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The article discusses research which evaluated the crystal structure and physical properties of silver salts with helical coordination polymer. Topics discussed include the reaction of silver ion with the unsymmetrical ligand, geometric parameters relevant to the coordination geometry and the X-ray crystal structure.

In the title coordination polymer, [Ag2(C4H4O4S)], each AgI cation is four-coordinated by three of the four carboxylate O atoms and the S atom from symmetry-related sulfanediyldiacetate ligands, thus defining a distorted tetrahedral geometry at the metal centre. The AgI cations are bridged by sulfanediyldiacetate groups, leading to a two-dimensional layer structure. These layers are interconnected via Ag-S bonds to form a three-dimensional coordination polymer network overall. [ABSTRACT FROM AUTHOR]

Abstract: The self-assembly reaction of the flexible ligand 1,2-bis(1,2,4-triazol-4-yl)ethane (btre) and AgClO4 gives a novel coordination polymer {[Ag(btre)](ClO4)} n (1). Adjacent two silver(I) atoms are linked through four nitrogen atoms of two N1/N2 atoms of two btre ligands and form Ag2N4 6-membered rings and construct a one-dimensional chain. The chains extend through btre bridges in four different directions alternatively to construct a novel three-dimensional network. Compound 1 exhibits luminescence emission maxima at 326nm upon excitation at 260nm in the solid state at room temperature. The anion exchange of compound 1 with BF4 − and NO3 − occurs smoothly in a typical aqueous media. [Copyright &y& Elsevier]

abstract: A novel one-dimensional silver(I) complex, derived from 2-hydroxypyridine with Ag2O in an ammonia solution, have been prepared and structurally characterized. Each Ag atom in the complex is three-coordinate in a T-shaped geometry with two phenolate O atoms and one pyridine N atom. Adjacent Ag atoms are linked by Ag–Ag interactions, forming an Ag4 unit. The Ag4 units are further linked by four phenolate O atoms, forming a one-dimensional chain running along the c axis. The fluorescence of the complex has been studied. The complex show strong urease inhibitory activity. [Copyright &y& Elsevier]

The aims of this work were to evaluate the antibacterial and antiproliferative potential in vitro of the metal complex with 4-aminobenzoic acid (Ag-pABA) and a drug delivery system based on bacterial cellulose (BC-Ag- p ABA). The Ag- p ABA complex was characterized by elemental analysis, high resolution mass spectrometry and single-crystal X-ray diffraction techniques, which indicated a 1:2 metal/ p ABA composition plus a nitrate ion coordinated to silver by the oxygen atom, with the coordination formula [Ag (C 7 H 7 NO 2) 2 (NO 3)]. The coordination of p ABA to the silver ion occurred by the nitrogen atom. The in vitro antibacterial activity of the complex evaluated by minimum inhibitory concentration assays demonstrated the effective growth inhibitory activity against Gram-positive, Gram-negative biofilm producers and acid - alcohol resistant Bacillus. The antiproliferative activities against a panel of eight tumor cells demonstrated the activity of the complex with a significant selectivity index (SI). The DNA interaction capacity and the Ames Test indicated the absence of mutagenicity. The BC-Ag- p ABA composite showed an effective capacity of sustained release of Ag- p ABA. The observed results validate further studies on its mechanisms of action and the conditions that mediate the in vivo biological effects using animal models to confirm its safety and effectiveness for treatment of skin and soft tissues infected by bacterial pathogens, urinary tract infections and cancer. A silver (I) complex was synthesized and characterized with the ligand 4-aminobenzoic acid. The complex was tested, in vitro , for antibacterial activities against Gram-positive, Gram-negative, and alcohol-acid resistant bacteria, and antitumor activity against a panel of 8 tumor cell lines. Unlabelled Image • Broad spectrum of Ag-p-aminobenzoic acid antibacterial and antitumor action • Displays high in vitro toxicity for pathogenic and opportunist bacteria • Selective toxicity for tumor cells lines • Ability to interact with DNA and absence of mutagenic activity • Bacterial cellulose as sustained drug delivery system [ABSTRACT FROM AUTHOR]

