119Sn Nuclear Magnetic Resonance Research Articles

Diorganotin (IV) amino acid complexes as potential anticancer agents. Synthesis, structural characterization, and in vitro assays

Nine new organotin (IV) derivatives from L-amino acids (l-lysine, L-ornithine, L-glutamic acid, and L-aspartic acid) were synthesized by one-pot ultrasound-assisted methodology. All compounds were characterized by ATR-FTIR (Attenuated total reflectance-Fourier Transform Infrared), LRMS (low-resolution mass spectrometry), and solution NMR (1H, 13C, 119Sn Nuclear Magnetic Resonance) spectroscopies. Complexes Bu2Sn(Lys) (1), Ph2Sn(Lys) (2), Bu2Sn(Orn) (3), and Ph2Sn (Glu-OMe) (6a) were crystallized, and the structures were established by single-crystal X-ray diffraction analysis. Diffraction results evidenced that complexes 1 to 3 were five-coordinated mononuclear species while the phenyl substituted derivative Ph2Sn (Glu-OMe) (6a) forms a polymeric network via Sn–O–Sn bridging whereby the tin atom is six-coordinated. In turn, 119Sn NMR results revealed that all tin complexes exist as mononuclear penta-coordinated species in solution. The tin derivatives were screened for ADME (Adsorption, Distribution, Metabolism, and Excretion) properties via the freely available tools SWISS ADME, and the results were analyzed hereafter. The antiproliferative activity of the complexes was tested against three human cancer cell lines: colorectal adenocarcinoma HT-29, breast adenocarcinoma MDA-MB-231, and chondrosarcoma SW-1353 using a non-tumoral cell line of human osteoblast as control, demonstrating selective inhibitory activities against cancer cells. Hence, these compounds could be a promising alternative to classical chemotherapy agents.

Synthesis, characterization and discovery of multiple anticancer mechanisms of dibutyltin complexes based on salen-like ligands

A series of novel dibutyltin complexes based on salen-like ligands (S01–S03) were synthesized and characterized using ultraviolet-visible spectra，infrared spectra, 1H, 13C, and 119Sn nuclear magnetic resonance, high-resolution mass spectrometry, X-ray crystallography, and thermogravimetric analysis. Complex S03 had excellent anticancer activity in vitro (IC50 = 1.5 ± 0.2 μM in CAL-27 cell lines), which highly activated ROS expression levels and induced apoptosis and cell cycle arrest at the G2/M phase. Interestingly, complex S03 induced cancer cell death through multiple mechanisms (mitochondrial pathway, ER-stress pathway, and DNA damage pathway). This study reveals new mechanisms of organotin complexes and provides new insights into the development of organotin metal complexes as anticancer drugs in the future, and compounds with multiple anticancer mechanisms may be a new strategy for delaying or overcoming drug resistance to chemotherapy and target therapy.

Exact two-component theory becoming an efficient tool for NMR shieldings and shifts with spin–orbit coupling

We present a gauge-origin invariant exact two-component (X2C) approach within a modern density functional framework, supporting meta-generalized gradient approximations such as TPSS and range-separated hybrid functionals such as CAM-B3LYP. The complete exchange-correlation kernel is applied, including the direct contribution of the field-dependent basis functions and the reorthonormalization contribution from the perturbed overlap matrix. Additionally, the finite nucleus model is available for the electron-nucleus potential and the vector potential throughout. Efficiency is ensured by the diagonal local approximation to the unitary decoupling transformation in X2C as well as the (multipole-accelerated) resolution of the identity approximation for the Coulomb term (MARI-J, RI-J) and the seminumerical exchange approximation. Errors introduced by these approximations are assessed and found to be clearly negligible. The applicability of our implementation to large-scale calculations is demonstrated for a tin pincer-type system as well as low-valent tin and lead complexes. Here, the calculation of the Sn nuclear magnetic resonance shifts for the pincer-type ligand with about 2400 basis functions requires less than 1 h for hybrid density functionals. Further, the impact of spin–orbit coupling on the nucleus-independent chemical shifts and the corresponding ring currents of all-metal aromatic systems is studied.

