Ag Complexes Research Articles

Synthesis, X-ray Structure, Antimicrobial and Anticancer Activity of a Novel [Ag(ethyl-3-quinolate)2(citrate)] Complex

A novel Ag(I) citrate complex with ethyl-3-quinolate (Et3qu) was synthesized. Its structure was confirmed using X-ray single crystal to be [Ag(Et3qu)2(citrate)]. It crystallized in the Triclinic crystal system and P-1 space group with unit cell parameters of a = 8.6475(2) Å, b = 11.4426(3) Å, c = 15.2256(3) Å, α = 73.636(2)°, β = 79.692(2)° and γ = 86.832(2)°, while the unit cell volume was 1422.19(6) Å3. In the unit cell, there are two [Ag(Et3qu)2(citrate)] molecules and one unit as the asymmetric formula. The molecular structure comprised one Ag(I) coordinated with two Et3qu molecules via two almost equidistant Ag-N bonds and one citrate ion acting as a mono-negative monodentate ligand via a short Ag-O bond (2.5401(14) Å). Hence, Ag(I) is tri-coordinated and has a highly distorted triangular planar coordination geometry which is more like to be described as a slightly distorted T-shape. The supramolecular structure of the [Ag(Et3qu)2(citrate)] complex was analyzed using Hirshfeld calculations. The H···H (39.3–40.1%), O···H (33.2-34.0%), C···C (9.1–9.5%) and C···H (7.2–7.4%) contacts shared significantly in the packing of the studied Ag(I) complex. The antimicrobial and anticancer activities of the Ag(I) complex were investigated. The [Ag(Et3qu)2(citrate)] complex has broad-spectrum antimicrobial activity specifically against the fungus A. fumigatus. In addition, the IC50 values of 1.87 ± 0.09 µg/mL and 0.95 ± 0.06 µg/mL against the breast MCF-7 and lung A-549 cell lines, respectively, revealed the potent anticancer activity of the [Ag(Et3qu)2(citrate)] complex compared to the free Et3qu (IC50 = 30.64 ± 1.98 and 22.89 ± 1.48 µg/mL, respectively).

Inhibitory Effect and Mechanism of Chitosan-Ag Complex Hydrogel on Fungal Disease in Grape.

Hydrogel antibacterial agent is an ideal antibacterial material because of its ability to diffuse antibacterial molecules into the decayed area by providing a suitable microenvironment and acting as a protective barrier on the decay interface. The biocompatibility and biodegradation make the removal process easy and it is already widely used in medical fields. However, there have been few reports on its application for controlling postharvest diseases in fruit. In this study, the Chitosan–silver (CS–Ag) complex hydrogels were prepared using the physical crosslinking method, which is used for controlling postharvest diseases in grape. The prepared hydrogels were stable for a long period at room temperature. The structure and surface morphology of CS–Ag composite hydrogels were characterized by UV-Vis, FTIR, SEM, and XRD. The inhibitory effects of CS–Ag hydrogel on disease in grape caused by P. expansum, A. niger, and B. cinerea were investigated both in vivo and in vitro. The remarkable antibacterial activity of CS–Ag hydrogels was mainly due to the combined antibacterial and antioxidant effects of CS and Ag. Preservation tests showed that the CS–Ag hydrogel had positive fresh-keeping effect. This revealed that CS–Ag hydrogels can play a critical role in controlling fungal disease in grapes.

From Isostructurality to Structural Diversity of Ag(I) Coordination Complexes Formed with Imidazole Based Bipodal Ligands, and Disclosure of a Unique Topology.

