Tin Atom Research Articles

Imine-functionalized organotin(IV) carboxylates: Syntheses, structures and antibacterial activities

Six new imine-functionalized organotin(IV) carboxylates viz. {[(n-Bu)2Sn(L1)]2O]}2 (1), [(t-Bu)2Sn(L1)2] (2), [Ph3Sn(L1)] (3), [(t-Bu)4Sn2(OH)2(L2)2] (4), [Ph3Sn(L2)] (5) and [(t-Bu)2Sn(L3)2] (6) have been synthesized and characterized by FT-IR spectroscopy, elemental analysis, 1H, 13C{1H} and 119Sn{1H} NMR spectroscopy. The solid-state molecular structures of all compounds have been elucidated by single-crystal X-ray diffraction analyses. Compound 1 shows a ladder-type structure consisting of four tin atoms. Compounds 2–3 and 5–6 are mononuclear and contain only one tin atom in each compound. Interestingly, compound 4 exhibits a hydroxide-bridged dinuclear structure. All compounds were evaluated for their antibacterial activities against E. coli XL-1 Blue cells, and compound 1 showed maximum activity amongst all compounds.

Regulating the P-band center of SnS2-SnO2 heterostructure to boost the redox kinetics for high-performance lithium-sulfur battery

Lithium-sulfur batteries (LSBs) are considered a strong contender for the new-generation secondary energy storage system due to their high capacity and energy density. However, the sluggish reaction kinetics and the shuttle effect of lithium polysulfides (LPSs) severely hinder the cycle stability. The robust design of both the separator and cathode exhibit an effective role in restricting the shuttle effect and accelerating redox kinetics through the LPSs trapping and catalyzing effect. In this paper, a CNT-modified tin sulfide and tin oxide (SnS2-SnO2-CNTs) heterostructure was constructed as a multifunctional catalyst to modify both the separator and cathode to achieve high-performance LSBs. The formation of SnS2-SnO2 heterostructure promotes the movement of the P band center of the tin atom to the Fermi level, which realizes the association process of adsorption, capture, and conversion of LPSs, thus effectively suppressing the shuttle effect. The SnS2-SnO2 heterogeneous interface can also reduce the deposition barrier of Li2S, thus greatly promoting the redox kinetics. Together with the improved electron transfer, the resulting LSBs with the robust electrode and separator exhibit superior electrochemical performance with a high initial capacity of 930.2 mAh g−1 at 1 C with a high sulfur loading of 4.3 mg cm−2 and a remarkable capacity of up to 580.3 mAh g−1 at an ultrahigh rate of 7.4 C.

Lithium Salt of 2,5-Bis(trimethylsilyl)stannolyl Anion: Synthesis, Structure, and Nonaromatic Character

The aromatic character of silolyl and germolyl anions markedly depends on the substituents in the 2,5-positions; carbon-substituted derivatives are nonaromatic, whereas silyl-substituted ones tend to exhibit an aromatic character. However, only carbon-substituted derivatives have been reported for stannolyl anions. In this study, we present the synthesis and structure of a 2,5-disilylated stannolyl anion. Transmetalation of a 2,5-disilyl-1-zirconacyclopentadiene with SnCl4 gave a dichlorostannole 1, which reacted with potassium tris(trimethylsilyl)silanide to introduce a bulky silyl group on the tin atom. Reduction of the 1-chloro-1-silylstannole 2 with lithium generated the lithium salt of the desired stannolyl anion 3 that adopts an η1-coordination to the lithium atom. We concluded that the stannolyl anion 3 is nonaromatic based on the pyramidalized tin center and the C–C bond alternation in the five-membered ring as well as the NMR properties.

