44-sql Layer Research Articles

Nuclearity enlargement from [PW9O34@Ag51] to [(PW9O34)2@Ag72] and 2D and 3D network formation driven by bipyridines

The structural transformations of metal nanoclusters are typically quite complex processes involving the formation and breakage of several bonds, and thus are challenging to study. Herein, we report a case where two lacunary Keggin polyoxometallate templated silver single-pods [PW9O34@Ag51] (SD/Ag51b) fuse to a double-pod [(PW9O34)2@Ag72] by reacting with 4,4’-bipyridine (bipy) or 1,4-bis(4-pyridinylmethyl)piperazine (pi-bipy). Their crystal structures reveal the formation of a 2D 44-sql layer (SD/Ag72a) with bipy and a 3D pcu framework (SD/Ag72c) with pi-bipy. The PW9O349− retains its structure during the cluster fusion and cluster-based network formation. Although the two processes, stripping of an Ag-ligands interface followed by fusion, and polymerization, are difficult to envisage, electrospray ionization mass spectrometry provides enough evidences for such a proposal to be made. Through this example, we expect the structural transformation to become a powerful method for synthesizing silver nanoclusters and their infinite networks, and to evolve from trial-and-error to rational.

Microwave synthesis of 1-D, 2-D, and 3-D blue luminescent coordination polymers of d10 metals with a new rigid tris-triazole ligand

The microwave heating hydrothermal and solvothermal reactions (120 °C, 20 min) of a new rigid tris-triazole ligand, 2-fluoro-3,5,6-tri(1H-1,2,4-triazol-1-yl)-1,4-benzenedicarbonitrile, with Zn(II), Cd(II) and Pb(II) metal salts afforded four crystalline coordination polymers (CPs), namely, {[Zn(L)2(H2O)2]·2H2O}n (1), {[Cd(L)2(H2O)2]·2H2O}n (2), {[Cd(L)(NO3)(DMF)]·0.5DMF·0.25CH3CN}n (3) and {[Pb(L)2(H2O)2]·H2O}n (4), respectively, where the starting ligand undergoes in situ hydrolysis to form a new ligand 2-oxidanyl-3,5,6-tri(1H-1,2,4-triazol-1-yl)terephthalonitrile (HL). Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction, and thermogravimetric (TG) analyses. Both complexes 1 and 2 are isostructural, featuring 1-D looped-chain structures. Complex 3 displays a 2-D 44-sql layer structure, while complex 4 presents a 3,6-connected 3-D framework with an anatase topology. The remarkable structural diversity of complexes 1–4 may illustrate the powerful effect of metal ions and solvent systems in coordination assemblies. Furthermore, since HL is a rigid ligand with the large conjugated π-system, all these complexes exhibit strong blue luminescence emissions in the solid state at room temperature.

Structural modulation and luminescent properties of four CdII coordination architectures based on 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole and flexible/rigid dicarboxylate ligands

To systematically investigate the influence of the flexible or rigid auxiliary ligands on the structures and properties of transition metal compounds, we synthesized four new d10 coordination polymers (CPs) from 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole (4-Hpzpt) and flexible/rigid dicarboxylate ligands, [Cd(4-pzpt)2]n (1), [Cd3(4-pzpt)2(suc)2]n (2), [Cd2(4-Hpzpt)(nbc)2(H2O)]n (3) and {[Cd2(4-pzpt)2(tfbdc)(H2O)4]·H2O}n (4) (H2suc=1,2-ethanedicarboxylic acid, H2nbc=hthalene-1,4-dicarboxylic acid, H2tfbdc =2,3,5,6-tetrafluoroterephthalic acid). Single crystal X-ray analysis indicates that compound 1 shows a 44-sql layer, which is extended to a 3D network via nonclassical C–H…N hydrogen bonds. Compound 2 possesses a 6-connected pcu-4120.63 net composed of trinuclear CdII-clusters. Compound 3 represents a rare 3D (3,4,4,5)-connected topology with a Schläfli symbol of (4·6·7)(4·53·72)(53·6·7·9)(42·55·6·72). Compound 4 exhibits a 2D+2D→2D parallel interpenetrated 63-hcb network. The adjacent 2D networks are interdigitated with each other to form the resulting 3D supramolecular architecture through classical O–H…N and O–H…O hydrogen bonds. Structural diversities indicate that the nature of flexible/rigid-dicarboxlates plays crucial roles in modulating structures of these compounds. Moreover, the luminescent properties of them have been briefly investigated.