Two Ag(I) complexes with 1,3-bis(imidazol-1-ylmethyl)benzene (bib) and counterions BF4− (1) and PF6− (2) were synthesized in order to check their behavior in forming molecular/crystal structures. This allows comparison with the final products of analogous syntheses performed with similar bidentate ligands containing methyl substituents on the benzene ring, namely 1,3-bis(imidazol-1-ylmethyl)-5-methylbenzene (bimb) and 1,3-bis(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (bitmb). The Ag(I) complexes obtained with the methylated ligands mentioned above form isostructural pairs of waved 1D chains or dinuclear boxes, of general formula {[Ag(bimb)]X}n and [Ag2(btmb)2]X2, respectively (X = BF4−, PF6−), under the same reaction conditions. SCXRD analyses of 1 and 2 revealed the formation of polymeric coordination compounds of formula {[Ag2(bib)3](BF4)2}n and {[Ag(bib)]PF6}n, respectively, different from those observed for bimb. The 3D coordination polymer 1 forms a unique 5,5-c net of 5,5T188 topological type, observed for the very first time for a coordination compound, with silver cations adopting a trigonal geometry, whereas 2 shows the presence of 1D single-stranded cationic helices with linear coordination of the metal centers. Interestingly, these complexes differ not only from the mentioned isostructural pairs of related Ag(I) complexes, but also from the isostructural pair of compounds obtained as the final product when reacting bib and bimb with the larger counterion CF3SO3−. Hirshfeld surface analyses indicate a higher contribution of F⋯H intermolecular contacts in 2 than in 1, with H⋯H contacts being dominant in the latter.

Synthesis and structural characterisation of four 1:1:2 ionic/mononuclear complexes of Ag(I) and Cu(I) salts with tertiary organophosphine and 1,2-diamines

Crystallization of copper(I) halide : triphenylphosphine mixtures from 1,2-diaminoethane (en = ethylenediamine) has yielded adducts 1:1:2 CuX:PPh3:en stoichiometry (X = Cl or I); the chloride and iodide have been characterized by room temperature single crystal X-ray structure determinations; the iodide is a hemisolvate. In both cases, the complex is ionic, the four coordinate CuPN3 environment comprising both bidentate and unidentate en, i.e [(κ2-N,N’-en)(κ1-N-en)(PPh3)Cu]+X−. In each case, there are two crystallographically independent cations which are conformationally different. Adduct [(PPh3)(κ 2-N,N’-en)(κ 1-N-en)Cu]Cl is very unstable and decomposes on air, whereas [(κ 2-N,N’-en)(κ 1-N-en)(PPh3)Cu]I is sufficiently stable both in the solid state and in solution to be characterized. Adducts of similar stoichiometry are obtained with silver(I) nitrate, and with silver(I) perchlorate with PCy3, and 1,2-diaminopropane (pn): the single crystal X-ray structure determinations confirm the ionic/mononuclear formulations [(κ2-N,N’-en)(κ1-N-en)(PPh3)Ag]NO3 and [(κ2-N,N’-en)(κ1-N-en)(PCy3)Ag]ClO4 that persist also in acetonitrile, as confirmed by conductance values typical of 1:1 electrolytes in this solvent.

Cover Feature: Role of Anionic Backbone in NHC‐Stabilized Coinage Metal Complexes: New Precursors for Atomic Layer Deposition (Chem. Eur. J. 16/2022)

A series of new N-heterocyclic carbene (NHC) based Cu(I) and Ag(I) complexes were synthesized, analyzed, and evaluated for their potential usage in atomic layer deposition (ALD) of coinage metal thin films. Employing the same set of diketonate-type ligands for both metals did result in thermally stable Cu(I) complexes suitable for ALD, while the Ag(I) complexes exhibit an inherently unstable nature and different bonding features. More information can be found in the Research Article by Anjana Devi et al. (DOI: 10.1002/chem.202103798).

Thiacalixarenes with Sulfur Functionalities at Lower Rim: Heavy Metal Ion Binding in Solution and 2D-Confined Space.

