Organosilicon Groups Research Articles

The First Chiro‐Inositol Organosilicon Ferroelectric Crystal

AbstractOrganosilicons have been used extensively in aerospace, electronics, food, medicine and other fields, due to their low viscosity, hydrophobicity, corrosion resistance, non‐toxic, and physiologically inert features. Despite extensive interest, however, organosilicon ferroelectric crystals have never been found. Here, by using the chemical design strategy, we successfully obtained a molecular ferroelectric D‐chiro‐inositol‐SiMe3 with polar P43 symmetry, whose spontaneous polarization can be electrically switchable on thin film. The introduction of organosilicon groups endows the thin films with excellent softness, ductility and flexibility (extremely low hardness of 72.8 MPa and small elastic modulus of 5.04 GPa) that are desirable for biomedical and human‐compatible applications. As the first case of organosilicon ferroelectric crystal to date, this work offers a new structural paradigm for molecular ferroelectrics, and highlights their potential for flexible bio‐electronic applications.

Synthesis of some silyl derivatives of graphene oxide

In this work, we synthesized some organosilicon derivatives of graphene oxide (GO) containing various groups such as trimethyl, triethyl, dimethyl-tert-Bu, and dimethyl-vinyl. Also, some reactions were done in the presence of DES, as catalyst. This green catalyst improved the yields of reactions successfully. Synthesis of methoxy, and ethoxy vinyl silyl ethers of GO were done. In this work, hybrid organic-inorganic was done. In the next step, network polymers of GO with styrene, and methacrylic acid (MAA) were done. Incorporation of organosilicon groups were modified GO properties for example thermal stability or it.

Selective replacement of organosilicon units in the cluster [(PhSi)4S6] with coinage metal complex fragments.

Adamantane-type organo-group 14 chalcogenide clusters were shown to possess extreme non-linear optical properties. Reactivity studies of corresponding organosilicon sulfide clusters towards copper and silver complexes indicate a replacement of exactly one of the organosilicon groups with a metal complex fragment to form [(Et3PAg)3(PhSi)3S6] (1) and [Na2(thf)2.33][(Me3PCu)(PhSi)3S6] (2)-in striking contrast to reactions of organotin chalcogenide clusters, which are more significantly and less systematically re-organized. The silicon compounds are thus more suited for controlled modifications of their geometric and electronic structures.

Synthesis of phosphorus‐containing flame retardants and investigation of their flame retardant behavior in textile applications

ABSTRACTFlame retardants are a growing area of research interest. Nonhalogenated, durable, and nonleachable flame retardants are one of the main strategies used in the research of flame retardant polymers. In this regard, the covalent attachment of phosphorus‐containing flame retardants onto cotton fabric has been developed. Two types of reactive phosphorus‐containing flame retardants (MKT‐1 and MKT‐2) have been synthesized and used as a surface coating for cotton fabric. MKT‐1 possesses anhydride and acid functionalities that can react with the OH functionalities in cellulose. In addition, MKT‐2 has both acid and organosilicon groups that can also react with the hydroxy group present in cellulose. The structures of the reactive flame retardants (MKT‐1 and MKT‐2) were characterized using 13C and 31P nuclear magnetic resonance spectroscopy. Thermal properties of the coated and uncoated cotton fabrics were investigated using thermogravimetric analysis. Surface characterization was carried out using scanning electron microscopy and X‐ray photoelectron spectroscopy. A standard test method used to evaluate the flammability of blankets (BS 5852) was also applied to characterize the fire retardant properties of the coated and uncoated cotton fabrics studied. Different loadings of MKT‐1 and MKT‐2 on the fabric (10, 20, and 30% by weight in dimethylformamide solution) were applied in the dip coating process. The cotton fabric coated with 30% MKT‐2 does not burn after being subjected to a propane burner for 20 s and also produced the highest char yield (36%) at 500 °C. Inductively coupled plasma–optical emission spectrometry showed that MKT‐1 contains 8.23 ± 0.33 P% whereas MKT‐2 contains 3.88 ± 0.15 P%. Although MKT‐1 possess a higher P content than MKT‐2, the additive effect caused by the organosilicon and nitrogen groups present in MK‐2 enhance its flame retardant properties. Furthermore, the covalently attached flame retardant materials are durable and do not hydrolyze during washing. The mechanical properties of coated fabrics were characterized by a tensile test and significant change in elongation at break was observed. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47935.

