Presence Of SnCl4 Research Articles

Technetium-99m radiolabeling of graphene quantum dots (GQDs) as a new probe for glioblastoma tumor imaging

Purpose Cancer diagnosis involves a multi-step process. Accurate identification of the tumor, staging and development of cancer cells is crucial for selecting optimal treatments to minimize disease recurrence. Quantum dots (QDs) represent an exciting class of fluorescent nanoprobes in molecular detection and targeted tumor imaging. Materials and methods In this study, graphene quantum dots (GQDs) were synthesized by pyrolysis of citric acid (CA) as a carbon precursor under high temperatures. The morphology of the obtained GQDs was first characterized using physical (TEM and DLS) and spectroscopic (fluorescence, FTIR and UV–Vis) methods. In the following,99mTc-labeled GQDs were prepared in the presence of SnCl2.2H2O as a reducing agent between 95 and 100 °C. The biodistribution and tumor targeting efficiency of radiolabeled GQDs as a novel agent for C6 glioma tumor scintigraphy in an animal model were evaluated. Furthermore, organ uptake, human serum albumin binding and tumor accumulation were measured. Results The TEM image of the prepared GQDs showed a relatively uniform size distribution in the range of diameter 6-9 nm and spherical shape. Radiolabeled GQDs showed a radiochemical yield of >97% (n = 3). Through incubation in human serum, almost 15% of 99mTc-labeled GQDs degraded after 6 h. The amount of uptake in xenograft models of glioma C6 rats was 1.10 ± 0.36% of injection dose per gram after 1 h. The kidneys, intestinal and glioma tumor sites were observed via scintigraphy imaging. Conclusion Our data suggest that 99mTc-labeled GQDs, as a new radiotracer, efficiently accumulate in the tumor site and could be included as a radiotracer for detecting glioma tumors.

Development of Novel Amino Acids Containing N‐mercaptophenetyl (MPE)‐type Auxiliary and Orthogonal Protecting Groups for Sequential Ligation of Multiple Peptides

AbstractChemoselective peptide ligation using ligation auxiliaries is a powerful methodology to extend the scope of native chemical ligation beyond ligation at Cys. Herein, we report the development of novel amino acids containing an N‐mercaptophenethyl (MPE)‐type auxiliary and protecting groups (i. e., tert‐butyloxycarbonyl (Boc), 1,3‐thiazolidine (Thz), and allyloxycarbonyl (Alloc)). These developed amino acids can be introduced into a peptide via 9‐fluorenylmethoxycarbonyl‐based solid‐phase peptide synthesis, enabling deprotection and native chemical ligation in one pot. The combination of Thz‐type and Alloc‐type acids enables sequential peptide ligation, which is applicable to the synthesis of peptides branched from a Lys side chain. We also found that the multiple N‐MPE groups are efficiently cleaved upon treatment with tris(2‐carboxyethyl)phosphine and morpholine in the presence of SnCl2.

Indirect Determination of Amitriptyline Hydrochloride by Square Wave Voltammetry of SnCl2.2H2O

A simple, fast and sensitive electroanalytical method consist studying the square wave of SnCl2.2H2O at hanging mercury dropping electrode in aqueous solution for the indirect determination of (AMI) drug. SnCl2.2H2O has revealed a major reduction potential at (-0.450) Volt against the reference electrode (Ag/AgCl/Sat.KCl). The calibration curve in the Phosphate buffer as the supporting electrolyte at pH=2 was constracted. The range concentrations up to (0.99X10-5–9.91X10-5) M, the correlation coefficient (r= 0.9989) and then studied the decreased of peak current of the drug by the (HMDE) behavior in the presence of SnCl2.2H2O. Results were as follow: The calibration curves were (0.316 X10-6 -3.136 X10-6) M and thismethods was successfully applied to determination of AMI in apharmaceutical formulations.

Direct Synthesis of Two-Dimensional SnSe and SnSe2 through Molecular Scale Preorganization.

