AgSCN Research Articles

Thiocarbonyl Pseudohalides - The Curious Case of Thiocarbonyl Dithiocyanate.

Thiocarbonyl dithiocyanate (1) and chlorothiocarbonyl thiocyanate (2) were synthesized from thiophosgene and ammonium or silver thiocyanate, respectivley. Their crystal structures show syn-anti (1) and syn (2) conformations, which were confirmed in the bulk phases by powder X-ray diffraction, vibrational spectroscopy and DFT calculations. Further calculations explain the isolation of the kinetic reaction products by a lower transition states opposed to the thermodynamic reaction products. Reaction of 1 with ethanol gave a dithiobiuret derivative (3). In a proof-of-principle study we show that it in turn can be used for the complexation of nickel to yield (4).

AgSCN as a new hole transporting material for inverted perovskite solar cells

A novel HTM based on silver thiocyanate (AgSCN) was designed to be useable in p-i-n perovskite solar cells (PSCs). With mass yield, the AgSCN was synthesized in the lab and elucidated by XRD, XPS, Raman spectroscopy, UPS, and TGA. The production of thin, highly conformal AgSCN films that allow for quick carrier extraction and the collection was made possible by a fast solvent removal approach. Photoluminescence experiments have shown that adding AgSCN has improved the ability to transfer charges between HTL and perovskite layer compared to PEDOT:PSS at the interface. Crystallographic discrepancies in the polycrystalline perovskite film are discovered upon further examination of the film's microstructure and morphology, pointing to the development of templated perovskite on the surface of AgSCN. In comparison to devices due to the well-known PEDOT:PSS, the open circuit voltage (VOC) is increased by AgSCN with its high work function by 0.1–1.14 V (1.04 V for PEDOT:PSS). With a power conversion efficiency (PCE) of 16.66%, a high-performance PSCs are effectively generated using CH3NH3PbI3 perovskite compared to 15.11% for controlled PEDOT:PSS devices. The solution-processed inorganic HTL was demonstrated employing straightforward in order to build durable and effective flexible p-i-n PSCs modules or their use as a front cell in hybrid tandem solar cells.

Silver thiocyanate treatment-induced enhancement of photoluminescence efficiency of CsPbBr3 perovskite quantum dots

Silver thiocyanate treatment-induced enhancement of photoluminescence efficiency of CsPbBr3 perovskite quantum dots

Synthesis and structural characterization of some 1:1 and 1:2 adducts of silver(I) salts with hindered Pmes3, PPhmes2 and PPh2mes bases (Ph = phenyl, mes = 2,4,6-trimethylpheny1))

A number of 1:2 or 1:1 Ag(I)X:L complexes formed between silver(I) salts, Ag(I)X, and P-donor ligands (L) PPh(3-n)mesn (‘mes’ = 2,4,6-trimethylphenyl) have been synthesized and spectroscopically and structurally characterized. Ag(I)X:Pmes3 (1:2) (solvated) are of the ionic form [Ag(Pmes3)2]+X−, with linear two-coordinate silver atom environments; for X = C1O4−, CF3SO3− (= 'tfs−'); with X = NO3−, the 1:1 complex [(mes3P)Ag(O,O’–NO3)] is obtained but with Ag(I)tfa ('tfa−' = CF3CO2−), [(mes3P)Ag(O,O'-tfa)(NCMe)] has been defined, incorporating MeCN solvent. The 1:2 adducts with PPhmes3/NO3− and PPh2mes3/C1O4−, tfs−, NO3−, tfa−, ac− (=CH3CO2−), SCN− are all of the form [(X-O,O’)AgL2] (unidentate SCN excepted). Ag(I)I:PPhmes2 (1:1) takes the 'cubane' tetramer form, while Ag(I)SCN:PPh2mes (1:1) adopts the (expanded) chair tetramer alternative. A remarkable Ag(I)I:PPh2mes adduct has been isolated, being of 4:3 (x2) Ag(I)I:L stoichiometry, comprising a pair of Ag4I4 cubane units each with three associated phosphine ligands, fused through a central Ag4I4 four-membered ring, the array being centrosymmetric.

