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17 pages, 2508 KiB

Open AccessArticle

The Influence of HCl Concentration on the Rate of the Hydrolysis–Condensation Reaction of Phenyltrichlorosilane and the Yield of (Tetrahydroxy)(Tetraphenyl)Cyclotetrasiloxanes, Synthesis of All Its Geometrical Isomers and Thermal Self-Condensation of Them under “Pseudo”-Equilibrium Conditions

by Irina M. Petrova, Yury I. Lyakhovetsky, Nikolai S. Ikonnikov and Nataliya N. Makarova

Molecules 2021, 26(14), 4383; https://doi.org/10.3390/molecules26144383 - 20 Jul 2021

Cited by 1 | Viewed by 1865

Abstract

The rate of hydrolysis–condensation reaction of phenyltrichlorosilane in water-acetone solutions and the product yields were shown to significantly depend on the concentration of HCl (C_HCl) in the solutions. The main product of the reaction was all-cis-(tetrahydroxy)(tetraphenyl)cyclotetrasiloxane. This was different [...] Read more.

The rate of hydrolysis–condensation reaction of phenyltrichlorosilane in water-acetone solutions and the product yields were shown to significantly depend on the concentration of HCl (C_HCl) in the solutions. The main product of the reaction was all-cis-(tetrahydroxy)(tetraphenyl)cyclotetrasiloxane. This was different from the earlier published results of analogous reactions of m-tolylSiCl₃, m-ClPhSiCl₃, and α-naphtylSiCl, in which some products of other types were formed. For example, trans-1,1,3,3-tetrahydroxy-1,3-di-α-naphtyldisiloxane was obtained in the case of α-naphtylSiCl₃. All-cis-(tetrahydroxy)(tetraphenyl)cyclotetrasiloxane was treated in acetone with HCl to give the other three geometric isomers (cis-cis-trans-, cis-trans-, and all-trans-). The thermal self-condensation of these four isomers under “pseudo”-equilibrium conditions (under atmospheric pressure) was investigated in different solvents, in quartz or molybdenum glass flasks. The compositions of the products were monitored by APCI-MS and ²⁹Si NMR spectroscopy. It was shown that all-cis- and cis-cis-trans-isomers in toluene or anisole mostly gave the cage-like Ph-T_8,10,12,14 and uncompleted cage-like Ph-T_10,12OSi(HO)Ph compounds. In contrast to these two isomers, the cis-trans–isomer in toluene mainly formed dimers with the loss of one or two molecules of water. However, in acetonitrile, significant amounts of Ph-T_10,12 and Ph-T_10,12OSi(HO)Ph species were formed along with the dimers. All-trans-isomer did not enter into the reaction at all. Full article

(This article belongs to the Special Issue Synthesis of Functional Silicon Compounds)

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9 pages, 1181 KiB

Open AccessArticle

Preparation of Silicophosphate Alternating Hybrid Copolymers via Nonaqueous Acid-Base Reactions of Phosphoric Acid and Organo-Bridged Bis(chlorosilane)

by Kenji Okada, Masanari Takano, Yasuaki Tokudome, Yomei Tokuda and Masahide Takahashi

Molecules 2020, 25(1), 127; https://doi.org/10.3390/molecules25010127 - 28 Dec 2019

Cited by 1 | Viewed by 2988

Abstract

A design of atomic and oligomer level structure in organic-inorganic hybrid materials is highly important for various applications. Nonaqueous acid-base reaction allows us to prepare silicophosphates with controlled inorganic networks (–(O–P–O–Si)_n) at atomic level because phosphorous and silicon-based precursors can react [...] Read more.

A design of atomic and oligomer level structure in organic-inorganic hybrid materials is highly important for various applications. Nonaqueous acid-base reaction allows us to prepare silicophosphates with controlled inorganic networks (–(O–P–O–Si)_n) at atomic level because phosphorous and silicon-based precursors can react directly, resulting in an alternating copolymer network. Organic functionalization in those materials has been realized so far by using organic-modified phosphorous acid and/or organo-chlorosilane as precursors. In the present study, silicophosphate oligomers exhibiting inorganic-organic hybrid chains of (–(O–P–O–Si–R–Si)_n) (R: bridging organic functional groups), are prepared from phosphoric acid and organo-bridged bis(chlorosilane). The 1, 2-bis(chlorodimethylsilyl)ethane ((C₂H₄)(Me₂SiCl)₂) and 1, 4-bis(chlorodimethylsilyl)benzene ((C₆H₄)(Me₂SiCl)₂) were used as organo-bridged bis(chlorosilane). Different types of silicophosphate oligomers with different network structures and terminal groups (P-OH and/or Si-Cl) were prepared by changing the reaction temperature and molar ratio of precursors. The formation of low molecular weight oligomers of ring and cage morphologies (ring tetramer, cage pentamer, and ring hexamer) is suggested in the product prepared from phosphoric acid and (C₆H₄)(Me₂SiCl)₂ molecule at 150 °C. Those silicophosphate hybrid oligomers are expected to be used as building blocks of hybrid materials with well-defined network structures for desired functionalities. Full article

