scholarly journals The preparation and characterization of structurally stable 5-coordinate polystannanes

2021 ◽  
Author(s):  
Aman U. Khan
Keyword(s):  
Good Yield ◽  
Polymeric Materials ◽  
Organotin Compounds ◽  
Tetrahedral Geometry ◽  
Molecular Weights ◽  
Trigonal Bipyramidal ◽  
Chelating Ligand ◽  
The Stability ◽  
Structurally Stable

Tetraorganotin compounds [2-(MeOCH2)C6H4]SnR3 (R = Me, n-Bu, Ph) containing a C,O-chelating ligand were prepared in good yield from the reaction of the R3SnCl and [2-(MeOCH2)C6H4]Li. Tethered organotin compounds Ph3Sn(CH2)3OC6H4R (R = Ph, H, CF3, OCH3) were prepared in good yield from the hydrostannylation reactions of the corresponding vinyl ethers with Ph3SnH. Conversion of two organotin compounds to triorganotin chlorides and diorganotin chlorides, (Ph3-nClnSn(CH2)3OC6H4R; R = H, Ph: n = 1, 2), was successfully carried out and characterisation afforded by NMR spectroscopy. X-ray crystallographic studies revealed a tetrahedral geometry for the tetraorganotin Ph3Sn(CH2)3OC6H4CF3, while five-coordinate trigonal bipyramidal structures with relatively short Sn-O (2.7-2.8 Å) interactions were observed for both mono- (Ph2ClSn(CH2)3OC6H4R; R = H, Ph) and dichloride (PhCl2Sn(CH2)3OC6H4R; R = H, Ph) species. Penta-coordinate diorganotin dichlorides containing a C,N- chelating ligand[2-(Me2NCH2)C6H4]RSnCl2 (R = Me, n-Bu, Ph) or C,O- chelating ligand [2-(MeOCH2)C6H4]RSnCl2 (R = Me, n-Bu, Ph) were prepared by treating RSnCl3 with the lithiated salts [2-(Me2NCH2)C6H4]Li and [2-(MeOCH2)C6H4]Li respectively. Organotin chlorides were successfully reduced with LiAlH4 or NaBH4 to produce novel hydrides. Catalytic dehydrocoupling of diorganotin dihydrides to yield polystannanes was explored using a variety of dehydrocoupling catalysts such as Wilkinson’s catalyst, Cp2ZrMe2 or TMEDA. In almost every instance this resulted in the formation of yellow coloured gummy polymeric materials of moderate molecular weights (Mw = 1 × 104 - 1 × 105 Da) and PDI’s (1.3-2.0). The stability of polystannanes containing tethered O or C,N- or C,O-chelating ligands was investigated in both solid and in solution using NMR and UV-Vis spectroscopies. These studies revealed an enhanced stability to ambient light in the solid state and in solution in the dark when compared to known poly(dialkyl)stannanes.

scholarly journals The preparation and characterization of structurally stable 5-coordinate polystannanes

2021 ◽  
Author(s):  
Aman U. Khan
Keyword(s):  
Good Yield ◽  
Polymeric Materials ◽  
Organotin Compounds ◽  
Tetrahedral Geometry ◽  
Molecular Weights ◽  
Trigonal Bipyramidal ◽  
Chelating Ligand ◽  
The Stability ◽  
Structurally Stable