Three series of structurally and electronically varied silver complexes of coumarin and allyl substituted N–heterocyclic carbene (NHC) ligands derived from 1,2,4–triazole core have been prepared and characterized. The ionic 1,2,4–triazolium salts have been prepared by successive N–alkylation method using allyl bromide and appropriately substituted 4–bromomethylcoumarin derivatives. Further, in–situ deprotonation method for triazolium salts was followed with different silver sources (silver oxide and silver acetate) and reaction conditions to obtain structurally diverse silver NHC coordination architectures. Furthermore, the structure of 4–bromomethyl–6–chlorocoumarin, a triazolium salt and two silver complexes has been established by single crystal X–ray diffraction technique. The silver NHC complexes displayed a linear coordination geometry with monoclinic crystal system. Supramolecular assembly of the salt and the complexes evidenced moderate π − π stacking interactions between adjacent coumarin rings. Since silver(I) NHC complexes are well known for medicinal properties, present complexes have been studied for their potent antioxidant and antihaemolytic abilities. Bis–NHC coordinated silver hexafluorophosphate complexes displayed DPPH radical scavenging activity with an IC 50 value in the range 61 ± 14 to 131 ± 7 μM, while others displayed moderate to poor activity. Similarly, antihaemolytic activity has been carried out at 100 μM concentration, and the complexes exhibited lysis of red blood cells as low as 2.32 ± 0.05%. Three series of structurally different silver(I) complexes bearing 1,2,4-triazole based NHC ligands have been prepared and characterized. Bis-NHC coordinated complexes displayed excellent DPPH radical scavenging activity with an IC 50 value in the range 61 ± 14 to 131 ± 7 μM. Similarly, antihaemolytic activity has been carried out at 100 μM concentration, and the complexes exhibited lysis of red blood cells as low as 2.32 ± 0.05%. Unlabelled Image • Three series of silver(I) 1,2,4-triazole based NHC complexes were reported. • Bis-NHC complexes displayed excellent DPPH radical scavenging activity. • IC 50 for DPPH activity in the range 61 ± 14 to 131 ± 7 μM. • Lysis of red blood cells by complexes found as low as 2.32 ± 0.05%. [ABSTRACT FROM AUTHOR]

The preparation and X-ray crystal structure of tetrakis(pyrazol-1-ylmethyl)methane are described. This new ligand reacts with silver(I) nitrate to give a M2L2 complex, in which the ligand bridges two trigonal silver atoms with bidentate and monodentate coordination domains. As such the ligand is hypodentate with one non-coordinated pyrazole group. [Copyright &y& Elsevier]

The aim of this study was to present the synthesis, characterization, and investigation of the antiproliferative activity of new metal N- Heterocyclic Carbene (NHC) salts (1a-c) and their Ag(I) complexes (2a-c). All synthesized compounds were characterized using elemental analysis, LC-MS, FT-IR, 1H NMR, and 13C NMR spectroscopy techniques. Salts and complexes were tested for antiproliferative activities on human breast and prostate cancer cell lines (MCF-7, MDA-MB-23, DU-145) and L-929 normal cells for 24 h, 48 h and 72 h using MTT assays. The Ag(I)-NHC complexes (2a-c) showed dose and time-dependent cytotoxic activity against all cell lines. MDA-MB-231 and MCF-7 human breast carcinoma cells were the most sensitive to displaying IC 50 lower than 1 μM at all time points for 2a and 2b complexes respectively. The IC 50 s for Ag(I)-NHC were higher in normal cells especially compared to the breast cancer cells, suggesting that complexes possessed noteworthy selectivity for human breast cancer cells. Complex 2a showed high selectivity (≥13-fold) for MDA-MB-231 breast cancer cells at all time points. These results also demonstrated that complex 2b has 4-7-fold selectivity against MCF-7 breast cancer cells. Image 1 • Synthesis of New Ag(I) N Heterocyclic Carbene (NHC) Complexes. • Antiproliferative activities against three human cancer cell lines (MCF-7, DA-MB-231, PC-3) and L-929 normal cells. • Benzyl substituted complex (2a) showed highest selectivity (≥13-fold) for MDA-MB-231 breast cancer cells. • Naphthyl substituted complex (2b) the most active complex against MCF-7 breast cancer cells (Selectivity Index 4–7 fold). • Biological activity depends on the nature of the group bound to benzimidazole and cancer cell line. [ABSTRACT FROM AUTHOR]

Two 1D tpa complexes [Ag(tpa)(2‐apy)]n (1) and {[Ag(3‐apy)]·(tpa)·(H2O)}n (2) have been obtained from higher dimensional silver complex reaction systems and characterized. The complexes of 1 and 2 exhibit superprotonic conductivities with 3.27 × 10−2 S·cm−1 and 2.25 × 10−2 S·cm−1 respectively, in the same order of magnitude with that of the 1D 2,5‐tpa complex. The structures and topological analyses show the relative positions of substituents in neutral ligands affect the existence modes of tpa ligands, influencing the topological results and distributions of proton conduction sites, which do not affect the proton conductivities of the complexes dramatically. Instead, the dimensionalities of the complexes are closely related to the proton conductivities, indicating that in high humidity, abundant hydrogen‐bond networks are formed in pores and between main frameworks of the proton conductive compounds and influence the performance. Two lower dimensional new silver(I) compounds have been obtained by replacing bidentate 2,5‐tpa with mono‐dentate tpa ligand in the reaction systems. In high humidity conditions, the dimensionality of coordination polymer has close relationship with the proton conductivity. [ABSTRACT FROM AUTHOR]

The article discusses helical structures that are common in supramolecular chemistry and materials science due to it's similarities in biological systems like nucleic acids and proteins. Topics include double-helical chain, silver complex, unsymmetrical ligand, and crystal structure. Other topics include coordination geometry, thermogravimetry analysis (TGA), and photoluminescence.

