Sn Bond Research Articles

TiO2 supported on reed straw biochar as an adsorptive and photocatalytic composite for the efficient degradation of sulfamethoxazole in aqueous matrices

Heterogeneous photocatalysis namely titanium dioxide supported on reed straw biochar (acid pre-treated) (TiO2/pBC) was synthesized by sol-gel method. The morphology, surface area and structure of TiO2/pBC were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), and X-ray diffraction (XRD). Low calcination condition maintained the structure of biochar completely and prevented the agglomeration of TiO2 particles. Due to the combination of adsorption and photocatalysis, TiO2/pBC performed higher removal efficiency of sulfamethoxazole (SMX) than pure TiO2 powder under UV light irradiation. The photocatalytic degradation (PCD) of SMX was also studied with the water collected from the Yellow River. Three high concentration inorganic anions (Cl−, NO3−, SO42−) of the river exerted certain degree of detrimental effects on the contaminant degradation. TiO2/pBC showed stable photocatalytic activity after five sequential PCD cycles. The biochar was able to promote further PCD on TiO2 by adsorbing SMX and intermediates thereby prolonging the separation lifetime of electrons (e−) and valence band hole (h+). The transformation intermediates of SMX were identified and three possible degradation reactions of hydroxylation, opening of isoxazole ring and cleavage of SN bond might occur during the PCD of SMX.

Oxidation of sulfonamide antibiotics by chlorine dioxide in water: Kinetics and reaction pathways

Sulfonamides (SAs), commonly used as human and veterinary antibiotics, are of great concerns because of their frequent detections in aquatic environment. This study investigated the oxidation of six SAs (i.e., sulfamethoxazole (SMX), sulfamethizole, sulfamethazine, sulfadimethoxine, sulfamerazine, and sulfathiazole) by chlorine dioxide (ClO2). The results indicate that the reactions followed the second-order kinetic model, with rate constants ranging from 3.85×103 to 2.59×104M−1s−1 at pH 7.0 and 20°C. For each SA, the rate constant increased by 1.6–2.2 orders of magnitude as the solution pH increased from 4.0 to 9.5. The activation energies of the selected SAs ranged from 31.6 to 39.8kJmol−1. In addition, SMX was selected as a model compound to explore the degradation pathways during ClO2 oxidation. The reactivity of SMX toward ClO2 was strongly related to the ionization equilibrium of the amido-nitrogen in SMX molecule. The cleavage of SN and CS bonds and the hydroxylation of aniline moiety in the SMX molecule constituted the major degradation pathways. ClO2 oxidation was likely to decrease the antibacterial activity of SMX solution because of the destruction of p-aminobenzenesulfonamide moiety. The obtained rate constants could well predict the fate of SAs during ClO2 oxidation in a surface water, where an effective removal of SAs by ClO2 can be expected under practical water treatment conditions.

Theoretical insights into the nature of PtSn bond: Reevaluating the bonding/back-bonding properties of trichlorostannate with comparison to the cyano ligand.

The coordinating properties of the trichlorostannate ligand in hydrido platinum trichlorostannato and platinum bis-trichlorostannato complexes, containing various phosphine ligands, have been elucidated by means of charge decomposition analysis, the Ziegler-Rauk Energy Decomposition with the Natural Orbitals for Chemical Valence, Domain-Averaged Fermi Hole, and natural bond orbital methods. Trichlorostannate has been found to be a strong σ-donor and a weak π-acceptor ligand with coordination properties not far from those of the cyano ligand. For back-bonding, the tin-chlorine σ∗ orbitals are mostly responsible. In contrast to previous assumptions, the 5d orbitals of tin play no role at all in the interaction with the platinum center. QTAIM calculations suggest, that the platinum-tin interaction should be interpreted as donor-acceptor, rather than covalent type. Trichlorostannate has been found to have weaker trans influence in comparison to the cyano ligand. © 2017 Wiley Periodicals, Inc.