Sonochemical synthesis of SnS and SnS2 quantum dots from aqueous solutions, and their photo- and sonocatalytic activity

Our study reports the ultrasound-assisted synthesis of SnS and SnS2 in the form of nanoparticles using aqueous solutions of respective tin chloride and thioacetamide varying sonication time. The presence of both compounds is confirmed by powder X-ray diffraction, energy-dispersive X-ray spectroscopy, as well as Raman and FT-IR spectroscopic techniques. The existence of nanoparticles is proven by powder X-ray diffraction investigation and by high resolution transmission electron microscopy observations. The size of nanocrystallites are in the range of 3–8 nm and 30 50 nm for SnS, and 1.5–10 nm for SnS2. X-ray photoelectron spectroscopy measurements, used to investigate the chemical state of tin and sulphur atoms on the surface of nanoparticles, reveal that they are typically covered with tin on the same oxidation degree as respective bulk compound. Values of optical bandgaps of synthesized nanoparticles, according to the Tauc method, were 2.31, 1.47 and 1.05 eV for SnS (60, 90 and 120 min long synthesis, respectively), and 2.81, 2.78 and 2.70 eV for SnS2 (60, 90 and 120 min long synthesis, respectively). Obtained nanoparticles were utilized as photo- and sonocatalysts in the process of degradation of model azo-dye molecules by UV-C light or ultrasound. Quantum dots of SnS2 obtained under sonication lasting 120 min were the best photocatalyst (66.9 % color removal), while quantum dots of SnS obtained under similar sonication time were the best sonocatalyst (85.2 % color removal).

XUV Absorption Spectroscopy and Photoconversion of a Tin-Oxo Cage Photoresist.

Extreme ultraviolet lithography has recently been introduced in high-volume production of integrated circuits for manufacturing the smallest features in high-end computer chips. Hybrid organic/inorganic materials are considered as the next generation of photoresists for this technology, but detailed knowledge about the response of such materials to the ionizing radiation used (13.5 nm, 92 eV) is still scarce. In the present work, we use broadband high-harmonic radiation in the energy range 22-70 eV for absorption spectroscopy and photobleaching (that is, the decrease of absorbance) of thin films of an n-butyltin oxo-cage, a representative of the class of metal-based EUV photoresist. The shape of the absorption spectrum in the range 22-92 eV matches well with the spectrum predicted using tabulated atomic cross sections. The photobleaching results are consistent with loss of the butyl side groups due to the breaking of Sn-C bonds following photoionization. Bleaching is strongest in the low-energy range (<40 eV), where the absorption is largely due to the carbon atoms in the organic groups. At higher energies (42-70 eV), absorption is dominated by the tin atoms, and since these remain in the film after photoconversion, the absorption change in this region is smaller. It is estimated that after prolonged irradiation (up to ∼3 J cm-2 in the range 22-40 eV) about 70% of the hydrocarbon groups are removed from the film. The rate of bleaching is high at the beginning of exposure, but it rapidly decreases with increasing conversion. We rationalize this using density functional theory calculations: the first Sn-C bonds are efficiently cleaved (quantum yield Φ ≈ 0.9), because the highest occupied molecular orbitals (HOMOs) (from which an electron is removed after photoionization) are located on Sn-C sigma bonds. In the photoproducts, the HOMO is localized on tin atoms that have lost their hydrocarbon group (formally reduced to the Sn(II) oxidation state), and holes formed on those tin atoms lead to less efficient cleavage reactions. Our results reveal the primary reaction steps following excitation with ionizing radiation of tin-oxo cages. Our methodology represents a systematic approach of studying and quantitatively assessing the performance of new photoresists and as such enables the development of future EUV photoresists.

Organometallic tin monochalcogenides [SnX (X = O, S, Se, and Te)] as alternative ligands for carbonyls: A DFT study

Quantum mechanical DFT calculations were performed on the Fe(CO)5 and for the axial and equatorial isomers of [Fe(CO)4(SnX)] (X = O, S, Se, Te) complexes. The equatorial isomer of [Fe(CO)4(SnX)] complexes is more stable than the axial isomer using energetic values. These complexes' bonding nature is analysed by NPA and EDA results. The bond index of the bond between Fe and SnX is provided by the WBI analysis. The FMO studies of these complexes show lesser HOMO-LUMO energy gaps in the values of 4.00 to 4.76 eV than that of [Fe(CO)5]. From the NBO analysis, the contribution to the bond formation of the Sn atom to the Fe-Sn bond is greater than that of the Fe atom. Similar contributions are seen in the carbonyl group (in the Fe-C bond), although the contribution of the carbon atom is larger than that of the tin atom.