Structure and dynamics of ionic liquids: Trimethylsilylpropyl-substituted cations and bis(sulfonyl)amide anions.

Ionic liquids with cationic organosilicon groups have been shown to have a number of useful properties, including reduced viscosities relative to the homologous cations with hydrocarbon substituents on the cations. We report structural and dynamical properties of four ionic liquids having a trimethylsilylpropyl functional group, including 1-methyl-3-trimethylsilylpropylimidazolium (Si-C3-mim+) cation paired with three anions: bis(fluorosulfonyl)imide (FSI-), bis(trifluoromethanesulfonyl)imide (NTf2-), and bis(pentafluoroethanesulfonyl)imide (BETI-), as well as the analogous N-methyl-N-trimethylsilylpropylpyrrolidinium (Si-C3-pyrr+) cation paired with NTf2-. This choice of ionic liquids permits us to systematically study how increasing the size and hydrophobicity of the anions affects the structural and transport properties of the liquid. Structure factors for the ionic liquids were measured using high energy X-ray diffraction and calculated from molecular dynamics simulations. The liquid structure factors reveal first sharp diffraction peaks (FSDPs) for each of the four ionic liquids studied. Interestingly, the domain size for Si-C3-mim+/NTf2- indicated by the maxima for these peaks is larger than for the more polar ionic liquid with a similar chain length, 1-pentamethyldisiloxymethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide (SiOSi-mim+/NTf2-). For the series of Si-C3-mim+ ionic liquids, as the size of the anion increases, the position of FSDP indicates that the intermediate range order domains decrease in size, contrary to expectation. Diffusivities for the anions and cations are compared for a series of both hydrocarbon-substituted and silicon-substituted cations. All of the anions show the same scaling with temperature, size, and viscosity, while the cations show two distinct trends-one for hydrocarbon-substituted cations and another for organosilicon-substituted cations, with the latter displaying increased friction.

A simple and efficient synthesis of organosilicon compounds containing 1,2,3-triazole moieties catalyzed by ZSM-5 zeolite-supported Cu–Co bimetallic oxides

A new efficient procedure for preparation of 1,2,3-triazole derivatives by 1,3-dipolar cycloaddition of benzyl halides, sodium azide, and propargyl alcohol over Cu–Co/ZSM-5 bimetallic nanocatalyst in aqueous media under conventional heating and ultrasonic irradiation was developed. The maximum activity of the catalyst was reported under ultrasonic irradiation with a noticeable reduction in the reaction time. The generated products were utilized as substrates for the synthesis of a series of new 1,2,3-triazole derivatives containing organosilylvinyl substituent and bulky organosilicon groups using (RSiMe2)3CLi (R = Me, Ph).

Functionalized polynorbornenes with organosilicon groups in the side chains. Synthesis and photophysical properties

Using the method of metathesis polymerization carbon-chain homopolymers containing triрhenylsilyl, tritolylsilyl and trithienylsilyl groups in the side chains, as well as their copolymers with additional carbazole-containing units have been synthesized. Photophysical properties of the obtained compounds were investigated. All polymer products show an intense photoluminescence in the blue region of the spectrum. The largest quantum yield (61.4%) was shown by the copolymer with triphenylsilyl and carbazole side groups.

