Silver Cations Research Articles

Transformation of Cs3Bi2Br9 to Cs2AgBiBr6 Lead‐Free Perovskite Microcrystals Through Cation Exchange

AbstractAll‐inorganic lead‐free Cs2AgBiBr6 double perovskites have gained significant attention due to their potential as stable and nontoxic photoactive semiconductors. Currently, it remains challenging to synthesize homogeneous microcrystals (MCs) exhibiting excellent properties, which are necessary for large‐area device integration. This work proposes a two‐step synthesis approach involving the introduction of a foreign silver cation to transform the 0D layered Cs3Bi2Br9 to 3D Cs2AgBiBr6 perovskite structure. This work has studied the cation exchange (CE) transformation mechanism by isolating intermediates to be able to follow the evolution of the crystal lattice as well as the structural and optical properties over time. Moreover, complete CE results in phase‐pure, highly crystalline Cs2AgBiBr6 MCs exhibiting excellent photonic properties, superior to their counterparts synthesized by anti‐solvent precipitation. These findings highlight the potential of CE‐induced transformation as a means of synthesizing novel, stable perovskites.

Coordination versus Insertion: On the Interaction of 5 d-Transition Metal Carbonyl Clusters with Silver(I).

The title silver(I) complex salts [Ag{Re2 (CO)10 }{Re(CO)5 }2 ]+ [Al(ORF )4 ]- (AgRe4 ; ORF =-OC(CF3 )3 ) and [Ag{Ir4 (CO)12 }2 ]+ [Al(ORF )4 ]- (AgIr8 ) form upon reaction of Ag+ [Al(ORF )4 ]- and the transition metal carbonyls (TMCs) Re2 (CO)10 and Ir4 (CO)12 respectively. The solid-state structure of the AgRe4 cluster shows an unexpected asymmetric coordination motif, wherein the silver(I) cation has inserted into the Re-Re bond of one Re2 (CO)10 moiety, while the other dirhenium carbonyl coordinates only over one metal atom towards the silver(I) cation. The AgIr8 cluster is formed by the edge-on coordination of two Ir4 tetrahedra and the silver cation in a D2 symmetric fashion with a torsion angle of 46.5°. QTAIM analysis shows bond paths between the silver atom and the nearby metal atoms in all cases, whereas only the non-inserted Re2 (CO)10 moiety shows additional bond paths between the carbonyl ligands and the silver cation. In addition, the insertion of the Ag+ cation into the Re-Re bond in Re2 (CO)10 removes the bond path between the two rhenium atoms. The EDA-NOCV analysis suggests an increase of the interaction energy between the silver(I) cation and the respective metal carbonyls from the metal centered transition metal carbonyl (TMC) donors W(CO)6 <Re2 (CO)10 <Os3 (CO)12 <Ir4 (CO)12 . In all cases, the dominating orbital interaction is σ-donation [TMC]→Ag+ ←[TMC].

Excited State Engineering in Ag29 Nanocluster through Peripheral Modification with Silver(I) Complexes for Bright Near-Infrared Photoluminescence

The optical property of an ionic metal nanocluster (NC) is affected by the ionic interaction with counter ions. Here, we report that the modification of trianionic [Ag29(BDT)12(TPP)4]3- NC (BDT: 1.3-benzenedithiol; TPP: triphenylphosphine) with silver(I) complexes led to the intense photoluminescence (PL) in the near-infrared (NIR) region. The binding of silver(I) complexes to the peripheral region of Ag29 NC is confirmed by the single-crystal X-ray diffraction (SCXRD) measurement, which is further supported by electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy. The change of excited-state dynamics by the binding of silver(I) complexes is discussed based on the results of a transient absorption study as well as temperature-dependent PL spectra and PL lifetime measurements. The modification of Ag29 NCs with cationic silver(I) complexes is considered to give rise to a triplet excited state responsible for the intense NIR PL. These findings also afford important insights into the origin of the PL mechanism as well as the possible light-driven motion in Ag29-based NCs.