Two-dimensional tin monoselenide (SnSe) and tin diselenide (SnSe2) materials were efficiently produced by the thermolysis of molecular compounds based on a new class of seleno-ligands. Main group metal chalcogenides are of fundamental interest due to their layered structures, thickness-dependent modulation in electronic structure, and small effective mass, which make them attractive candidates for optoelectronic applications. We demonstrate here the synthesis of stable tin selenide precursors by in situ reductive bond cleavage in the dimeric diselenide ligand (SeC2H4N(Me)C2H4Se)2 in the presence of SnCl4. New molecular precursors [SnIV(SeC2H4N(Me)C2H4Se)2], [SnIVCl2(SeC2H4N(Me)C2H4Se)], and [SnIV(SC2H4N(Me)C2H4S)(SeC2H4N(Me)C2H4Se)] were thoroughly characterized by multinuclear magnetic resonance studies and single-crystal X-ray diffraction analysis that revealed the Sn(IV) center to be octahedrally coordinated by two tridentate dianionic chelating ligands or trigonally pyramidally coordinated by one chelating ligand and two chlorido ligands. Preorganization of metal-selenium bonds in both compounds offered direct and reproducible synthetic access to two-dimensional tin chalcogenides (SnSe and SnSe2) via simple adjustment of the pyrolysis temperature. Additionally, SnSe2 and SnSxSe2-x particles could be successfully synthesized by microwave-assisted decomposition of the molecular precursors, which was unambiguously corroborated by both experimental and computational analyses that explained the formation of a selenium rich SnSxSe2-x phase from a single molecular precursor containing both Sn-Se and Sn-S bonds.

The Removal of Pertechnetate from Aqueous Solution by Synthetic Hydroxyapatite: The Role of Reduction Reagents and Organic Ligands.

The use of knowledge from technetium radiochemistry (even from nuclear medicine applications) allows us to select an sorbent for 99mTc radionuclide sorption, which is hydroxyapatite. Using radioisotope indication, the 99mTcO₄- sorption process on synthetic hydroxyapatite was studied by the batch method in the presence of SnCl2 and FeSO4 reducing agents. The complexing organic ligands' effect on the 99mTcO₄- sorption under reducing conditions was investigated. In the presence of Sn2+ ions without the addition of organic ligand, the sorption percentage reached above 90% independently of the environment. In the presence of Fe2+ ions without the addition of organic ligand, the sorption of 99mTcO₄- was significantly lower and was at approximately 6%, depending on the concentration of Fe2+ ions in solution. The effect of complexing organic ligands on the 99mTcO₄- sorption on hydroxyapatite from the aqueous solution, acetate buffer and phosphate buffer decreases in the following order for Sn2+: oxalic acid > ethylenediaminetetraacetic acid > ascorbic acid. In the presence of Fe2+ ions without organic ligands, the sorption reached up to 15% depending on the composition of the solution. The addition of oxalic acid and ascorbic acid increased the sorption up to 80%. The ethylenediaminetetraacetic acid had no significant effect on the sorption of technetium on hydroxyapatite.

Conversion of Free Fatty Acid in Calophyllum inophyllum Oil to Fatty Acid Ester as Precursor of Bio-Based Epoxy Plasticizer via SnCl2-Catalyzed Esterification.

The preparation and application of bio based plasticizers derived from vegetable oils has gained increasing attention in the polymer industry to date due to the emerging risk shown by the traditional petroleum-based phthalate plasticizer. Epoxy fatty acid ester is among the prospective alternative plasticizers since it is ecofriendly, non-toxic, biodegradable, low migration, and low carbon footprint. Epoxy plasticizer can be synthesized by the epoxidation reaction of fatty acid ester. In this study, the preparation of fatty acid ester as a green precursor of epoxy ester plasticizer was performed via esterification of free fatty acid (FFA) in high acidic Calophyllum inophyllum Seed Oil (CSO) using methanol in the presence of SnCl2.2H2O catalyst. The analysis of the process variables and responses using Box-Behnken Design (BBD) of Response Surface Methodology (RSM) was also accomplished. It was found that the quadratic model is the most appropriate model for the optimization process. The BBD analysis demonstrated that the optimum FFA conversion and residual FFA content were 75.03% and 4.59%, respectively, achieved at the following process condition: a reaction temperature of 59.36 °C, a reaction time of 117.80 min, and a catalyst concentration of 5.61%. The fatty acid ester generated was an intermediate product which can undergo a further epoxidation process to produce epoxy plasticizer in polymeric material production.