Sulfur-containing groups preorganized on macrocyclic scaffolds are well suited for liquid-phase complexation of soft metal ions; however, their binding potential was not extensively studied at the air–water interface, and the effect of thioether topology on metal ion binding mechanisms under various conditions was not considered. Herein, we report the interface receptor characteristics of topologically varied thiacalixarene thioethers (linear bis-(methylthio)ethoxy derivative L2, O2S2-thiacrown-ether L3, and O2S2-bridged thiacalixtube L4). The study was conducted in bulk liquid phase and Langmuir monolayers. For all compounds, the highest liquid-phase extraction selectivity was revealed for Ag+ and Hg2+ ions vs. other soft metal ions. In thioether L2 and thiacalixtube L4, metal ion binding was evidenced by a blue shift of the band at 303 nm (for Ag+ species) and the appearance of ligand-to-metal charge transfer bands at 330–340 nm (for Hg2+ species). Theoretical calculations for thioether L2 and its Ag and Hg complexes are consistent with experimental data of UV/Vis, nuclear magnetic resonance (NMR) spectroscopy, and single-crystal X-ray diffractometry of Ag–thioether L2 complexes and Hg–thiacalixtube L4 complex for the case of coordination around the metal center involving two alkyl sulfide groups (Hg2+) or sulfur atoms on the lower rim and bridging unit (Ag+). In thiacrown L3, Ag and Hg binding by alkyl sulfide groups was suggested from changes in NMR spectra upon the addition of corresponding salts. In spite of the low ability of the thioethers to form stable Langmuir monolayers on deionized water, one might argue that the monolayers significantly expand in the presence of Hg salts in the water subphase. Hg2+ ion uptake by the Langmuir–Blodgett (LB) films of ligand L3 was proved by X-ray photoelectron spectroscopy (XPS). Together, these results demonstrate the potential of sulfide groups on the calixarene platform as receptor unit towards Hg2+ ions, which could be useful in the development of Hg2+-selective water purification systems or thin-film sensor devices.

Fabrication and characterization of pore-selective silver-functionalized honeycomb-patterned porous film and its application for antibacterial activity

Pore-selective silver (Ag)-functionalized honeycomb-patterned (HCP) polystyrene (PS) films were fabricated via a modified breath figure method using an interfacial chemical reaction and its application for an antibacterial film using the role of micro-trapping pit was systematically studied. PS polymer solution containing ferrocene which acts as a reducing agent was cast under humid conditions containing silver nitrate (AgNO3) to induce an interfacial chemical reaction between ferrocene and AgNO3 at the water droplet/polymer solution interface. The confinement of Ag+ to the humidity is possible due to the formation of the water complex of Ag+ such as Ag+(H2O)n stabilized by the Lennard–Jones potential and electrostatic interactions. Ag+ may be carried to the polymer solution surface via the water humidity despite being a heavy metal. Scanning electron microscopy and elemental mapping analysis revealed that the pores of the obtained films were selectively coated by Ag. The contact angle of the HCP porous films was greatly decreased by the pore selective Ag functionalization, which acts as a micro-trapping pit for the antibacterial activity. The antibacterial activity of the film against Escherichia coli and Staphylococcus aureus was assessed by the micro-dilution method, selective fluorescence imaging, and crystal violet assay. The study of BF for a functional HCP film by accompanying an interfacial chemical reaction for the pore-selective Ag functionalization shows that specific metal or inorganic materials could be pore-selectively functionalized by a similar method under several conditions, thus potentially giving the HCP films various applications.