Thermoelectric properties and figure of merit of perovskite-type Sr1−xLaxSnO3 ceramics

Abstract The thermoelectric properties of perovskite-type Sr 1−x La x SnO 3 ceramics with x=0.01–0.05 were evaluated from the Seebeck coefficient S , electrical conductivity σ , and thermal conductivity κ measured at high temperatures. The La-doped ceramics were n -type semiconductors exhibiting thermally activated electrical conduction behaviors in the temperature range of 473–1073 K. Eelectron carriers were introduced into the conduction band from doped La atoms up to x=0.03, which was the solubility limit of La at Sr site. The temperature dependence of the κ values for the ceramics was unaffected by both the La content and the microstructures. Estimations of the electronic thermal conductivities by the Wiedemann-Franz law revealed that the phonon thermal conductivities were dominant for all ceramics. The dimensionless figure of merit ZT increased with increasing temperature for all ceramics and reached 0.02–0.05 at 1073 K. In contrast to cubic Ba 1−x La x SnO 3 ceramics, bending of the Sn–O–Sn bonds due to octahedral tilting distortion in Sr 1−x La x SnO 3 lowered the electron mobility, decreasing the power factor S 2 σ and ZT values, although it effectively reduced the phonon mean free path, decreasing the κ values.

Coordination Chemistry of [E(Idipp)]2+Ligands (E = Ge, Sn): Metal Germylidyne [Cp*(CO)2W≡Ge(Idipp)]+and Metallotetrylene [Cp*(CO)3W–E(Idipp)]+Cations

The synthesis and full characterization of the NHC-stabilized tungstenochlorostannylene [Cp*(CO)3W–SnCl(Idipp)] (1Sn), the NHC-stabilized chlorogermylidyne complex [Cp*(CO)2W═GeCl(Idipp)] (2), the tungsten germylidyne complex salt [Cp*(CO)2W≡Ge(Idipp)][B(C6H3-3,5-(CF3)2)4] (3), and the cationic metallostannylene [Cp*(CO)3W–Sn(Idipp)][Al(OC(CF3)3)4] (4Sn) are reported (Idipp = 2,3-dihydro-1,3-bis(2,6-diisopropylphenyl)-1H-imidazol-2-ylidene, Cp* = η5-C5Me5). Metathetical exchange of SnCl2(Idipp) with Li[Cp*W(CO)3] afforded selectively 1Sn. Photolytic decarbonylation of the Ge analogue [Cp*(CO)3W–GeCl(Idipp)] (1Ge) afforded the NHC-stabilized chlorogermylidyne complex (2), featuring a trigonal-planar coordinated germanium center and a W–Ge double bond (W–Ge 2.3496(5) Å). Chloride abstraction from 2 with Na[B(C6H3-3,5-(CF3)2)4] yielded the germylidyne complex salt 3, which contains an almost linear W–Ge–C1 linkage (angle at Ge = 168.7(1)°) and a W–Ge triple bond (2.2813(4) Å). Chloride elimination from 1Ge afforded the tungstenogermylene salt [Cp*(CO)3W–Ge(Idipp)][B(C6H3-3,5-(CF3)2)4] (4Ge), which in contrast to 1Ge could not be decarbonylated to form 3 despite the less strongly bound carbonyl ligands. The tin compounds 1Sn and 4Sn did not afford products bearing multiple W–Sn bonds. Treatment of 4Ge with Me2NC≡CNMe2 yielded unexpectedly the neutral germyl complex 5 containing a pendant 1-germabicyclo-[3,2,0]-hepta-2,5-diene ligand instead of the anticipated [2 + 1]-cycloaddition product at the Ge-center.

Effect of substrate temperature on the morphological, structural, and optical properties of RF sputtered Ge1−xSnx films on Si substrate**Project supported by the Universiti Sains Malaysia (Grant No. 1001/PFIZIK/846072).

In this study, Ge1−xSnx alloy films are co-sputtered on Si(100) substrates using RF magnetron sputtering at different substrate temperatures. Scanning electron micrographs, atomic force microscopy (AFM), Raman spectroscopy, and x-ray photoemission spectroscopy (XPS) are conducted to investigate the effect of substrate temperature on the structural and optical properties of grown GeSn alloy films. AFM results show that RMS surface roughness of the films increases from 1.02 to 2.30 nm when raising the substrate temperature. This increase could be due to Sn surface segregation that occurs when raising the substrate temperature. Raman spectra exhibits the lowest FWHM value and highest phonon intensity for a film sputtered at 140 °C. The spectra show that decreasing the deposition temperature to 140 °C improves the crystalline quality of the alloy films and increases nanocrystalline phase formation. The results of Raman spectra and XPS confirm Ge–Sn bond formation. The optoelectronic characteristics of fabricated metal-semiconductor-metal photodetectors on sputtered samples at room temperature (RT) and 140 °C are studied in the dark and under illumination. The sample sputtered at 140 °C performs better than the RT sputtered sample.