Synthesis and structural characterization of diorganotin(IV) complexes with a tridentate N‐heterocyclic podand ligand and investigation of their catalytic activity in Baeyer–Villiger oxidation of cyclic ketones to lactones

Diorganotin(IV) complexes of composition [Me2SnL] (1), [n‐Bu2SnL] (2), and [Bz2SnL] (3) were synthesized by reacting the N2,N6‐di(pyridin‐2‐yl)pyridine‐2,6‐dicarboxamide pro‐ligand (H2L, where H2 denotes the two acidic protons) with Me2SnO, n‐Bu2SnO, and Bz2SnO, respectively, in refluxing toluene. The amide ligand leads to highly stable diorganotin(IV) complexes via the dianionic tridentate donor set (Npy, N−, N−) with pendent pyridine arms, and the coordination domain is completed by the respective two alkyl ligands. Solution‐state structures of the compounds 1–3 were studied by 1H, 13C, and 119Sn nuclear magnetic resonance (NMR) spectroscopy, revealing that the complexes adopt a five‐coordinate structure in non‐coordinating solvent. Additionally, homogenity and purity of the bulk materials of 1–3 were judged using the high‐resolution mass spectrometry in acetonitrile solution. The molecular and crystal structures of 1·0.5C6H6, 2, and 3 in the solid phase were established by single‐crystal X‐ray diffraction analysis. For all three compounds, the core defined by the rigid tridentate pyridine dicarboxamide ligand and the Sn‐coordinating C atoms adopts nearly C2v symmetry and thus matches none of the most popular geometries for five‐coordinated species, namely square‐pyramidal or trigonal‐bipyramidal coordination. Thermogravimetric analysis (TGA) was performed to probe the thermal stabilities of 1–3. The results serve as a basis for designing highly efficient diorganotin(IV) mimics for catalytic applications. Catalytic studies of ε‐caprolactone formation via Baeyer–Villiger oxidation of cyclohexanone with aqueous H2O2 were performed under microwave (MW) irradiation. The consequences of several reaction parameters like catalyst quantity, time, temperature, and solvent were studied.

New Organotin (IV) Compounds Derived from Dehydroacetic Acid and Thiosemicarbazides: Synthesis, Rational Design, Cytotoxic Evaluation, and Molecular Docking Simulation.

Organotin complexes were prepared through a one-pot reaction with three components by reacting thiosemicarbazide or 4-methyl-3-thiosemicarbazide or 4-phenylthiosemicarbazide, dehydroacetic acid (DHA) and dibutyl, diphenyl, dicyclohexyl, and bis[(trimethylsilyl)methyl]tin(IV) oxides; all complexes were characterized by infrared (IR), ultraviolet-visible (UV-vis), mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectroscopy. The 119Sn NMR revealed chemical shifts corresponding to a pentacoordinated environment in solution. The X-ray crystallography of the two complexes evidenced the formation of monomeric complexes with a pentacoordinated geometry around tin via three donor atoms from the ligand, the sulfur of the thiol, the nitrogen of the imine group, and the oxygen of the pyran ring. The geometries of the five-coordinated complexes 3a (Bu2SnL3), 3c (Ph2SnL3), and 3d (Cy2SnL3) acid were intermediate between square pyramidal and trigonal bipyramidal, and complex 1a (Bu2SnL1) adopted a bipyramidal trigonal geometry (BPT). The sulforhodamine B assay assessed the cytotoxicity of organotin(IV) complexes against the MDA-MB-231 and MCF-7 (human mammary adenocarcinoma) cell lines and one normal COS-7 (African green monkey kidney fibroblast). The IC50 values evidenced a significant antiproliferative effect on cancer cells; the complexes were more potent than the positive cisplatin control and the corresponding ligands, dehydroacetic acid thiosemicarbazone (L1), dehydroacetic acid-N(4)-methylthiosemicarbazone (L2), and dehydroacetic acid-N(4)-phenylthiosemicarbazone (L3). The IC50 values also indicated that the organotin(IV) complexes were more cytotoxic against the triple-negative breast cell line MDA-MB-231 than MCF-7, inducing significant morphological alterations. The interactions of organotin(IV) 1c (Ph2SnL1), 1d (Cy2SnL1), and 1e (((CH3)3SiCH2)2SnL1) were evaluated with ss-DNA by fluorescence; intensity changes of the fluorescence were indicative of the displacement of ethidium bromide (EB), confirming the interaction of the organotin(IV) complexes with ss-DNA; the results showed a DNA binding affinity. The thermodynamic parameters obtained through isothermal titration calorimetry showed that the interaction of 1c (Ph2SnL1), with ss-ADN, was exothermic. Molecular docking studies also demonstrated that the organotin(IV) complexes were intercalated in DNA by conventional hydrogen bonds, carbon-hydrogen bonds, and π-alkyl interactions. These complexes furthermore showed a greater affinity towards DNA than cisplatin.