On fault-tolerant metric dimension of supramolecular networks

The idea of a fault-tolerant metric dimension can be used in chemistry to examine a molecule’s structural resistance to the failure of particular atoms or chemical bonds. This is especially important when creating molecules for specific uses, like drug candidates, as they may be exposed to biological systems or the environment, which could cause certain atoms or bonds to change or break. One such is the dialkyltin complex, which has two alkyl groups joined to a tin atom. The nitrogen atom of an N-salicylidene-L-valine molecule is coupled to the alkyl groups in the dialkyltin complex-1 of N-salicylidene-L-valine, making it a useful catalyst for numerous processes in organic synthesis. The purpose of this study is to identify the fault-tolerant metric dimension of the chain in N-salicylidene-L-valine dialkyltin complex-3.

Amidinatotetrylenes Donor Functionalized on Both N Atoms: Structures and Coordination Chemistry.

E(hmds)(bqfam) (E = Ge (1a), Sn (1b); hmds = N(SiMe3)2, bqfam = N,N'-bis(quinol-8-yl)formamidinate), which are amidinatotetrylenes equipped with quinol-8-yl fragments on the amidinate N atoms, have been synthesized from the formamidine Hbqfam and Ge(hmds)2 or SnCl(hmds). Both 1a and 1b are fluxional in solution at room temperature, as the E atom oscillates from being attached to the two amidinate N atoms to being chelated by an amidinate N atom and its closest quinolyl N atom (both situations are similarly stable according to density functional theory calculations). The hmds group of 1a and 1b is still reactive and the deprotonation of another equivalent of Hbqfam can be achieved, allowing the formation of the homoleptic derivatives E(bqfam)2 (E = Ge, Sn). The reactions of 1a and 1b with [AuCl(tht)] (tht = tetrahydrothiophene), [PdCl2(MeCN)2], [PtCl2(cod)] (cod = cycloocta-1,5-diene), [Ru3(CO)12] and [Co2(CO)8] have been investigated. The gold(I) complexes [AuCl{κE-E(hmds)(bqfam)}] (E = Ge, Sn) have a monodentate κE-tetrylene ligand and display fluxional behavior in solution the same as that of 1a and 1b. However, the palladium(II) and platinum(II) complexes [MCl{κ3E,N,N'-ECl(hmds)(bqfam)}] (M = Pd, Pt; E = Ge, Sn) contain a κ3E,N,N'-chloridotetryl ligand that arises from the insertion of the tetrylene E atom into an M-Cl bond and the coordination of an amidinate N atom and its closest quinolyl N atom to the metal center. Finally, the binuclear ruthenium(0) and cobalt(0) complexes [Ru2{μE-κ3E,N,N'-E(hmds)(bqfam)}(CO)6] and [Co2{μE-κ3E,N,N'-E(hmds)(bqfam)}(μ-CO)(CO)4] (E = Ge, Sn) have a related κ3E,N,N'-tetrylene ligand that bridges two metal atoms through the E atom. For the κ3E,N,N'-metal complexes, the quinolyl fragment not attached to the metal is pendant in all the germanium compounds but, for the tin derivatives, is attached to (in the Pd and Pt complexes) or may interact with (in the Ru2 and Co2 complexes) the tin atom.

Investigating the antimicrobial potential of diorganotin(IV) complexes incorporating hydrazone ligands: Synthesis, structural elucidation, X-ray crystallography, DFT, and antimicrobial activity