Synthesis of sulfonamides from azoles and sodium sulfinates at ambient temperature

NBS or NIS mediated direct SN bond formation between azoles and sodium sulfinates is described. The reaction shows good substrate scope and tolerates a wide range of functionalities in both azoles and sodium sulfinate substrates. Pyrazoles are also suitable for this method, various 4-halopyrazoles derivatives were obtained by using N-halosuccinimide (NXS) as the halogen source.

Ideal Strength and Deformation Mechanism in High-Efficiency Thermoelectric SnSe

The widespread use of thermoelectric conversion technology requires thermoelectric materials of high thermoelectric efficiency and high fracture strength. Single crystal SnSe shows an extremely high zT value in the moderate temperature range, but its mechanical properties have rarely been studied so far. Here we use density functional theory to determine the ideal strength and deformation mechanism of perfect SnSe single crystals for shear deformations. The lowest ideal strength of SnSe is found to be 0.59 GPa under the (100)/⟨001⟩ shear load, which agrees with experimental evidence that single crystals cleave along the (100) slip plane. The van der Waals-like Se–Sn bond, which couples the different Se–Sn layered substructures, is much softer than the covalent Se–Sn bond which constructs the Se–Sn layered substructure. This creates pathways of easy slip between Se–Sn layered substructures, which can release shear stress and lead to structural failure. Meanwhile, the layered substructures themselves can re...

Heteroatoms doped graphene for catalytic ozonation of sulfamethoxazole by metal-free catalysis: Performances and mechanisms

In this study, reductive graphene oxides (rGO) and heteroatoms (N and P) doped graphene oxides (NGO, PGO) were synthesized and firstly applied in catalytic ozonation of sulfamethoxazole (SMX). As metal-free materials, NGO and PGO were found to exhibit significant abilities in catalytic ozonation of SMX, of which the efficiency were both more than 2.5 times to ozonation system and 1.5 times to the undoped rGO, respectively. Materials characterization showed the doping of heteroatoms into graphene oxides layers would modulate the configuration and properties of graphene oxides meanwhile create new active sites to enhance the catalytic performance. Density functional theory (DFT) calculations were then employed to give an in-depth probe of the degradation mechanism. The theoretical calculations were in good correspondence with the experimental results, indicating that the S atom was the most susceptible attacking site, which resulted in the cleavage of SN and SC bond of SMX during the catalytic ozonation processes. This study proposes a new insight into catalytic ozonation of SMX by NGO and PGO materials.

Silver(i)-promoted insertion into X-H (X = Si, Sn, and Ge) bonds with N-nosylhydrazones.

Silver(i)-promoted carbene insertion into X-H (X = Si, Sn, and Ge) bonds has been realized by using unstable diazo compounds, which are generated in situ from N-nosylhydrazones as carbene precursors. The reaction tolerates a wide range of functional groups and delivers a number of valuable silicon-containing compounds in very high yields (up to 96%). Moreover, organostannanes and organogermanes were as well effectively obtained in very good yields under optimal conditions.

119Sn MAS NMR Study of the Interaction of Probe Molecules with Sn-BEA: The Origin of Penta- and Hexacoordinated Tin Formation

119Sn CPMG MAS NMR was applied to study the adsorption of acetonitrile, methanol, isopropyl alcohol, isobutyl alcohol, and water over Sn-BEA enriched with 119Sn isotope. Two signals observed at ca. −422 and −443 ppm over dehydrated samples were attributed to tetracoordinated framework tin sites with strong and weak Lewis acidity, respectively. The adsorption of acetonitrile and methanol resulted in the observation of pentacoordinated tin species, due to the formation of 1:1 adsorption complexes over both Sn sites. Water adsorption led first to formation of pentacoordinated tin species, which were further converted into hexacoordinated species at longer reaction times. The latter transformation was found to be kinetically limited and was attributed to chemical interaction of tin sites with water, such as hydrolysis of Si–O–Sn bonds. The adsorption of isopropyl alcohol and isobutyl alcohol was accompanied by the formation of pentacoordinated Sn species in the case of weak sites and hexacoordinated Sn over s...

