Silver Coordination Compounds Research Articles

Predictive calculation of the stability constants of silver(I) ion with pyridine and 2,2′-bipyridyl in a solvent environment

In the present study, the stability constants of silver(I) coordination compounds with 2,2′-bipyridyl (bpy, L) in mixed methanol–acetonitrile solvents (MeOH-AN, χAN = 0.0 ÷ 1.0 mol fr.) were determined by the potentiometric method at 25.0 °C. The influence of reagents solvation on the change in stability of [Ag(bpy)]+ and [Ag(bpy)2]+ complexes upon changing the composition of the solvent MeOH→(MeOH-AN) was analyzed. It has been established that the determining factor in the shift of the complex formation equilibrium along the first and second steps of coordination with a change in the composition of the solvent is the contribution from the central ion resolvation. The obtained results and data on the thermodynamics of complex formation reactions of Ag+ with bpy and pyridine (py, L) in a few binary non-aqueous solvents were compared. The possibility of carrying out an estimated calculation of the stability constants of [Ag(L)]+ in non-aqueous solvents was confirmed.

Structural, spectroscopic, and chemical bonding analysis of luminescent bis(diphenylphosphino)methane derived binuclear heteroleptic silver(I) complex of norharmane with argentophilic interaction

Silver(I) coordination compounds have a fascinating geometrical diversity, the ability to have different coordination numbers (typically from 2 to 4), and the ability to form argentophilic (Ag∙∙∙Ag) interactions. In this work, a binuclear Ag(I) heteroleptic complex with norharmane ‘β-carboline’ and bis(diphenylphosphino)methane (PP) ligands has been synthesized and characterized by various spectroscopic and single-crystal X-ray diffraction analyses. The bonding of Ag(I) coordination and Ag···Ag interaction is explored in depth. The theoretical approaches employed were perturbation theory within the context of the natural bond orbital (NBO) framework, quantum theory of atoms in the molecule (QTAIM), and electron localization function (ELF) analysis.

Synthesis, spectral elucidation, thermal study, DFT calculations and biological application of new nano sized coordination compounds of a barbiturate based ligand

Novel titanium (IV), vanadyl (II), nickel (II), copper (II), cobalt (II), mercury (II) and silver (I) coordination compounds were established from a ligand created from a diazotization coupling process between 1-(4-aminophenyl)ethanone and barbituric acid. Analytical, spectroscopic, and thermal approaches were used to detect the best structural geometry of the compounds. The coordination compounds were constructed with (1M:2L) stoichiometry. With the exception of titanium (IV), vanadyl (II), and silver (I), all chelated compounds were non-electrolytes. Except for the vanadyl complex, which possessed square pyramidal geometry, and the silver one with tetrahedral geometry, the chelates of titanium (IV), copper (II), nickel (II), mercury (II) and cobalt (II) possessed an octahedral one. The ligand functioned as an ON-neutral bidentate moiety. The thermal manner of all compounds was studied by thermogravimetric analysis (TGA). According to XRD and TEM analysis, all compounds were nanosized. Theoretical calculations were performed to gain more information about the structure of the ligand and Ag chelate by DFT/B3LYP/LanL2DZ. The ligand and some of its chelates were explored as antibacterial, antifungal, and antitumor agents. According to the findings, the (H2L) activity was enhanced by complexation. The antitumor activity of the Ag(I) chelate was dramatically higher than that of the ligand and other chelates, with an IC50 of 11.5 gmL-1. For antimicrobial, Cu(II) chelate outperformed other complexes and the control drug against A. brasiliensis, B. cereus and P. vulgaris.