Sixteen diorganotin(IV) complexes having the general formula R2SnL1-4, (where R = Me, Et, Bu, and Ph) have been synthesized from hydrazone ligands, which were obtained by the condensation reaction of 4-(benzyloxy)-2-hydroxybenzaldehyde with hydrazide derivatives. The synthesized compounds were fully characterized by several spectroscopic and physicochemical techniques, like elemental analysis, FT-IR, (1H, 13C, and 119Sn) NMR, mass spectrometry, UV–Vis. and TGA. The obtained spectroscopic data revealed that hydrazone ligand bound to the tin atom in a tridentate fashion via phenolic O, imine N, and enolic O donor atoms and forms a pentacoordinated environment which was further confirmed by the X-ray crystallography diffraction analysis of complex 4. Complex 4 crystallizes in triclinic cell with space group P-1 and exhibits a distorted trigonal bipyramidal geometry. The equilibrium geometry of selected compounds was estimated using density functional theory (DFT) calculations implemented at B3LYP/LanL2DZ theory level to get insight into geometric and electronic structures using Gaussian 9 software package. Furthermore, the synthesized compounds were tested for their in vitro antimicrobial activity against four bacterial and two fungal strains. The results demonstrated that diorganotin(IV) complexes displayed better activity as compared to the hydrazone ligands. The best results are shown by complexes 4, 8, 12 and 16 with MIC values in the range of 0.0048–0.0050 µmol/mL, respectively against B. subtilis and C albicans strains, further suggesting their greater lipophilicity which may have a substantial impact on facilitating microbial cell penetration.

Anticancer effect of organotin complexes derived from 2,6-naphthalenedicarboxylic acid by enhancing the ROS generation

Enhancing ROS generation is crucial for anti-metastasis and anti-proliferation effects in anticancer chemotherapeutics. Herein, five organotin complexes [(Ph3Sn)2L] (1) [(R3Sn)2L]n (R = Et 2, R = n-Bu 3), [(n-Bu3Sn)2L(4,4′-bpe)]n (4), [(n-Bu3Sn)2L(4,4′-bipy)]n (5) were synthesized based on appropriate organotin precursors, 2,6-naphthalenedicarboxylic acid (H2L) and auxiliary ligand (4,4′-bipy = 4,4′-bipyridine, 4,4′-bpe = 1,2-di(4-pyridyl)ethylene). It was found that complex 1 exhibits a tetra-coordinated monomeric structure, complexes 2 and 3 show the 2D coordination polymer, and complexes 4 and 5 display the 1D chain with the central tin atoms as all penta-coordinated. These complexes showed high anti-tumor activity in vitro against four cancer cells (A549, HCT116, HepG-2 and HeLa), with IC50 values changed from 0.34±0.01 μM to 25.54 ± 1.55 μM. Additionally, complex 1 could be effective in inhibiting HepG-2 cell migration. Simultaneously, anticancer mechanism studies show that complex 1 induces excessive ROS production in HepG-2 cells, which in turn leads to the occurrence of ROS-induced downstream events, followed by the disintegration of the redox balance, depolarization of mitochondrial membrane potential, nucleus damage and ultimately apoptosis. This work suggests that enhancing the ability of organotin complexes to generate reactive oxygen species and disrupt intracellular redox balance may be a promising anticancer strategy.

Promoted polysulfide conversion process and improved rate performance by tin atom modified carbon in Li-S batteries

Dissolution of polysulfides limits the improvement of rate performance in Li-S batteries. Introducing catalytic agents is the key to promote polysulfide conversion process and improve rate performance of Li-S batteries. Both metallic atoms catalysts and metal sulfide catalysts can promote polysulfide conversion process. However, the comparison of catalyzing abilities between metallic atoms catalysts and metal sulfide catalysts in Li-S batteries still needs to be studied. SnS modified carbon (C/SnS) and Sn atom modified carbon (C/Sn) are obtained by controlling hydrothermal and carbonization processes in this paper. Electrochemical performance of C/SnS/S and C/Sn2S3/S composite electrodes are also studied, which are obtained by loading sulfur on C/SnS and C/Sn. Results show that C/Sn2S3/S composite electrodes possess higher rate performance (553 mAh·g−1 at 5C) than C/SnS/S composite electrodes, which is ascribe to stable catalyzing abilities of Sn atom modified carbon. Electron transportation abilities and Li-ion diffusion process are both promoted in C/Sn2S3/S composite electrodes. The comparison of catalyzing abilities between C/SnS and C/Sn composites provides reference for design and regulation of composite structures.