Effect of aliovalent bismuth substitution on structure and optical properties of CsSnBr3

Aliovalent substitution of the B component in ABX3 metal halides has often been proposed to modify the band gap and thus the photovoltaic properties, but details about the resulting structure have remained largely unknown. Here, we examine these effects in Bi-substituted CsSnBr3. Powder X-ray diffraction (XRD) and solid-state 119Sn, 133Cs and 209Bi nuclear magnetic resonance (NMR) spectroscopy were carried out to infer how Bi substitution changes the structure of these compounds. The cubic perovskite structure is preserved upon Bi-substitution, but with disorder in the B site occurring at the atomic level. Bi atoms are randomly distributed as they substitute for Sn atoms with no evidence of Bi segregation. The absorption edge in the optical spectra shifts from 1.8 to 1.2 eV upon Bi-substitution, maintaining a direct band gap according to electronic structure calculations. It is shown that Bi-substitution improves resistance to degradation by inhibiting the oxidation of Sn.

Diorganotin(IV) complexes based on tridentate ONO ligands as potential anticancer agents

Eight new diorganotin(IV) complexes (1a-2d), namely {[X-C6H4(O)C=N-N=C(Me)COO]R2Sn(CH3OH)}n (1a, 2a), {[X-C6H4(O)C=N-N=C(Me)COO]R2Sn(CH3OH)}2 (1b, 1c, 1d, 2b), and {[X-C6H4(O)C=N-N=C(Me)COO]R2Sn}2 (2c, 2d) (X = H-, p-Me-, p-OH-, p-NO2-; R = o-Cl-C6H4CH2- or o-Me-C6H4CH2-), have been synthesized by microwave “one-pot” reaction with arylformylhydrazine, pyruvic acid, and the corresponding R2SnCl2. All the complexes have been characterized by FT-IR (Fourier transform infrared spectroscopy), multinuclear NMR (1H, 13C, and 119Sn nuclear magnetic resonance spectroscopies), HRMS (high-resolution mass spectroscopy) and single-crystal X-ray structural analysis. The antiproliferative activity of all complexes was tested against the cancer cell lines NCI-H460, MCF-7 and HepG2. The diorganotin complex 1c has been shown to be more potent antitumor agents against HepG2 than other complexes and cisplatin. Flow cytometry analysis observation demonstrated that complex 1c mediated cell apoptosis of HepG2 cells and arrested cell cycle in the S phase. The single cell gel electrophoreses assay results show that the 1c induce DNA damage. The DNA binding activities of the 1c were studied by UV–visible absorption spectrometry, fluorescence competitive, circular dichroism measurements, and molecular docking, results shown 1c can be well embedded in the groove and cleave DNA.

One‐pot microwave‐assisted synthesis of dialkytin 2‐[(4‐methylbenzoyl) hydrazono]‐3‐phenylpropanoic acid complexes and their anticarcinoma activities and DNA‐binding properties

AbstractUnder microwave irradiation, five organotin complexes were produced through the reaction of 4‐methylbenzhydrazide, sodium phenylpyruvate and corresponding dialkyltin. Fourier transform infrared spectroscopy; 1H, 13C and 119Sn nuclear magnetic resonance spectroscopy; high‐resolution mass spectrometry; X‐ray crystallography and thermogravimetric analysis (TGA) were performed to characterise the synthesised complexes. The in vitro antitumour activity for the complexes involved was assessed using the MTT assay on the human carcinoma cells of HepG2, NCI‐H460 and MCF7. 2‐Oxo‐3‐pheny propionic acid p‐methyl benzoylhydrazone dibutyltin, C5, exhibited an intensive anticarcinoma activity. Cell apoptosis revealed that C5 mediated the cell apoptosis of HepG2 cells. DNA binding in C5 was investigated through UV‐visible absorption spectrometry and viscosity measurement. Molecular docking was performed for predicting C5‐DNA binding, which revealed C5 could be implanted into the DNA double helix.