Syntheses and structures of three entangled coordination polymers based on the bifunctional ligand 4-((3-(pyridin-4-yl)-1H-pyrazol-1-yl)methyl)benzoic acid

Self-assembly of transition metal salts with long bifunctional ligand affords three entangled coordination frameworks, namely, [Co(ppmba)2] (1), [Zn(ppmba)2]·0.5H2O (2) and [Cd(ppmba)2]·0.25H2O (3) (Hppmba=4-((3-(pyridin-4-yl)-1H-pyrazol-1-yl)methyl)benzoic acid). Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by element analyses, IR spectra, X-ray powder diffraction, and TG analyses. Compound 1 is a peculiar (2D→3D) interdigitated architecture that is assembled from bilayer motifs. Compounds 2 and 3 exhibit fascinating (2D→3D) entangled frameworks constructed from undulating 44-sql layers, which have both polycatenane and interdigitation characters. In addition, the magnetic properties of compound 1 and the photoluminescence properties of compounds 2 and 3 were studied.

Structures and Photoluminescence Properties of Four Cadmium(II) Coordination Polymers Synthesized by Rigid Ligands and N-Donor Ligands

Four metal–organic coordination polymers, [Cd2(dna)2(2,2′-bpy)2]n (1), {[Cd4(dna)4(im)3]·5H2O}n (2), {[Cd2(dna)2(4,4′-bpy)(H2O)2]·2EtOH}n (3), and {[Cd4(dna)4(1,3-dpp)4(H2O)4]·2H2O}n (4) (H2dna = 4,6-dimethyl-5-nitroisophthalic acid; 2,2′-bpy = 2,2′-bipyridine; im = imidazole; 4,4′-bpy = 4,4′-bipyridine; 1,3-dpp = 1,3-di(4-pyridyl)propane; and EtOH = ethanol, have been solvothermally synthesized and characterized. Compound 1 displays a one-dimensional (1D) ladder structure and the neighbouring ladders are further stabilized by π···π interactions to form a two-dimensional (2D) layer. Compound 2 forms a 2D layer based on infinite 1D [Cd2(COO)4]n chain and the im ligands act as terminal ligands, preventing expansion of the dimensionality. Compound 3 features a 2D 44-sql layer based on binuclear [Cd2(COO)4] secondary building units as 4-connected nodes, and is further linked to be an unusual three-dimensional (3D) supramolecular architecture by hydrogen bonds involving the coordinated water molecules, carboxylate groups, and lattice ethanol molecules. Compound 4 possesses a 2-fold interpenetrated dia net. The diverse structures and topologies of compounds 1–4 indicate that the N-containing ligands have significant effects on the formation of the final network structures. In addition, the thermal stabilities, structure comparison, and photoluminescence properties of the complexes have been investigated.

A series of 2D Cd(II) coordination polymers constructed from dicarboxylate acids and a flexible imidazole-based ligand