Exploring the stability and aromaticity of rare earth doped tin cluster MSn16- (M = Sc, Y, La).

Rare earth elements have high chemical reactivity, and doping them into semiconductor clusters can induce novel physicochemical properties. The study of the physicochemical mechanisms of interactions between rare earth and tin atoms will enhance our understanding of rare earth functional materials from a microscopic perspective. Hence, the structure, electronic characteristics, stability, and aromaticity of endohedral cages MSn16- (M = Sc, Y, La) have been investigated using a combination of the hybrid PBE0 functional, stochastic kicking, and artificial bee colony global search technology. By comparing the simulated results with experimental photoelectron spectra, it is determined that the most stable structure of these clusters is the Frank-Kasper polyhedron. The doping of atoms has a minimal influence on density of states of the pure tin system, except for causing a widening of the energy gap. Various methods such as ab initio molecular dynamics simulations, the spherical jellium model, adaptive natural density partitioning, localized orbital locator, and electron density difference are employed to analyze the stability of these clusters. The aromaticity of the clusters is examined using iso-chemical shielding surfaces and the gauge-including magnetically induced currents. This study demonstrates that the stability and aromaticity of a tin cage can be systematically adjusted through doping.

2D nature of magnetic states at SnO2 surfaces: a combined experimental and theoretical study.

For undoped SnO2, room temperature ferromagnetism could be seen uniquely in 2-dimensional configurations, particularly in ultra-thin films (whose thickness is ideally below 100 nm). Both bulk samples and nano-powders of pristine SnO2 are diamagnetic, indicating that a 2D surface is a key point in shaping up the magnetic properties in SnO2. As a complement to our experiments, we have performed a series of quantum-mechanical calculations for the bulk rutile-structure SnO2 as well as its (001) and (101) surfaces. The calculations included several atomic configurations with and without vacancies in/under the studied surfaces. The stability of the non-magnetic ground state of rutile SnO2 bulk was cross-checked and confirmed by its phonon spectrum computed within the harmonic approximation. Regarding the surfaces, the bulk-like (001) surface containing Sn vacancies has turned out to be ferromagnetic, while the shift of Sn vacancies under the surface resulted in a more complex ferrimagnetic state. The bulk-like (001) surface without vacancies and that with the O vacancies are predicted to be non-magnetic. Regarding the (101) surfaces, those terminated by a single layer of oxygen atoms and those terminated by tin atoms are non-magnetic, while a surface terminated by two layers of oxygen has turned out to be ferromagnetic.

Efficient photo-dissociation-induced production of hydrogen radicals using vacuum ultraviolet light from a laser-produced plasma

One of the critical issues in lithography using extreme ultraviolet (EUV) light is tin contamination of the EUV collector mirrors in the tin-based LPP-EUV light source. The contamination can be removed by the reaction of tin atoms with hydrogen radicals producing stannane (SnH4), which is gaseous at the normal temperature. Hydrogen radicals can be produced from hydrogen molecules through photo-dissociation and photo-ionization induced by broadband radiation emitted from the EUV light source. In this work, an efficient production of hydrogen radical using vacuum ultraviolet (VUV) light emitted from laser-produced high-Z plasma is experimentally demonstrated. A two-dimensional radiation hydrodynamic simulation, coupled with photoionization and photo-dissociation cross sections, also shows the efficient hydrogen radical production by increased VUV light emission, as observed in the experiment.