Crystallochemical Characterizations, Raman Spectroscopy and Studies Nuclear Magnetic Resonance (NMR) of Cu<sub>2</sub>Zn(Sn, Si)S<sub>4 </sub> Compounds for Photovoltaic Applications

In this study, Si-doped Cu2ZnSnS4 compounds (Cu2ZnSn1-xSixS4, 0 ≤ x ≤ 1) were prepared by solid state reaction method for use of materials for photovoltaic cells. The structural and spectroscopic properties of the as-prepared compounds were studied by X-ray diffraction (XRD), 119Sn, 29Si and 65Cu Magic Angle Spinning nuclear magnetic resonance (MAS NMR) and Raman spectroscopy. The Si-substitution in the Sn-site induces three different types of XRD patterns which depend largely on the Si content in the compound. For 0 ≤ x ≤ 0.5, XRD analysis reveals the presence of a pure tetragonal phase of solid solution with I-42m as a space group. Mixed tetragonal and orthorhombic phases were observed for 0.5 1 at high content of Si (x ≥ 0.8). 119Sn MAS NMR spectra show the presence of Sn/Si disorder as a function of the Si content. The 65Cu MAS NMR spectra of the quadratic solid solution confirm the presence of the two copper sites (Cu-2a and Cu-2c) at 780 ppm while in the case of the orthorhombic solid solution samples, a very broad band is observed. The optical properties were investigated of all compounds by UV-Vis diffuse reflectance and the obtained optical band gap values (1.31 to 2.43 eV) confirm a semiconductor character.

Aroylhydrazone Diorganotin Complexes Causes DNA Damage and Apoptotic Cell Death: From Chemical Synthesis to Biochemical Effects.

Under microwave irradiation, eighteen new aroylhydrazone diorganotin complexes (1a–9b) were produced through the reaction of aroylhydrazine, 2-ketobutyric acid, and the corresponding diorganotin. Fourier transform infrared spectroscopy, 1H, 13C, and 119Sn nuclear magnetic resonance spectroscopies, high-resolution mass spectroscopy, X-ray crystallography, and thermogravimetric analysis (TGA) were performed to characterize the complexes. The in vitro anticancer activity for complexes were assessed using a CCK-8 assay on human cancer cells of HepG2, NCI-H460, and MCF-7. Complex 4b revealed more intensive anticancer activity against MCF-7 cells than the other complexes and cisplatin. Flow cytometry analysis and transmission electron microscope observation demonstrated that complex 4b mediated cell apoptosis of MCF-7 cells and arrested cell cycle in S phase. Western blotting analysis showed that 4b induced DNA damage in MCF-7 cells and led to apoptosis by the ATM-CHK2-p53 pathway. The single cell gel electrophoreses assay results showed that 4b induced DNA damage. The DNA binding activity of 4b was studied by UV–Visible absorption spectrometry, fluorescence competitive, viscosity measurements, gel electrophoresis, and molecular docking, and the results show that 4b can be well embedded in the groove and cleave DNA.

Synthesis, characterization, and antioxidant material activities of organotin (IV) carboxylates with tin-para methoxy benzoic acid

This study compares whether the antioxidant activity of Para Methoxy Benzoic Acid (L) and its organotin complexes has increased or decreased using methods of: 2,2-diphenyl-1-picrylhydrazyl (DPPH) and CUPRAC technique for di and tri-organotin(IV) compounds. The condensation reactions of Tin-Para Methoxy Benzoic Acid as a ligand with di and tri-organotin(IV) compounds yielded four organotin complexes (1–4). Infrared spectroscopy (FTIR), 119Sn nuclear magnetic resonance (NMR), and 1H NMR techniques were utilized to investigate the resultant complexes. Because of the metal moiety, the ensuing organic tin(IV) complexes exhibited stronger antioxidant activity than the ligands produced from it, and compound 3 had higher antioxidant activity than the others.

119Sn and 7Li Solid-State NMR of the Binary Li–Sn Intermetallics: Structural Fingerprinting and Impact on the Isotropic 119Sn Shift via DFT Calculations

We report the 119Sn and 7Li solid-state nuclear magnetic resonance (NMR) spectroscopic characterization of all thermodynamically stable intermetallic phases of the binary Li–Sn system. The isotropi...

Design of Promising Heptacoordinated Organotin (IV) Complexes-PEDOT: PSS-Based Composite for New-Generation Optoelectronic Devices Applications.