An enhancement in the diesel engine performance, combustion, and emission attributes fueled by diesel-biodiesel and 3D silver thiocyanate nanoparticles additive fuel blends

The unique characteristics of the nanosized silver thiocyanate structure motivated the researchers to apply it as an effective agent nanoparticles additive in Diesel/Biodiesel fuel blends. Nanostructure of silver thiocyanate was measured by High resolution transmission electron microscope giving nano diameter between the values of 7.23:7.98 nm. The engine test has been achieved using 200, 400, and 600 ppm nanoparticles of silver thiocyanate additives to the blends of D50B50 (50%diesel & 50% biodiesel by volume). The tested blends are subjecting to a continuous stirring by using a mechanical movement pump to enhance the harmony of the nano-solid inside the blended fuel. During the engine test, the obtained fuel blends are stable and steady and the engine is running smoothly at fixed speeds of 1400 RPM and loads variation. The nanoparticles silver thiocyanate act as an oxygenated contributing catalyst. However, the existence of the extra oxygen inside the engine cylinder participates in reducing the unburned hydrocarbon emissions. The obtained results showed that the 400-ppm nanosized silver thiocyanate comparatively presents a better performance, combustion, and emission with respect to another tested dos. Unburned hydrocarbons and smoke emissions were dramatically reduced by adding the silver thiocyanate nanoparticle, which has working as combustion exciter that enhances the heat release rate process inside the DI-engine cylinder.

Diesel/ biodiesel /silver thiocyanate nanoparticles/hydrogen peroxide blends as new fuel for enhancement of performance, combustion, and Emission characteristics of a diesel engine

In the present study, sunflower and soybean oil commixture with 50:50 V/V % had been used to produce biodiesel by using a homogeneously catalyzed transesterification. The influence of biodiesel blend, nano blended fuel, and nanoemulsion fuel blends on the combustion, performance, as well as emissions of DI diesel engine, had been examined in the laboratory at various engine loads and a steady speed of 1400 rpm. Volumetric proportions of fuel mixtures: D50B50N000 (50% diesel-50% biodiesel), D50B50N200 (D50B50 + 200 ppm silver thiocyanate AgSCN (SCP1∖), D50B50N200 + 2% hydrogen peroxide (H2O2), and D50B50N200 + 4%H2O2 were arranged to fuelling a one-cylinder engine. The exhaust emissions of the engine were compared at pure diesel fuel and biodiesel blend D50B50N000, which indicated a reduction in CO, UHC, and NOx emissions upon adding a 200-ppm of silver thiocyanate SCP1∖ as a nano additive. This reduction increased upon adding and increasing the volumetric percentage of H2O2 where the D50B50N200 + 4% H2O2 fuel blend has lower emission values. The results show that CO2 emissions for the investigated fuel blends were elevated than diesel fuel. The presence of nanosized AgSCN and H2O2 enhanced the combustion process because of elevated nanoparticle surface/volume ratio and the occurrence of micro-explosion phenomena of the sprayed fuel particles, which increased the in-cylinder pressure and heat release rate (HRR). A noticeable decrease in brake specific fuel consumption (BSFC) was observed owing to the positive effect of using nano biodiesel blend and nanoemulsion fuels. A consequent increment in brake thermal efficiency (BTE) was indicated for nano biodiesel blend and nanoemulsion biodiesel blend fuels, where D50B50N200 + 4%H2O2 has the highest BTE of 27.16% compared to all tested fuels. Exhaust gas temperature (EGT) values were evaluated and analyzed for all tested fuels.

