Guest-Stimulated Nonplanar Porphyrins in Flexible Metal-Organic Frameworks.

Nonplanar porphyrins with out-of-plane distortions play crucial roles in many biological functions and chemical applications. The artificial construction of nonplanar porphyrins usually involves organic synthesis and modification, which is a highly comprehensive approach. However, incorporating porphyrins into guest-stimulated flexible systems allows to manipulate the porphyrin distortion through simple ad/desorption of guest molecules. Here, a series of porphyrinic zirconium metal-organic frameworks (MOFs) is reported that exhibit guest-stimulated breathing behavior. X-Ray diffraction analysis and skeleton deviation plots confirm that the material suffers from porphyrin distortion to form a ruffled geometry under the desorption of guest molecules. Further investigation reveals that not only the degree of nonplanarity can be precisely manipulated but also the partial distortion of porphyrin in a single crystal grain can be readily achieved. As Lewis acidic catalyst, the MOF with nonplanar Co-porphyrin exhibits active properties in catalyzing CO2 /propylene oxide coupling reactions. This porphyrin distortion system provides a powerful tool for manipulating nonplanar porphyrins in MOFs with individual distortion profiles for various advanced applications.

Preparation, characterization, and electrochemical sensing performance of a novel pristine Cd-MOF and its composite with carbon nanotubes.

A novel Cd(II)-organic framework (Cd-MOF) {[Cd(isba)(bbtz)2(H2O)]·H2O}n (1) and its composite with CNTs (Cd-MOF@CNTs), [H2isba = 2-iodo-4-sulfobenzoicacid; bbtz = 1, 4-bis(1,2,4-triazolyl-1-methyl)benzene], were synthesized successfully under ambient conditions. The Cd-MOF is a 2D (4, 4) topological framework, further extending into a two-fold interpenetrated 3D supramolecular network via hydrogen bonding. The activation energy for proton transfer in the composite Cd-MOF@CNT/Nafion membrane is lower than that in pristine Cd-MOF/Nafion, leading to its more temperature-insensitive proton conductivity. Hence, the proton conduction of the composite Cd-MOF@CNT/Nafion membrane was greatly improved. Cyclic voltammograms indicate that the Cd-MOF/GCE only has an oxidation peak with the peak potential suitable for the oxidation of glucose in 0.1 M NaOH. The i-t current response demonstrates that the Cd-MOF/GCE exhibits sensitive and selective oxidative sensing of glucose in the linear range of 0-5 mM with a limit of detection (LOD) of 9.64 µM. Different from the pristine Cd-MOF, Cd-MOF@CNTs shows a pair of irreversible redox peaks with an anodic peak potential appropriate for the glucose oxidation and a cathodic peak potential suitable for the hydrogen peroxide reduction in 0.1 M NaOH. So, the Cd-MOF@CNTs/GCE can be used not only for the electrocatalytic oxidation of glucose, but also for the electrocatalytic reduction of H2O2. The current-time response curve demonstrates that the Cd-MOF@CNTs/GCE exhibits more sensitive and selective oxidative sensing for glucose exponentially in the 0-18.5 mM range with a lower LOD down to 2.63 µM. The reductive sensing of H2O2 increases linearly in the range of 0-14.0 mM (LOD = 33.70 µM). Moreover, the Cd-MOF@CNTs/GCE can detect glucose and H2O2 efficiently in real-world samples. Cd-MOF@CNTs may act as a dual non-enzymatic electrochemical sensory material for glucose and H2O2.

Band gap, sorption properties and fluorescence sensing behaviour of a novel 1D→2D cathenane-like cobalt(II)-organic framework.