Combined Effects of Polluted Particles and Environmental Factors on Electrochemical Migration Failure

With the miniaturization of printed circuit board (PCB), the distance between the circuit traces or assembled component terminals is becoming smaller and smaller. Under the certain temperature, relative humidity, and bias voltage (THB), it is easier for the insulation performance between circuits to degrade due to electrochemical migration (ECM). The airborne dust deposited on the PCB during a long-term service may change the failure mechanism and time to failure (TTF) of ECM between circuits. In this paper, the mechanism and the characteristics of the combined effects of quartz particles in airborne dust, the temperature, the relative humidity and the bias voltage on the ECM failure of immersion silver finished PCB were studied by THB experiments. Then, the influencing significance of four factors on TTF of ECM were studied by the orthogonal test and range analysis. The results show that the silver cations migrate firstly but the exposed copper substrate on the positive electrode become the main migrated substance finally. The TTF of ECM changes non-monotonously with the increase of particle coverage density due to the bidirectional function of the insoluble particles, which can increase water condensation on PCB by the capillary action, but can extend the migration path of metal cations by physical barriers. The turning point is about the coverage density of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$350~\mu \text{g}$ </tex-math></inline-formula> /cm 2. The insoluble particles with high coverage density can significantly shorten the TTF of ECM on the PCB than that with low coverage density under the same THB conditions.

Antioxidant Activity Enhancement Effect of Silver-Ionized Water: Silver Cation Prepared by Electrolysis

In the present study, tap water, alkaline electrolyzed water (AlEW) and tourmaline water (TMW) were used as the electrolytes to generated the silver-ionized water (SIW), AlEW-SIW and TMW-SIW, respectively. The antioxidant properties of the samples containing ascorbic acid (AsA) were investigated by WST-kit method. The results showed that the SOD activity of AsA (2 mmol/L) dissolved in SIW (66.0%) was enhanced by about 8% compared to that of the tap water (57.9%). The SOD activity of the AlEW-SIW solution (77.3%), which was higher than that of the SIW solution, and lower than that of the AlEW solution (83.6%). The SOD activity of the TMW-SIW solution (83.0%) was similar to that of the TMW solution (82.5%). Furthermore, to classify the sample solutions, discriminant analyses were performed based on near infrared (NIR) spectral data, which was consistent with the results of the WST-kit method. The SOD activity of the AlEW-SIW and TMW-SIW solutions decreased slowly with storage time, and their SOD activities were higher than that of AlEW, TMW and the tap water solutions at storage time of 14 days. In summary, AlEW-SIW and TMW-SIW showed similar antioxidant activity enhancement as AlEW and TMW, and they also maintained the stability of the antioxidant activity of AsA during storage.

Self-Assembly of a Two-Dimensional Coordination Polymer Based on Silver and Lanthanide Tetrakis-Acylpyrazolonates: An Efficient New Strategy for Suppressing Ligand-to-Metal Charge Transfer Quenching of Europium Luminescence.

A new strategy for the easy polymerization of anionic [Ln(Qcy)4]- (HQcy-4-(cyclohexanecarbonyl)-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one) into two-dimensional layers of [AgLn(Qcy)4]n (Ln = Sm, Eu, Gd, Tb and Dy) is proposed by binding the single molecular anions [Ln(Qcy)4]- to silver cations through the coordination of the pyridinic nitrogen atoms of the pyrazolonate rings. The luminescent properties of [AgLn(Qcy)4]n have been studied in detail, and it was shown that the previously described low photoluminescence quantum yield (PLQY) of [Eu(Qcy)4]- is due to Ligand-To-Metal Charge Transfer (LMCT) quenching, which is effectively suppressed in the heterometallic [AgEu(Qcy)4]n polymer. Sensibilization coefficients for H3O[Eu(Qcy)4], [AgEu(Qcy)4]n, and H3O[Sm(Qcy)4] complexes (n ≈ 1) were estimated via theoretical analysis (also by using Judd-Ofelt theory for Sm3+) and PLQY measurements.