Two silver(I) complexes: Synthesis, structures, and electrochemicalH2O2sensing

AbstractTwo new silver(I) complexes, formulated as [Ag2(L1)2](picrate)2(1), {[Ag2(L2)2(terephthalate)](C2H5OH)3(H2O)}n(2) (L1 = 1,3‐bis(2‐benzimidazyl)benzene, L2 = 1,3‐bis(1‐methylbenzimidazol‐2‐yl)‐2‐thiapropane), were synthesized and characterized by X‐ray crystallography, elemental analysis, infrared, and UV–Vis spectroscopy. The crystal analysis results showed that the complexes exhibited different structures: binuclear for1and one‐dimensional polymeric for2. Their Ag(I) centers displayed different coordination geometric structures: two‐coordinated linear in1, whereas four‐coordinated distorted tetrahedron in2. The electrochemical sensing performance of Ag(I) complexes modified carbon paste electrode (CPE‐1 and CPE‐2) toward hydrogen peroxide (H2O2) was evaluated by chronoamperometry in 0.2 M phosphate buffer saline (pH = 6) at −0.2 V. The CPE‐1 was found to have a wide linear response from 1.0 × 10−5to 4.0 × 10−3 M, lower detection limit of 1.73 μM, excellent anti‐interference ability, and stability. The CPE‐2 does not have recognition properties for H2O2, which may be due to the large steric hindrance around Ag(I) centers that is not easy to combine with H2O2to form a catalytic transition state. The above studies proved that Ag(I) complexes can be used as effective components of electrode materials for the electrochemical recognition of H2O2.

Role of Anionic Backbone in NHC-Stabilized Coinage Metal Complexes: New Precursors for Atomic Layer Deposition.

Cu and Ag precursors that are volatile, reactive, and thermally stable are currently of high interest for their application in atomic‐layer deposition (ALD) of thin metal films. In pursuit of new precursors for coinage metals, namely Cu and Ag, a series of new N‐heterocyclic carbene (NHC)‐based CuI and AgI complexes were synthesized. Modifications in the substitution pattern of diketonate‐based anionic backbones led to five monomeric Cu complexes and four closely related Ag complexes with the general formula [M( tBuNHC)(R)] (M=Cu, Ag; tBuNHC=1,3‐di‐tert‐butyl‐imidazolin‐2‐ylidene; R=diketonate). Thermal analysis indicated that most of the Cu complexes are thermally stable and volatile compared to the more fragile Ag analogs. One of the promising Cu precursors was evaluated for the ALD of nanoparticulate Cu metal deposits by using hydroquinone as the reducing agent at appreciably low deposition temperatures (145–160 °C). This study highlights the considerable impact of the employed ligand sphere on the structural and thermal properties of metal complexes that are relevant for vapor‐phase processing of thin films.

Theoretical Studies on the Photophysical Properties of the Ag(I) Complex for Thermally Activated Delayed Fluorescence Based on TD-DFT and Path Integral Dynamic Approaches.

Theoretical calculation not only is a powerful tool to deeply explore photophysical processes of the emitters but also provides a theoretical basis for material renewal and design strategy in the future. In this work, the interconversion and decay rates of the thermally activated delayed fluorescence (TADF) process of the rigid Ag(dbp)(P2-nCB) complex are quantitatively calculated by employing the optimally tuned range-separated hybrid functional (ω*B97X-D3) method combined with the path integral approach to dynamics considering the Herzberg–Teller and the Duschinsky rotation effects within a multimode harmonic oscillator model. The calculated results show that the small energy splitting ΔE(S1–T1) = 742 cm–1 (experimental value of 650 cm–1) of the lowest singlet S1 and triplet T1 state and proper vibrational spin–orbit coupling interactions facilitate the reverse intersystem crossing (RISC) processes from the T1 to S1 states. The kRISC rate is estimated to be 1.72 × 108 s–1 that is far more than the intersystem crossing rate kISC of 7.28 × 107 s–1, which will greatly accelerate the RISC process. In addition, the multiple coupling routes of zero-field splitting (ZFS) interaction can provide energetically nearby lying states, to speed up the RISC pathway, and restrict the phosphorescence decay rate. A smaller ZFS D-tensor of 0.143 cm–1, E/D ≈ 0.094 ≪ 1/3, and Δg > 0 are obtained, indicating that the excited singlet states are hardly mixed into the T1 state; thus, a lower phosphorescence decay rate (kp = 9.29 × 101 s–1) is expected to occur, and the T1 state has a long lifetime, which is helpful for the occurrence of the RISC process. These works are in excellent agreement with the experimental observation and are useful for improving and designing efficient TADF materials.