A novel hydrolytic stable CoII-organic framework, namely poly[[bis(2-amino-4-sulfonatobenzoato-κO1)tetraaquatris{µ-1,4-bis[(imidazol-1-yl)methyl]benzene-κ2N3:N3'}dicobalt(II)] tetrahydrate], {[Co(C7H5NO5S)(C14H14N4)1.5(H2O)2]·2H2O}n, (1), based on multifunctional 2-amino-5-sulfobenzoic acid (H2asba) and the auxiliary flexible ligand 1,4-bis[(imidazol-1-yl)methyl]benzene (bix), was prepared using the solution evaporation method. The purity of (1) was confirmed by elemental analysis and powder X-ray diffraction (PXRD) analysis. Complex (1) shows a novel 1D→2D interpenetrating network, which is further extended into a 3D supramolecular framework with channels occupied by the lattice water molecules. The 2-amino-4-sulfonatobenzoate (asba2-) ligand adopts a monodentate coordination mode. The bix ligands exhibit gauche-gauche (GG) and trans-trans (TT) conformations. A detailed analysis of the solid-state diffuse-reflectance UV-Vis spectrum reveals that an indirect band gap exists in the complex. The band structure, the total density of states (TDOS) and the partial density of states (PDOS) were calculated using the CASTEP program. The calculated band gap (Eg) matches well with the experimental one. The complex exhibits a reversible dehydration-rehydration behaviour. Interestingly, gas sorption experiments demonstrate that the new fully anhydrous compound obtained by activating complex (1) at 400 K shows selective adsorption of CO2 over N2. Complex (1) retains excellent framework stability in a variety of solvents and manifests distinct solvent-dependent fluorescence properties. Moreover, the complex shows multiresponsive fluorescence sensing for some nitroaromatics in aqueous medium.

Preparation, characterization and luminescence-sensing properties of two ZnII MOFs with mixed 5-amino-2,4,6-tribromoisophthalic acid and bipyridyl-type ligands.

The bromo-substituted aromatic dicarboxylic acid 5-amino-2,4,6-tribromoisophthalic acid (H2ATBIP), in the presence of the N-donor flexible bipyridyl-type ligands 1,3-bis(pyridin-4-yl)propane (bpp) and N,N'-bis(pyridin-4-ylmethyl)oxalamide (4-bpme) and ZnII ions, was used as an O-donor ligand to assemble two novel luminescent metal-organic frameworks (MOFs), namely poly[[(µ-5-amino-2,4,6-tribromoisophthalato-κ2O1:O3)[µ-1,3-bis(pyridin-4-yl)propane-κ2N:N']zinc(II)] dimethylformamide monosolvate], {[Zn(C8H2Br3NO4)(C13H14N2)]·C3H7NO}n, (1), and poly[[(µ-5-amino-2,4,6-tribromoisophthalato-κ2O1:O3)diaqua[µ-N,N'-bis(pyridin-4-ylmethyl)oxalamide-κ2N:N']zinc(II)] monohydrate], {[Zn(C8H2Br3NO4)(C14H14N4O2)(H2O)2]·H2O}n, (2), using the solution evaporation method. Both (1) and (2) were characterized by FT-IR spectroscopy, elemental analysis (EA), solid-state diffuse-reflectance UV-Vis spectroscopy, and powder and single-crystal X-ray diffraction analysis. Complex (1) shows a two-dimensional (2D) corrugated layer simplified as a 2D (4,4) topological network. The supramolecular interactions (π-π stacking, hydrogen bonding and C-Br...Br halogen bonding) play significant roles in the formation of an extended three-dimensional (3D) supramolecular network of (1). Complex (2) crystallizes in the chiral space group P212121 and exhibits a novel 3D homochiral framework, showing a diamond-like topology with Schläfli symbol 66. The homochirality of (2) is further confirmed by the solid-state circular dichroism (CD) spectrum. The second harmonic generation (SHG) property of (2) was also investigated. The hydrogen and C-Br...Br/O halogen bonding further stabilize the framework of (2). The central ZnII ions in (1) and (2) show tetrahedral and octahedral coordination geometries, respectively. The coordinated and uncoordinated water molecules in (2) could be removed selectively upon heating. Most importantly, (1) and (2) show rapid and highly sensitive sensing for a large pool of nitroaromatic explosives (NAEs).

Synthesis and characterization of two one-dimensional CdII coordination polymers (CPs) with 5-amino-2,4,6-tribromoisophthalic acid and flexible N-donor bipyridyl ligands.

