Highly selective guest uptake in a silver sulfonate network imparted by a tetragonal to triclinic shift in the solid state

Syntheses, structures, and antimicrobial activity of new remarkably light-stable and water-soluble tris(pyrazolyl)methanesulfonate silver(I) derivatives of N-methyl-1,3,5-triaza-7-phosphaadamantane salt - [mPTA]BF4

Two new silver(I) complexes of formula [Ag(mPTA)4](Tpms)4(BF4) (1) and [Ag(Tpms)(mPTA)](BF4) (2) (mPTA = N-methyl-1,3,5-triaza-7-phosphaadamantane cation, Tpms = tris(pyrazol-1-yl)methanesulfonate anion) have been synthesized and fully characterized by elemental analyses, (1)H and (31)P{(1)H} NMR, ESI-MS, and IR spectroscopic techniques. The single-crystal X-ray diffraction study of 1 discloses a noncoordinated nature of the Tpms species, existing as counterions around the highly charged metal center [Ag(mPTA)](5+), 1 being the first reported coordination compound bearing a κ(0)-Tpms. 1 features high solubility and stability in water (S25 °C ≈ 30 mg·mL(-1)). The two complexes interact with calf thymus DNA via intercalation mode, binding to the BSA with decrease of its tryptophan fluorescence with a static quenching mechanism. The two new silver complexes exhibit significant antibacterial and antifungal activities screened in vitro against the standard strains of Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans.

Preparation and topological properties of two structures with p-sulfobenzoic ligands and Zn2+ and Mn2+ ions

There has been recent interest in coordinated polymers due to their structural and topological properties; therefore, the search for efficient synthesis processes to construct these materials by exploiting different organic ligands has intensified.

A novel three-dimensional AgI coordination polymer based on mixed naphthalene-1,5-disulfonate and aminoacetate ligands

The three-dimensional coordination polymer poly[[bis(μ₃-2-aminoacetato)di-μ-aqua-μ₃-(naphthalene-1,5-disulfonato)-hexasilver(I)] dihydrate], {[Ag₆(C₁₀H₆O₆S₂)(C₂H₄NO₂)₄(H₂O)₂]·2H₂O}n, based on mixed naphthalene-1,5-disulfonate (L1) and 2-aminoacetate (L2) ligands, contains two Ag(I) centres (Ag1 and Ag4) in general positions, and another two (Ag2 and Ag3) on inversion centres. Ag1 is five-coordinated by three O atoms from one L1 anion, one L2 anion and one water molecule, one N atom from one L2 anion and one AgI cation in a distorted trigonal-bipyramidal coordination geometry. Ag2 is surrounded by four O atoms from two L2 anions and two water molecules, and two AgI cations in a slightly octahedral coordination geometry. Ag3 is four-coordinated by two O atoms from two L2 anions and two AgI cations in a slightly distorted square geometry, while Ag4 is also four-coordinated by two O atoms from one L1 and one L2 ligand, one N atom from another L2 anion, and one AgI cation, exhibiting a distorted tetrahedral coordination geometry. In the crystal structure, there are two one-dimensional chains nearly perpendicular to one another (interchain angle = 87.0°). The chains are connected by water molecules to give a two-dimensional layer, and the layers are further bridged by L1 anions to generate a novel three-dimensional framework. Moreover, hydrogen-bonding interactions consolidate the network.

Antibacterial action of 4,4'-bipyrazolyl-based silver(I) coordination polymers embedded in PE disks

Coupling the rigid spacer 4,4'-bipyrazole (H(2)BPZ), in its anionic or neutral form, to different silver(I) salts allowed isolation of the novel coordination polymers [Ag(2)(BPZ)] (1) and [Ag(H(2)BPZ)(X)] (X = NO(3), 2; ClO(4), 3; BF(4), 4; PF(6), 5; CH(3)SO(3), 6; CF(3)SO(3), 7), which were fully characterized by infrared and emission spectroscopies, thermal analysis, and X-ray powder diffraction. The crystal structure of 1 consists of 2-D layers containing 1-D chains of Ag(I) ions bridged by exo-tetradentate bipyrazolato moieties. The crystal structures of the [Ag(H(2)BPZ)(X)] species 2-7 feature 1-D chains of [Ag(H(2)BPZ)] stoichiometry, along which the metal centers are bridged by exo-bidentate bipyrazolyl spacers. Contacts among adjacent chains are mediated by the counterions through nonbonding interactions involving the Ag(I) ions and the pyrazolyl N-H groups. Thermogravimetric analyses disclosed the good thermal stability of these materials, decomposing in the range 200-300 °C. Under UV irradiation at room temperature, all the species showed a yellow-green emission centered in the range 520-522 nm. When embedded into polyethylene disks, 1, 2, and 4-7 demonstrated their activity as topical antibacterial agents against suspensions of E. coli, P. aeruginosa, and S. aureus: complete reduction of the three bacterial strains was achieved in 24 h, reduction of S. aureus reaching ca. 90% in only 2 h. Biocidal action was expressed also by contact susceptibility tests.