Synthesis, structure and electrochemical H2O2-sensing of two silver(I) complexes with bisbenzimidazole ligands

Two new binuclear Ag(I) complexes of the types, [Ag2(Mebba)2(fumarate)]·2C2H5OH (1) and [Ag2(Meobb)2(μ-Cl)2] (2) (Mebba = bis(N-methylbenzimidazol-2-ylmethyl) aniline, Meobb = 1,3-bis(N-ethyl-benzimidazol-2-yl)-2-oxopropan), have been synthesized and characterized. Structural analysis showed that silver(I) centre in two complexes were both four-coordinated distorted tetrahedron geometry, but their bridging modes are significantly different: bridged by the fumarate in complex 1, μ2-Cl monoatomic bridging in complex 2. The electrochemical sensing performances of carbon paste electrode modified with silver(I) complex 1 (CPE-1) and complex 2 (CPE-2) towards H2O2 were investigated by chronoamperometry in 0.2 M phosphate buffer solution (PBS, pH = 6) at −0.2 V. The CPE-1 exhibits a wide linear detection range from 0.5 μM to 4.0 mM and lower detection limit 0.61 μM with a relatively high sensitivity of 9.9935 µA/mM, and has excellent anti-interference ability and stability. There is not electrochemical H2O2-sensing performance for the CPE-2, which may be due to the fact that silver(I) ions and chloride ions form a more stable complex that is not easy to combine with hydrogen peroxide to form a catalytic transition state. The research results show that silver(I) complexes based on bisbenzimidazole ligands have the potential to become electrode materials.

BSA binding affinity, free radical scavenging capacity and antibacterial activity of new Silver(I) complexes with Schiff base ligands

In this work, four silver(I) complexes with Schiff bases derived from ninhydrin and selected amino acids (methionine, histidine, cysteine, and phenylalanine) were synthesized. The aim of this study is to determine the potential biological activity of these complexes. FTIR and UV/VIS spectroscopy were used for structural characterization of the products. Antioxidant activity was examined in vitro using DPPH method. Antimicrobial screening was performed by diffusion technique on reference bacterial strains from the ATCC collection. Interaction with bovine serum albumin (BSA) was examined using UV/VIS spectroscopy. Based on the obtained spectral data, it is assumed that all Schiff bases coordinate the Ag(I) ion as a tridentate ONO donor ligand. The antioxidant activity of the synthesized compounds is extremely high, with a range of IC50 values of 0.023-0.06 mg/mL. Antimicrobial screening determined the inhibitory ability of almost all complexes for concentrations of 1 and 2 mg/mL, with zones of inhibition in the range of 9-19 mm. Examination of the interaction of BSA with Ag(I) complexes revealed the same change in the absorption maximum (hyperchromic shift) in the region of about 205 nm, which indicates that the interaction of BSA and the complex results in conformational changes of BSA.  Â

Two binuclear silver(I) complexes containing V‐shaped bis (benzimidazole) ligands: Syntheses, structures, and electrochemical sensing toward hydrogen peroxide