The bromo-substituted aromatic dicarboxylic acid 5-amino-2,4,6-tribromoisophthalic acid (H2ATBIP) was used to assemble with CdII ions in the presence of the N-donor flexible bipyridyl ligands 3,3'-(diazene-1,2-diyl)dipyridine (mzpy) and 1,3-bis(pyridin-3-ylmethyl)urea (3bpmu), leading to the formation of two chain coordination polymers by adopting solution methods, namely, catena-poly[[[triaqua(5-amino-2,4,6-tribromoisophthalato-κO)cadmium(II)]-µ-3,3'-(diazene-1,2-diyl)dipyridine-κ2N1:N1'] dihydrate], {[Cd(C8H2Br3NO4)(C10H8N4)(H2O)3]·2H2O}n or {[Cd(ATBIP)(mzpy)(H2O)3]·2H2O}n, (1), and catena-poly[[[tetraaquacadmium(II)]-µ-1,3-bis(pyridin-3-ylmethyl)urea-κ2N1:N1'-[diaquabis(5-amino-2,4,6-tribromoisophthalato-κO)cadmium(II)]-µ-1,3-bis(pyridin-3-ylmethyl)urea-κ2N1:N1'] octahydrate], {[Cd(C8H2Br3NO4)(C12H12N4O)(H2O)3]·4H2O}n or {[Cd(ATBIP)(3bpmu)(H2O)3]·4H2O}n, (2). Both complexes were characterized by FT-IR spectroscopic analysis, thermogravimetric analysis (TGA), solid-state diffuse reflectance UV-Vis spectroscopic analysis, and single-crystal and powder X-ray diffraction analysis (PXRD). The mzpy and 3bpmu ligands bridge the CdII metal centres in (1) and (2) into one-dimensional chains, and the ATBIP2- ligands show a monodentate coordination to the CdII centres in both coordination polymers. A discrete water tetramer exists in (1). Within the chains of (1) and (2), there are halogen bonds between adjacent ATBIP2- and mzpy or 3bpmu ligands, as well as hydrogen bonds between the ATBIP2- ligands and the coordinated water molecules. With the aid of weak interactions, the structures of (1) and (2) are further extended into three-dimensional supramolecular networks. An analysis of the solid-state diffuse reflectance UV-Vis spectra of (1) and (2) indicates that a wide indirect band gap exists in both complexes. Complexes (1) and (2) exhibit irreversible and reversible dehydration-rehydration behaviours, respectively, and the solid-state fluorescence properties of both complexes have been studied.

Two new CoII coordination polymers with multifunctional 5-amino-2,4,6-tribromoisophthalic acid and flexible isomeric bis(imidazole) ligands: preparation, crystal structure and characterization.

Two new CoII coordination polymers (CPs), namely, catena-poly[[[(5-amino-2,4,6-tribromobenzene-1,3-dicarboxylato-κO)aquacobalt(II)]-bis[µ-1,3-bis(imidazol-1-ylmethyl)benzene-κ2N:N']] 4.75-hydrate], {[Co(C8H2Br3NO4)(C14H14N4)2(H2O)]·4.75H2O}n, (1), and poly[(µ-5-amino-2,4,6-tribromobenzene-1,3-dicarboxylato-κ2O1:O3)[µ-1,2-bis(imidazol-1-ylmethyl)benzene-κ2N:N']cobalt(II)], [Co(C8H2Br3NO4)(C14H14N4)]n, (2), have been synthesized successfully by the assembly of multifunctional 5-amino-2,4,6-tribromoisophthalic acid (H2ATBIP) and CoII ions in the presence of the flexible isomeric bis(imidazole) ligands 1,3-bis(imidazol-1-ylmethyl)benzene (mbix) and 1,2-bis(imidazol-1-ylmethyl)benzene (obix). The isomeric mbix and obix ligands have a big influence on the structures of CPs (1) and (2). CP (1) is composed of chains of nanometre-sized elliptical rings, in which the CoII atom exhibits a distorted octahedral coordination geometry and ATBIP2- acts as a monodentate ligand. Two adjacent chains are interlinked by π-π stacking interactions and hydrogen bonds, resulting in a supramolecular double chain. Hydrogen-bonded R86(16) rings extend adjacent supramolecular double chains into a two-dimensional supramolecular layer. Halogen bonding and a hydrogen-bonded R42(8) ring further link the two-dimensional supramolecular layers, leading to the formation of a three-dimensional supramolecular network. The CoII ion in CP (2) is tetracoordinated, exhibiting a distorted tetrahedral configuration. The ATBIP2- ligand exhibits a bis(monodentate) coordination bridging mode, linking adjacent CoII ions into zigzag chains, which are further bridged by the auxiliary bridging obix ligand, resulting in a two-dimensional (4,4) topological network. Interlayer hydrogen and halogen-halogen bonding further extend the two-dimensional layers into a three-dimensional supramolecular network. A detailed analysis of the solid-state UV-Vis-NIR diffuse-reflectance spectra of (1) and (2) indicates that a wide optical band gap exists in both (1) and (2). CP (1) exhibits an irreversible dehydration-rehydration behaviour.