Ag/Ag3PO4 Nanoparticle-Decorated Hydroxyapatite Functionalized Calcium Carbonate: Ultrasound-Assisted Sustainable Synthesis, Characterization, and Antimicrobial Activity

Silver nanoparticles are usually prepared by the reduction of silver cations through chemical and non-sustainable procedures that involve the use of reducing chemical agents. Therefore, many efforts have been made in the search for sustainable alternative methods. Among them, an ultrasound-assisted procedure could be a suitable and sustainable method to afford well-dispersed and nanometric silver particles. This paper describes a sustainable, ultrasound-assisted method using citrate as a reducing agent to prepare silver@hydroxyapatite functionalized calcium carbonate composites. For comparison, an ultrasound-assisted reduction was performed in the presence of NaBH4. The composites obtained in the presence of these two different reducing agents were compared in terms of nanoparticle nature, antimicrobial activity, and cytotoxic activity. The nanoparticle nature was investigated by several techniques, including X-ray powder diffraction, field-emission scanning electron microscopy, transmission electron microscopy, UV-Vis spectroscopic measurements, and X-ray photoemission spectroscopy. Nanoparticles with a predominance of Ag or Ag3PO4 were obtained according to the type of reducing agent used. All composites were tested for antimicrobial and antibiofilm activities against Gram-positive and Gram-negative (Staphylococcus aureus and Pseudomonas aeruginosa, respectively) bacteria and for cytotoxicity towards human skin keratinocytes and human fibroblasts. The nature of the nanoparticles, Ag or Ag3PO4, and their predominance seemed to affect the in vitro silver release and the antimicrobial and antibiofilm activities. The composites obtained by the citrate-assisted reduction gave rise to the best results.

On the Cation-π capabilities of infinitene (∞). Evaluation of bonding and circular dichroism properties for Infinitene-Ag(I)n (n = 1–4) complexes from relativistic DFT calculations

The helicoidal π-conjugated structure from helicenes is able to feature cation-π bonding towards Ag(I) atoms, resulting in the variation of their inherent high optical rotation values. Recently, the characterization of infinitene ([12]infinitene) as two fused [6]helicene structures with a central crossover section suggests the extension of such coordination characteristics to large and more complex structural landscapes. Herein, we evaluated the possible cation-π features of infinitene towards one to four silver cations from density functional calculations and their role in the optical rotation of the infinity-shaped backbone. The nature of the cation-π interaction for infinitene, shows a favorable formation of single and multiple Ag(I) aggregation, with a slight distortion of the structural backbone. Hence, the formation of cation- π complexes in infinitene is plausible, suggesting the expansion of its chemistry towards the formation of metal complexes in fused helicene species.

Stacking Interactions and Photovoltaic Performance of Cs2AgBiBr6 Perovskite

Elpasolite Cs2AgBiBr6 also known as double perovskite has been touted in recent years as a promising alternative to the lead‐based perovskite for light harvesting. Its structure and properties mainly stem from the replacement of Pb2+ cation with a pair of aliovalent silver (Ag+) and bismuth (Bi3+) cations. Although the elpasolite Cs2AgBiBr6 exhibits improved stability, its photophysical properties and device performance are inferior to those of the Pb‐based perovskites. To date, numerous efforts have been geared toward the development of efficient Cs2AgBiBr6 solar cells. However, the indirect, wide bandgap and high exciton binding energy of Cs2AgBiBr6 have limited such efforts. This has been attributed to its low (zero) electronic dimensionality (0D), formation of small polaronic states, and interfacial imperfections with charge transporting layers. In this review, the different aspects of the elpasolite Cs2AgBiBr6 in relation to compositional and interlayer interactions in solar cell are discussed, and its suitability for photovoltaic application is assessed, accompanied by potential measures to further advance its performance. An alternate application of Cs2AgBiBr6 in photocatalysis, which takes advantage of its less toxicity and better stability, is also discussed.