Synthesis, antimicrobial activities and QSAR studies of heterocyclic Schiff base ligands with organosilicon(IV) halides

A series of heterocyclic Schiff base ligands 4-hydroxy-3-[1-{(2-hydroxy-aryl) imino}-ethyl]-6-methyl-pyran-2-one; aryl = phenyl, 4-methylphenyl, 4-chlorophenyl or 4-nitrophenyl (1–4) and their organosilicon(IV) complexes R2Si(L) (R = Et, Bu or Ph) (5–16) were synthesized and characterized. The elemental analyses, molar conductance and spectral (IR, 1H, 13C and 29Si NMR) data suggested pentacoordinated environment around the silicon atom, where tridentate ligands coordinate through the azomethine nitrogen and oxygen of hydroxyl groups. The ligands and their organosilicon complexes were tested in vitro against pathogenic bacteria and fungi to assess their antimicrobial properties. The activity of the ligands improved against most of the strains of the tested microorganisms on complexation to the organosilicon groups. The antimicrobial activities were correlated with QSAR studies using the linear free energy relationship model which indicate the importance of topological parameters, third-order and valence first-order molecular connectivity indices (3 χ v and 1 χ v ), to explain the antibacterial and antifungal activities of all synthesized compounds.

Preparation of Water-Tolerant UV-Curable SixOy(OH)z/PA Aqueous Dispersion Films

In this experiment, silicon oxide groups (SixOy(OH)z) and carbon–carbon double bonds (C═C) were introduced onto the PA molecular chains. In the first step, acrylic resins (PA), grafted by organosilicon groups, were prepared by solution polymerization. In the second step, UV curable SixOy(OH)z/PA aqueous dispersions, with a high silicon content, were prepared by hydrolyzation and condensation of PA and silane coupling agents (KH-570). Aqueous dispersions possess certain stability when the KH-570 consumption ranges from 0 wt % to 30.0 wt %. With increased content of C═C, the water absorption of UV cured SixOy(OH)z/PA aqueous dispersion films soaked in the water for 24 h was decreased from 78% to 0%. Furthermore, heat curing further improved the water tolerance of the UV cured aqueous dispersion films. The water absorption change of the films caused by heat curing could reach up to 17%.

ChemInform Abstract: Synthesis of β‐Amino Ketones Containing Organosilicon Groups: Catalytic Enantioselective Three‐Component Mannich‐Type Reaction.

AbstractWith cyclic ketones (I) or (V), the process affords mixtures of diastereomers where the anti‐isomer is always formed as main component.

Synthesis of new α-aminonitriles containing organosilicon groups via three component Strecker reactions

A three-component efficient procedure is described for the synthesis of α-aminonitriles containing bis(trimethylsilyl)ethenyl groups from 4-[2,2-bis(trimethylsilyl)ethenyl]benzaldehyde (1), aromatic amines and trimethylsilyl cyanide (TMSCN). Reactions have been studied in the presence of various Lewis acids as catalysts or in ionic liquids under mild conditions. Compound (1) was obtained via Peterson olefination of terephthaldehyde with tris(trimethylsilyl)methyllithium, (Me3Si)3CLi, in THF at 0 °C.

Synthesis of β-Amino Ketones Containing Organosilicon Groups: Catalytic Enantioselective Three-Component Mannich-Type Reaction

Aldimines, generated in situ from 4-[2,2-bis(trimethylsilyl)ethenyl]benzaldehyde and aromatic amines, undergo Mannich-type reactions with cyclic and acyclic ketones. The one-pot reaction is efficiently catalysed by zirconium oxychloride (ZrOCl2.8H2O) at room temperature. β-Amino carbonyl compounds containing bis(trimethylsilyl)ethenyl groups are obtained in acceptable to good yields with moderate to high stereoselectivity under solvent-free conditions.