The electrochemical dissolution of single silver nanoparticles enlightened by hyperspectral dark-field microscopy

Nowadays, silver nanoparticles are extensively employed in several branches of industry and medicine. Hence, those particles are amongst the most studied class of nanomaterials, yet their reactivity and in particular their reactivity in biological systems is still poorly understood. This discrepancy leads to a huge demand for further insights into the reaction dynamics of electrochemical reactions. For this purpose, coupled opto- and spectro-electrochemical dark-field microscopy is used herein to study the electrochemical oxidation and dissolution process of individual silver nanoparticles in thiocyanate solutions. It is observed, that upon electrochemical oxidation of silver, a silver thiocyanate complex is formed. This is indicated by a change of both the measured plasmon resonance frequency and scattering intensity, simultaneous to the detection of an oxidative current. Subsequently, this silver pseudo-halide is chemically converted to a silver thiocyanate complex with higher solubility in the presence of high thiocyanate concentrations. This follow-up reaction is only detectable thanks to in situ spectroscopy as no current is associated with this chemical conversion but a distinct change in the spectroscopy response of the individual particles is seen. We were thus able to reveal that the total conversion of silver nanoparticles in the presence of thiocyanate is a multi-step process which lasts much longer than the electrochemical response suggests.

The ability of silver(I) thiocyanate 4-methoxyphenyl phosphine to induce apoptotic cell death in esophageal cancer cells is correlated to mitochondrial perturbations.

First generation silver(I) phosphines have garnered much interest due to their vast structural diversity and promising anticancer activity. Increasing incidences of cancer, side-effects to chemotherapeutic agents and redevelopment of tumors due to resistance prompts the exploration of alternative compounds showing anticancer activity. This study revealed the effective induction of cell death by a silver(I) thiocyanate 4-methoxyphenyl phosphine complex in a malignant esophageal cell line. Apoptotic cell death was confirmed in treated cells. Moreover, mitochondrial targeting via the intrinsic cell death pathway was evident due to low levels of ATP, altered ROS activity, mitochondrial membrane depolarization, cytochrome c release and caspase-9 cleavage. The complex displayed low cytotoxicity towards two human non-malignant, skin and kidney, cell lines. The findings reported herein give further insight into the selective targeting of silver(I) phosphines and support our belief that this complex shows great promise as an effective chemotherapeutic drug.

What happens to the silver ions? - Silver thiocyanate nanoparticle formation in an artificial digestion.

An artificial digestion of silver nitrate is reported. It is shown that AgSCN nanoparticles emerge from ionic silver in saliva and remain present during the entire digestion process. The particles were characterized by infrared spectroscopy and small- and wide-angle X-ray scattering (SAXS/WAXS) regarding their composition and size distribution.

Facile synthesis of silver/silver thiocyanate (Ag@AgSCN) plasmonic nanostructures with enhanced photocatalytic performance.

A nanostructured plasmonic photocatalyst, silver/silver thiocyanate (Ag@AgSCN), has been prepared by a simple precipitation method followed by UV-light-induced reduction. The ratio of Ag to silver thiocyanate (AgSCN) can be controlled by simply adjusting the photo-induced reduction time. The formation mechanism of the product was investigated based on the time-dependent experiments. Further experiments indicated that the prepared Ag@AgSCN nanostructures with an atomic ratio of Ag/AgSCN = 0.0463 exhibited high photocatalytic activity and long-term stability for the degradation of oxytetracycline (84%) under visible-light irradiation. In addition to the microstructure and high specific surface area, the enhanced photocatalytic activity was mainly caused by the surface plasmon resonance of Ag nanoparticles, and the high stability of AgSCN resulted in the long-term stability of the photocatalyst product.

Anticancer activity of silver(I) cyclohexyldiphenylphosphine complexes toward SNO cancer cells

Silver and its derivatives have been and are currently used as antimicrobial and antibacterial agents. However, their use is rather limited to date as anticancer agents. Thus, this study focuses on the synthesis and characterization of three silver(I) complexes which have the ability to adopt different geometries, and to induce cancer cell death in SNO esophageal cancer cells. Silver thiocyanate was reacted in different ratios with cyclohexyldiphenylphosphine to obtain 1:1 (complex 1), 1:2 (complex 2), and 1:3 (complex 3) molar ratios of silver(I):cyclohexyldiphenylphosphine complexes. These complexes were characterized using conventional spectroscopic techniques, which included 1H, 13C, and 31P NMR, FTIR, and microanalysis (%C, H, N, S). In addition, the single-crystal X-ray structures of complexes 1 and 2 were determined. Moreover, all three complexes displayed toxic activity toward the malignant SNO cells with IC50 concentrations below 5 μM as determined with an alamarBlue® viability assay. Morphological and flow cytometric analyses were included to identify the possible mode of cancer cell death. These biochemical assays revealed that all three treatments induced apoptosis due to the presence of specific apoptotic markers.