Poly[(μ(4)-5-bromo-pyridine-3-sulfonato)-silver(I)]

The silver(I) complex, [Ag(C(5)H(3)BrNO(3)S)](n), was obtained by reaction of AgNO(3) and 5-bromopyridine-3-sulfonic acid. The Ag(I) ion is coordinated by an O(3)N donor set in a slightly distorted tetra-hedral geometry. The Ag(I) ions are linked by μ(4)-5-bromo-pyridine-3-sulfonate ligands, forming a layer parallel to (100). The layers are further connected via C-H⋯Br hydrogen-bonding inter-actions into a three-dimensional supra-molecular network. The Ag⋯Ag separation is 3.0159 (6) Å, indicating the presence of argentophilic inter-actions.

Flexible two-dimensional square-grid coordination polymers: structures and functions

Coordination polymers (CPs) or metal-organic frameworks (MOFs) have attracted considerable attention because of the tunable diversity of structures and functions. A 4,4'-bipyridine molecule, which is a simple, linear, exobidentate, and rigid ligand molecule, can construct two-dimensional (2D) square grid type CPs. Only the 2D-CPs with appropriate metal cations and counter anions exhibit flexibility and adsorb gas with a gate mechanism and these 2D-CPs are called elastic layer-structured metal-organic frameworks (ELMs). Such a unique property can make it possible to overcome the dilemma of strong adsorption and easy desorption, which is one of the ideal properties for practical adsorbents.

Supramolecular inorganic frameworks: “dynamic” challenges for structural chemistry

The supramolecular chemistry of discrete assemblies of various topologies (cages, grids, helices, etc.) has been extensively studied. With regards to the supramolecular chemistry of infinite solids, attention is usually focussed on the design of an efficient, programmed assembly motif through the choice of suitable building blocks. However, as well illustrated by the discrete structures, a hallmark property of a supramolecular system is its ability to reversibly assemble to optimize its structure, effectively error checking. For a rigid infinite framework, this feature is less obvious. Error checking is manifested in an extended framework through structural rearrangements in the solid state. Coordination frameworks, as they are often at least partially sustained by weaker interactions, can demonstrate such dynamic behavior in response to some external stimulus. Selected examples, chosen to illustrate a range of network types and rearrangements, will be discussed in this short review.

A series of silver(I) pyridone-sulfonates with 1-D "butterfly" chain, 2-D lamellar network and 3-D pillared layered frameworks: syntheses, structures and characterizations

A series of silver(I) pyridone-sulfonates, namely [Ag5(HL1)3(NO3)2(H2O)]n (1) [Ag2(HL1)2]n.2nH2O (2), [Ag2(HL1)(NO3)]n (3), and [Ag3(HL2)2(NO3)(H2O)]n (4) (HL1 = 4(1H)-pyridone-3-sulfonate monoanion, HL2 = 2(1H)-pyridone-5-sulfonate monoanion), have been synthesized and characterized by elemental analyses, IR, TG, PL and X-ray analyses. Complex 1, which exhibits a novel continuous silver polyhedral framework containing four kinds of coordination spheres, has been recently reported. Complex 2 presents the first one-dimensional (1-D) "butterfly" array composed of SO3-bridged columns of Ag(I) ions and symmetric pendant organic groups in silver(I) sulfonates, while complex 3 possesses a two-dimensional (2-D) layer structure in which the inorganic network substructure consists of helical chains of edge-sharing Ag1 distorted octahedra linked through dimers of edge-sharing Ag2 distorted anti-trigonal prisms by sharing two corners and two edges. Replacing H2L1 by H2L2 leads to the formation of complex 4, a three-dimensional (3-D) pillared layered framework, which is also extended by the rare mu4 nitrate anion. In complexes 1-4, all the inorganic parts can be considered as being built up from versatile polyhedra of silver(I) centers by sharing corners, edges or faces. The sulfonic group shows some novel coordination modes, which is first reported here. Solid-state fluorescence quenching and thermal stability are discussed for all of these complexes.