Tetraorganotin compounds [2-(MeOCH2)C6H4]SnR3 (R = Me, n-Bu, Ph) containing a C,O-chelating ligand were prepared in good yield from the reaction of the R3SnCl and [2-(MeOCH2)C6H4]Li. Tethered organotin compounds Ph3Sn(CH2)3OC6H4R (R = Ph, H, CF3, OCH3) were prepared in good yield from the hydrostannylation reactions of the corresponding vinyl ethers with Ph3SnH. Conversion of two organotin compounds to triorganotin chlorides and diorganotin chlorides, (Ph3-nClnSn(CH2)3OC6H4R; R = H, Ph: n = 1, 2), was successfully carried out and characterisation afforded by NMR spectroscopy. X-ray crystallographic studies revealed a tetrahedral geometry for the tetraorganotin Ph3Sn(CH2)3OC6H4CF3, while five-coordinate trigonal bipyramidal structures with relatively short Sn-O (2.7-2.8 Å) interactions were observed for both mono- (Ph2ClSn(CH2)3OC6H4R; R = H, Ph) and dichloride (PhCl2Sn(CH2)3OC6H4R; R = H, Ph) species. Penta-coordinate diorganotin dichlorides containing a C,N- chelating ligand[2-(Me2NCH2)C6H4]RSnCl2 (R = Me, n-Bu, Ph) or C,O- chelating ligand [2-(MeOCH2)C6H4]RSnCl2 (R = Me, n-Bu, Ph) were prepared by treating RSnCl3 with the lithiated salts [2-(Me2NCH2)C6H4]Li and [2-(MeOCH2)C6H4]Li respectively. Organotin chlorides were successfully reduced with LiAlH4 or NaBH4 to produce novel hydrides. Catalytic dehydrocoupling of diorganotin dihydrides to yield polystannanes was explored using a variety of dehydrocoupling catalysts such as Wilkinson’s catalyst, Cp2ZrMe2 or TMEDA. In almost every instance this resulted in the formation of yellow coloured gummy polymeric materials of moderate molecular weights (Mw = 1 × 104 - 1 × 105 Da) and PDI’s (1.3-2.0). The stability of polystannanes containing tethered O or C,N- or C,O-chelating ligands was investigated in both solid and in solution using NMR and UV-Vis spectroscopies. These studies revealed an enhanced stability to ambient light in the solid state and in solution in the dark when compared to known poly(dialkyl)stannanes.

Characterization of Electron Beam Irradiated Polyvinylpyrrolidone-Dextran (PVP/DEX) Blends

2012 ◽  
Vol 188 ◽  
pp. 102-108 ◽  
Author(s):  
Maria Dumitraşcu ◽  
Mădălina Georgiana Albu ◽  
Marian Vîrgolici ◽  
Cătălin Vancea ◽  
Viorica Meltzer
Keyword(s):  
Electron Beam ◽  
Electron Beam Irradiation ◽  
Polymeric Materials ◽  
Beam Irradiation ◽  
Molecular Weights ◽  
The Past ◽  
Polymeric Blends ◽  
Irradiation Treatment ◽  
Ft Ir

In the past years an increased interest to create new polymeric blends with application in the medical area for development of new types of biomaterials has appeared. Electron beam irradiation is well known as a method of producing important changes in polymer structure, being an alternative to chemical synthesis of biomaterials based on polymeric materials. The aim of the present study was to investigate the behaviour of some polyvinylpyrrolidone-dextran (PVP/DEX) blends under electron beam irradiation. Aqueous solutions of PVP with molecular weights of 360 000 Da (PVP 360), 40 000 Da (PVP 40), and DEX with molecular weight of 500 000 Da (DEX), were mixed as to obtain 50:50 blends of PVP40/DEX and PVP360/DEX. The obtained blends were irradiated with electron beam at different radiation doses and after irradiation treatment were processed by freeze-drying. PVP/DEX blends were characterized by infrared spectroscopy (FT-IR) and thermal analysis. The analyses were conducted in order to establish the relation between radiation dose and changes of structural and thermal properties.

Alkylaluminum complexes containing pyridyl amido ligands. Syntheses and characterization of AlMe2[N(CH2-2-Py)2], Al2Me5[N(CH2-2-Py)2], and Al2Me4[2,3,5,6-tetra(2-pyridyl)piperazyl], an unusual carbon–carbon bond coupling product

1996 ◽  
Vol 74 (11) ◽  
pp. 2032-2040 ◽  
Author(s):  
Steven J. Trepanier ◽  
Suning Wang
Keyword(s):  
Nitrogen Atom ◽  
Aluminum Atom ◽  
Planar Geometry ◽  
X Ray Diffraction ◽  
Tetrahedral Geometry ◽  
Amido Ligands ◽  
Trigonal Bipyramidal Geometry ◽  
Trigonal Bipyramidal ◽  
Carbon Carbon Bond