Widely Tunable Plasmon Resonances from Visible to Near-Infrared of Hollow Silver Nanoshells

Abstract Tuning of localized surface plasmon resonance (LSPR) of metal nanostructures has attracted a great deal of interest, and the controlled syntheses of them have been extensively studied for fine tuning of their LSPR. In this paper, we report widely tunable LSPR from visible to near-infrared of hollow silver nanoshells synthesized by reduction of silver thiocyanate. The silver nanoshell exhibits size- and thickness-dependent LSPR for symmetric dipole mode from visible to near-infrared regions, while the antisymmetric dipole resonance is not changed. By combining characterization of the nanoshells by transmission electron microscopy and theoretical simulation based on discrete dipole approximation, we reveal that the LSPRs are controlled by the size and shell thickness of the nanoshells and also that dimples on the shell surfaces would significantly affect the LSPRs of symmetric dipole, and quadrupole mode for larger nanoshells.

Synthesis of silver(I) p-substituted phenyl diphenyl phosphine complexes with the evaluation of the toxicity on a SNO cancer cell line

Cancer is a disease that is responsible for many deaths worldwide. It is therefore crucial to synthesise and evaluate new anticancer agents that may be more effective towards the cancer cells. A number of silver(I) p-substituted phenyl diphenyl phosphine complexes, were synthesised in a 1:2M ratio of silver thiocyanate to phosphine ligand. Once characterised, these complexes, [Ag{PPh2(4-C6H4CHCH2)-κP}2-μ-SCN-κ2S:N;κ2N:S]2 1; [Ag{PPh2(4-MeC6H4)-κP}2-μ-SCN-κ2S:N;κ2N:S]2 2; [Ag{PPh2(4-NMe2C6H4)-κP}2-μ-SCN-κ2S:N;κ2N:S]2 3, as well as [Ag(PPh3-κP)2-μ-SCN-κ2S:N;κ2N:S]2 4, were evaluated on a malignant SNO cell line for anticancer activity. The cytotoxicity of the complexes was compared to that of complex 4 and other silver(I) phosphine complexes. After a 24h exposure of the complexes, the mode of cell death was determined by morphological studies of the cells under a microscope. An alamarBlue® viability assay was used to evaluate the toxicity of these complexes. All the complexes showed high toxicity at a 10μM treatment (silver concentration), compared to the untreated, vehicle and apoptotic (cisplatin) control. Morphological studies suggest an apoptotic mode of cell death.

The effect of 1:2 Ag(I) thiocyanate complexes in MCF-7 breast cancer cells.

There is much interest currently in the design of metal compounds as drugs and various metal compounds are already in clinical use. These include gold(I) compounds such as auranofin and the anti-cancer platinum(II) complex, cisplatin. Bis-chelated gold(I) phosphine complexes have also shown great potential as anticancer agents, however, their efficacy has been limited by their high toxicity. In this study, silver(I) thiocyanate compounds linked to four specific ligands, were synthesized and characterized. These silver-phosphine adducts included [AgSCN{P(4-MeC6H4)3}2]2 (1); [AgSCN{P(4-ClC6H4)3}2]2 (2); [AgSCN{P(4-MeOC6H4)3}2]2 (3); [AgSCN(PPh3)2]2 (4). The compounds were found to be toxic to MCF-7 breast cancer cells while the ligands on their own were not toxic. Our findings further indicate that the silver(I) phosphine compounds induce apoptotic cell death in these breast cancer cells. In addition, the compounds were not toxic to nonmalignant fibroblast cells at the IC50 concentrations. This is an indication that the compounds show selectivity towards the cancer cells.