Five new Cd(II)-based coordination polymers 1–5 with a flexible ligand 1,4-bis(2-methylimidazol-1-ylmethyl)-2,3,5,6-tetramethylbenzene (bmimx) and five dicarboxylate acids (1,2-H2BDC=1,2-benzenedicarboxylic acid, H2HMPH=homophthalic acid, 1,3-H2BDC=1,3-benzenedicarboxylic acid, 1,3-H2ADA=1,3-adamantanediacetic acid and H2ADI=adipic acid) have been synthesized under hydro(solvo)thermal conditions, namely, [Cd(bmimx)0.5(1,2-BDC)]n (1), {[Cd(bmimx)(HMPH)]·H2O}n (2), {[Cd(bmimx)(1,3-BDC)]·1.5H2O}n (3), {[Cd(bmimx)0.5(ADA)]·H2O}n (4) and {[Cd(bmimx)(ADI)]·2H2O}n (5). Structural analysis indicates that all the complexes exhibit 2D layer structures. Complexes 1 and 4 present binodal (3,4)-connected layers with 3,4L83 topology. Complex 2 displays a 44-sql layer with 1D helical chains, while 3 only shows a pleated net with the 44-sql topology. Complex 5 exhibits a sheet structure with hcb topology. The backbones of the dicarboxylate ligands play an important role in determining the structural diversity. Their thermal and luminescent properties are also discussed.

Two interpenetrating CuII/NiII-coordinated polymers based on an unsymmetrical bifunctional N/O-tectonic: Syntheses, structures and magnetic properties

Two new interpenetrating CuII/NiII coordination polymers, based on a unsymmetrical bifunctional N/O-tectonic 3-(pyrid-4′-yl)-5-(4″-carbonylphenyl)-1,2,4-triazolyl (H2pycz), {[Cu-(Hpycz)2]·2H2O}n (1) and {[Ni(Hpycz)2]·H2O}n (2), have been solvothermally synthesized and structure characterization. Single crystal X-ray analysis indicates that compound 1 shows 2-fold parallel interpenetrated 44-sql layers with the same handedness. The overall structure of 1 is achiral—in each layer of doubly interpenetrating nets, the two individual nets have the opposite handedness to the corresponding nets in the adjoining layers—while 2 features a rare 8-fold interpenetrating 66-dia network that belongs to class IIIa interpenetration. In addition, compounds 1 and 2 both show similar paramagnetic characteristic properties.

Structural diversity and properties of six coordination polymers derived from 1,2/1,3-phenylenedioxydiacetic acids and varied N-donor co-ligands

Based on two positional isomers of phenylenedioxydiacetate ligands and different N-containing co-ligands, six novel coordination polymers, formulated as {[Zn(o-PDOA)(bpp)]·2H2O}n (1), {[Cd(o-PDOA)(bix)]·3H2O}n (2), [Cd(m-PDOA)(bix)]n (3), [Cd(m-PDOA)(bib)]n (4), [Zn(m-PDOA)(bix)]n (5), {[Zn(m-PDOA)(bib)]·2H2O}n (6), (o/m-H2PDOA=1,2/1,3-phenylenedioxydiacetic acid; bix=1,4-bis(imidazol-ylmethyl)benzene; bib=1,4-bis(1H-imidazol-1-yl)-butane; bpp=1,3-bis(4-pyridyl)propane), have been synthesized under hydrothermal conditions. Compound 1 features a three-dimensional (3D) 2-fold interpenetrating cds topology. In 2, the (H2O)6 clusters interlink the 1D double [Cd2(o-PDOA)2(bix)2]n chains into a 3D supramolecular network. Compound 3 is a (3,5)-connected 2D layer with (42.6)(42.67.8) topology. Compound 4 exhibits a 3-fold interpenetrating pcu topological network, while, 5 is a 2D puckered meso-helical 44-sql layer built by alternately arranged right-handed and left-handed helical chains. In contrast to 1–5, compound 6 possesses a 1D loop-like chain and, interestingly, rare D4 tetrameric (H2O)4 cluster extends the chains into a 3D supramolecular framework. Moreover, the thermal stabilities and luminescent properties of compounds 1–6 have also been investigated.