Synthesis of new imines and amines containing organosilicon groups

The Peterson olefination reaction of terephthalaldehyde with tris(trimethylsilyl)methyl lithium, (Me 3Si) 3CLi, in THF at 0 °C gives 4-[2,2-bis(trimethylsilyl)ethenyl]benzaldehyde ( 1) and 4,4-bis[2,2-bis(trimethylsilyl)ethenyl]benzene ( 2). The new aldehyde ( 1) reacts with variety of amines in ethanol to afford the corresponding imines ( 3) containing vinylbis(trimethylsilyl) group. The newly synthesized imines ( 3) can be completely converted into amines containing vinylbis(trimethylsilyl) group with an excess amount of NaBH 4. In the case of N-[4-(2,2-bis(trimethylsilyl)ethenyl)benzyl]-2,6-dimethylaniline LiAlH 4 was used as a reducing agent in THF.

Synthesis, characterization and thermal behaviors of polymers containing organosilicon groups

Various bis(silyl)ethenyl groups were attached to the aromatic ring of poly(α-methylstyrene) via Peterson olefination reaction of (RMe2Si)3CLi (R = H, Me and Ph) with formylated poly(α-methylstyrene) (Pα-MS-CHO) to give poly(α-methylstyrene)-co-[2,2-bis(silyl)ethenyl(α-methylstyrene)] as functionalized poly(α-methylstyrene) (Pα-MS-SiMe2H, Pα-MS-SiMe3 and Pα-MS-SiMe2Ph). The trimethylsilyl groups of Pα-MS-SiMe3 have been converted to 2,2-dibromoethenyl and epoxybis(silanes) groups via NBS-based bromodesilylation and MCPBA-based epoxidation respectively. The thermal degradation behaviors of the polymers were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).

Synthesis of novel calix[4]arenes containing organosilicon groups

Metalation of (RSiMe 2) 3CH ( 1a R = H, 1b R = Me, 1c R = Ph) with lithium diisopropylamide (LDA) or methyllithium in THF gave organolithium reagents (RSiMe 2) 3CLi, which reacted with the formylated calixarene ( 2), to give the corresponding 5,17-bis[2,2-bis(organosilyl)-1-ethenyl]-25,26,27,28-tetrapropoxycalix[4]arenes ( 3a, 3b and 3c) via the Peterson olefination. The compounds (RSiMe 2) 3CLi were treated with 25,26,27,28-tetrakis(4-bromobutoxy)calix[4]arene ( 4) to give 25,26,27,28-tetrakis[4-(tris(dimethylsilyl)methyl)butoxy] calix[4]arene ( 5a) and 25,26,27,28-tetrakis[4-(tris(trimethylsilyl)methyl)butoxy] calix[4]arene ( 5b) via nucleophilic substitution reactions. However the compound 25,26,27,28-tetrakis[4-(tris(dimethylphenylsilyl)methyl)butoxy] calix[4]arene ( 5c) was not obtained, presumably because (PhSiMe 2) 3C- is highly sterically hindered and the reactivity of its derivatives is low. The compound 5a has potential as a core for dendrimers.

Synthesis and optical properties of fluorene‐based polymers incorporating organosilicon unit

AbstractThe synthesis and optical properties of polymers bearing the repeating unit of terfluorene and various organosilicon groups were investigated. Polymers with high molecular weight and good solubility could be obtained by Suzuki coupling polymerization from silylene‐containing fluorene‐based dibromo monomers and 9,9‐dihexylfluorene‐2,7‐bis(trimethyleneborate). From UV spectra of polymers bearing acyclic silylene bridge, the organosilicon units not only interrupted a π‐conjugation but also contributed to an electronic communication between connected fluorenes. The emission maximum wavelengths (ca. 400 nm) blue‐shifted when compared with that of polyfluorene (418 nm) and the fluorescence quantum yields were considerably high (>0.82) in the CHCl3 solution. On the other hand, rather broad emission was observed at 480 nm and the fluorescence quantum yield was quite low (0.004) in the solution‐state PL spectrum of tetraphenylsilole‐containing polymer. The polymer emitted visible green light in the spin‐coated film. The fluorescence peak intensity at 486 nm gradually decreased when the film was illuminated with the UV light of 359 nm in air. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4786–4794, 2007