Catalytic pyrolysis of rice husk with SnCl2, Al2O3.4SiO2.H2O, and MoS2 for improving the chemical composition of pyrolysis oil and gas

Pyrolysis of Indian variety rice husk was carried out in a semi-batch reactor in the presence of SnCl2, Al2O3.4SiO2.H2O, and MoS2 catalysts at a fixed temperature (550 °C), heating rate (50 °C min−1), and N2 flow rate (0.3 L min−1). The yield of pyrolysis oil increased in the presence of Al2O3.4SiO2.H2O catalyst but deteriorated in presence of SnCl2, and MoS2 catalyst. At 550 °C, the maximum pyrolysis oil yield from non-catalytic pyrolysis (NCP) was 37.46 wt% and with Al2O3.4SiO2.H2O catalyst it was 38.41 wt%. The yield of H2 (7.27 mol %) in pyrolysis-gas after catalytic pyrolysis (CP) was 0.72 mol% higher than NCP (6.55 mol %). The gross calorific value (GCV) of pyrolysis-gas after CP increased to 5.99 MJ m−3 from 3.84 MJ m−3 (NCP). High lignin contained in rice husk gave a better CH4 yield of 10.13 mol. %. Reduction in water content (3.07–5.77 wt %) of pyrolysis oil after CP elevated the high heating value (HHV) to 28.61 from 22.41 MJ kg−1. A 3.0–4.58 mol. % reductions in the acidic compound content after CP impacted the pH and TAN of pyrolysis oils. The Al2O3.4SiO2.H2O catalyst elevated the area percentage of naphthenic (0.54 mol. %), olefinic (1.98 mol. %), aromatic (4.18 mol. %), and paraffinic (4.42 mol. %) compounds in pyrolysis oil. A 3.86 mol. % increase in the phenolic compounds was observed in presence of MoS2 catalyst. Approximately, 22 wt% loss in oxygen with 21 and 2.65 wt% increases in the carbon and hydrogen content of biochar elevated the HHV to 30.60 MJ kg−1 after CP.

The synthetic potential of α,α-diallylcyrene

The reaction of cyrene with allyl bromide in THF in the presence of ButOK gave the α,α-diallyl derivative of cyrene in 50% yield. This derivative smoothly undergoes iodo- cyclization on the keto group that is converted into a ketal center to give annulated bis-tetrahydrofuran; intramolecular cationic cyclization in the presence of SnCl4 or TiCl4 results in 2-oxabicyclo[3.3.1]nonan-9-ones. The prospects of using these reactions towards the synthesis of trichothecene sesquiterpenoids modified in the central moiety were assessed.

One‐pot three‐component synthesis of novel chromeno[3,2‐c]pyridine‐1,9(2H)‐diones by using SnCl2⋅2H2O as catalyst

AbstractAn efficient method was developed to prepare a novel series of chromeno[3,2‐c]pyridine‐1,9(2H)‐diones from bio‐based 4‐hydroxy‐6‐methylpyridine‐2‐ones, aromatic aldehydes and dimedone in the presence of SnCl2⋅2H2O in ethanol at 70°C. Mild conditions as well as the operational simplicity, easy workup, and environmentally friendly are the most advantages of this multicomponent synthesis of potentially bioactive new products.