A new copper(II) supramolecular coordination polymer and a dinuclear compound with multifunctional 2-amino-5-sulfobenzoic acid and flexible N-donor ligands: synthesis, structure and characterization.

Multifunctional 2-amino-5-sulfobenzoic acid (H2afsb) can exhibit a variety of roles during the construction of supramolecular coordination polymers. The pendant carboxylic acid, sulfonic acid and amino groups could not only play a role in directing bonding but could also have the potential to act as hydrogen-bond donors and acceptors, resulting in extended high-dimensional supramolecular networks. Two new CuII coordination compounds, namely catena-poly[[[diaquacopper(II)]-µ-1,6-bis(1H-1,2,4-triazol-1-yl)hexane-κ2N4:N4'] bis(3-amino-4-carboxybenzenesulfonate) dihydrate], {[Cu(C10H16N6)2(H2O)2](C7H6NO5S)2·2H2O}n or {[Cu(bth)2(H2O)2](Hafsb)2·2H2O}n, (1), and bis(µ-2-amino-5-sulfonatobenzoato-κ2O1:O1')bis{µ-1,2-bis[(1H-imidazol-1-yl)methyl]benzene-κ2N3:N3'}bis[aquacopper(II)] trihydrate, [Cu2(C7H5NO5S)2(C14H14N4)2(H2O)2]·3H2O or [Cu2(afsb)2(obix)2(H2O)2]·3H2O, (2), have been obtained through the assembly between H2afsb and the CuII ion in the presence of the flexible N-donor ligands 1,6-bis(1H-1,2,4-triazol-1-yl)hexane (bth) and 1,2-bis[(1H-1,2,4-triazol-1-yl)methyl]benzene (obix), respectively. Compound (1) consists of a cationic coordination polymeric chain and 3-amino-4-carboxybenzenesulfonate (Hafsb-) anions. Compound (2) exhibits an asymmetric dinuclear structure. There are hydrogen-bonded networks within the lattices of (1) and (2). Interestingly, both (1) and (2) exhibit reversible dehydration-rehydration behaviour.

Preparation and characterization of two new CuII supramolecular coordination polymers incorporating sulfobenzoate and flexible heterocyclic ligands.

The assembly of CuII with the multifunctional ligand 2-amino-4-sulfobenzoic acid (H2asba) in the presence of the auxiliary flexible ligands 1,4-bis(triazol-1-ylmethyl)benzene (bbtz) and 1,4-bis(imidazol-1-ylmethyl)benzene (bix) under ambient conditions resulted in two new supramolecular coordination polymers, namely poly[[(3-amino-4-carboxybenzenesulfonato-κO)aquabis[µ2-1,4-bis(triazol-1-ylmethyl)benzene-κ2N4:N4']copper(II)] 3-amino-4-carboxybenzenesulfonate tetrahydrate], {[Cu(C7H6NO5S)(C12H12N6)2(H2O)](C7H6NO5S)·4H2O}n, (1), and poly[[bis(µ2-2-amino-4-sulfonatobenzoato-κ3O1:N,O1')tetraaqua[µ2-1,4-bis(triazol-1-ylmethyl)benzene-κ2N4:N4']dicopper(II)] tetrahydrate], {[Cu2(C7H5NO5S)2(C14H14N4)(H2O)4]·4H2O}n, (2). Single-crystal X-ray structure diffraction analysis of (1) reveals that the bbtz ligand acts as a bridge, linking adjacent CuII ions into a two-dimensional cationic (4,4) topological network, in which the coordinated 3-amino-4-carboxybenzenesulfonate (Hasba-) anion uses its sulfonate group to bind with the CuII ion in a monodentate fashion and the carboxylate group remains protonated. The lattice Hasba- anion resides in the two-dimensional layer and balances the charge. The carboxylate group of the 2-amino-4-sulfonatobenzoate (asba2-) ligand in (2) is involved in bidentate coordination, connecting adjacent CuII ions into carboxylate-bridged chains which are further bridged by the auxiliary flexible bix ligand in a trans-gauche (TG) mode, resulting in the formation of a two-dimensional network architecture. The amino group of the asba2- ligand in (2) also takes part in the coordination with the central CuII ion. The six-coordinated CuII centres in (1) and (2) exhibit distorted octahedral coordination geometries. Extensive hydrogen bonding exists in both (1) and (2). The interlayer hydrogen bonds in both compounds further extend adjacent two-dimensional layers into three-dimensional supramolecular network architectures. Furthermore, a detailed analysis of the solid-state UV-Vis-NIR (NIR is near IR) diffuse reflectance data indicates that (1) and (2) may have potential as wide band gap indirect semiconductor materials. Compounds (1) and (2) show reversible and irreversible dehydration-rehydration behaviours, respectively.