Photochemical transformation of the plant activator Acibenzolar-S-methyl in solution

Acibenzolar-S-methyl (BTH) is used to protect plants from pathogens by triggering Systemic Acquired Resistance. While this compound absorbs solar light strongly, little is known on its ability to undergo photodegradation and on the generated photoproducts. In the present work, we studied the photolysis of BTH dissolved in solvents of different polarities: n-heptane to mimic the hydrophobic surface of leaves and more polar solvents to simulate polar environmental compartments. We found that BTH is easily photodegraded in simulated solar light. The quantum yield of photolysis at 313 nm ranges from 0.048 to 0.092 depending on the solvent. LC-ESI-HRMS analyses in negative and positive modes revealed the presence of numerous photoproducts arising from two initial reaction pathways. As confirmed by DFT calculations, the main pathway involves the SN bond cleavage followed by N2 loss. The scission of the thioester bond with the generation of acyl and SCH3 radicals also takes place. Based on these findings, it can be predicted that BTH should undergo fast photodegradation once released in the environment and lead to numerous new compounds.

Evolution of Raman and Mössbauer spectra at high pressures up to 75 GPa and a phase transition in CaSnO3 perovskite

Raman and Mossbauer spectra from 119Sn nuclei in CaSnO3 perovskite have been studied at high pressures up to 75 GPa. A linear increase in the frequency of the main Raman modes and a monotonic decrease in the isomer shift in Mossbauer spectra in the pressure range of 0–40 GPa are established. It is shown that the pressure-induced increase in Raman frequencies can be associated with the variation of the angle between the Sn–O–Sn bonds in chains of oxygen octahedra SnO6 along the c axis. The sharp variation of the parameters of the Raman and Mossbauer spectra is observed in the pressure region of 40–55 GPa, indicating the structural phase transformations, which can be associated with the transition into the post-perovskite state. Raman spectra of CaSnO3 samples with the ilmenite structure have been obtained for the first time.

ChemInform Abstract: Gold‐Catalyzed Bis(stannylation) of Propiolates.

The first example of gold-catalyzed addition of Sn–Sn bonds to alkynes is reported. A cationic gold(I) complex bearing a phosphite ligand is reported to efficiently catalyze the bis(stannylation) of propiolates with hexabutylditin under mild conditions.

Remote Substituent Effects on the Structures and Stabilities of P═E π-Stabilized Diphosphatetrylenes (R2P)2E (E = Ge, Sn).

A rare P-E π interaction between the lone pair of a planar P center and the vacant p orbital at the Ge or Sn center provides efficient stabilization for P-substituted tetrylenes (R2P)2E (E = Ge, Sn) and enables isolation of the first example of a compound with a crystallographically authenticated P═Sn bond. Subtle changes in the electronic properties of the bulky aryl substituents in these compounds change the preference for planar versus pyramidal P centers in the solid state; however, variable-temperature NMR spectroscopy indicates that in solution these species are subject to a dynamic equilibrium, which interconverts the planar and pyramidal P centers. Consistent with this, density functional theory studies suggest that there is only a small energy difference between the planar and pyramidal forms of these compounds and reveal a small singlet-triplet energy separation, suggesting potentially interesting reactivities.

Tamejiro Hiyama

Tamejiro Hiyama

Radical Cations of the Monomer and van der Waals Dimer of a Methionine Residue as Prototypes of (2 Center-3 Electron) SN and SS Bonds. Molecular Simulations of Their Absorption Spectra in Water.