Synthesis of Cationic Silver Nanoparticles with Highly Potent Properties against Oral Pathogens and Their Biofilms

AbstractDental caries is a major disease associated with the proliferation of acidogenic bacterial species such as Streptococcus mutans that are part of the commensal microbiota of the mouth. Silver nanoparticles (AgNPs) are attractive antibacterial agents as they target multiple sites in bacteria which reduces antimicrobial resistance. In this study, we synthesised stable, highly positively charged AgNPs capped with branched PEI (BPEI‐AgNPs) and characterized them using UV–vis absorption, transmission electron microscopy (TEM), the size of which were approximately 7.5 nm. The antibacterial activity and anti‐biofilm capacity of BPEI‐AgNPs was investigated against cariogenic bacteria. Our results demonstrated that BPEI‐AgNPs are potent clinical oral antiseptics. The cytotoxicity of the BPEI‐AgNPs was also studied against two mammalian cell lines. The results indicated that BPEI‐AgNPs were non‐cytotoxic and were safer than commercially used dental antiseptics. We conclude that the BPEI‐AgNPs are safe for oral clinical application and are an effective oral antimicrobial agent.

Post-glass melting synthesis and photochromic properties of composite AgCl-AgPO3 glasses

We herein present a simple, fast, low-temperature, post-glass melting fabrication protocol in which a photochromic silver cation based modified zone is incorporated within silver metaphosphate glass (AgPO3). The selection of AgPO3 glass is mainly based on its relative “soft” nature (Tg = 192 °C) that enables the integration of silver cations from the surface deposited AgCl layer, while being transparent in most of the visible range, and therefore suitable for smart photochromic window applications. The suggested synthesis procedure permits the controlled formation of a silver cation modified layer within the host glass matrix, while the characteristics of the layer itself can be adjusted correspondingly. Our findings reveal a direct relationship between the developed composite AgCl–AgPO3 glass photochromic response and the morphological features of the integrated layer, i.e., thickness and position. More importantly, the photochromic response time with various UV irradiation doses is also studied, where remarkable response times of several seconds are obtained. Processes and efforts to further enhance the photochromic performance by utilizing the presence of silver nanoparticles within the glass matrix are also presented and discussed.

Silver cation tagged on 5,7,12,14-tetraphenyl-6,13-diazapentacene and its dihydro-form.

The attachment of silver(I) cations to 5,7,12,14-tetraphenyl-6,13-diazapentacene and its reduced dihydro-form has been studied by electrospray ionization mass spectrometry (ESI-MS). The structure elucidation of the Ag+ complexes has been accomplished in gas-phase collision experiments in conjunction with density functional theory (DFT) calculations. The oxidized form provides a favourable cavity for the Ag+ ion, leading to the [1 : 1] complex with the highest resilience towards dissociation and severely hindering the attainment of a second molecular ligand. When the nitrogen is hydrogenated in the reduced dihydro-form, the cavity is partly blocked. This leads to a less strongly bound [1 : 1] complex ion but facilitates the attachment of a second molecular ligand to the Ag+. The resulting complex is the most stable among the [2 : 1] complexes. DFT calculations provide valuable insight into the geometries of the complex ions. Adding silver(I) to the reduced dihydro-form for cationization also induces its oxidation in solution. The oxidative dehydrogenation reaction, for which a mechanism is proposed, proceeds by first order kinetics and is markedly accelerated by day light.

Template synthesis of an intermediate in silver salt metathesis using a calix[4]arene-based diphosphine ligand.

The synthesis and solid-state characterisation of the heterobimetallic rhodium(III)/silver(I) complex [Rh(2,2'-biphenyl)(CxP2)Cl]⊃Ag+ is described, where CxP2 is a trans-spanning calix[4]arene-based diphosphine and the silver cation is datively bound to the chloride ligand within the cavity of the macrocycle.