The synthesis of four mononuclear heptacoordinated organotin (IV) complexes of mixed ligands derived from tridentated Schiff bases and pyrazinecarboxylic acid is reported. This organotin (IV) complexes were prepared by using a multicomponent reaction, the reaction proceeds in moderate to good yields (64% to 82%). The complexes were characterized by UV-vis spectroscopy, IR spectroscopy, mass spectrometry, 1H, 13C, and 119Sn nuclear magnetic resonance (NMR) and elemental analysis. The spectroscopic analysis revealed that the tin atom is seven-coordinate in solution and that the carboxyl group acts as monodentate ligand. To determine the effect of the substituent on the optoelectronic properties of the organotin (IV) complexes, thin films were deposited, and the optical bandgap was obtained. A bandgap between 1.88 and 1.98 eV for the pellets and between 1.23 and 1.40 eV for the thin films was obtained. Later, different types of optoelectronic devices with architecture “contacts up/base down” were manufactured and analyzed to compare their electrical behavior. The design was intended to generate a composite based on the synthetized heptacoordinated organotin (IV) complexes embedded on the poly(3,4-ethylenedyoxithiophene)-poly(styrene sulfonate) (PEDOT:PSS). A Schottky curve at low voltages (<1.5 mV) and a current density variation of as much as ~3 × 10−5 A/cm2 at ~1.1 mV was observed. A generated photocurrent was of approximately 10−7 A and a photoconductivity between 4 × 10−9 and 7 × 10−9 S/cm for all the manufactured structures. The structural modifications on organotin (IV) complexes were focused on the electronic nature of the substituents and their ability to contribute to the electronic delocalization via the π system. The presence of the methyl group, a modest electron donor, or the non-substitution on the aromatic ring, has a reduced effect on the electronic properties of the molecule. However, a strong effect in the electronic properties of the material can be inferred from the presence of electron-withdrawing substituents like chlorine, able to reduce the gap energies.

Magnetic anisotropy and spin dynamics in the kagome magnet Fe4Si2Sn7O16 : NMR and magnetic susceptibility study on oriented powder

${\mathrm{Fe}}_{4}{\mathrm{Si}}_{2}{\mathrm{Sn}}_{7}{\mathrm{O}}_{16}$ hosts an undistorted kagome lattice of ${\mathrm{Fe}}^{2+}$ ($3{d}^{6}, S=2$) ions. We present results of bulk magnetization and Sn nuclear magnetic resonance (NMR) measurements on an oriented ${\mathrm{Fe}}_{4}{\mathrm{Si}}_{2}{\mathrm{Sn}}_{7}{\mathrm{O}}_{16}$ powder sample oriented in geometries parallel ($\ensuremath{\parallel}$) and perpendicular ($\ensuremath{\perp}$) to the external applied magnetic field used for orienting the powder (${B}_{\text{ori}}$). The bulk susceptibility $\ensuremath{\chi}$ shows a broad peak at ${T}_{N}\ensuremath{\sim}3$ K associated with antiferromagnetic ordering. NMR spectra indicate the presence of planar anisotropy in the kagome planes. From an analysis of the static NMR shift ($K$) and dynamic spin-lattice relaxation rate ($1/{T}_{1}$) we conclude the presence of dominant magnetic fluctuations in the kagome planes. For the $\ensuremath{\parallel}$ orientation, $K$ scales linearly with the bulk susceptibility for temperatures down to $\ensuremath{\sim}4$ K, while in the $\ensuremath{\perp}$ orientation $K$ starts to deviate strongly below $T\ensuremath{\sim}30$ K. We associate this deviation with the onset of spin-tilting towards the kagome planes. These correlations are also reflected in the $1/{T}_{1}$ data for the $\ensuremath{\parallel}$ orientation, which starts to decrease below $T\ensuremath{\sim}30$ K. In this correlated regime, ${T}_{N}&lt;T&lt; \ensuremath{\sim}30$ K, we discuss the formation of positive chiral spin correlations in the kagome planes.