In English

Molecular models for tin dioxide nanoparticles containing 1-7 metal atoms and coordinated or constitutive water have been constructed. Dependent on the composition of the models, the coordination number of the tin atom varied from 4 to 6, and that of oxygen was 2 or 3. The considered models contained both terminal (Sn–OH) and bridging (Sn–OH–Sn) hydroxyl groups, and also bridging (Sn–O–Sn) groups. Their equilibrium spatial and electronic structures were calculated using the second-order Møller-Plesset perturbation theory method with the SBKJC valence-only basis set. To assess the gas-phase acidity of the dioxide surface, the deprotonation energy of the studied models was determined. The adsorption energy of water molecules and hydroxide ions on aprotic (incompletely coordinated) tin atoms, which act as Lewis acid centers, was calculated. In order to estimate the pKa value of the surface of tin dioxide, the Gibbs free energy was calculated for the process of formation of ion pairs due to the proton transfer from hydroxyl groups to adsorbed water molecules. Based on the analysis of the energy effects of the coordination of water molecules and of hydroxide ion, the removal of a proton and its transfer on the hydrated surface of tin dioxide, quantitative estimates have been made of the acid-base characteristics of the active sites of the SnO2 surface. The dependence of the acidity of hydroxyl groups and coordinated water molecules on the coordination number of the oxygen atom and the neighboring tin atom, as well as on the dimensions of the cluster model, was revealed. It is shown that the acidity of protonic and aprotic sites naturally decreases with an increase in the coordination number of the tin atom. The method of calculating the value of pKa used in the work for the smallest model of the SnO2×2H2O composition allows one to reproduce the experimental data for stannic acids.

Fast and ecofriendly triple sulfonamides mixture utilization using UV irradiation and spherical SnO2 nanoparticles with controllable parameters and antibacterial activity

One of the solutions for the growing problem of water purification is photocatalytic degradation of the pollutants. Semiconductor nanoparticles are widely under study as a promising photocatalyst for this purpose. However, there is still lack of understanding of the relation between properties of nanoparticles, in their turn related with synthesis conditions, and photocatalytic efficiency, as well as of the other factors influencing the process.For the first time, a possibility to regulate photocatalytic activity of SnO2 nanoparticles under UV light via regulation of structural parameters is shown. A method for obtaining spherical nanoparticles with different parameters was developed. Obtained nanoparticles were fully characterized. Special attention was paid to the study of oxygen vacancies. With the help of quantum computational methods, it was shown, that the concentration of vacancies is around 1 per 32 tin atoms. Obtained data on oxygen vacancies were further used for the evaluation of pollutant-nanoparticle surface interaction to get closer to the calculations of real systems.On the example of methylene blue, it was shown that the greater is the amount of oxygen vacancies and the lower the amount of defects, the higher photocatalytic activity. The obtained dependence is confirmed by the fact that the photoresponse increases with a decrease of amount of defects in the sample. Degradation kinetics of sulfonamides mixture was studied, and its dependence on active complex formation was shown based on the quantum chemical calculation data. Degradation of antibiotics in water from Neva River reached more than 95% in 35 min, which indicates that developed photocatalyst efficiency is not affected by pollutants contained in open water in the centre of the metropolis. It was shown, that the use of nanoparticles allows to speed up the process of bacteria destruction under UV light, which indicates the antibacterial activity of obtained nanoparticles.

New insights into visible light active SnS semiconductor for the elimination of methylene blue: RSM and DFT approaches

In this study, a response surface methodology (RSM) based on a central composite design (CCD) was performed by varying five pivotal variables: concentration of pollutant (mg/L), mass of catalyst (g), time (min), temperature (°C), and pH to evaluate the degradation efficiency of Methylene Blue (MB) using nanostructured SnS under visible light irradiation. The quadratic model displayed a notable level of reliability and fitness, as evidenced by its R2 value of 0.925. The optimized conditions obtained (Concentration of pollutant: 13.38 mg/L, mass of catalyst: 0.09 g, irradiation time: 25.26 min, temperature: 47.34 °C and pH: 8.36) yielded a degradation efficiency of 99 %, which is highly remarkable. Furthermore, based on density functional theory (DFT), the adsorption energy (Eads), charge transfer, and density of states (DOS) are investigated to study the application of tin sulfide as an adsorbent for Methylene Blue adsorption. When the MB molecule was positioned in a horizontal configuration at a distance of 3.136 Å from SnS, the significant adsorption energy of −3.22 eV was obtained. Due to the bond formation between tin atoms of SnS and carbon atoms of MB, it can be stated that there is a strong chemical interaction between SnS and MB molecule in this configuration. Regarding vertical orientation, adsorption energy was obtained to be −0.45 eV and no sign of any bond formation or breaking was observed, indicating that the adsorption process may be physisorption. The computational and experimental results proved that SnS is a promising candidate for MB adsorption and degradation.