Synthesis of Thio‐/Selenopyrrolines via SnCl4‐Catalyzed (3+2)‐Cycloadditions of Donor‐Acceptor Cyclopropanes with Thio‐/Selenocyanates

AbstractA straightforward protocol has been developed to access thio‐/selenopyrrolines through a (3+2)‐cycloaddition of aryl thio‐/selenocyanates with donor‐acceptor cyclopropanes (DACs) in the presence of SnCl4 as a Lewis acid catalyst. Further, good chemoselectivity was observed when DACs were treated with 3‐cyano phenyl thiocyanate. These results suggest that thiocyanate is more reactive than nitrile moiety in such (3+2)‐cycloaddition reactions.

Quasiliving Cationic Polymerization of Anethole: Accessing High-Performance Plastic from the Biomass-Derived Monomer

Quasiliving cationic polymerization of the naturally occurring β-methylstyrene derivative, anethole, is reported for the first time. The effect of solvent polarity, initiator nature as well as Lewis acid, proton trap, and initiator concentrations on the cationic polymerization of anethole in the presence of SnCl4 as a coinitiator was studied in detail. It was shown that SnCl4-coinitiated cationic polymerization of anethole proceeds in a quasiliving fashion in the presence of different initiators (cumyl chloride, p-methoxystyrene–HCl, and dicumyl chloride) using 2,6-lutidine as a proton trap and toluene as a solvent at −50 and −60 °C affording poly(anethole)s with the number-average molecular weight up to 24,000 g mol–1 and relatively low polydispersity (D̵ = 1.25–1.51). The quasiliving nature of polymerization was confirmed by the linearity of first-order kinetic plot, linear increase of Mn with increasing conversion, as well as by monomer addition experiment. The analysis of size exclusion chromatography traces of the synthesized polymers revealed the presence of a high-molecular-weight fraction (from 9 to 20% depending on solvent polarity and temperature), which is generated due to competitive chain transfer to the monomer via its alkylation by growing macrocations and occurring simultaneously with propagation. The synthesized poly(anethole)s are characterized by a high value of glass transition temperature (Tg up to 255 °C), high thermal stability (Td5 = 386 °C), and high Young’s modulus (3.1 ± 0.5 GPa) comparable with values for such commercially available plastics as polystyrene and poly(methyl methacrylate). In addition, the obtained polymer shows increased resistance to bacterial (Escherichia coli) growth on the polymer surface in comparison with polystyrene.

High-performance methylammonium-free ideal-band-gap perovskite solar cells

Summary The development of mixed tin-lead (Sn-Pb)-based perovskite solar cells (PSCs) with low band gap (1.2–1.4 eV) has become critical not only for pushing single-junction devices toward the maximum efficiency given by the Shockley-Queisser limit, but also for enabling all-perovskite tandem devices beyond this limit. However, achieving high power-conversion efficiency (PCE) and long-term device operation stability simultaneously remains a significant challenge for Sn-Pb-based PSCs. Here, we demonstrate near ideal-band-gap (∼1.34 eV) methylammonium-free Sn-Pb-based PSCs with high efficiency (∼20%) and promising operational stability of maintaining >80% of initial PCE over 750 h under maximum-power-point tracking. The key to this success is the use of a SnCl2⋅3FACl complex additive that improves the microstructure and reduces the development of residual stress in the Sn-Pb perovskite thin films, which in turn enhances the efficiency and stability of the Sn-Pb-based ideal-band-gap PSCs.

Inter- and Intramolecular Cycloaddition Reactions of Ethenetricarboxylates with Styrenes and Halostyrenes

AbstractInter- and intramolecular cycloaddition reactions of ethenetricarboxylates with styrenes and α-halostyrenes have been investigated. The reactions of ethenetricarboxylates with styrenes or α-bromostyrenes in the presence of SnCl4 or SnBr4 stereoselectively gave 2,4-cis-substituted cyclobutanes. The intramolecular cycloaddition reactions of a series of styrene-functionalized ethenetricarboxylate amides, including in situ generated derivatives, showed high diversity of reaction modes depending on the structures and substituents of the substrates. The regioselectivity and stereoselectivity of the reactions as well as reaction mechanisms were discussed based on the DFT calculations.