Synthesis and characterization of a cadmium(II)-organic supramolecular coordination compound based on the multifunctional 2-amino-5-sulfobenzoic acid ligand.

Much attention has been paid by chemists to the construction of supramolecular coordination compounds based on the multifunctional ligand 5-sulfosalicylic acid (H3SSA) due to the structural and biological interest of these compounds. However, no coordination compounds have been reported for the multifunctional amino-substituted sulfobenzoate ligand 2-amino-5-sulfobenzoic acid (H2asba). We expected that H2asba could be a suitable building block for the assembly of supramolecular networks due to its interesting structural characteristics. The reaction of cadmium(II) nitrate with H2asba in the presence of the auxiliary flexible dipyridylamide ligand N,N'-bis[(pyridin-4-yl)methyl]oxamide (4bpme) under ambient conditions formed a new mixed-ligand coordination compound, namely bis(3-amino-4-carboxybenzenesulfonato-κO1)diaquabis{N,N'-bis[(pyridin-4-yl)methyl]oxamide-κN}cadmium(II)-N,N'-bis[(pyridin-4-yl)methyl]oxamide-water (1/1/4), [Cd(C7H6NO5S)2(C14H14N4O2)2(H2O)2]·C14H14N4O2·4H2O, (1), which was characterized by single-crystal and powder X-ray diffraction analysis (PXRD), FT-IR spectroscopy, thermogravimetric analysis (TG), and UV-Vis and photoluminescence spectroscopic analyses in the solid state. The central CdII atom in (1) occupies a special position on a centre of inversion and exhibits a slightly distorted octahedral geometry, being coordinated by two N atoms from two monodentate 4bpme ligands, four O atoms from two monodentate 4-amino-3-carboxybenzenesulfonate (Hasba-) ligands and two coordinated water molecules. Interestingly, complex (1) further extends into a threefold polycatenated 0D→2D (0D is zero-dimensional and 2D is two-dimensional) interpenetrated supramolecular two-dimensional (4,4) layer through intermolecular hydrogen bonding. The interlayer hydrogen bonding further links adjacent threefold polycatenated two-dimensional layers into a three-dimensional network. The optical properties of complex (1) indicate that it may be used as a potential indirect band gap semiconductor material. Complex (1) exhibits an irreversible dehydration-rehydration behaviour. The fluorescence properties have also been investigated in the solid state at room temperature.

Synthesis, structure and characterization of two new metal-organic coordination polymers based on the ligand 5-iodobenzene-1,3-dicarboxylate.

Two new coordination polymers (CPs) formed from 5-iodobenzene-1,3-dicarboxylic acid (H2iip) in the presence of the flexible 1,4-bis(1H-imidazol-1-yl)butane (bimb) auxiliary ligand, namely poly[[µ2-1,4-bis(1H-imidazol-1-yl)butane-κ(2)N(3):N(3')](µ3-5-iodobenzene-1,3-dicarboxylato-κ(4)O(1),O(1'):O(3):O(3'))cobalt(II)], [Co(C8H3IO4)(C10H14N4)]n or [Co(iip)(bimb)]n, (1), and poly[[[µ2-1,4-bis(1H-imidazol-1-yl)butane-κ(2)N(3):N(3')](µ2-5-iodobenzene-1,3-dicarboxylato-κ(2)O(1):O(3))zinc(II)] trihydrate], {[Zn(C8H3IO4)(C10H14N4)]·3H2O}n or {[Zn(iip)(bimb)]·3H2O}n, (2), were synthesized and characterized by FT-IR spectroscopy, thermogravimetric analysis (TGA), solid-state UV-Vis spectroscopy, single-crystal X-ray diffraction analysis and powder X-ray diffraction analysis (PXRD). The iip(2-) ligand in (1) adopts the (κ(1),κ(1)-µ2)(κ(1), κ(1)-µ1)-µ3 coordination mode, linking adjacent secondary building units into a ladder-like chain. These chains are further connected by the flexible bimb ligand in a trans-trans-trans conformation. As a result, a twofold three-dimensional interpenetrating α-Po network is formed. Complex (2) exhibits a two-dimensional (4,4) topological network architecture in which the iip(2-) ligand shows the (κ(1))(κ(1))-µ2 coordination mode. The solid-state UV-Vis spectra of (1) and (2) were investigated, together with the fluorescence properties of (2) in the solid state.