Tin Sulfide Nanoparticles as a p-Type Semiconductor Material: Synthesis and Characterization

In this paper, the synthesis and characterization of tin sulfide as a p-type semiconductor material are reported. The low-cost, straightforward use of the transparent conductive tin sulfide technique of chemical bath deposition. The pH levels (7, 8, 9, and 10) were changed while maintaining a fixed bath temperature to create the tin sulfide nanoparticles. XRD, FTIR, and UV-visible were all used to look at the tin sulfide nanoparticles used in this study and learn about their structure and how they move light. Created via chemical bath deposition at various pH values to examine how pH affects the characteristics of the nanoparticles. Tin sulfide structural analysis and crystalline size are revealed by its X-ray diffraction pattern, and both are shown to be affected by changes in pH. Correspondingly, for pH 7, pH 8, pH 9, and pH 10. Tauc plot was used to determine the SnS nanoparticles' optical bandgap energies. From pH 7 to pH 10, it was noticed that the size of the SnS nanoparticle crystallite decreased. It was shown that the quantum confinement effect makes the band gap energy of SnS nanoparticles go up as the sizes of the crystallites get smaller. FTIR spectra confirm the dominating bond stretching of sulfur (S) and tin (Sn) atoms. The SnS nanoparticles generated with enhanced optical characteristics might be employed as an absorber layer in the development of SnS-based heterojunction solar cells, according to optical characterization, which demonstrates that the direct energy band gap (Eg), which is seen to rise with increasing pH values, is increasing with pH values.

Design of bifunctional 1D nanostructures for the catalytic conversion of carbon dioxide into cyclic carbonates

One dimensional silica-based nanotubes represent an innovative and promising morphology in the context of heterogeneous catalysis. Here these nanostructures were prepared for the first time as bifunctional materials, with hafnium or tin atoms inserted as single sites in the silica structure and imidazolium moieties anchored at the surface. The low dimensional solids thus present both acid sites owing to the presence of metal cations in tetrahedral coordination (co-catalyst) and nucleophilic species coming from the counterion of the imidazolium moieties (catalyst). The design of the catalysts consisted of two main steps. The Hf- or Sn-doped silica solids were initially prepared using a straightforward sol-gel method including a pH adjustment step allowing a quantitative insertion of the metal cations in the silica framework. These materials were post-functionalized with imidazolium moieties. The solids were extensively characterized thus confirming the presence of well-defined and open tubular structure, high specific surface area, successful insertion of Hf and Sn in the silica framework, and a correct functionalization with imidazolium salts. The different catalysts were tested in the valorization of CO2 with styrene oxide to give the corresponding cyclic carbonate. The bifunctional solids were stable and recyclable. The versatility of the best catalyst, represented by the Hf-based material, was confirmed using different epoxides. Finally, by tuning the reaction conditions or changing the imidazolium salt, a further boost of the catalytic performances was achieved.

Studying the Composition of Cluster Ions by Matrix- and Surface-Activated Laser Desorption/Ionization in Samples Obtained from Solutions of Sodium Stannate and Tin(II) Chloride

The purpose of this work was to study the composition of cluster ions in samples containing sodium stannate and tin(II) chloride. It has been shown that the composition of mass spectra is influenced by such parameters as the laser radiation energy and the substance content in the sample being studied. Conditions for preparing samples and recording mass spectra using these parameters were optimized. Presumptive identification of peaks in the recorded mass spectra was carried out. It has been shown that many of the ion peaks observed in the mass spectra may correspond to clusters containing tin. In the mass spectra of sodium stannate, ions of the general composition SnxOyNazHm were detected, in which the number of tin atoms reaches eight, and the maximum ion mass-to-charge ratio (m/z) is 1100. In the mass spectra of tin(II) chloride, there are ions of the general composition SnxOyHmClp and SnxCly, where the number of tin atoms reaches 4, and the highest m/z value is 1000.