catena-Poly[[diaqua-manganese(II)]-di-μ-pyridine-3-sulfonato-κN:O;κO:N]

In the title polymeric complex, [Mn(C₅H₄NO₃S)₂(H₂O)₂]_n, the Mn atom is located on a centre of inversion and is coordinated by two O atoms and two N atoms derived from four different pyridine-3-sulfonate (pySO₃) ligands, and two O atoms derived from two water mol­ecules in a distorted trans-N₂O₄ octa­hedral geometry. The metal atoms are bridged by the pySO₃ ligands to form a one-dimensional chain. The chains are further connected into a three-dimensional architecture via hydrogen bonds.

catena-Poly[[diaquacadmium(II)]bis-(μ-pyridine-3-sulfonato)-κN:O;κO:N]

In the title polymeric complex, [Cd(C(5)H(4)NO(3)S)(2)(H(2)O)(2)](n), the Cd atom is located on a centre of inversion and is coordinated by two O atoms and two N atoms, derived from four different pyridine-3-sulfonate ligands, and two O atoms derived from two water mol-ecules, forming a distorted trans-N(2)O(4) octa-hedral geometry. The topology of the polymer is a one-dimensional chain mediated by bridging pyridine-3-sulfonate anions. These are connected into a three-dimensional architecture via hydrogen bonds.

Mechanical gas capture and release in a network solid via multiple single-crystalline transformations

Metal-organic frameworks have demonstrated functionality stemming from both robustness and pliancy and as such, offer promise for a broad range of new materials. The flexible aspect of some of these solids is intriguing for so-called 'smart' materials in that they could structurally respond to an external stimulus. Herein, we present an open-channel metal-organic framework that, on dehydration, shifts structure to form closed pores in the solid. This occurs through multiple single-crystal-to-single-crystal transformations such that snapshots of the mechanism of solid-state conversion can be obtained. Notably, the gas composing the atmosphere during dehydration becomes trapped in the closed pores. On rehydration, the pores open to release the trapped gas. Thus, this new material represents a thermally robust and porous material that is also capable of dynamically capturing and releasing gas in a controlled manner.

Structural Study of Silver(I) Sulfonate Complexes with Pyrazine Derivatives

In this Article, 11 silver complexes, namely, [Ag(L1)(2-Pyr)(H2O)] (1), Ag(L1)(2,3-Pyr) (2), [Ag2(L1)2(2Et,3Me-Pyr)2(H2O)] (3), [Ag(2,6-Pyr)](L1).1.5H2O (4), Ag(L1)(2,5-Pyr) (5), [Ag(H2O)2](L2).H2O (6), [Ag(L2)(2-Pyr)] (7), [Ag(L2)(2,3-Pyr)].1.5H2O (8), [Ag(L2)(2Et,3Me-Pyr)].2H2O (9), [Ag2(L2)(2,6-Pyr)(H2O)2](L2).H2O (10) and [Ag(L2)(2,5-Pyr)].H2O (11) (2-Pyr=2-methylpyrazine; 2,3-Pyr=2,3-dimethylpyrazine; 2Et,3Me-Pyr=2-ethyl-3-methylpyrazine; 2,6-Pyr=2,6-dimethylpyrazine; 2,5-Pyr=2,5-dimethylpyrazine; L1=p-aminobenzenesulfonate anion and L2=6-amino-1-naphthalenesulfonate anion), have been synthesized and characterized by elemental analyses, IR spectroscopy, and X-ray crystallography. In 1, 3, and 4, Ag(I) centers are linked by bridging pyrazine ligands to form one-dimensional chains, whereas compound 2 shows a double-chain structure through weak Ag-C interactions. The structure analyses show that both 5 and 11 form two-dimensional networks composed of 26-membered metallocycles. Unexpectedly, compounds 6 and 10 show discrete structures. In compound 7, silver(I) centers are bridged by sulfonate anions to form a polymeric helical structure, and the 2-Pyr molecule acts as a monodentate ligand. Compounds 8 and 9 show hinged chain structures containing 14-membered rings, and these chains interlace with each other to generate unique three-dimensional structures. These results indicate that the substituting groups and the substituting sites of pyrazine derivatives play an important role in the framework formation of silver complexes. Additionally, the luminescent properties of these compounds are also discussed.