(This article belongs to the Special Issue Synthesis of Functional Silicon Compounds)

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18 pages, 5492 KiB

Open AccessFeature PaperArticle

Control of Crystalline-Amorphous Structures of Polyhedral Oligomeric Silsesquioxanes Containing Two Types of Ammonium Side-Chain Groups and Their Properties as Protic Ionic Liquids

by Ryoya Hasebe and Yoshiro Kaneko

Molecules 2019, 24(24), 4553; https://doi.org/10.3390/molecules24244553 - 12 Dec 2019

Cited by 9 | Viewed by 3477

Abstract

Polyhedral oligomeric silsesquioxanes (POSSs), Am-POSS(x,y), prepared by hydrolytic condensation, contains two types of ammonium side-chain groups, where the numbering of x and y represents the type of ammonium ions in the POSS structure, corresponding to primary (1), secondary (2 [...] Read more.

Polyhedral oligomeric silsesquioxanes (POSSs), Am-POSS(x,y), prepared by hydrolytic condensation, contains two types of ammonium side-chain groups, where the numbering of x and y represents the type of ammonium ions in the POSS structure, corresponding to primary (1), secondary (2), tertiary (3), and quaternary (4) ammonium ions. Mixtures of the two starting materials selected from organotrialkoxysilanes containing primary, secondary, and tertiary amines and a quaternary ammonium salt [(RO)₃Si(CH₂)₃R′, R = CH₃ or CH₂CH₃, R′ = NH₂, NHCH₃, N(CH₃)₂, and N(CH₃)₃Cl] were dissolved in dimethyl sulfoxide (DMSO). The hydrolytic condensation was performed in the presence of bis(trifluoromethansulfonyl)imide (HNTf₂) and water. All Am-POSS(x,y) structures consisted of a cage-type octamer (T₈-POSS), as confirmed by ²⁹Si NMR spectrometry and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses indicated that Am-POSS(1,3), Am-POSS(1,4), and Am-POSS(2,4) had amorphous structures. These POSSs have two or three differences in the number of methyl groups between the two types of ammonium side-chains. Conversely, Am-POSS(1,2), Am-POSS(2,3), and Am-POSS(3,4) had crystalline structures. The difference in the number of methyl groups between the two types of ammonium side-chains in these POSSs is only one. Therefore, the crystalline-amorphous structure of Am-POSS(x,y) is controlled by the side-chain group combinations. Furthermore, Am-POSS(1,3), Am-POSS(1,4), and Am-POSS(2,4) are protic ionic liquids with relatively low flow temperatures. Full article

(This article belongs to the Special Issue Synthesis of Functional Silicon Compounds)

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10 pages, 5443 KiB

Open AccessArticle

Mercapto-Functionalized Porous Organosilica Monoliths Loaded with Gold Nanoparticles for Catalytic Application

by Hongwei Li, Junhui Pan, Chengtao Gao, Mengyu Ma, Liangyu Lu, Yuzhu Xiong and Fuping Dong

Molecules 2019, 24(23), 4366; https://doi.org/10.3390/molecules24234366 - 29 Nov 2019

Cited by 5 | Viewed by 2885

Abstract

Porous organosilica monoliths have attracted much attention from both the academic and industrial fields due to their porous structure; excellent mechanical property and easily functionalized surface. A new mercapto-functionalized silicone monolith from a precursor mixture containing methyltrimethoxysilane; 3-mercaptopropyltrimethoxysilane; and 3-mercaptopropyl(dimethoxy)methylsilane prepared via a [...] Read more.