The induction of cell death by phosphine silver(I) thiocyanate complexes in SNO-esophageal cancer cells.

Esophageal cancer is one of the least studied cancers and is found to be prominent in black South African males. It is mainly diagnosed in the late stages, and patients tend to have a low 5-year survival rate of only 10%. Silver is generally used as an antimicrobial agent, with limited reports on anticancer studies. In this study, dimeric silver(I) thiocyanate complexes were used containing a variation of 4-substitued triphenylphosphines, including [AgSCN(PPh(3))(2)](2) (1), [AgSCN{P(4-MeC(6)H(4))(3)}(2)](2) (2), [AgSCN{P(4-FC(6)H(4))(3)}(2)](2) (3) and [AgSCN{P(4-ClC(6)H(4))(3)}(2)](2) (4). All four complexes, with their respective phosphine ligands, PPh(3) (L1), P(4-MeC(6)H(4))(3) (L2), P(4-FC(6)H(4))(3) (L3) and P(4-ClC(6)H(4))(3) (L4), were subjected to in vitro toxicity studies in SNO-esophageal cancer cells, using an alamarBlue(®) assay. Morphological changes, including blebbing and apoptotic body formation, were observed. Phosphatidylserine externalization, a marker of apoptosis, was quantified by flow cytometry. The phosphine ligands L1-L4, on their own, had minimal effect on the malignant while complexes 1-4 resulted in significant cell death. A 10x decreased concentration of these complexes had similar effects than cisplatin, used as the positive control. These complexes show promise as anticancer agents.

Synthesis and photocatalytic property of a new silver thiocyanate semiconductor

A new AgSCN photocatalytic material with a novel nonmetal acid structure was synthesized by an ion-exchange method. Its structure and properties were characterized in detail. UV–vis absorption spectrum showed that AgSCN had the optical indirect band gap of 3.51eV. The valence level of AgSCN was determined as 1.52eV by X-ray photoelectron spectrometer. The photodegradation efficiency of rhodamine B over AgSCN was 2.74 times that of N-doped TiO2 (N-TiO2) under UV light radiation. The photodegradation rate constant was 4.8 times that of N-TiO2. The high photocatalytic activity mainly resulted from SCN− and the high position of valence band. OH radicals, as the dominant active species in photocatalysis, primarily originated from the multi-step reduction of O2 by photogenerated electron.

FITC functionalized magnetic core–shell Fe3O4/Ag hybrid nanoparticle for selective determination of molecular biothiols

A sensing strategy for chromogenic detection of molecular biothiols has been proposed based on fluorescein isothiocyanate (FITC) functionalized magnetic core–shell Fe3O4/Ag hybrid nanoparticles. Ag coated magnetic Fe3O4 nanoparticles were initially synthetized. FITC was subsequently conjugated on the surface of core–shell nanoparticles by Ag–SCN linkage and then the fluorescence of FITC was quenched. Upon addition of molecular biothiols, since the AgS bond is stronger than Ag–SCN, a place-displacement between thiols and FITC would occur and thereby the fluorescence of FITC would recover. Thus, a fluorescence “off-on” probe was attained by virtue of biothiols, so after magnetic separation, the fluorescence signal change of FITC in clear solution could be employed for quantitative determination of typical molecular biothiols such as glutathione (GSH) and cysteine (Cys). High sensitivity was obtained with the detection limits of 10nM and 20nM for GSH and Cys, respectively. As well as, the assay strategy presented excellent selectivity toward molecular biothiols against other amino acids. Furthermore, confocal imaging was achieved in living cells, indicating that this fluorescent probe is potentially applicable for imaging molecular thiols in biological systems.