Two new silver(I) complexes, formulated as [Ag2L12(isophthalate)]·(C2H5OH)5(1), [Ag2L22(isophthalate)](2)(L1 = 1,3‐bis[(N‐methyl‐benzimidazole)methylene]‐2‐aniline, L2 = 1,3‐bis[(N‐ethyl‐benzimidazole)methylene]‐2‐aniline), were synthesized by volatilization method and characterized by X‐ray crystallography, elemental analysis, IR and UV/Vis spectroscopy. The crystal analysis showed that although complexes1and2were both binuclear, their Ag(I) centers exhibited different coordination geometric structures: four‐coordinated distorted tetrahedron in complex1, whereas three‐coordinated planar triangle in complex2. The electrochemical sensing performances of carbon paste electrode modified with Ag(I) complexes (CPE‐1 for complex1and CPE‐2 for complex2) toward H2O2were evaluated by cyclic voltammogram and chronoamperometry in 0.2 M phosphate‐buffered saline (PBS, pH = 6.0) at −0.2 V. The results show that both CPE‐1 and CPE‐2 showed excellent electrocatalytic activity, quick response time (≤5 s) and high selectivity toward H2O2. The linear response range was from 5.0 × 10−7to 4.0 × 10−3 M. The CPE‐1 exhibits better sensitivity and limit of detection (LOD) than CPE‐2, which is related to the coordination environment of Ag(I) ions. Sensors based on Ag(I) complexes have great application prospects in the field of electrochemical sensing.

Synthesis and characterisation of phenanthroline-oxazine ligands and their Ag(I), Mn(II) and Cu(II) complexes and their evaluation as antibacterial agents.

A series of phenanthroline-oxazine ligands were formed by a cyclisation reaction between L-tyrosine amino acid esters and 1,10-phenanthroline-5,6-dione (phendione). The methyl derivative of the phenanthroline-oxazine ligand 1 was complexed with Ag(I), Mn(II) and Cu(II) to form [Ag(1)2]ClO4, [Mn(1)3](ClO4)2 and [Cu(1)3](ClO4)2. The activity of these metal complexes was tested against the bacteria Escherichia coli and Staphylococcus aureus. Each of the metal complexes was more active than1 against S. aureus and the Mn(II) and Cu(II) complexes also showed greater activity than 1 towards E. coli. The effect of increasing the length of the alkyl moiety on the phenanthroline-oxazine ligands and their corresponding tris homoleptic Cu(II) complexes was investigated. In all cases both the ligands and their complexes were more active against Gram-positive S. aureus than against Gram-negative E. coli. Differences in the lipophilicity of the ligands and their corresponding Cu(II) complexes did alter the antibacterial activity, with the hexyl and octyl derivatives and their complexes showing the greatest activity and comparing well with clinically used antibiotics. The most active Cu(II) complexes and their respective ligands were also active against Methicillin-resistant S. aureus (MRSA). In vivo toxicity studies, conducted using the Galleria mellonella model, showed that all of the compounds were well tolerated by the insect larvae.

Qualitative and quantitative contributions of intermolecular interactions of dinuclear Ag complexes of sulfathiazole and sulfadiazine: X-ray crystallographic, Hirshfeld surface analysis, DFT studies and biological activities

Two dinuclear Ag complexes of N-heterocycle ‘sulfa’ derivatives: sulfathiazole (STZ) and sulfadiazine (SDZ) have been synthesized and characterized. Crystal structures of both the Ag-STZ and Ag-SDZ complexes have been determined by single crystal X-ray diffraction technique. In both the dinuclear Ag complex, two Ag atoms bridged together forming argentophilic interaction with Ag – Ag separation distance of 2.846 (4) Å in Ag-STZ and 2.828 (3) Å in Ag-SDZ respectively. In Ag-STZ complex, the coordination geometry surrounding silver atoms (Ag) is tridentate and tetradentate whereas, in Ag-SDZ complex, the geometry surrounding Ag is tetradentate and pentadentate respectively while coordinating to the respective bidentate ligand. Qualitative and quantitative contributions of each intermolecular interaction as established by X-ray data are investigated using Hirshfeld surface and energy framework analysis. Atomic charge explored by Mulliken charge distributions and natural bond orbital (NBO) analysis confirmed the nature and type of intermolecular interactions as established by X-ray data. In vitro cytotoxicity of the Ag complexes and those of the free ligands have been carried out against brine shrimp.