Comparative study of antimicrobial potential and DNA/BSA binding affinity of silver(I) and gold(III) coordination compounds with 1,6-naphthyridine

In the present study, synthesis of silver(I) and gold(III) coordination compounds with 1,6-naphthyridine (1,6-naph), {[Ag(1,6-naph)(H2O)](BF4)}n (1) and [AuCl3(1,6-naph)] (2), was reported. The methods used for the structural characterization of a new compound 1 included IR, NMR (1H and 13C) and UV–Vis spectroscopy, cyclic voltammetry and single-crystal X-ray diffraction analysis. The crystallographic results showed that compound 1 represents silver(I) coordination polymer, in which 1,6-naph ligand acts as a bidentate bridging ligand connecting two Ag(I) ions via its N1 and N6 nitrogen atoms, while the third coordination site of the metal ion is occupied by the water oxygen atom, resulted in a T-shape geometry. Compounds 1 and 2 were evaluated in vitro for antimicrobial activity against five bacterial and two Candida species, while their cytotoxicity was tested on the normal human lung fibroblast cell line (MRC-5). Compound 1 has manifested a remarkable antifungal activity on both tested Candida strains (C. albicans and C. parapsilosis) with minimal inhibitory concentrations (MICs) of 1.43 and 11.38 µM (0.49 and 3.9 µg/mL), respectively, while no significant antimicrobial activity was observed for 2. Moreover, silver(I) coordination polymer 1 inhibits the hyphae formation of C. albicans at subinhibitory concentration. The binding affinity of both compounds 1 and 2 with calf thymus DNA (ct-DNA) and bovine serum albumin (BSA) was studied by fluorescence spectroscopy, indicating their ability to interact with these biomolecules, with compound 2 being more reactive.

A Silver Compound with Potential Applications as an Anticancer, Antibacterial, Antifungal, and Anti-Alzheimer's Agent.

This study investigated the biological activity of the silver coordination compound K-22. The IC50 values of K-22 on cancer cell lines range from 0.797 μg/mL to 3.426 μg/mL, indicating that K-22 might preferably inhibit A549, Saos-2, MCF-7, and HT-29 cell proliferation and thus have better therapeutic activity. Furthermore, K-22 stimulated apoptosis via up-regulation of the mRNA and protein expression level of Bax/Bcl-2 ratio in A549, Saos-2, MCF-7, and HT-29. K-22 exhibited antimicrobial activity against S. aureus, E. faecalis, K. pneumonia, P. aeruginosa, C. utilis, and C. albicans. Experimental results show that the compound has inhibitory potential with an IC50 value of 178.10 μM for the BChE (butyrylcholinesterase) enzyme, which has a vital role in the progression of Alzheimer's disease. As a result, compound K-22 exhibits a strong potential for medical use due to its anticancer, antibacterial, antifungal, and anti-Alzheimer properties.

1-(Azidomethyl)-5H-Tetrazole: A Powerful New Ligand for Highly Energetic Coordination Compounds.

Highly energetic 1‐(azidomethyl)‐5H‐tetrazole (AzMT, 3) has been synthesized and characterized. This completes the series of 1‐(azidoalkyl)‐5H‐tetrazoles represented by 1‐(azidoethyl)‐5H‐tetrazole (AET) and 1‐(azidopropyl)‐5H‐tetrazole (APT). AzMT was thoroughly analyzed by single‐crystal X‐ray diffraction experiments, elemental analysis, IR spectroscopy and multinuclear (1H, 13C, 14N, 15N) NMR measurements. Several energetic coordination compounds (ECCs) of 3d metals (Mn, Fe, Cu, Zn) and silver in combination with anions such as (per)chlorate, mono‐ and dihydroxy‐trinitrophenolate were prepared, giving insight into the coordination behavior of AzMT as a ligand. The synthesized ECCs were also analyzed by X‐ray diffraction experiments, elemental analysis, and IR spectroscopy. Differential thermal analysis for all compounds was conducted, and the sensitivity towards external stimuli (impact, friction, and ESD) was measured. Due to the high enthalpy of formation of AzMT (+654.5 kJ mol−1), some of the resulting coordination compounds are extremely sensitive, yet are able to undergo deflagration‐to‐detonation transition (DDT) and initiate pentaerythritol tetranitrate (PETN). Therefore, they are to be ranked as primary explosives.