Synthesis, structure and characterization of two copper(II) supramolecular coordination polymers based on a multifunctional ligand 2-amino-4-sulfobenzoic acid.

Copper(II) coordination polymers have attracted considerable interest due to their catalytic, adsorption, luminescence and magnetic properties. The reactions of copper(II) with 2-amino-4-sulfobenzoic acid (H(2)asba) in the presence/absence of the auxiliary chelating ligand 1,10-phenanthroline (phen) under ambient conditions yielded two supramolecular coordination polymers, namely (3-amino-4-carboxybenzene-1-sulfonato-κO(1))bis(1,10-phenanthroline-κ(2)N,N')copper(II) 3-amino-4-carboxybenzene-1-sulfonate monohydrate, [Cu(C7H6N2O5S)(C12H8N2)2](C7H6N2O5S)·H2O, (1), and catena-poly[[diaquacopper(II)]-µ-3-amino-4-carboxylatobenzene-1-sulfonato-κ(2)O(4):O(4')], [Cu(C7H6N2O5S)(H2O)2]n, (2). The products were characterized by FT-IR spectroscopy, thermogravimetric analysis (TGA), solid-state UV-Vis spectroscopy and single-crystal X-ray diffraction analysis, as well as by variable-temperature powder X-ray diffraction analysis (VT-PXRD). Intermolecular π-π stacking interactions in (1) link the mononuclear copper(II) cation units into a supramolecular polymeric chain, which is further extended into a supramolecular double chain through interchain hydrogen bonds. Supramolecular double chains are then extended into a two-dimensional supramolecular double layer through hydrogen bonds between the lattice Hasba(-) anions, H2O molecules and double chains. Left- and right-handed 21 helices formed by the Hasba(-) anions are arranged alternately within the two-dimensional supramolecular double layers. Complex (2) exhibits a polymeric chain which is further extended into a three-dimensional supramolecular network through interchain hydrogen bonds. Complex (1) shows a reversible dehydration-rehydration behaviour, while complex (2) shows an irreversible dehydration-rehydration behaviour.

Synthesis, structure and properties of a new three-dimensional interpenetrated metal-organic framework with 3,3'-azodibenzoic acid (H2azdc) and 1,4-bis(1H-imidazol-1-yl)butane (bimb): {[Cd(azdc)(bimb)2]·H2O}n.

A new three-dimensional interpenetrated Cd(II)-organic framework based on 3,3'-azodibenzoic acid [3,3'-(diazenediyl)dibenzoic acid, H2azdc] and the auxiliary flexible ligand 1,4-bis(1H-imidazol-1-yl)butane (bimb), namely poly[[bis[µ2-1,4-bis(1H-imidazol-1-yl)butane-κ(2)N(3):N(3')][µ2-3,3'-(diazenediyl)dibenzoato-κ(2)O:O']cadmium(II)] monohydrate], {[Cd(C14H8N2O4)(C10H14N2)2]·H2O}n, (1), was obtained by a typical solution reaction in mixed solvents (water and N,N'-dimethylformamide). Each Cd(II) centre is six-coordinated by two O atoms of bis-monodentate bridging carboxylate groups from two azdc(2-) ligands and by four N atoms from four bimb ligands, forming an octahedral coordination environment. The Cd(II) ions are connected by the bimb ligands, resulting in two-dimensional (4,4) layers, which are further pillared by the azdc(2-) ligands, affording a threefold interpenetrated three-dimensional α-Po topological framework with the Schläfli symbol 4(12)6(3). The thermal stability and solid-state fluorescence properties of (1) have been investigated.

Synthesis, characterization and properties of a family of lead(II)-organic frameworks based on a multi-functional ligand 2-amino-4-sulfobenzoic acid exhibiting auxiliary ligand-dependent dehydration-rehydration behaviours.