Cascade signal amplification using Hg2+-induced oxidation of silver nanoparticles and cation exchange reaction for ICP-MS bioassay.

Combining the Hg2+-induced oxidization of silver nanoparticles with the cation exchange reaction between Ag+ and CuS nanoparticles for cascade signal amplification, a sensitive, universal and label-free ICP-MS bioassay for nucleic acids and proteins was developed. By replacing the loop sequence of the T-Hg-T hairpin structure with specific sequences or aptamers to different biomarkers, it has great promise for the early detection of biomarkers potentially for diagnosis of cancerous diseases.

Prospects for the Use of Metal Cations for the Development of Antimicrobial Complexes

It is known that antibacterial drugs with prolonged use cause antibiotic resistance in bacteria. Fast formation of resistance of microorganisms to modern antibacterial drugs requires the search for new methods of treatment. An alternative direction is the use of metal nanoparticles and their oxides as a basis for the creation of antimicrobial agents of a new generation, therefore, the study of methods for the synthesis of metal nanoparticles, their physico-chemical and pharmacological properties seems promising. The review examines the mechanisms of antibiotic resistance formation in biofilm and possible ways to overcome them for nanoscale metal particles, describes the synthesis and mechanism of action of nanoparticles containing silver, copper and zinc cations, presents the results of studies evaluating the effect of metal nanoparticles on antibiotic sensitivity in gram-positive and gram-negative bacteria, as well as fungi in comparison with the action of known dosage forms. Cu2+ and Zn2+ cations have a pronounced antibacterial effect in cultures Staphylococcus aureus and Pseudomonas aeruginosa. Ag+ cations showed the greatest efficacy against S. aureus, Escherichia coli, Klebsiella pneumoniae and Candida albicans.

Superfluid helium droplet-mediated surface-deposition of neutral and charged silver atomic species.

Experimental and theoretical work has delivered evidence of the helium nanodroplet-mediated synthesis and soft-landing of metal nanoparticles, nanowires, clusters, and single atoms on solid supports. Recent experimental advances have allowed the formation of charged metal clusters into multiply charged helium nanodroplets. The impact of the charge of immersed metal species in helium nanodroplet-mediated surface deposition is proved by considering silver atoms and cations at zero-temperature graphene as the support. By combining high-level ab initio intermolecular interaction theory with a full quantum description of the superfluid helium nanodroplet motion, evidence is presented that the fundamental mechanism of soft-deposition is preserved in spite of the much stronger interaction of charged species with surfaces, with high-density fluctuations in the helium droplet playing an essential role in braking them. Corroboration is also presented that the soft-landing becomes favored as the helium nanodroplet size increases.

New cationic coinage metal complexes featuring silyl group functionalized phosphine: syntheses, structures and catalytic studies in alkyne-azide cycloaddition reactions.

A series of coinage metal complexes bearing rarely explored ortho-silylated phosphine is reported. The treatment of diphenyl(2-(trimethylsilyl)phenyl)phosphine (1) with CuCl and [Cu(CH3CN)4]BF4 furnished the corresponding neutral [(1)CuCl]2 (2) and mono-cationic [(1)2Cu(CH3CN)]BF4 (3) complexes, respectively. The reactions of 1 with AgX (X = BF4-, NO3-) in 2 : 1 ratio furnished the corresponding mono cationic dicoordinate silver(I) complexes of the type [(1)2Ag]X (X = BF4- (4a), NO3- (4b)). The ortho-silylated phosphine ligand (1) was conveniently converted into the corresponding sulfide (5a) and selenide (5b) species, and their reactions with [Cu(CH3CN)4]BF4 yielded mono-cationic, homoleptic tris(silylphosphinochalcogenide)copper(I) complexes of the type [(5a/5b)3Cu]BF4 (6a/6b). The molecular structures of 2-4 and 6 were established by single-crystal X-ray diffraction analysis. The copper complexes 2, 3, and 6a were employed as catalysts in azide-alkyne cycloaddition reactions. Among these complexes, 3 was extensively used in the preparation of various mono- and bis-triazoles consisting of tolyl, benzyl, carbazolyl, and propargylic ether groups. Three sets of substituted triazole derivatives were achieved under mild conditions by employing copper(I) catalytic systems. The mechanistic studies indicated the formation of a heteroleptic copper(I) triazolide intermediate which was detected by high-resolution mass spectral analysis.