Anisotropic superconductivity and quantum oscillations in the layered dichalcogenide TaSnS2

${\mathrm{TaSnS}}_{2}$ single crystal and polycrystalline samples are investigated in detail by magnetization, electrical resistivity, and specific heat as well as Raman spectroscopy and nuclear magnetic resonance (NMR). Studies are focused on the temperature and magnetic field dependence of the superconducting state. We determine the critical fields for both directions $B\ensuremath{\parallel}c$ and $B\ensuremath{\perp}\phantom{\rule{0.16em}{0ex}}c$. Additionally, we investigate the dependence of the resistivity, the critical temperature, and the structure through Raman spectroscopy under high pressure up to 10 GPa. At a pressure of $\ensuremath{\approx}3\phantom{\rule{0.28em}{0ex}}\mathrm{GPa}$ the superconductivity is suppressed below our minimum temperature. The Sn NMR powder spectrum shows a single line which is expected for the ${\mathrm{TaSnS}}_{2}$ phase and confirms the high sample quality. Pronounced de Haas-van Alphen oscillations in the ac susceptibility of polycrystalline sample reveal two pairs of frequencies indicating coexisting small and large Fermi surfaces. The effective mass of the smaller Fermi surface is $\ensuremath{\approx}0.5{m}_{\mathrm{e}}$. We compare these results with the band structures from DFT calculations. Our findings on ${\mathrm{TaSnS}}_{2}$ are discussed in terms of a quasi-two-dimensional BCS superconductivity.

Triorganotin(IV) derivatives with semirigid heteroditopic hydroxo‐carboxylato ligands: Synthesis, characterization, and cytotoxic properties

Three organic hydroxy‐carboxylic acids separated by a semirigid aromatic diaza scaffold and carrying alkyl groups of different steric hindrance (H′HL1, cyclopropyl; H′HL2, cyclohexyl; H′HL3, adamantyl) were employed as pro‐ligands. Their reaction with suitable triorganotin precursors leads to 10 complexes of compositions: [Me3Sn(HL1)]n·0.5nC6H5CH3 1, [Et3Sn(HL1)]n 2, [nBu3Sn(HL1)]n 3, [Ph3Sn(HL1)]n 4, [Me3Sn(HL2)]2·2CH2Cl2 5, [Et3Sn(HL2)]2 6, {[nBu3Sn(HL2)][nBu3Sn(HL2)(H2O)]} 7, [Ph3Sn(HL2)]n·nC2H5OH 8, [nBu3Sn(HL3)]n 9, and [Ph3Sn(HL3)]n 10. The solid‐state structures of 1–10 were deduced from single‐crystal X‐ray diffraction studies along with two of the pro‐ligands: H′HL1 and H′HL2. In the solid state, four different extended structure types were observed. In compounds 1–3 with aliphatic substituents at the tin atoms and a small substituent at the ligand backbone (cyclopropyl), 1D coordination polymers based on carboxylate bridging were observed, whereas compounds 4 and 8–10 with large substituents attached to the metal and the ligand (cyclohexyl and adamantyl) were 1D coordination polymers based on heteroditopic binding of the ligands. Albeit having essentially the same ligand conformation, the compounds having smaller substituents at the tin atoms (5, R = Me; 6, R = Et) comprise 24‐membered macrocyclic ring structures. In 7, water molecules are coordinated to half the tin atoms, giving dinuclear fragments {[HL2][nBu3Sn][HL2][nBu3Sn(H2O)]}, which are linked through OwH···Osal hydrogen bonds into 1D hydrogen‐bonded tapes. In solution, the tin atoms in 1–10 are coordinated to a single monoanionic [HL1–3]− ligand molecule utilizing anisobidentate coordination with the carboxylate group, as revealed from 119Sn nuclear magnetic resonance spectral results. The antiproliferative activity of the tri‐n‐butyl and triphenyltin compounds 3, 4, and 7–10 was evaluated against the cervical cancer cells (HeLa) and normal kidney cells (HEK) using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay. Of these, the adamantyl‐substituted tin complexes 9 and 10 present increased activity with IC50 values of 0.51 ± 0.01 and 0.41 ± 0.03 (μM) and good selectivity. The cell death mechanism was identified as apoptosis based on dual staining with fluorescent dyes (Hoechst 33342/propidium iodide and acridine orange/ethidium bromide) and might be related to reactive oxygen species.

A Surface Morphological Study, Poly(Vinyl Chloride) Photo-Stabilizers Utilizing Ibuprofen Tin Complexes against Ultraviolet Radiation

In this work, three Ibuprofen tin complexes were synthesized and characterized by Fourier Transform Infrared spectroscopy (FTIR), 1H and 119Sn-Nuclear Magnetic Resonance (NMR), and Energy Dispersive X-ray (EDX) spectroscopies to identify the structures. The complexes were mixed separately with poly(vinyl chloride) (PVC) to improve its photo-stability properties. Their activity was demonstrated by several approaches of the FTIR to exhibit the formation of new groups within the polymer structure due to the exposure to UV light. Moreover, the polymer’s weight loss during irradiation and the average molecular weight estimation using its viscosity before and after irradiation were investigated. Furthermore, different techniques were used to study the surface morphology of the PVC before and after irradiation. Field-emission scanning electron microscopy (FESEM) and optical microscope demonstrated that applying Ibuprofen tin complexes keeps the surface of PVC smoother, with fewer cracks and spots after irradiation comparing to the blank PVC. Finally, It seems possible that such synthesized Ibuprofen tin complexes can work as excellent photo-stabilizers of PVC. In particular, complex 1 showed the best results among other stabilizers due to the large conjugation system of the stabilizer.