A systematic investigation is reported of the use of the multi-functional ligand 2-amino-4-sulfobenzoate (asba(2-)) to construct lead(II)-organic frameworks in the presence and absence of N-donor auxiliary ligands phen, bipy and bix [phen = 1,10-phenanthroline, bipy = 2,2'-bipyridine and bix = 1,4-(methylene-benzene)bisimidazole]. Under ambient, aqueous conditions the assembly of asba(2-) with Pb(II) and phen or bipy leads to two iso-structural 2D double-layer frameworks, {[Pb2(asba)2(phen)2(H2O)]·2H2O}n (1) and {[Pb2(asba)2(bipy)2(H2O)]·2H2O}n (2). [Pb2(asba)2(bix)2(H2O)2]n (3) is obtained in the presence of the auxiliary ligand bix and possesses a 3D network built up from 2D Pb(II)-asba(2-)-bridged double-layer pillared by bix. A 2D (4,4) topological network [Pb(asba)(H2O)]n (4) is obtained in the absence of any second ligand or presence of some bistriazole bridging spacers. The coordination modes of the ligand asba(2-) in 1-4 are greatly dependent on the type of auxiliary ligand and the compounds exhibit auxiliary ligand-dependent dehydration-rehydration behaviours; 1 shows in situ rapid and reversible dehydration-rehydration behaviour in air, while the iso-structural compound 2 loses crystallinity in air and transforms into {[Pb2(asba)2(bipy)2(H2O)]·H2O}n (2A) verified by TGA, elemental analysis and powder X-ray diffraction analysis (PXRD). 3 also shows reversible dehydration-rehydration behaviour, but it takes around one week to rehydrate even after exposure to water vapor, while the dehydrated phase of 4 rehydrates to a new crystalline material. 1 and 3 fall within the category of the "recoverable collapsing" and "guest-induced re-formation" frameworks. The water molecules in 1 and 3 have some influence on their solid state fluorescent emission intensity.

Preparation, structural diversity and characterization of a family of Cd(II)-organic frameworks.

Two Cd(II)-organic frameworks based on 5-iodoisophthalate (IIP(2-)), {[Cd(IIP)(bte)(H2O)]·H2O}n (1) and [Cd(IIP)(bpp)(H2O)]n (2), were obtained either at an ambient temperature or under solvothermal conditions at 120 °C in the presence of 1,4-bis(1,2,4-triazol-1-yl)ethane (bte) and 1,3-bis(4-pyridyl)propane (bpp) as auxiliary ligands, respectively. 1 is a novel discrete single-walled Cd(II)-organic tube (SWCOT) which further extends into a 3D supramolecular interdigitated microporous columnar architecture supported by C-I···I halogen bonds and hydrogen bonds, while 2 exhibits an interesting two-fold interpenetrated 3D diamond network architecture. When the auxiliary ligands bte or bpp were replaced by a longer spacer ligand with more flexibility, 1,4-bis(triazol-1-ylmethyl)benzene (bbtz), the unique discrete single-walled Cd(II)-organic nanotube (SWCONT), {[Cd(IIP)(bbtz)(H2O)]·H2O}n (3), which further extends into a 3D supramolecular microporous framework supported by face-to-face π···π stacking interactions and hydrogen bonds, was generated at room temperature. Under solvothermal conditions at 120 °C, an interesting two-fold 2D "embracing" (4,4) topological network, [Cd(IIP)(bbtz)(H2O)] (4), which further extends into a two-fold 3D "embracing" supramolecular framework through O-H···O hydrogen bonds, is obtained. 4 loses crystallinity in air, leading to the formation of [Cd(IIP)(bbtz)]·0.5H2O (4A) evidenced by elemental analysis, thermogravimetric analysis (TGA) and powder X-ray diffraction (PXRD). Remarkably, in situ rapid and reversible dehydration-rehydration in static air occurs in 1-3, indicating their potential applications as water absorbent and sensing materials. Dehydrated 1 and 3 show selective gas adsorption of CO2 over N2 and dehydrated 3 can adsorb methanol and ethanol vapors strongly. These compounds exhibit blue fluorescence in the solid state.

Poly[[bis-(µ-3-amino-5-carb-oxy-benzoato-κ(2)N:O(1))diaqua-zinc] dihydrate].

The Zn(II) atom in the title polymeric compound, {[Zn(C(8)H(6)NO(4))(2)(H(2)O)(2)]·2H(2)O}(n), lies on a center of inversion and is coordinated by two amine N atoms and two carboxyl-ate O atoms from two 3-amino-5-carb-oxy-benzoate anions along with two water mol-ecules in a distorted octa-hedral geometry. The bridging nature of the anion generates a layer motif parallel to (100). Hydrogen bonds of the N-H⋯O and O-H⋯O types exist in the structure. One H atom of the coordinated water mol-ecule and one H atom of the solvent water mol-ecule are each disordered over two positions in a 1:1 ratio.