Application of Amine-based Ru Compounds in the Olefin Metathesis of Methyl Eugenol: A Comparison with Grubbs Catalysts

Methyl eugenol olefin metathesis was conducted with non-carbene Ru-complexes ([RuCl2(PPh3)2amine]) in the absence and presence of SnCl2 or CuCl2 as additives and their catalytic activities were compared with that of a commercial Grubbs catalyst 2nd Generation (G2).

Modifications of 5,12-dihydroindolo[3,2-a]carbazole scaffold via its regioselective C2,9-formylation and C2,9-acetylation

The effective approaches for regioselective double formylation and acetylation of 5,12-dialkyl-6,7-diaryl-substituted 5,12-dihydroindolo[3,2-a]carbazoles by their treatment with dichloromethyl methyl ether in the presence of SnCl4 or with acetyl chloride in the presence of AlCl3 to afford the 2,9-diformyl or 2,9-diacetyl derivatives, respectively, were developed. Furthermore, new 2,9-bis(2,2-dicyanovinyl) derivatives were synthesized by the Knoevenagel condensation of diformyl-containing substrates with malononitrile, when new 2,9-bis(quinoxaline-2-yl)- and 2,9-bis(benzo[g]quinoxaline-2-yl) derivatives were formed via microwave-promoted oxidation of diacetyl-containing substrates with SeO2 to the corresponding diglyoxals, followed by the reaction of these intermediates with o-phenylendiamine or 2,3-diaminonaphthalene, respectively. The basic optical and electrochemical properties of some 5,12-dihydroindolo[3,2-a]carbazoles were investigated.

Novel 1,4-dihydropyrano[2,3-c]pyrazole derivatives: Synthesis, characterization, biological evaluation and in silico study

In the present study, a series of novel and biologically potent 6-amino-1-(2,4-dinitrophenyl)-4-phenyl-1,4-dihydropyrano [2,3-c]pyrazole-5-carbonitrile derivatives (5a-5u) have been synthesized through multicomponent reaction between various substituted aromatic aldehyde derivative (4a-4u), 2, 4-dinitrophenyl hydrazine (1), ethyl acetoacetate (2) and malononitrile (3) in the presence of SnCl2 as a prompt catalyst using both microwave irradiation method as well as conventional method. The structure of synthesized compounds were confirmed by various spectroscopic methods such as 1H NMR, 13C NMR, IR, Mass analysis and elemental analysis. All the synthesized compounds were subjected in vitro antibacterial, anti-tuberculosis screening and cytotoxicity MTT assay. In vitro biological study revealed that the synthesized compound 5a, 7a and 8a are showing good anti-bacterial and anti-tuberculosis activity. The in silico study of ADME pharmacokinetic properties were also predicted for synthesized compounds for checking their bioavailability. Furthermore, molecular docking study of synthesized compounds with enoyl-ACP reductase (oxidoreductase) was carry out to find out the binding affinity of compounds. Docking study demonstrated that compound 7b and 7a possessed superior binding affinity with target enzyme by strong hydrogen bonding. We have also carried out molecular dynamics simulation to check the stability of docked complex, conformational changes and primary molecular interaction.

NEW APPROACH TO THE SYNTHESIS OF 2,2':5',2''-TERTHIOPHENE-5,5''- AND 2,2':5',2'':5'',2'''-QUATERTHIOPHENE-5,5'''-DICARBOXYLIC ACIDS

The reaction of bromosuccinimide with esters of 3-substituted 2,2'-bithiophene-5-carboxylic acids was used to obtain their 5'-bromo derivatives, which were further converted to esters of 3,3'''-disubstituted 2,2':5',2'':5'',2'''-quaterthiophene-5,5'''-dicarboxylic acids by heating in DMF with catalytic amounts of Pd(PPh 3 ) 4 . Ester of 3-decyl-2,2'-bithiophene-5-carboxylic acid was acylated at the С-5' position with lauroyl chloride in the presence of SnCl 4 , producing the respective ketone that was used in Vilsmeier–Haack reaction (DMF, POCl 3 ). The 3-chloroacrylaldehyde derivative that was thus obtained was further used in reaction with ethyl thioglycolate in the presence of sodium ethoxide, giving ester of 3,3''-decyl-2,2':5',2''-terthiophene-5,5''-dicarboxylic acid. Alkaline hydrolysis of the obtained esters led to the corresponding 2,2':5',2'':5'',2'''-quaterthiophene-5,5'''- and 2,2':5',2''-terthiophene-5,5''-dicarboxylic acids. Authors: Anastasia S. Kostyuchenko, Evgeny B. Ulyankin, Anton L. Shatsauskas, Vladislav Yu. Shuvalov, Alexander S. Fisyuk*