DETERMINATION OF THE STABILITY OF COMPLEX COMPOUNDS OF COPPER (II), ZINC (II), CADMIUM (II) AND SILVER (I) WITH COVALENTLY IMMOBILIZED SULFUR CONTAIN LIGANDS

"The purpose of this study is to determine the stability of the obtained coordination compounds of some d-metals with covalent immobilized sulfur-containing ligands. To achieve this goal, coordination compounds of copper (II), zinc (II), cadmium (II) and silver (I) ions with covalent immobilized sulfur-containing ligands - О,О-di- (2-aminoethyl) -dithiophosphate potassium - polyester matrix (KD2AEDTP-PEM), O,O-di- (2-aminoethyl) -dithiophosphate potassium - carbamide-formaldehyde matrix (KD2AEDTP-KFM). Studies were carried out to determine the acid-base properties of covalent-immobilized sulfur-containing ligands - KD2AEDTP-PEM, KD2AEDTP-KFM and the concentration stability of the obtained coordination compounds with ions of copper (II), zinc (II), cadmium (II), and silver (I). Based on the results of integral and differential potentiometric titrations, it was established that the ionization constants (pK) of the dithiophosphoric group in KD2AEDTP-PEM and KD2AEDTP-KFM are 3.23 and 3.35, and the ionization constants of the amino group are 9.76 and 9.63, respectively. As a result of studies of polymer ligands by potentiometric titration via the method of individual weighed portions, it was shown that polyfunctional polymer ligands have the ability to form stable coordination compounds with metal ions of copper (II), zinc (II), cadmium (II) and silver (I). "

The effect of reagents solvation on change in the stability of coordination compounds of silver(I) ion with pyridine in mixed methanol–acetonitrile solvents

In this study, potentiometric titration was used to determine the stability constants of mono- and bis(pyridine) complexes with silver(I) in mixed methanol–acetonitrile solvents. Gibbs free energies of transfer of pyridine from methanol to methanol–acetonitrile mixtures were determined by the method of distribution between two immiscible phases. The effect of solvent composition on change in the solvation state of pyridine was analyzed. The replacement of methanol by acetonitrile leads to the desolvation of pyridine. The resolvation of pyridine occurs predominantly due to the resolvation of the nitrogen atom at the concentration of acetonitrile >0.5 mol fr. The enthalpic contribution was shown to have a major contribution in ΔtrG0(Py)MeOH→(MeOH-AN). The effect of reagents solvation on the stability of [AgPy]+ and [AgPy2]+ complexes upon the change of the solvent composition was investigated. The resolvation of silver(I) was established to be a key factor controlling the stability of both complexes in MeOH-AN mixtures. The possibility of predictive calculation of the stability constants [AgPy]+ in individual and mixed non-aqueous solvents through the change in the Gibbs free energy of the solvation of the complexing ion was shown. Proper data are compared with data reported in the literature.

A Novel Tetranuclear Silver Compound with bis(3,5-dimethylpyrazol-1-yl)acetate: a Simple Synthesis Yielding Complex Crystal Structure

A novel tetranuclear silver coordination compound with the formula [Ag4(bdmpza)4]×10H2O (bdmpza = bis(3,5-dimethylpyrazol-1-yl)acetate) was synthesized by a reaction between an aqueous solution of silver nitrate and an aqueous solution prepared by bis(3,5-dimethylpyrazol-1-yl)acetic acid and potassium hydroxide (1:1 molar ratio). The obtained compound was characterized by elemental analysis, coupled thermogravimetric-mass spectrometry analysis, vibrational IR spectroscopy, and its crystal structure was determined by single-crystal X-ray diffraction method. Furthermore, the obtained crystal structure was additionally evaluated by Hirshfeld surface analysis.

Stability of Metronidazole and Its Complexes with Silver(I) Salts under Various Stress Conditions.

Metronidazole is a drug widely used in the prevention and treatment of bacterial infections. Due to its possibility of the formation of stable metal complexes, it was decided to broaden its activity spectrum by introducing the silver(I) coordination compounds i.e., [Ag(MTZ)2NO3] and [(Ag(MTZ)2)2]SO4, which have significant antibacterial properties. The paper presents a description of a new qualitative and quantitative analysis of metronidazole in bulk and possible pharmaceutical preparations by thin-layer chromatography with densitometric detection. Optimal separation conditions were selected, and the analytical procedure was validated according to the ICH guidelines. The obtained data indicate that the method is sufficiently sensitive, precise, and accurate. The stability of the metronidazole solutions obtained from tablets, pure metronidazole, and its silver(I) complexes was tested. The research was carried out in various environments, at different temperatures, in H2O2 solution, and during exposure to radiation (UV, sunlight). The greatest degradation was found in the alkaline environment and at higher temperatures. The silver(I) complexes exhibited relatively high stability under analyzed conditions that are higher than standard metronidazole solutions and tablets. The observations were confirmed by the kinetic and thermodynamic analysis. The described studies of new metronidazole silver(I) complexes increase the potential for their application in infections both in humans and animals.