A series of new benzimidazolium salts (1a-g) were synthesized from the reaction of 1-(4-vinylbenzyl)benzimidazole with various alkyl halides. These salts were used to synthesize silver N-heterocyclic carbene (Ag-NHC) complexes (2a-f). The thirteen compounds were characterized by FT-IR, NMR ((1)H and (13)C) spectroscopic methods and an elemental analysis technique. These selected candidates were tested for their in vitro antimicrobial activities. Antibacterial and antifungal results indicated that the new salts, and particularly their silver complexes, were found to be strongly effective against seven Gram (-) bacterial strains, three Gram (+) bacterial strains and one yeast (Candida albicans).

This study reports the synthesis, characterisation and antimicrobial activity of five novel silver N-heterocyclic carbene (Ag-NHC) complexes obtained by N-propylphthalimide and N-methyldioxane substituted benzimidazolium salts with silver oxide. The reactions were performed at room temperature for 24 h in the absence of light. The obtained complexes were identified and characterised by (1)H and (13)C NMR, FT-IR and elemental analysis techniques. The minimum inhibitory concentration (MIC) of the complexes was determined for E. coli, P. aeruginosa, E. faecalis, S. aureus, C. tropicalis and C. albicans in vitro through agar and broth dilution. The results indicated that these complexes exhibit antimicrobial activity. In particular, complex 3 presented the significant broad spectrum antimicrobial activity.

Heterotopic ligands offer the possibility of preparing polynuclear bimetallic complexes. Recent studies of heteroditopic ligands and their metal complexes have focused on novel supramolecular systems, biological activity, and the development of MRI contrast agents. The heteroditopic ligand Bipy-CH 2 -O-CH 2 -C(pz) 3 (Bipy-L; Bipy is 2,2'-bipyridine and pz is pyrazolyl) reacts with AgBF 4 to produce the coordination polymer catena-poly[[silver(I)-(μ-5-{[tris(pyrazol-1-yl)methoxy]methyl-κ 2 N,N'}-2,2'-bipyridine-κ 2 N,N')] diethyl ether hemisolvate], {[Ag(C 22 H 20 N 8 O)]BF 4 ·0.5C 4 H 10 O} n , and with Re(CO) 5 Br to form the discrete compound bromidotricarbonyl(5-{[tris(pyrazol-1-yl)methoxy]methyl}-2,2'-bipyridine-κ 2 N,N')rhenium(I), [ReBr(C 22 H 20 N 8 O)(CO) 3 ]. The silver(I) compound is a one-dimensional coordination polymer, built up by a κ 2 coordination mode of the bipyridine group and a κ 2 -κ 0 coordination mode of the -C(pz) 3 donor set. In [ReBr(Bipy-L)(CO) 3 ], the ligand coordinates only via the bipyridine end, leaving the -C(pz) 3 donor set free for further coordination interactions.

The title compound, [Ag(qPyr) 2 ]CF 3 SO 3 where qPyr = 1-(quinoline-2-yl-methyl-ene)amino-pyrene, C 26 H 16 N 2 , was synthesized from a reaction of silver tri-fluoro-methane-sulfonate and qPyr in di-chloro-methane-methanol mixed media. In this design, the qPyr ligand was chosen for its characteristic excitation and emission profiles, which could enable the tracking of the silver complex within biological targets. The Ag I atom resides in a distorted tetra-hedral N 4 coordination sphere. Analysis of the packing pattern revealed significant intra- and inter-molecular π-π stacking inter-actions between the [Ag(qPyr) 2 ] + cations. In addition, a weak C-H⋯O hydrogen bond consolidates the packing between cations and anions.

A major challenge in lubrication technology is to enhance lubricant performance at extreme temperatures that exceed conventional engine oil thermal degradation limits. Soft noble metals such as silver have low reactivity and shear strength, which make them ideal solid lubricants for wear protection and friction reduction between contacting surfaces at high temperatures. However, achieving adequate dispersion in engine lubricants and metallic silver deposition over predetermined temperatures ranges presents a significant chemical challenge. Here we report the synthesis, characterization, and tribological implementation of the trimeric silver pyrazolate complex, [Ag(3,5-dimethyl-4-n-hexyl-pyrazolate)]3 (1). This complex is oil-soluble and undergoes clean thermolysis at ∼310 °C to deposit lubricious, protective metallic silver particles on metal/metal oxide surfaces. Temperature-controlled tribometer tests show that greater than 1 wt % loading of 1 reduces wear by 60% in PAO4, a poly-α-olefin lubricant base fluid, and by 70% in a commercial fully formulated 15W40 motor oil (FF oil). This silver-organic complex also imparts sufficient friction reduction so that the tribological transition from oil as the primary lubricant through its thermal degradation, to 1 as the primary lubricant, is experimentally undetectable.