1-{[4'-(1H-1,2,4-Triazol-2-ium-1-ylmeth-yl)biphenyl-4-yl]meth-yl}-1H-1,2,4-triazol-2-ium bis-(3-carb-oxy-5-iodo-benzoate)-5-iodo-benzene-3,5-dicarb-oxy-lic acid-water (1/2/2).

The neutral carb-oxy-lic acid mol-ecule and the carboxyl-ate anion in the title compound, C(18)H(18)N(6) (2+)·2C(8)H(4)IO(4) (-)·2C(8)H(5)IO(4)·2H(2)O, are both nearly planar (r.m.s. deviations = 0.034 and 0.045 Å, respectively). In the cation, the mid-point of the C-C bond linking the two benzene rings lies on a center of inversion, and the triazole ring is approximately perpendicular to the adjacent benzene ring [dihedral angle = 83.2 (3)°]. In the crystal, the cations, anions, carb-oxy-lic acid and lattice water mol-ecules are linked by N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds, generating a ribbon running along [1-10]. The crystal studied was a non-merohedral twin with the components in a 51.2 (1):48.8 (1) ratio.

Poly[[diaqua-(1,10-phenanthroline-κN,N')(µ(3)-4-sulfonato-benzene-1,2-dicarboxyl-ato-κO:O,O:O)dysprosium(III)] dihydrate].

The 4-sulfophthalate trianion in the polymeric title complex, {[Dy(C(8)H(3)O(7)S)(C(12)H(8)N(2))(H(2)O)(2)]·2H(2)O}(n), bridges three water/phenanthroline-coordinated Dy(III) atoms to form a three-dimensional network architecture. The metal atom is further chelated by a carboxyl-ate group and is covalently bonded to a monodentate carboxyl-ate group and to a monodentate sulfonate group in a distorted square-anti-prismatic geometry. The coordinating and the solvent water mol-ecules are hydrogen bonded to the network. In the crystal, one solvent water mol-ecule is disordered over two positions [major component = 59 (3)%].

Poly[[diaqua-(1,10-phenanthroline-κN,N')(µ(3)-4-sulfonato-benzene-1,2-di-car-boxyl-ato-κO:O,O:O)erbium(III)] dihydrate].

The 4-sulfophthalate trianion in the polymeric complex, {[Er(C(8)H(3)O(7)S)(C(12)H(8)N(2))(H(2)O)(2)]·2H(2)O}(n), bridges three water/phenanthroline-coordinated Er(III) ions to form a three-dimensional network architecture. The metal atom is further chelated by a carboxyl-ate group and is covalently bonded to a monodentate carboxyl-ate group as well as to a monodentate sulfonate group in a distorted square anti-prismatic geometry. The coordinating water molecules and the lattice water molecules, one of which is disordered over two positions [major component 65 (3)%], are hydrogen bonded to the network.

(5-Amino-isophthalato-κN)triaqua-(1,10-phenanthroline-κN,N')nickel(II) trihydrate.

The Ni(II) atom in the title compound, [Ni(C(8)H(5)NO(4))(C(12)H(8)N(2))(H(2)O)(3)]·3H(2)O, is six-coordinated in an NiN(3)O(3) octa-hedral geometry. The triply water-coordinated Ni(II) atom is chelated by the phenantroline ligand and is additionally coordinated by the amino group of the 5-amino-isophtalate anion. The anion, the coordinated and the uncoordinated water mol-ecules inter-act through an extensive O-H⋯O and N-H⋯O hydrogen-bonding network, generating a three-dimensional cage-like network.

5-Amino-2,4,6-triiodo-isophthalic acid-4,4'-bipyridine N,N'-dioxide-water (1/1/1).

The aromatic rings of the N,N'-dioxide molecule in the title compound, C(8)H(4)NI(3)O(4)·C(10)H(8)N(2)O(2)·H(2)O, are twisted by 14.0 (2)°. The -CO(2)H substituents of the 5-amino-2,4,6-triiodo-isophthalic acid are twisted by 83.0 (2) and 86.5 (2)° out of the plane of the aromatic ring. In the crystal, the three components are linked by O-H⋯O hydrogen bonds into a three-dimensional network. An N-H⋯O inter-action also occurs. One of the amino H atom is not involved in hydrogen bonding.