Synthesis, crystal structures, properties, and photothermal conversion performance of two xanthene-functionalized silver(I) coordination compounds

For further understanding of the molecular absorption mechanisms of photothermal conversion by coordination compounds, two newly prepared xanthene-functionalized silver(I) complexes, [Ag2(X9A)2(dppm)2] (1) (where dppm = bis(diphenylphosphino)methane and X9A = 9H-xanthene-9-carboxylato(-1)) and [Ag4(X9A)4(dppm)2]·6CH3OH (2), have been isolated and structurally characterized. We report here the syntheses, crystal structures, characterizations by various spectroscopic (IR, UV–Vis, powder XRD) techniques, as well as photothermal conversion performance of 1 and 2. Their X-ray crystal structures reveal that 1 is a binuclear silver(I) coordination compound bridged by two dppm molecules with two monodentate 9H-xanthene-9-carboxylato(-1) ligands, and 2 can be described as the dimer of 1 bridged by two 9H-xanthene-9-carboxylato(-1) anions in the μ3-η1,η2 coordination mode. Their photothermal conversion experimental results give new insight into understanding the molecular mechanisms for improving the performance of photothermal conversion molecular materials.

Dithiol-Dithione Tautomerism of 2,3-Pyrazinedithiol in the Synthesis of Copper and Silver Coordination Compounds.

A promising strategy for new electrically conductive coordination polymers is the combination of d10 metal ions, which tolerate short metal···metal distances, with dithiolene linkers, known for their "non-innocent" redox behavior. This study explores the coordination chemistry of 2,3-pyrazinedithiol (H2pdt) toward Cu+ and Ag+ ions, highlighting similarities and differences. The synthetic approach, starting with the fully protonated ligand, allowed the isolation of a homoleptic bis(dithiolene) complex with formal CuI atoms, [Cu(H2pdt)2]Cl (1). This complex was further transformed to a 1D coordination polymer with short metal···metal distances, 1D[Cu(Hpdt)] (2Cu). The larger Ag+ ion directly built up a very similar coordination polymer, 1D[Ag(Hpdt)] (2Ag), without any appearance of an intermediate metal complex. The coordination polymer 1D[Cu(H2pdt)I] (4), like complex 1, bears fully protonated H2pdt ligands in their dithione form. Upon heating, both compounds underwent auto-oxidation coupled with a dehydrogenation of the ligand to form the open-shell neutral copper(II) complex [Cu(Hpdt)2] (3) and the coordination polymer 1D[Cu2I2(H2pdt)(Hpdt)] (5), respectively. For all presented compounds, crystal structures are discussed in-depth. Furthermore, properties of 1, 3, and those of the three 1D coordination polymers, 2Ag, 2Cu, and 4, were investigated by UV-vis-NIR spectroscopy, cyclic voltammetry, and variable-temperature magnetic susceptibility, and direct current (dc)-conductivity measurements. The experimental results are compared and discussed with the aid of DFT simulations.

New Silver(I) Coordination Compound Loaded into Polymeric Nanoparticles as a Strategy to Improve In Vitro Anti-Helicobacter pylori Activity.