Structures and properties of four coordination polymers constructed from 1,3-bis-(4-pyridyl)-propane and aromatic dicarboxylic acids

Four coordination polymers associated with 1,3-bis-(4-pyridyl) propane (bpp) and 5-methylisophthalic acid (H2mip) or 5-nitroisophthalic acid (H2nip) formulated as [Zn(bpp)(mip)]n (1), [Co(bpp)(mip)]n (2), [Zn2(bpp)2(nip)2]n (3) and [Co(bpp)(nip)(H2O)]n (4) have been synthesized under hydrothermal conditions. Single crystal analyses reveal that complex 1 presents a four-fold interpenetrating framework based on three-dimensional (3D) subunits with dia topology. Compound 2 has a 1D binuclear chain structure. Complex 3 shows 2D 44-sql layer structure packing in ABAB mode. Complex 4 exhibits a two-fold interpenetrating framework based on three-dimensional (3D) subunits with dia topology. These compounds have been characterized by infrared spectroscopy, elemental analysis, thermogravimetric analysis and powder X-ray diffraction. In addition, the photoluminescence of 1 and 3 and magnetic properties of 2 and 4 were investigated.

Hydrothermal Synthesis, Crystal Structure and Spectroscopic Characterization of a Novel 2D → 3D Parallel Polycatenated Coordination Framework [Cd(cmb)(bix)] n

A novel entangled coordination polymer [Cd(cmb)(bix)] n (1) [H2cmb = 2,2′-(2-(carboxymethoxy)benzoic acid), bix = 1,4-bis(imidazol-1-ylmethyl)benzene], has been synthesized by hydrothermal reaction of Cd(Ac)2·2H2O, bix and H2cmb, and characterized by elemental analysis, IR spectra, PXRD, and single-crystal X-ray diffraction. The structure determination reveals that the complex 1 shows a new 2D → 3D parallel polycatenation framework based on highly undulating 2D 44 -sql layers, in which each layer is polycatenated with adjacent two others (one above and one below, DOC = 4) which have parallel but not coincident mean planes. Moreover, the thermal stability and photoluminescence property of 1 were also discussed. A novel 2D → 3D parallel polycatenated coordination polymer [Cd(cmb)(bix)] n (1), based on highly undulating 2D 44 -sql layers, has been hydrothermally synthesized and characterized. Moreover, the thermal stability and photoluminescence property of 1 were also investigated.

Preparation and crystal structure of a triple parallel interpenetrated copper coordination polymer based on a flexible bis(imidazole) ligand

A Cu(II) coordination polymer, [Cu(L)(bdc)] n (L = 1,4-bis(imidazole)butane, bdc = 1,3-benzenedicarboxylate) has been hydrothermally synthesized and characterized by elemental analysis, IR spectrum, thermogravimetric analysis, and single-crystal X-ray diffraction. The complex is a rare example of a threefold parallel interpenetrated coordination bonding network based on undulant [Cu4(μ 2-L)2(μ 2-bdc)2] parallelograms with 44-sql layer. The heterogeneous catalytic activity of the complex was tested for the degradation of Congo red azo dye in a Fenton-like process in which the degradation efficiency reached 94 % after 100 min. Kinetic analysis indicates that the degradation rate of the dye can be approximated by pseudo-first-order kinetics.

Two New Zn(II) Coordination Polymers Constructed from Asymmetric Biphenyl-Dicarboxylate and Imidazole-Containing Ligands: Structures and Photoluminescent Properties

Two new coordination polymers, [Zn(2,4′-bpdc) (L1)0.5·(H2O)] n (1) and {[Zn(3,4′-bpdc) (L1)]·(H2O)} n (2), have been obtained from hydrothermal reactions of zinc (II) nitrate with the ligands 1,4-bis(imidazol-1-yl)benzene (L) and two asymmetric biphenyl-dicarboxylate [biphenyl-2,4′-dicarboxylate (2,4′-bpdc) and biphenyl-3,4′-dicarboxylate (3,4′-bpdc)]. Single-crystal X-ray diffraction analysis the two coordination polymer show different structures due to the different dicarboxylate ligands. Complex 1 features a 3D mab topological net. Complex 2 is unusual case that has 3D frameworks constructed from 2D 44-sql layers by parallel polycatenation. The photoluminescent properties of 1 and 2 have also been investigated.