Modification of styrene polymer with organosilicon groups

AbstractThe homopolymer of 4‐chloromethylstyrene (P1) and its copolymers with styrene (in various mole ratios) were synthesized by bulk and solution free radical polymerizations, respectively, at 70 ± 1°C using α,α′‐azobis(isobutyronitrile) as an initiator. Lithiation of these soluble polymers in THF at −78°C was done and reacted with electrophiles such as tert‐BuMe2Si, Et3Si, and Me3SiCH2 in the presence of 4,4′‐di‐tert‐butylbiphenyl (DTBB) as a catalyst to produce modified polystyrene. In the other way, trimethylsilylmethyl lithium substitute as a nucleophile was covalently linked to the homopolymer and copolymer. The polymers were characterized by IR, 1H NMR, 13C NMR, differential scanning calorimetry (DSC), and gel permeation chromatography. DSC showed that incorporation of silyl substitute in the side chains of homopolymer and copolymers increases the rigidity of the polymers and, subsequently, their glass transition temperature. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:414–420, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20314

Trialkylsilanes as reagents for the UV-induced surface modification of polybutadiene

A photochemical process for the modification of polymer surfaces using organosilane compounds has been developed. The process is based upon the UV irradiation of polybutadiene in the presence of liquid ethyldimethylsilane (C 2H 5)(CH 3) 2Si–H and gaseous trimethylsilane (CH 3) 3Si–H. UV irradiation was carried out with a medium pressure Hg lamp and a 193 nm ArF* excimer laser. The modified polymer surfaces were investigated by infrared (FTIR) and X-ray photoelectron spectroscopy (XPS), contact angle measurements and atomic force microscopy (AFM). It is found that the photoassisted surface modification with trialkylsilanes leads to the introduction of trialkylsilyl groups onto the surface of the target polymer. From quantitative XPS data the composition of the modified polymer suface (C, O and Si) was determined. The surface modification with trialkylsilanes results in a significant lowering of surface tension γ of polybutadiene. The silane/UV process was found to be very sensitive to small amounts of oxygen in the process gas. Summing up, it is demonstrated that UV irradiation in the presence of gaseous silane compounds is a convenient way to introduce organosilicon groups onto the surface of technical polymers.

Synthesis and characterization of 4-chloromethylstyrene polymers containing bulky organosilicon groups

Abstract The homopolymer of 4-chloromethylstyrene and its copolymers with styrene (in 1:3 and 1:1 mole ratio) were synthesized by bulk and solution freeradical polymerisations, respectively, at 70±1°C using α,α'-azoisobutyronitrile as an initiator. Highly sterically hindered tris(trimethylsilyl)methyl (Tsi) substituents were then covalently linked to the obtained homopolymer and copolymers. The polymers were characterized by IR, 1H NMR and 13C NMR, differential scanning calorimetry (DSC) and gel permeation chromatography. DSC showed that incorporation of Tsi substituents in the side chains of homopolymer and copolymers increases the rigidity of the polymers and, subsequently, their glass transition temperature.

Homolytic 1,5-transfer of chiral organosilicon groups from an enoxy oxygen to an alkoxy oxygen--implications for mechanism.

Reaction of the optically active silanes, ((Ssi)-(-)-6), formed by treatment of racemic 2-methylenecycloheptanone oxide with LDA followed by (R)-(+)-chloromethyl(1-naphthyl)-phenylsilane, with tributyltin hydride under standard radical conditions affords (2R/2S)-[(S)-(methyl(1-naphthyl)-phensylsilyloxy)methyl]cycloheptanone, (Ssi)-(-)-7, providing strong evidence that homolytic 1,5-transfers of organosilicon groups from enoxy oxygen to alkoxy oxygen proceed with retention of configuration, most likely through a frontside attack mechanism rather than via a hypervalent intermediate.