Oligo-nuclear silver thiocyanate complexes with monodentate tertiary phosphine ligands, including novel ‘cubane’ and ‘step’ tetramer forms of AgSCN : PR3 (1 : 1)4

Adducts of a number of tertiary pnicogen ligands ER(3) (triphenyl-phosphine and -arsine (PPh(3),AsPh(3)), diphenyl,2-pyridylphosphine (PPh(2)py), tris(4-fluorophenyl)phosphine (P(C(6)H(4)-4F)(3)), tris(2-tolyl)phosphine (P(o-tol)(3)), tris(cyclohexyl)phosphine (PCy(3))), with silver(I) thiocyanate, AgSCN are structurally and spectroscopically characterized. The 1:3 AgSCN : ER(3) complexes structurally defined (for PPh(3),AsPh(3) (diversely solvated)) take the form [(R(3)E)(3)AgX], the thiocyanate X = NCS being N-bound, thus [(Ph(3)E)Ag(NCS)]. A 1:2 complex with PPh(2)py, takes the binuclear form [(pyPh(2)P)(2)Ag()Ag(PPh(2)py)(2)] with an eight-membered cyclic core. 1:1 complexes are defined with PPh(2)py, P(o-tol)(3) and PCy(3); binuclear forms [(R(3)P)Ag()Ag(PR(3))] are obtained with P(o-tol)(3) (two polymorphs), while novel isomeric tetranuclear forms, which may be envisaged as dimers of dimers, are obtained with PPh(2)py, and, as further polymorphs, with PCy(3); these latter may be considered as extensions of the 'cubane' and 'step' forms previously described for [(R(3)E)AgX](4) (X = halide) complexes. Solvent-assisted mechanochemical or solvent-assisted solid-state synthesis methods were employed in some cases, where complexes could not be obtained by conventional solution methods, or where such methods yielded a mixture of polymorphs unsuitable for solid-state spectroscopy. The wavenumbers of the ν(CN) bands in the IR spectra are in broad agreement with the empirical rule that distinguishes bridging from terminal bonding, but exceptions occur for compounds that have a double SCN bridged dimeric structure, and replacement of PPh(3) with PPh(2)py apparently causes a significant decrease in ν(CN) to well below the range expected for bridging SCN in these structures. (31)P CP MAS NMR spectra yield additional parameters that allow a correlation between the structures and spectra.

A Triple-Stranded Ladder-Type Coordination Polymer

Stepwise synthesis and structural characterization of one-dimensional coordination polymers whose topologies depend on the anions are reported. A simple ladder-type precursor, {[Ag2(L)2](ClO4)2}n (1), was prepared by the reaction of bis(4-pyridylmethyl)sulfide (L) with AgClO4. Treatment of 1 with potassium thiocyanate and potassium cyanide afforded a twisted ribbon-type chain of type [Ag(L)SCN]n (2) and a triple-rail ladder of type [Ag3(L)2(CN)3]n (3), respectively. The result demonstrates that replacement of the noncoordinated perchlorate anions by pseudohalide ions in the coordination sphere of 1 plays a crucial role in determining the structures of the resulting species.

Flow-injection spectrophotometric determination of captopril in pharmaceutical formulations using a new solid-phase reactor containing AgSCN immobilized in a polyurethane resin

A simple flow-injection analysis procedure was developed for determining captopril in pharmaceutical formulations employing a novel solid-phase reactor containing silver thiocyanate immobilized in a castor oil derivative polyurethane resin. The method was based on silver mercaptide formation between the captopril and Ag(I) in the solid-phase reactor. During such a reaction, the SCN- anion was released and reacted with Fe3+, which generated the FeSCN2+ complex that was continuously monitored at 480 nm. The analytical curve was linear in the captopril concentration range from 3.0 × 10-4 mol L-1 to 1.1 × 10-3 mol L-1 with a detection limit of 8.0 × 10-5 mol L-1. Recoveries between 97.5% and 103% and a relative standard deviation of 2% for a solution containing 6.0 × 10-4 mol L-1 captopril (n = 12) were obtained. The sample throughput was 40 h-1 and the results obtained for captopril in pharmaceutical formulations using this procedure and those obtained using a pharmacopoeia procedure were in agreement at a 95% confidence level.