Porous organosilica monoliths have attracted much attention from both the academic and industrial fields due to their porous structure; excellent mechanical property and easily functionalized surface. A new mercapto-functionalized silicone monolith from a precursor mixture containing methyltrimethoxysilane; 3-mercaptopropyltrimethoxysilane; and 3-mercaptopropyl(dimethoxy)methylsilane prepared via a two-step acid/base hydrolysis–polycondensation process was reported. Silane precursor ratios and surfactant type were varied to control the networks of porous monolithic gels. Gold nanoparticles were loaded onto the surface of the porous organosilica monolith (POM). Versatile characterization techniques were utilized to investigate the properties of the synthesized materials with and without gold nanoparticles. Scanning electron microscopy was used to investigate the morphology of the as-synthesized porous monolith materials. Fourier transform infrared spectroscopy was applied to confirm the surface chemistry. ²⁹Si nuclear magnetic resonance was used to investigate the hydrolysis and polycondensation of organosilane precursors. Transmission electron microscopy was carried out to prove the existence of well-dispersed gold nanoparticles on the porous materials. Ultraviolet–visible spectroscopy was utilized to evaluate the high catalytic performance of the as-synthesized Au/POM particles Full article

(This article belongs to the Special Issue Synthesis of Functional Silicon Compounds)

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8 pages, 1591 KiB

Open AccessCommunication

Synthesis and Characterization of Unsymmetrical Double-Decker Siloxane (Basket Cage)

by Rungthip Kunthom, Nobuhiro Takeda and Masafumi Unno

Molecules 2019, 24(23), 4252; https://doi.org/10.3390/molecules24234252 - 22 Nov 2019

Cited by 8 | Viewed by 3577

Abstract

The one-pot synthesis of an unsymmetrical double-decker siloxane with a novel structure via the reaction of double-decker tetrasodiumsilanolate with 1 equiv. of dichlorotetraphenyldisiloxane in the presence of an acid is reported herein for the first time. The target compound bearing all phenyl substituents [...] Read more.

The one-pot synthesis of an unsymmetrical double-decker siloxane with a novel structure via the reaction of double-decker tetrasodiumsilanolate with 1 equiv. of dichlorotetraphenyldisiloxane in the presence of an acid is reported herein for the first time. The target compound bearing all phenyl substituents on the unsymmetrical siloxane structure was successfully obtained, as confirmed by ¹H-NMR, ¹³C-NMR, ²⁹Si-NMR, IR, MALDI-TOF, and X-ray crystallography analyses. Additionally, the thermal properties of the product were evaluated by TG/DTA and compared with those of other siloxane cage compounds. Full article

(This article belongs to the Special Issue Synthesis of Functional Silicon Compounds)

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18 pages, 6920 KiB

Open AccessArticle

A Study of the Influence of the HCl Concentration on the Composition and Structure of (Hydroxy)Arylsiloxanes from the Hydrolysis–Condensation Reaction of Aryltrichlorosilanes

by Irina M. Petrova, Yury I. Lyakhovetsky, Vladimir V. Chernyshev, Nikolai S. Ikonnikov and Nataliya N. Makarova

Molecules 2019, 24(22), 4195; https://doi.org/10.3390/molecules24224195 - 19 Nov 2019

Cited by 2 | Viewed by 2955

Abstract

The hydrolysis–condensation reactions of m-tolyl, m-chlorophenyl, and α-naphtyl-trichlorsilanes, (1, 2, and 3, respectively) in water-acetone solutions were examined for how they were influenced by the change in the concentration of HCl (C_HCl). The composition [...] Read more.

The hydrolysis–condensation reactions of m-tolyl, m-chlorophenyl, and α-naphtyl-trichlorsilanes, (1, 2, and 3, respectively) in water-acetone solutions were examined for how they were influenced by the change in the concentration of HCl (C_HCl). The composition of the products was monitored by ²⁹Si NMR spectroscopy and atmospheric pressure chemical ionization mass spectrometry (APCI-MS). The acidity of the medium was shown to affect the yields of the products, and so, what products were formed. For 3, e.g., APCI-MS showed peaks of α-naphtyl-T₈ and α-naphtyl-T₁₀ as the most abundant in the spectra taken after 48 and 240 h for the reaction conducted at C_HCl = 0.037 mol L⁻¹. Unlike this, at C_HCl = 0.15 mol L⁻¹, those peaks were of [α-naphtyl(HO)₂SiO]₂(α-naphtyl)(HO)Si and/or [α-naphtyl(HO)Si]₃, [α-naphtyl(HO)Si]_4,5, and α-naphtyl-T₈ after 192 h. However, at both C_HCl values, the main product (and an intermediate) after 24 h was trans-1,1,3,3-tetrahydroxy-1,3-di-α-naphtyldisiloxane. It was isolated and its structure established by ¹H-, ²⁹Si-NMR, and X-ray powder diffraction. Full article