Helicobacter pylori inhabits the gastric epithelium and can promote the development of gastric disorders, such as peptic ulcers, acute and chronic gastritis, mucosal lymphoid tissue (MALT), and gastric adenocarcinomas. To use nanotechnology as a tool to increase the antibacterial activity of silver I [Ag(I)] compounds, this study suggests a new strategy for H. pylori infections, which have hitherto been difficult to control. [Ag (PhTSC·HCl)2] (NO3)·H2O (compound 1) was synthesized, characterized, and loaded into polymeric nanoparticles (PN1). PN1 had been developed by nanoprecipitation with poly(ε-caprolactone) polymer and poloxamer 407 surfactant. System characterization assays showed that the PNs had adequate particle sizes and ζ-potentials. Transmission electron microscopy confirmed the formation of polymeric nanoparticles (PNs). Compound 1 had a minimum inhibitory concentration for H. pylori of 3.90 μg/mL, which was potentiated to 0.781 μg/mL after loading. The minimum bactericidal concentration of 7.81 μg/mL was potentiated 5-fold to 1.56 μg/mL in PN. Compound 1 loaded in PN1 displayed better activity for H. pylori biofilm formation and mature biofilm. PN1 reduced the toxicity of compound 1 to MRC-5 cells. Loading compound 1 into PN1 inhibited the mutagenicity of the free compound. In vivo, the system allowed survival of Galleria mellonella larvae at a concentration of 200 μg/mL. This is the first demonstration of the antibacterial activity of a silver complex enclosed in polymeric nanoparticles against H. pylori.

Serendipitous and Targeted Synthesis of High Nuclearity Clusters—Carbonate and Oxalate Encapsulating Silver Alkynides

Silver coordination compounds of the [Ag3L2] (where L = tBu-C≡C) family having perchlorate counterions exhibit template-driven self-assembly of the common square pyramidal building block. This behavior is similar to previously described observations; however, important differences arise from counterion–silver interactions. Penta- and hexameric clusters encapsulating chloride and oxalate, respectively, were crystallographically characterized. A high nuclearity cluster [(CO3)3(H2O)⊂Ag38L20]12+ was formed upon extended exposure to an ambient atmosphere by trapping three carbonates and one water molecule.

Synthesis, structural diversity, luminescent properties and antibacterial effects of cadmium(II) and silver(I) coordination compounds with bis(1,2,3-benzotriazol-1-yl)alkanes

A series of bis(benzo-1,2,3-triazolyl)alkanes were prepared by the reaction of 1,2,3-benzotriazole with the corresponding dibromoalkanes. Individual isomers of these flexible polydentate ligands were separated by selective copper(II) chloride complex formation. Seven new coordination compounds of 1,3-bis(benzo-1,2,3-triazol-1-yl)propane (L3), 1,4-bis(benzo-1,2,3-triazol-1-yl)butane (L4) and 1,6-bis(benzo-1,2,3-triazol-1-yl)hexane (L6) with cadmium(II) or silver(I) nitrates were prepared, characterized by single crystal X-ray diffraction, IR spectroscopy, thermogravimetric analysis and luminescence studies. It was found that depending on the solvent used, cadmium(II) nitrate forms discrete binuclear complex with the ligand L3 in acetone and 1D coordination polymer in acetonitrile. Ligands L4 and L6 with longer linkers formed 2D coordination polymers with silver nitrate both in acetone and acetonitrile. Silver coordination polymer with L6 demonstrated bactericidal effect towards Staphylococcus albus, Pseudomonas aeruginosa and Klebsiella pneumonia bacteria.

An unusual diverse coordination of silver(I) with N-allylthiohydantoin ligand in the presence of benzene- and p-toluenesulfonate anions

Crystalline silver(I) coordination compounds [Ag2(HL)4(C6H5SO3)2]·0.5C3H7OH (1) and [Ag2(HL)(L)(CH3C6H4SO3)] (2) (HL = 3-(prop-2-en-1-yl)-2-thioxoimidazolidin-4-one) have been obtained using silver(I) salts and the organic ligand HL. Three independent Ag(I) atoms in crystal 1 adopt exclusively different coordination environment: tetragonal pyramidal, seesaw and distorted tetrahedral. In crystal 2 metal ions coordination polyhedra are characterized by seesaw and distorted tetrahedral arrangements. Thiohydantoin molecules in both structures are attached to Ag(I) only through thiohydantoin S-atom, while its anionic form in 2 plays a role of N,S-linker. C6H5SO3− anions in 1 are bound to the Ag(I) ions in a bridging mode, connecting silver ions into serpentine-like {Ag4(C6H5SO3)4}n chains, within which silver ions are additionally bind with µ2-S atoms of HL. Simultaneous coordination of HL and L− moieties in polymeric chains of 2 allow the formation of Ag….Ag metallophilic interactions with the distance range of 2.99–3.13 Å.