The reactions of AlMe3 with di(2-pyridylmethyl)amine have been investigated. Two new complexes, AlMe2[N(CH2-2-Py)2] (1) and Al2Me4[2,3,5,6-tetra(2-pyridyl)piperazyl] (3), were obtained as the major and the minor product, respectively, from the reaction of AlMe3 with di(2-pyridylmethyl)amine in a 1:1 ratio in toluene at 23 °C. The reaction of AlMe3 with di(2-pyridylmethyl)amine in a 2:1 ratio yielded a dinuclear complex Al2Me5[N(CH2-2-Py)2] (2). These complexes were fully characterized by NMR, and elemental and single-crystal X-ray diffraction analyses. Crystal data: 1, C14H18N3Al, monoclinic, P21/m, a = 7.568(2), b = 7.340(1), c = 13.120(8) Å, β = 104.17(3)°, V = 706.6(4) Å3, Z = 2; 2, C14H27N3Al2, triclinic, [Formula: see text], a = 8.422(1), b = 16.711(6), c = 7.659(1) Å, α = 91.94(2)°, β = 113.08(1)°, γ = 85.17(2)°, V = 988.2(4) Å3, Z = 2; 3, C28H32N6Al2, monoclinic, P21/c, a = 7.522(8), b = 15.841(8), c = 11.584(4) Å, β = 98.53(5)°, V = 1365(1) Å3, Z = 2. Compound 1 is a mononuclear complex with the aluminum atom in an approximately trigonal bipyramidal geometry and the amido nitrogen atom in a trigonal planar geometry. Compound 2 contains two aluminum centers bridged by an amido nitrogen atom where one of the aluminum atoms has a tetrahedral geometry while the other has a trigonal bipyramidal geometry. The dinuclear compound 3 can be described as the result of two unusual C—C bonds coupling between the methylene carbon atoms of two molecules of 1. The aluminum coordination environment in 3 is similar to that of 1. Key words: aluminum, amide, pyridyl, 2,3,5,6-tetra(2-pyridyl)piperazine, structure.

Chemistry of the 1,3,5-Triaza-2-phosphorin-4,6-diones, Part XII*. Synthesis and Characterization of 2-PhenyI-2-(p-tolylthio)-1,3,5- trimethyI-1,3,5-triaza-4,6-dione-2-phosphorinonium Salts

1996 ◽  
Vol 51 (10) ◽  
pp. 1494-1500 ◽  
Author(s):  
Vasily A . Pinchuk ◽  
Ion Neda ◽  
Christian Müller ◽  
Holger Thönnessen ◽  
Peter G. Jones ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
New Products ◽  
Synthesis And Characterization ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Weak Hydrogen Bonds ◽  
C Nmr

The reaction of 1,5-bis(trimethylsilyl)-1,3.5-trimethylbiuret (1) with p-tolylsulfenyl chloride (2) furnished l-(p-tolylthio)-5-trimethylsilyl-1,3,5-trimethylbiuret (3). In the reaction of 3 with phenyldichlorophosphine, 2-phenyl-2-(p-tolylthio)-1,3,5-trimethyl-1,3,5-triaza-4,6-dione- 2-phosphorinonium chloride (4) was formed. The same product was obtained from the reaction of 2-phenyl-1,3,5-trimethyl-1,3,5-triaza-2λ3- phosphorin-4,6-dione (6) with p-tolylsulfenyl chloride (2). Compound 4 was isolated and characterized in the form of the hexachloroantimonate (4a). The spirophosphorane 2-phenyl-1,3,5-trimethyl-1,3,5-triaza-7,10-dioxa-8,9- perchlorobenzo-2λ5-phosphaspiro-[4.5]decan-4,6-dione (7) was prepared by the reaction of 4 with tetrachloroorthobenzoquinone. The new products were characterized by 1H - and 13C NMR spectroscopy, elemental analysis, 31P NMR spectroscopy in the case of 4a. 6 and 7, and mass spectrometry (4a). Single-crystal X-ray structural analyses of compounds 4a and 7 were conducted. The phosphorus atom of 4a has the expected tetrahedral geometry, with a rather short P-S bond of 204.9(2) pm. In 7 the geometry at phosphorus is almost ideal trigonal bipyramidal. Weak hydrogen bonds are formed from a C (:O) group to deuterochloroform of solvation.

scholarly journals Synthesis and structural characterization of organotin(IV) complexes formed with [o,o] donor atoms of carboxylic acids

2008 ◽  
Vol 73 (2) ◽  
pp. 179-187 ◽  
Author(s):  
Mukhtiar Hussain ◽  
Muhammad Zaman ◽  
Muhammad Hanif ◽  
Saqib Ali ◽  
Muhammad Danish
Keyword(s):  
Mass Spectrometry ◽  
Elevated Temperature ◽  
13C Nmr ◽  
Solid Phase ◽  
Spectroscopic Techniques ◽  
Tetrahedral Geometry ◽  
Distorted Tetrahedral Geometry ◽  
Trigonal Bipyramidal ◽  
Ft Ir