In the title compound, [Ag2(C3H6N2S)4(C18H15P)2](C2H3O2)2·[Ag(C2H3O2)(C3H6N2S)(C18H15P)2]2·2C2H3N·4H2O, the Ag(I) ion in the mononuclear neutral complex exhibits a distorted tetra-hedral environment with coordination by two P atoms from tri-phenyl-phosphane (PPh3) ligands, one S atom of an imidazolidine-2-thione (etu) ligand and one O atom of an acetate anion. The binuclear cationic complex comprises two inversion-related [Ag(C3H6N2S)2(C18H15P)] units with Ag(I) ions bridged by two S atoms from etu ligands forming a four-membered Ag-S-Ag-S ring. Each Ag(I) ion is coordinated by a P atom of a PPh3 ligand, two S atoms of bridging etu ligands and the terminal S atom of an etu ligand in a distorted tetra-hedral environment. In the crystal, the mononuclear complex is linked to lattice water mol-ecules through O-H⋯O and N-H⋯O hydrogen bonds, forming a chain along [100]. In addition, the binuclear complex mol-ecules are connected to acetate anions and lattice water mol-ecules via O-H⋯O, N-H⋯O and O-H⋯S hydrogen bonds, also along [100].

The title complex, [Ag3I2(C25H22P2)3]I·C7H8N2S, comprises a trinuclear [Ag3I2(C25H22P2)3](+) unit, an I(-) anion and one N,N'-phenyl-thio-urea mol-ecule (ptu). Two μ3-bridging I(-) anions are linked by three Ag(I) ions, leading to the formation of a dicapped triangular motif with Ag⋯Ag separations in the range 3.0823 (5)-3.2999 (5) Å. Each Ag(I) atom exhibits a distorted tetra-hedral geometry, with coordination to two I atoms and two P atoms from bis-(di-phenyl-phosphan-yl)methane ligands. In the crystal, the I(-) anion is linked to the ptu mol-ecule through two N-H⋯I hydrogen bonds [graph-set motif R 2 (1)(6)]. These N-H⋯I hydrogen bonds, in addition to weak C-H⋯S and C-H⋯I hydrogen bonds, form zigzag chains along [010]. Two of the phenyl rings of two dppm ligands are disordered over two sets of sites with refined occupancies of 0.557 (16) and 0.443 (16).

In the dinuclear title complex, [Ag2Cl2(C7H8N2S)(C25H22P2)2]·0.5CH3CN, each Ag(I) ion displays a distorted tetra-hedral coordination geometry with two P atoms from two bis-(di-phenyl-phosphan-yl)methane (dppm) ligands, one bridging chloride ion, one terminal chloride ion and one terminal S atom from the N,N'-phenyl-thio-urea (ptu) ligand. The dppm ligands and the bridging chloride ion force the two Ag atoms into close proximity, with a short Ag⋯Ag separation of 3.2064 (2) Å. In the crystal, complex mol-ecules are linked by N-H⋯Cl hydrogen bonds forming a dimer. The dimers are linked via weak C- H⋯Cl hydrogen bonds forming a two-dimensional supra-molecular architecture in the yz plane. In addition, an intra-molecular N-H⋯Cl hydrogen bond is observed.

The title complex, [Ag3Br2(C25H22P2)3]Br·C7H8N2S, comprises a trinuclear [Ag3Br2(C25H22P2)3](+) unit, a Br(-) anion and one N,N'-di-methyl-thio-urea mol-ecule (ptu). Three Ag(I) ions are linked via two μ3-bridging Br atoms, leading to a distorted triangular bipyramid with an Ag⋯Ag separation range of 3.1046 (6)-3.3556 (6) Å. The triangular Ag3 arrangement is stabilized by six P atoms from three chelating bis-(di-phenyl-phosphan-yl)methane (dppm) ligands. The Ag(I) ion presents a distorted tetra-hedral coordination geometry. In the crystal, the bromide anion is connected to the ptu mol-ecule through N-H⋯Br hydrogen bonds [graph-set motif R 2 (1)(6)]. Each bromide/ptu aggregate links the complex ion via C-H⋯S and C-H⋯Br hydrogen bonds, leading to the formation of a three-dimensional network. Two phenyl rings from two dppm ligands were modelled as disordered over two sites.