole) (bbi) ligand into the polyoxovanadate system, five novel polyoxoanion-templated architectures based on [As(8)V(14)O(42)](4-) and [V(16)O(38)Cl](6-) building blocks were obtained: [M(bbi)(2)](2)[As(8)V(14)O(42)(H(2)O)] [M = Co (1), Ni (2), and Zn (3)], [Cu(bbi)](4)[As(8)V(14)O(42)(H(2)O)] (4), and [Cu(bbi)](6)[V(16)O(38)Cl] (5). Compounds 1-3 are isostructural, and they exhibit a binodal (4,6)-connected 2D structure with Schl?fli symbol (3(4) x 4(2))(3(4) x 4(4) x 5(4) x 6(3))(2), in which the polyoxoanion induces a closed four-membered circuit of M(4)(bbi)(4). Compound 4 exhibits an interesting 3D framework constructed from tetradentate [As(8)V(14)O(42)](4-) cluster anions and cationic ladderlike double chains. There exists a bigger M(8)(bbi)(6)O(2) circuit in 4. The 3D extended structure of 5 is composed of heptadentate [V(16)O(38)Cl](6-) anions and flexural cationic chains; the latter consists of six Cu(bbi) segments arranged alternately. It presents the largest 24-membered circuit of M(24)(bbi)(24) so far observed made of bbi molecules and transition-metal cations. Investigation of their structural relations shows the important template role of the polyoxoanions and the synergetic interactions among the polyoxoanions, transition-metal ions, and flexible ligand in the assembly process. The magnetic properties of compounds 1-3 were also studied.     

Single-crystal-to-single-crystal transformation from 1 D staggered-sculls chains to 3 D NbO-type metal-organic framework through [2+2] photodimerization

A new approach to synthesize 3D structures through a [2+2] photodimerization process has been carried out by transforming two isostructures of 1D staggered-sculls chains [M(1,2-chdc)(bpe)(2)(H(2)O)(2)]?H(2)O (M = Zn, Mn) into 3D?NbO-type metal-organic frameworks through UV irradiation in single-crystal-to-single-crystal mode. (see figure; bpe = trans-1,2-(bis(4-pyridyl)ethene, chdc =cyclohexanedicarboxylate).