High-sensitivity thiocyanate spectrophotometric method for determination of perrhenate, an analogue of radioactive pertechnetate, under acidic condition

Spectrophotometric method is a simple and effective in situ analytical method for contaminants monitoring, but further improvement of its sensitivity and detection limit for radionuclides determination remains highly desirable. Herein, we report a simple and highly sensitive thiocyanate spectrophotometric method for the determination of radioactive Tc(VII) by studying its chemical analogue Re(VII) in different aqueous media. The colorless thiocyanate reacted with Re(VII) in hydrochloric acid solution in the presence of SnCl2 producing a stable colored Re(IV)-SCN complex, which was extracted into ethyl acetate and then measured at 427 nm. Under optimized conditions, a strong linear relationship can be obtained in the range of 0.25–10 mg L−1 for Re(VII) with R2 value > 0.9942, and the sensitivity of the method was found to be 0.004 μg cm−2 with detection limit of 0.027 mg L−1. This assay provides highly sensitive detection of Re(VII) in environmental media that is high in NO3−, Cu2+, and Fe3+. We applied it to the determination of Re(VII) in the wide range of background solutions, including deionized water, groundwater, and seawater, and analysis results showed that none of the molar absorptivities for both groundwater and seawater backgrounds was statistically different from the deionized water background when the paired Student’s t test, at 95% confidence level, was applied. The operational simplicity, accuracy, and precision of the proposed method suggest that it can be a good alternative for the in situ analysis of pertechnetate in environmental media.

New approach to the synthesis of 2,2':5',2''-terthiophene-5,5''-and 2,2':5',2'':5'',2'''-quaterthiophene-5,5'''-dicarboxylic acids

The reaction of bromosuccinimide with esters of 3-substituted 2,2'-bithiophene-5-carboxylic acids was used to obtain their 5'-bromo derivatives, which were further converted to esters of 3,3'''-disubstituted 2,2':5',2'':5'',2'''-quaterthiophene-5,5'''-dicarboxylic acids by heating in DMF with catalytic amounts of Pd(PPh3)4. Ester of 3-decyl-2,2'-bithiophene-5-carboxylic acid was acylated at the С-5' position with lauroyl chloride in the presence of SnCl4, producing the respective ketone that was used in Vilsmeier–Haack reaction (DMF, POCl3). The 3-chloroacrylaldehyde derivative that was thus obtained was further used in reaction with ethyl thioglycolate in the presence of sodium ethoxide, giving ester of 3,3''-decyl-2,2':5',2''-terthiophene-5,5''-dicarboxylic acid. Alkaline hydrolysis of the obtained esters led to the corresponding 2,2':5',2'':5'',2'''-quaterthiophene-5,5'''- and 2,2':5',2''-terthiophene-5,5''-dicarboxylic acids.

Ultrasound Assisted Synthesis of Quinoline Derivatives in the Presence of SnCl2·2H2O as a Precatalyst in Water: Evaluation of their Antibacterial Activities.

SnCl2·2H2O has been used as a convenient precatalyst for the one-pot and rapid synthesis of 2-substituted quinolines under ultrasound irradiation in water. The reaction involved a 3-component reaction of aniline, aldehydes, and ethyl 3,3-diethoxypropionate in the presence of aerial oxygen to give the desired products in good yields. Several of these compounds showed antibacterial activities when tested against gram-positive and gram-negative species. One compound i.e. 4b showed promising activities across both the species.