Unique entangling CdII-framework featuring 2D→3D inclined polycatenate motif and (4,6)-connected self-catenated H-bonding topology

A novel CdII-coordination framework [Cd(C4O4)(btb)(H2O)2]n (1) constructed by squaric acid (H2C4O4) and secondary N-donor spacer 1,4-bis(1,2,4-triazol-4-yl)butane (btb) is presented, which displays 2D → 3D inclined polycatenate framework consisting of two of sets of equivalent 2D 44-sql layers and (4,6)-connected self-catenated H-bonding topology. In addition, the thermal stability and photo-luminescence property of 1 were also investigated.

Two 2D → 3D entangled coordination polymers with polycatenated and polythreaded features based on 44-sql layers

Two fascinating 3D entangled coordination polymers, [Ni5(pda)5(bpp)5]·12H2O (1) and [Cd2(pda)2(1,10′-phen)2]·4H2O (2) (pda = phenylenediacrylate dianion; bpp = 1,3-bis(4-pyridyl)propane; 1,10′-phen = 1,10′-phenanthroline), have been successfully synthesized and characterized by single-crystal X-ray analysis. In complex 1, two 44-sql nets interweave in parallel and give rise to a 2-fold interpenetrated layer (2D → 2D). In addition, each layer interlocks two other layers, one above and one below (2D → 3D). This results in an interesting 3D coordination polymer containing interpenetration and polycatenation at the same time. Complex 2 exhibits a 2D → 3D polythreaded framework based on 2D 44-sql motifs with side arms. If π–π interactions are taken into account, the resulting structure displays a 2-fold interpenetrated 3D α-Po network. Interestingly, if crystals of 2 are dissolved in water and left undisturbed for about two weeks at room temperature, its supramolecular isomer [Cd2(pda)2(1,10′-phen)2]·H2O (3) is formed. On the contrary, when yellow block crystals of 3 are treated under microwave conditions, colorless plate crystals of 2 reappear. This means that there exists a reversible transformation process between 2 and its isomer 3. Furthermore, the fluorescence properties of 2 have been studied.

Supramolecular Organic Frameworks of Brominated Bisphenol Derivatives with Organoamines

Reactions of two brominated bisphenol derivatives, tetrabromobisphenol-F (TBBPF) and tetrabromobisphenol-A (TBBPA), with various organoamines resulted in six supramolecular organic frameworks (SOFs), formulated as (TBBPF2–)2·(HPZ+)2·(H2PZ2+) (1), (TBBPF–)2·(H2PZ2+)·2H2O·2MeOH (2), (TBBPF)·(TBBPF–)·(HDABCO+)·H2O (3), (TBBPF)·(HMTA) (4), (TBBPA)·(HMTA) (5), and (TBBPA)3·(HMTA)3·H2O (6) (PZ = piperazine; DABCO = diazabicyclo[2.2.2]octane; HMTA = hexamethylenetetramine). Compounds 1–6 were characterized by single-crystal and powder X-ray diffractions. The predominant driving forces in 1–6 are hydrogen bonds (H-bonds), by which the compounds assemble into supramolecular organic frameworks with versatile topological structures. Compound 1 contains TBBPF/PZ in a 2:3 ratio and exhibits 2D (two-dimensional) H-bonded supramolecular 44-sql layer structure built by the four-connected {H2PZ2+} moieties and {TBBPF2–}. Compound 2 shows a 2-fold interpenetrated 3D (three-dimensional) H-bonded networks comprised by TBBPF/...

Supramolecular Borromean sheet consisting of threefold parallel interwoven 44-sql layers assembled by a flexible bipyridinium ligand

An infinite two-dimensional supramolecular Borromean sheet consisting of threefold parallel interwoven 44-sql layers was obtained by the assembly of a flexible bipyridinium ligand with NiCl2 and phthalate.