The characteristics of actinomyces strptomyces griseorubiginosus 83 – the effective biosorbent of silver

The bacteria bound about the same amount of silver at the time of inoculation and when added after 24 hours Fourier transform infrared spectroscopy (FT-IR) and measurements of the ζ- potential showed that several groups, mainly carboxy groups are involved in the binding and biotransformation of silver cations. Also, volatile organic compounds profiling for L. lactis, demonstrated the presence of many compounds in the free space of bacteria, which were typical products of bacterial metabolism. Finally, it can be stated that the combination of various instrumental methods used has opened up new possibilities for the interpretation of physicochemical phenomena occurring at the interface between bacteria-bacteria and bacteria-metals- bacteria. The ability of the biomass of cultures of various taxonomic groups to sorb metals is used both for purification of wastewater from metals and in the additional separation of valuable and environmentally significant metals from various wastes. In this work 48 strains of actinomycetes were isolated from various samples of desert soils of Uzbekistan under agricultural crops. As a result of screening, a strain of Streptomyces sp. 83, efficiently absorbs silver from solutions. The morphological-cultural and physiological-biochemical characteristics of the selected

Nanosilver-loaded metal–organic framework UiO-66 with strong fungicidal activity

Green functionalization of the metal–organic framework UiO-66 with a high loading of dispersed cationic silver species, having an outstanding antifungal action.

Biocompatibility and biocidal effects of modified polylactide composites.

Polylactide (PLA) materials treated with antimicrobial fillers represent a suitable alternative to the production of medical devices. Their advantage is that they can prevent the growth of microorganisms and the formation of microbial biofilms on the surface and around composites. The work is focused on the evaluation of biocompatibility and biocide effect of PLA composite films filled with vermiculite and graphene oxide modified with silver (Ag+ and Ag nanoparticles), hexadecylpyridinium (HDP) and hexadecyltrimethylammonium (HDTMA) cations and their degradation leachates monitored at 1-3-6-month intervals. The antimicrobial effect of the leachates was detected by microdilution methods on gram-negative (Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis), gram-positive (Staphylococcus aureus, Streptococcus salivarius) bacteria and yeast (Candida albicans). The biocidal effect of composites on biofilm formation on the surface of composites was monitored by Christensen method and autoaggregation and motility tests. The biocompatibility of the composite and the leachates was assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) cytotoxicity assay. The evaluation of the antimicrobial effect of the leachates demonstrated that leachates of PLA composite filled with graphene oxide and Ag+ showed a stronger antimicrobial effect than leachates of PLA composite filled with vermiculite and Ag+ and Ag nanoparticles. The leachates of PLA composites containing vermiculite with HDP and HDTMA cations had a higher antimicrobial effect on G+ bacteria and yeast than G- bacteria. Bacterial growth, biofilm formation, autoaggregation and motility of the tested bacteria were most inhibited by the composite with vermiculite and Ag+ and Ag nanoparticles. Even after a 6-month degradation of this composite, bacterial growth and biofilm formation continued to be strongly inhibited up to 42 and 91%, respectively. The cytotoxic effect was proved only in the leachate of the composite with vermiculite containing HDP after 6 months of its degradation. Tests evaluating the biocompatibility of materials have shown that the vermiculite is the most preferred carrier and can be used in the future to bind other compounds. The study confirmed that PLA composite filled with vermiculite and Ag+ and Ag nanoparticles was the most stable and effective composite with the best biocompatible and biocidal properties.