Synthesis, spectral characterization and biological activities of Ag(I), Pt(IV) and Au(III) complexes with novel azo dye ligand (N, N, O) derived from 2-amino-6-methoxy benzothiazole

The novel ligand 2-[2'-(6-methoxybenzothiazolyl)azo]-3,5-dimethyl benzoic acid (6-MBTAMB), derived from 2-amino-6-methoxy benzothiazole, has been used to synthesize a series of new metal complexes of Ag(I), Pt(IV) and Au(III). The metal complexes were characterized by elemental analyses (CHNS), molar conductivity, crystal structure (XRD), spectroscopic techniques: FT-IR, 1H NMR, 13C NMR, UV–Vis, mass spectra, thermal analysis (TG–DTA), FE-SEM and magnetic properties. Results confirmed that the azo dye ligand behaves a tridentate and coordinates to the metal ion via nitrogen atom of azomethine group of heterocyclic benzothiazole ring, nitrogen atom of the azo group which is the farthest of the benzothiazole molecule and carboxylic oxygen. Antimicrobial properties of all newly synthesized azo compounds are also demonstrated against bacterial pathogenic organisms and fungi. These complexes are more effective against bacteria and less effective against fungi compared to standard antibacterial drugs (novobiocin) and antifungal drugs (cycloheximide). By using the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging test, it was discovered that the complexes had good antioxidant properties. In addition, the (6-MBTAMB) and metal complexes were docked with the crystal structure of FGF Receptor 2 (FGFR2) kinase domain harboring the pathogenic gain of function K659E mutation identified in endometrial cancer using the molecular operating environment (MOE) module. In vitro studies on human endometrial cancer cell lines (MFE-296) as well as healthy human umbilical vein endothelial cells (HUVEC) show uptake of the intact compounds by the cancer cells and increased activity against the cancer cells.Graphical abstract

Synthesis, characterization, biological properties, and molecular docking studies of new phosphoramide-based Ag(i) complexes

The effect of two new synthesized Ag(i) complexes on their biological properties was examined.

Tuning excited state energy levels by achieving coordination-induced thermally activated delayed fluorescence

In this study, a low steric hindrance D–A type spiro-ligand which possesses long afterglow was used to construct Ag(i) complexes. The excited states energy level is regulated for resulting in tiny ΔEST and efficient TADF through metal coordination.

Catalytically active silver nanoparticles stabilized on a thiol-functionalized metal-organic framework for an efficient hydrogen evolution reaction.

A post-synthetic technique, Solvent Assisted Ligand Incorporation (SALI), was used for thiol functionalization in the zirconium-based metal-organic framework NU-1000. This thiol-functionalized MOF was employed as a support for the growth of silver nanoparticles (Ag NPs) through coordination of a Ag(I) complex with a node-anchored thiol-ligand, followed by the reduction of Ag(I) to Ag(0). X-ray photoelectron spectroscopy revealed that the ratio of Ag(0) to Ag(I) proportionally increased with the loading of silver ions. The HER activity increased with the enhancement of Ag(0) in the system and the best efficiency was observed for the composite with ∼95% Ag(0). This composite displayed an overpotential of 165 mV in an acidic medium at 10 mA cm-2 and a Tafel slope of 53 mA dec-1. The loading of silver beyond the optimum value led to the aggregation of the particles which affected the overpotential substantially. The catalyst demonstrated appreciable static stability for 24 h, which promotes the use of the material as an HER catalyst. Therefore, these results emphasized that Ag NPs embedded onto a thiol-functionalized MOF is a propitious material for developing a clean and renewable energy source.

Homochiral imidazolium-based dicarboxylate silver(i) compounds: synthesis, characterisation and antimicrobial properties

Ag(i) complexes derived from chiral imidazolium-based dicarboxylate ligands have shown good antimicrobial activity toward Gram-negative bacteria. A chirality-antimicrobial tendency has been revealed.