Organotin(IV) carboxylates of the general formula RnSnL4-n (where R = Me, n-Bu or Ph, and L = ?-phenyl-2,3-(methylenedioxy)cinnamate anion or 2-(2,3-dimethlylanilino)nicotinate anion) have been prepared. The mono-, di- and tri-organotin(IV) carboxylates were synthesized by the reaction of organotin(IV) oxides or hydroxides with a stoichiometric amount of the ligand acids at an elevated temperature in dry toluene. The composition of the synthesized organotin(IV) complexes, the bonding behavior of the donor groups and structural assignments were studied by elemental analysis, FT-IR, 1H-, 13C-NMR and mass spectrometry. The spectral data suggest that the ligand acts in a bidentate manner, coordinating through the oxygen atoms. These spectroscopic techniques revealed a distorted tetrahedral geometry in the solution state for the tri-organotins, while a mean coordination number between five to six for the diorganotin(IV) dicarboxylates. In the solid phase, the tri-organotins were essentially trigonal bipyramidal polymeric while the di-organotins were octa?hedral. However, mono-organotin tricarboxylates were predicted to exist in the octahedral state both in solution as well as in the solid phase.

Electron Microscope Study of RNA's of Paramyxoviruses

1972 ◽  
Vol 30 ◽  
pp. 196-197
Author(s):  
Ruchama Baum ◽  
J.T. Seto
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Electron Microscope Study ◽  
Sendai Virus ◽  
Sodium Dodecyl ◽  
Rna Molecules ◽  
Virus Particles ◽  
Molecular Weights ◽  
Length Measurements

The ribonucleic acid (RNA) of paramyxoviruses has been characterized by biochemical and physiochemical methods. However, paramyxovirus RNA molecules have not been studied by electron microscopy. The molecular weights of these single-stranded viral RNA molecules are not known as yet. Since electron microscopy has been found to be useful for the characterization of single-stranded RNA, this investigation was initiated to examine the morphology and length measurements of paramyxovirus RNA's.Sendai virus Z strain and Newcastle disease virus (NDV), Milano strain, were used. For these studies it was necessary to develop a method of extracting RNA molecules from purified virus particles. Highly purified Sendai virus was treated with pronase (300 μg/ml) at 37°C for 30 minutes and the RNA extracted by the sodium dodecyl sulfate (SDS)-phenol procedure.

TEM characterization of Au/Polysilicon interactions

1990 ◽  
Vol 48 (4) ◽  
pp. 650-651
Author(s):  
N. David Theodore ◽  
Leslie H. Allen ◽  
C. Barry Carter ◽  
James W. Mayer
Keyword(s):  
Solid Phase ◽  
Single Crystal Silicon ◽  
Chemical Vapor ◽  
Electrical Contacts ◽  
Silicon Substrates ◽  
Crystal Silicon ◽  
Transmission Electron ◽  
Polysilicon Films ◽  
The Stability

Metal/polysilicon investigations contribute to an understanding of issues relevant to the stability of electrical contacts in semiconductor devices. These investigations also contribute to an understanding of Si lateral solid-phase epitactic growth. Metals such as Au, Al and Ag form eutectics with Si. reactions in these metal/polysilicon systems lead to the formation of large-grain silicon. Of these systems, the Al/polysilicon system has been most extensively studied. In this study, the behavior upon thermal annealing of Au/polysilicon bilayers is investigated using cross-section transmission electron microscopy (XTEM). The unique feature of this system is that silicon grain-growth occurs at particularly low temperatures ∽300°C).Gold/polysilicon bilayers were fabricated on thermally oxidized single-crystal silicon substrates. Lowpressure chemical vapor deposition (LPCVD) at 620°C was used to obtain 100 to 400 nm polysilicon films. The surface of the polysilicon was cleaned with a buffered hydrofluoric acid solution. Gold was then thermally evaporated onto the samples.