Synthesis and characterization of mixed-ligand silver(I) saccharinate complex containing (2-(2-pyridyl)benzimidazole

Se sintetizó un nuevo compuesto de coordinación de plata, [Ag(sac)(pbi)], por reacción de sacarinato de plata(I) con 2-(2-piridil)bencimidazol (pbi) con un rendimiento de 64%. La caracterización se realizó por análisis elemental, espectroscopia IR, UV-Visible, XPS, 1H-RMN y 13C-RMN. De acuerdo con los resultados obtenidos la plata está coordinada a través de tres átomos de nitrógeno, uno del sacarinato y los dos restantes del 2-(2-piridil)-bencimidazol formando con este ligando un anillo quelato de cinco miembros.

DNA metal complexes and metallization of a macromolecule in solution

The work considers DNA complexes with silver ions and a silver coordination compound containing phenanthroline ligands. The formation conditions of luminescent silver nanoclusters and nanoparticles having a plasmon resonance are analyzed. It is shown that nanoclusters form on reducing silver ions after the formation of their coordination bonds with nitrogenous bases of the macromolecule. The [Ag(Phen)2]NO3 compound cannot form such a bond and interacts with DNA by intercalating one of the phenanthroline ligands into a double helix. The preliminary binding of cis-DDP with DNA hinders the formation of silver nanoclusters.

Synthesis and Characterization of Coordination Compounds of Silver(I) Nitrite with Ligands Ethylenethiourea and N,N'-diethylthiourea

Silver(I) nitrate and ethylenethiourea ( etu) in 1 : 4 stochiometry have been reported [1]. Coordination compounds of A and B as silver(I) nitrite with etu and silver(I) nitrite with N,N’ -diethylthiourea ( detu) respectively, have never been done. The purposes of this study are to synthesize and characterize coordination compounds of A and B. Synthesis coordination compound of A with 1 : 4, while B with 1 : 2 stoichiometry. Both of coordination compounds are conducted directly in acetonitrile. Compounds obtained are characterized by melting point, electrical conductivity measurement, SEM-EDX , qualitative nitrite test, free energy calculation and structures prediction using Spartan’14 v1.1.0 . Coordination compounds of A and B are colourless needle and prism crystals; have melting point of 189°C and 103-105°C; free energy of -289,2567 and -1182.8101 kJ/mol respectively. Electrical conductivity measurement and qualitative nitrite test show that the obtained compound of A is an ionic and B is a molecular one. EDX analysis gives empirical formula prediction of two coordination compound A is C 12 H 24 AgN 9 O 2 S 4 and B is C 15 H 36 AgN 7 O 2 S 3 .

Synthesis of New Polyether Ether Ketone Derivatives with Silver Binding Site and Coordination Compounds of Their Monomers with Different Silver Salts.

Polyether ether ketone (PEEK) is a well-known polymer used for implants and devices, especially spinal ones. To overcome the biomaterial related infection risks, 4-4′-difluorobenzophenone, the famous PEEK monomer, was modified in order to introduce binding sites for silver ions, which are well known for their antimicrobial activity. The complexation of these new monomers with different silver salts was studied. Crystal structures of different intermediates were obtained with a linear coordination between two pyridine groups and the silver ions in all cases. The mechanical and thermal properties of different new polymers were characterized. The synthesized PEEKN5 polymers showed similar properties than the PEEK ones whereas the PEEKN7 polymers showed similar thermal properties but the mechanical properties are not as good as the ones of PEEK. To improve these properties, these polymers were complexed with silver nitrate in order to “cross-link” with silver ions. The presence of ionic silver in the polymer was then confirmed by thermogravimetric analysis (TGA) and X-ray powder diffraction (XRPD). Finally, a silver-based antimicrobial compound was successfully coated on the surface of PEEKN5.