Phase Evolution in Methylammonium Tin Halide Perovskites with Variable Temperature Solid-State 119Sn NMR Spectroscopy

Hybrid organic–inorganic metal-halide perovskite materials are an emerging class of materials that could profoundly change the optoelectronic and solar absorber research fields and have far-reaching applications. Unfortunately, the leading solar-absorbing candidates are lead-containing materials and suffer from chemical instability, eventually decomposing, resulting in detrimental long-term environmental concerns. A series of nontoxic group 14 Sn(II)-based hybrid organic–inorganic metal-halide perovskites is investigated using variable-temperature solid-state nuclear magnetic resonance (NMR) spectroscopy to examine their unique phases that appear between 150 and 540 K. Each phase of the MASnX3 (MA+ = CH3NH3+ and X– = Cl–, Br–, or I–) series is identified and compared to results from quantum chemical calculations of anionic polyhedron clusters. The analysis of the polyhedra about the Sn center is further related to the measured chemical shift anisotropy present when Sn deviates from octahedral symmetry. We also discuss the rapid degradation of pristine MASnI3 over 2 days studied using in situ 119Sn NMR spectroscopy. Finally, we report on the 1H, 13C, 119Sn, and 207Pb NMR structural properties of a Sn/Pb mixed B-site (MASn0.5Pb0.5I3) perovskite, demonstrating the sensitivity of the chemical shift to B-site substitution.

NMR and EPR study of cubic π-phase SnS semiconductor nanoparticles

We report an 119Sn nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) study of cubic π-phase SnS semiconductor nanoparticles. The data are compared with orthorhombic α-SnS. The NMR spectrum of cubic SnS reveals two inequivalent tin atoms in its crystal structure. The spin-lattice relaxation time of 119Sn nuclei in the cubic phase is much longer than that in the orthorhombic phase, indicating that the former is mainly governed by Raman scattering, while the latter is dominated by interaction of nuclear spins with unpaired electron spins of paramagnetic defects. This is supported by EPR measurements showing much larger content of paramagnetic defects in the orthorhombic phase compared with the cubic phase. The study provides novel research findings on the physical properties of the newly discovered cubic π-SnS, which is an emerging semiconducting material system for various applications.

Butyltin Keggin Ion with a Rare Four-Coordinate Ca Center.

Alkyltin clusters are exploited in nanolithography for the fabrication of microelectronics. The alkyltin Keggin family is unique among Keggin clusters across the periodic table; its members appear to favor the lower-symmetry β and γ isomers rather than the highly symmetrical α and ε isomers. Therefore, the alkyltin Keggin family may provide important fundamental information about the formation and isomerization of Keggin clusters. We have synthesized and structurally characterized a new butyltin Keggin cluster with a tetrahedral Ca2+ center, fully formulated [(BuSn)12(CaO4)(OCH3)12(O)4(OH)8]2+ (β-CaSn12). The synthesis is a simple one-step process. Extensive solution characterization including electrospray ionization mass spectrometry, small-angle X-ray scattering, and multinuclear (1H, 13C, and 119Sn) nuclear magnetic resonance shows β-CaSn12 is essentially phase-pure and stable. This differs from the previously reported Na-centered analogues that always form a mixture of β and γ isomers, with facile interconversion. Therefore, this study has clarified prior confusion over complex spectroscopic and crystallographic characterization of the Na-centered analogues. Density functional theory calculations showed the following stability order: γ-CaSn12 < γ-NaSn12 < β-CaSn12 < β-NaSn12. The β analogue is always more stable than the γ analogue, consistent with experiment. Notable outcomes of this study include a rare tetrahedral Ca coordination, a Na-free alkyltin cluster (important for microelectronics manufacturing), and a better understanding of Keggin families built of different metal cations.