Oxidation of peptides or proteins by the OH(•) radicals produced by pulse radiolysis yields species identified by their absorption spectra in the UV-visible domain. However, the case of methionine (Met) in peptides is complex because its oxidation can lead to various free radicals with 2 center-3 electron (2c-3e) bonds. We have performed Monte Carlo/density functional theory molecular simulations of the radical cation of the methylated methionine aminoacid, Met(•+), taken as a model of the methonine residue of peptides, and of the radical cation of its van der Waals dimer, Met2(•+). The cation of the methionine residue displays a 2c-3e SN bond. The cation of dimer Met2(•+) displays three quasidegenerate conformers, one stabilized by a 2c-3e SS bond and the other two stabilized by ion-molecule interactions and made up of a neutral and a cationic unit. These conformers are characterized by their charge and spin density localization and their UV-visible absorption spectra. These spectra enable a discussion of the absorption spectra of the literature; in particular, we emphasize the role of dimers before and after the oxidation process.

Optimization of contact metallizations for reliable wafer level Au[sbnd]Sn bonds

In this study, the focus was on the design for reliable wafer level hermetic Sn-Au based interconnection for MEMS devices by optimizing the contact metallization structures. The investigations were done in two parts: i) the formation and evolution of interconnection microstructures in AuSn|Cu, AuSn|Ni and AuSn|Pt systems were studied with bulk diffusion couples and ii) thin film structures (i.e. adhesion layers and diffusion barriers) for Pt metallization on AuSn SLID bonded wafers were investigated from manufacturability and reliability viewpoints. The failure analysis was carried out on as bonded as well as aged interconnections. Distinct thin film structures showed clear differences in shear strength and fracture mechanisms. The mechanical reliability of the interconnection was increased by i) introducing sputtered Ni metallization between TiW and AuSn bond, ii) increasing the Pt thickness from 100nm to 200nm and iii) using Mo diffusion barrier underneath the Pt layer. Based on the results obtained from diffusion couples the thermodynamic descriptions of the ternary systems were re-assessed and the thermodynamic data was utilized in rationalizing the observed interconnection microstructures, failure mechanisms in thin film samples and the effect of Pt metallization thickness on the re-melting temperature of the SLID bond.

Bis- and tris-phosphinostannane gold complexes featuring Au → Sn dative interactions: Synthesis, structures, and DFT calculations

As part of our interest in the coordination chemistry of heavy Group 14 elements, we have synthesized complexes of general formula [(o-(Ph2P)C6H4)2SnClPh]AuX (X=Cl (2-Cl), X=Br (2-Br), and X=I (2-I)) in which the chlorostanane unit acts as a σ-acceptor ligand toward gold. The existence of a Au→Sn dative bond is evidenced by a trigonal bipyramidal geometry about the tin atom as well as a distorted square planar geometry about the gold center. While the measured Au–Sn bond distances are crystallographically indistinguishable in this series, theoretical investigations reveal that the strength of the Au→Sn interaction increases in the order 2-I<2-Br<2-Cl. These results suggest that the Au→Sn interaction is affected by the ligands around gold. Lastly, we also report the tripodal complex [(o-(Ph2P)C6H4)3SnCl]AuSnCl3 (4) in which the gold atom is concomitantly coordinated to a Z-type tin ligand and an X-type tin ligand.

Anticarcinogenicity and Toxicity of Organotin(IV) Complexes: A Review

The excellent anticarcinogenicity and toxicity of organotin(IV) complexes of certain acrylates, methylenedioxyphenylpropenoic acid, piperonylic acid, phenylethanoates, carboxylic acid, acetic acid, benzohydroxamato, peptides, dipeptides, benzoates, schiff bases, xylene, nicotinic acid, pyrimidine, and aminoalcohols have been reviewed here. The high cytotoxic activity of complexes is affected by (1) the availability of coordination positions at Sn and (2) the occurrence of relatively stable ligand–Sn bonds, e.g., Sn–N and Sn–S, and which result in less hydrolytic decomposition. Furthermore, the lipophilicity due to the presence of the number of carbon atoms in the organotin moiety of organotin(IV) complexes warranted its impressive antitumor activity and cytotoxicity. The cytotoxic activity exhibited by [Ph3Sn(Meclo)] against L-929, A-549, and T24 cell lines shows that the coupling of meclofenamic acid to SnPh3(IV) metal center results in a metallic complex with important biological properties and remarkable cytotoxic activity, since it exhibits IC50 values in a micromolar range better to that of the antitumor drug cisplatin. However, it is observed during biological testing that the major role is attributed to the alkyl/aryl groups attached to tin atom, while ligands play secondary role.