(This article belongs to the Special Issue Synthesis of Functional Silicon Compounds)

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16 pages, 1985 KiB

Open AccessArticle

Hyperbranched Silicone MDTQ Tack Promoters

by Sijia Zheng, Shuai Liang, Yang Chen and Michael A. Brook

Molecules 2019, 24(22), 4133; https://doi.org/10.3390/molecules24224133 - 15 Nov 2019

Cited by 8 | Viewed by 3607

Abstract

Low molecular weight, highly crosslinked silicone resins are widely used as reinforcing agents for highly transparent elastomers and adhesion/tack promoters in gels. The resins are complex mixtures and their structure / property relationships are ill defined. We report the synthesis of a library [...] Read more.

Low molecular weight, highly crosslinked silicone resins are widely used as reinforcing agents for highly transparent elastomers and adhesion/tack promoters in gels. The resins are complex mixtures and their structure / property relationships are ill defined. We report the synthesis of a library of 2, 3 and 4-fold hyperbranched polymeric oils that are comprised of linear, lightly branched or highly branched dendronic structures. Rheological examination of the fluids and tack measurements of gels filled with 10, 25 or 50% dendronic oils were made. Viscosity of the hyperbranched oils themselves was related to molecular weight, but more significantly to branch density. The properties are driven by chain entanglement. When cured into a silicone gel, less densely branched materials were more effective in improving tack than either linear oils or Me₃SiO-rich, very highly branched oils of comparable molecular weight, because the latter oils underwent phase separation. Full article

(This article belongs to the Special Issue Synthesis of Functional Silicon Compounds)

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15 pages, 2118 KiB

Open AccessArticle

β-Amino- and Alkoxy-Substituted Disilanides

by Istvan Balatoni, Johann Hlina, Rainer Zitz, Alexander Pöcheim, Judith Baumgartner and Christoph Marschner

Molecules 2019, 24(21), 3823; https://doi.org/10.3390/molecules24213823 - 23 Oct 2019

Cited by 5 | Viewed by 2431

Abstract

Our recent study on formal halide adducts of disilenes led to the investigation of the synthesis and properties of β-fluoro- and chlorodisilanides. The reaction of the functionalized neopentasilanes (Me₃Si)₃SiSiPh₂NEt₂ and (Me₃Si)₃SiSiMe₂ [...] Read more.

Our recent study on formal halide adducts of disilenes led to the investigation of the synthesis and properties of β-fluoro- and chlorodisilanides. The reaction of the functionalized neopentasilanes (Me₃Si)₃SiSiPh₂NEt₂ and (Me₃Si)₃SiSiMe₂OMe with KO^tBu in the presence of 18-crown-6 provided access to structurally related β-alkoxy- and amino-substituted disilanides. The obtained Et₂NPh₂Si(Me₃Si)₂SiK·18-crown-6 was converted to a magnesium silanide and further on to Et₂NPh₂Si(Me₃Si)₂Si-substituted ziroconocene and hafnocene chlorides. In addition, an example of a silanide containing both Et₂NPh₂Si and FPh₂Si groups was prepared with moderate selectivity. Also, the analogous germanide Et₂NPh₂Si(Me₃Si)₂GeK·18-crown-6 could be obtained. Full article

(This article belongs to the Special Issue Synthesis of Functional Silicon Compounds)

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10 pages, 2419 KiB

Open AccessArticle

Synthesis and Properties of New Dithienosilole Derivatives as Luminescent Materials

by Dorota Zając, Damian Honisz, Mieczysław Łapkowski and Jadwiga Sołoducho

Molecules 2019, 24(12), 2259; https://doi.org/10.3390/molecules24122259 - 17 Jun 2019

Cited by 3 | Viewed by 2845

Abstract

Three new organosilicon compounds based on dithienosilole (DTSi) were synthesized in good yields. We report the optical and electrochemical properties of the resulting derivatives. We find that these compounds absorb the light in the ultraviolet and blue light range, and they exhibit luminescence [...] Read more.