Synthesis and Characterization of Some New Esters Containing Heterocyclic and Derived From Azo Dyes

2019 ◽  
Vol 9 (02) ◽  
Author(s):  
Zena G. Alrecabi ◽  
Zainab Amer ◽  
Naeemah Al-Lami
Keyword(s):  
Schiff Base ◽  
13C Nmr ◽  
Azo Dyes ◽  
Spectral Methods ◽  
Anthranilic Acid ◽  
Heterocyclic Compounds ◽  
Synthesis And Characterization ◽  
Cooh Group ◽  
Molecular Weights

This study including prepared new colored esters containing heterocyclic with high molecular weights. In the first part of work we synthesized azo dyes [1,2] from the reaction p-toluidine with β-naphthol and o-nitro phenol, thin we synthesized Schiff bases [3,4] by the reaction anthranilic acid with benzaldehyde and dimethyl benzaldehyde. The reaction azo dyes (contain OH group) with Schiff base (contain COOH group) these led to produce the new colored esters [A1-A4]. The second part of work was modification the (C=N-) group in esters to heterocyclic compounds by reacting with phenyl iso cyanide to produce new β-lactam [B1-B4] and with anthranilic acid to get new hydroquinazoline [C1-C4]. All these compounds were characterized by physical properties and spectral methods FTIR, 1H-NMR and 13C-NMR.

Preparation and Characterization of β-glucosidase Films for Stabilization and Handling in Dry Configurations

2020 ◽  
Vol 21 (8) ◽  
pp. 741-747
Author(s):  
Liguang Zhang ◽  
Yanan Shen ◽  
Wenjing Lu ◽  
Lengqiu Guo ◽  
Min Xiang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Protein Function ◽  
Protein Stabilization ◽  
Functional Protein ◽  
Elongation At Break ◽  
Gelatin Films ◽  
The Stability ◽  
And Function ◽  
General Method

Background: Although the stability of proteins is of significance to maintain protein function for therapeutical applications, this remains a challenge. Herein, a general method of preserving protein stability and function was developed using gelatin films. Method: Enzymes immobilized onto films composed of gelatin and Ethylene Glycol (EG) were developed to study their ability to stabilize proteins. As a model functional protein, β-glucosidase was selected. The tensile properties, microstructure, and crystallization behavior of the gelatin films were assessed. Result: Our results indicated that film configurations can preserve the activity of β-glucosidase under rigorous conditions (75% relative humidity and 37°C for 47 days). In both control films and films containing 1.8 % β-glucosidase, tensile strength increased with increased EG content, whilst the elongation at break increased initially, then decreased over time. The presence of β-glucosidase had a negligible influence on tensile strength and elongation at break. Scanning electron-microscopy (SEM) revealed that with increasing EG content or decreasing enzyme concentrations, a denser microstructure was observed. Conclusion: In conclusion, the dry film is a promising candidate to maintain protein stabilization and handling. The configuration is convenient and cheap, and thus applicable to protein storage and transportation processes in the future.

scholarly journals Semi-Crystalline Hydrophobic Polyamidoamines: A New Family of Technological Materials?

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1018
Author(s):  
Massimo Marcioni ◽  
Jenny Alongi ◽  
Elisabetta Ranucci ◽  
Mario Malinconico ◽  
Paola Laurienzo ◽  
...  
Keyword(s):  
Maximum Stress ◽  
Water Resistance ◽  
Prolonged Exposure ◽  
Water Soluble ◽  
Synthesis And Characterization ◽  
Molecular Weights ◽  
New Family ◽  
Methylene Groups ◽  
Methane Flame

The hitherto known polyamidoamines (PAAs) are not suitable as structural materials because they are usually water-soluble or swellable in water. This paper deals with the synthesis and characterization of semi-crystalline hydrophobic PAAs (H-PAAs) by combining different bis-sec-amines with bis-acrylamides obtained from C6–C12 bis-prim-amines. H-PAAs were initially obtained in a solution of benzyl alcohol, a solvent suitable for both monomers and polymers. Their number average molecular weights, M¯n, which were determined with 1H-NMR by evaluating the percentage of their terminal units, varied from 6000 to >10,000. The solubility, thermal properties, ignitability and water resistance of H-PAAs were determined. They were soluble in organic solvents, semi-crystalline and thermally stable. The most promising ones were also prepared using a bulk process, which has never been previously reported for PAA synthesis. In the form of films, these H-PAAs were apparently unaffected by water. The films underwent tensile and wettability tests. They showed similar Young moduli (260–263 MPa), whereas the maximum stress and the stress at break depended on the number of methylene groups of the starting bis-acrylamides. Their wettability was somewhat higher than that of common Nylons. Interestingly, none of the H-PAAs considered, either as films or powders, ignited after prolonged exposure to a methane flame.

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