Three new organosilicon compounds based on dithienosilole (DTSi) were synthesized in good yields. We report the optical and electrochemical properties of the resulting derivatives. We find that these compounds absorb the light in the ultraviolet and blue light range, and they exhibit luminescence in almost the entire range of visible light. After electropolymerization were significantly lowered, the values of the energy gap (even 1.51 eV for P2) and the ionization potential of the polymers were compared to monomers. Optoelectronic properties of the obtained compounds suggest that these derivatives of DTSi may be good candidates as the emissive layers in white organic light-emitting diodes (WOLEDs), which would reduce the amount of layers. Full article

(This article belongs to the Special Issue Synthesis of Functional Silicon Compounds)

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16 pages, 3414 KiB

Open AccessArticle

Synthesis, Self-Assembly and Characterization of Tandem Triblock BPOSS-PDI-X Shape Amphiphiles

by Yu Shao, Jia Chen, Xiang-Kui Ren, Xinlin Zhang, Guang-Zhong Yin, Xiaopeng Li, Jing Wang, Chrys Wesdemiotis, Wen-Bin Zhang, Shuguang Yang, Bin Sun and Meifang Zhu

Molecules 2019, 24(11), 2114; https://doi.org/10.3390/molecules24112114 - 04 Jun 2019

Cited by 4 | Viewed by 3620

Abstract

In this article, we report the facile synthesis, self-assembly, and characterization of shape amphiphiles (BPOSS-PDI-X) based on isobutyl-functionalized polyhedral oligomeric silsesquioxane (BPOSS), perylene tetracarboxylic diimide (PDI), and (60)fullerene (C₆₀) moieties. Firstly, an asymmetrically functionalized diblock shape amphiphile precursor (BPOSS-PDI-OH) was obtained [...] Read more.

In this article, we report the facile synthesis, self-assembly, and characterization of shape amphiphiles (BPOSS-PDI-X) based on isobutyl-functionalized polyhedral oligomeric silsesquioxane (BPOSS), perylene tetracarboxylic diimide (PDI), and (60)fullerene (C₆₀) moieties. Firstly, an asymmetrically functionalized diblock shape amphiphile precursor (BPOSS-PDI-OH) was obtained through the one-pot reaction between perylene-3,4,9,10-tetracarboxylic dianhydride and two different amines, namely BPOSS-NH₂ and 3-amino-1-propanol. It was further conjugated with C₆₀-COOH to give a tri-block shape amphiphile (BPOSS-PDI-C₆₀). Their chemical structures were thoroughly characterized by NMR, IR and MALDI-TOF MS spectrometry. In order to gain insights on the structure-property relationship, their self-assembly in gas phase, in solution, and in solid state were characterized using traveling wave ion mobility mass spectrometry (TWIM-MS), UV/Vis absorption, fluorescence emission spectrophotometer, and transmission electron microscopy, respectively. It was found that BPOSS-PDI-OH formed more complicated dimers than BPOSS-PDI-C₆₀. Both samples showed unique aggregation behaviors in solution with increasing concentration, which could be attributed neither to H- nor to J-type and might be related to the discrete dimers. While BPOSS-PDI-C₆₀ could hardly crystalize into ordered structures, BPOSS-PDI-OH could form nanobelt-shaped single crystals, which may hold potential applications in microelectronics. Full article

(This article belongs to the Special Issue Synthesis of Functional Silicon Compounds)

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Review

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11 pages, 2310 KiB

Open AccessFeature PaperReview

Alkoxy- and Silanol-Functionalized Cage-Type Oligosiloxanes as Molecular Building Blocks to Construct Nanoporous Materials

by Atsushi Shimojima and Kazuyuki Kuroda

Molecules 2020, 25(3), 524; https://doi.org/10.3390/molecules25030524 - 25 Jan 2020

Cited by 18 | Viewed by 4770

Abstract

Siloxane-based materials have a wide range of applications. Cage-type oligosiloxanes have attracted significant attention as molecular building blocks to construct novel siloxane-based nanoporous materials with promising applications such as in catalysis and adsorption. This paper reviews recent progress in the preparation of siloxane-based [...] Read more.

Siloxane-based materials have a wide range of applications. Cage-type oligosiloxanes have attracted significant attention as molecular building blocks to construct novel siloxane-based nanoporous materials with promising applications such as in catalysis and adsorption. This paper reviews recent progress in the preparation of siloxane-based nanoporous materials using alkoxy- and silanol-functionalized cage siloxanes. The arrangement of cage siloxanes units is controlled by various methods, including amphiphilic self-assembly, hydrogen bonding of silanol groups, and regioselective functionalization, toward the preparation of ordered nanoporous siloxane-based materials. Full article

(This article belongs to the Special Issue Synthesis of Functional Silicon Compounds)

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