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Abstract: Three new pentacyclic laddersiloxanes were prepared by a new method utilizing single stereoisomer of disiloxanediol as a growing unit. Thus, one diastereomer of disiloxanediol, (RS)–[i-PrPhSi(OH)]2O was isolated and treated with tetrachlorocyclotetrasiloxane, resulting in the formation of tricyclic laddersiloxanes with cis-Ph groups at terminals. All of the obtained isomers could be transformed into pentacyclic laddersiloxanes by dephenylchlorination followed by the reaction with (RS)–[i-PrPhSi(OH)]2O. The structures of new tricyclic and pentacyclic laddersiloxanes were determined by X-ray crystallography. The thermogravity properties of laddersiloxanes depending on the molecular weight and structures were summarized. [Copyright &y& Elsevier]

Synthesis of novel cage and cyclic silanols bearing Tip (2,4,6-triisopropylphenyl) groups was performed. Tip-substituted silanetriol, TipSi(OH)3 (1) was prepared from TipSiCl3, and can be handled without special care in the air. The versatility of this silanol is amply demonstrated as a starting material of various silanols with novel frameworks. Thus, the condensation of 1 using 2-chloro-1,3-dimethylimidazolinium chloride as a dehydrating agent afforded (TipSi)5O7OH (2) in 45% yield. When 1 was treated with (TipSiCl2)2O, cis,trans-cyclotrisiloxanetriol (3) as well as a novel incompletely condensed silsesquioxane, (TipSi)4O5(OH)2 (4) were obtained. In addition, the dehydrochlorinative condensation of (TipSiCl2)2O and (TipSi(OH)2)2O afforded 4 as single product. The structures of all these novel silanols were determined by X-ray crystallography, and their unique structures (hydrogen-bonded aggregates or intramolecular hydrogen bonding) were demonstrated. [Copyright &y& Elsevier]

In order to enrich hybrid materials, a novel fluorescent silsesquioxane-based polymer (denoted as PCS-OTS) was synthesized by Friedel-Crafts reaction starting from octavinylsilsesquioxane (OVS) with triphenylamine-functionalized silsesquioxane monomer (denoted as OTS) with AlCl3 as catalyst. PCS-OTS possessed a high surface area of 816 m2/g and a unique bimodal pore structure. The triphenylamine unit endowed PCS-OTS with excellent luminescence, which made it act as a sensitive chemical sensor and detect p-nitrophenol with high sensitivity (KSV = 81,230 M−1). Moreover, PCS-OTS can significantly remove dyes, and the respective adsorption capacity for Rhodamine B (RB), Congo red (CR) and Methyl Orange (MO) is 1935, 1420 and 155 mg/g. Additionally, it could simultaneously remove multiple dyes from water by simple filtration and be easily regenerated. This hybrid porous polymer can be a good choice for water treatment. [ABSTRACT FROM AUTHOR]

Abstract: Influence of mixing organic silicon compounds into 1 M (M: mol L−1) LiPF6-ethylene carbonate (EC)/ethylmethyl carbonate (EMC) (mixing volume ratio = 3:7) mixed solvent electrolytes on charge–discharge cycling efficiencies of lithium metal negative electrodes is examined. As organic silicon compounds, polyether-modified siloxanes with polyethylene oxide chains, chlorotrimethylsilane, tetraethoxysilane, cis-tetra [isobutyl (dimethylsiloxy)] cyclotetrasiloxane and cage-type silsesquioxane are investigated. Charge–discharge cycling tests of lithium are galvanostatically carried out using stainless steel working electrodes. Charge–discharge cycling efficiencies of lithium tend to improve by mixing organic silicon compounds. A cage-type silsesquioxane, octaphenyloctasilsesquioxane (Ph8T8) exhibits the highest cycling efficiency of approximately 80% with small mixing amount of 0.02 M Ph8T8. Mechanism of enhancement of lithium cycling efficiencies by mixing organic silicon compounds is considered to be due to the suppression of excess reduction of LiPF6-EC/EMC by lithium and the growth of surface film on lithium. [Copyright &y& Elsevier]

A new synthetic method for tricyclic laddersiloxanes, ladder‐type silsesquioxanes with defined structures, is developed based on intramolecular cyclization of hydrosilyl‐functionalized cyclic siloxanes. This method enables the construction of unprecedented laddersiloxanes with various ring sizes. Herein, the preparation of tricyclic laddersiloxanes containing 6‐8‐6‐, 8‐8‐8‐, or 12‐8‐12‐membered‐ring systems is reported. These products can be considered as bat‐shape siloxanes, owing to their rigid inorganic siloxane body with flexible oligosiloxane "wings" as side rings. The synthesized compounds are potential building blocks for well‐defined nanomaterials, porous materials, and host molecules. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A perfect 'Janus-cube' octasilsesquioxane, a nanometer-scale Janus particle with two different types of substituents, was synthesized through the cross-coupling of a 'half-cube' cyclic sodium siloxanolate with another half-cube cyclic fluorosiloxane. The structure was confirmed by X-ray crystallography to be a Janus cube. The overall synthesis is simple and does not require drastic separation methods compared with previous methods. The synthesis of the Janus cube demonstrates a novel siloxane bond-forming reaction involving the coupling a silanol salt and fluorosilane. The reaction is mild, does not result in acid generation, and could be applied to the construction of other novel siloxane compounds. [ABSTRACT FROM AUTHOR]

• A functional laddersiloxane bearing four vinyl groups on the T 4 unit is prepared. • The vinyl groups undergo quantitative hydrosilylation thanks to very low Pt loadings. • Tetrachloro laddersiloxanes are prepared in very high yields. • The laddersiloxanes reported are promising precursors for hybrid materials. A straightforward, efficient and scalable (gram scale) route to an unprecedented 6–8–6 laddersiloxane 3 bearing four vinyl groups on the cyclotetrasiloxane T 4 unit is reported. Compound 3 was fully characterized by multinuclear NMRs, mass spectrometry, and its structure was determined by X-ray crystallography. The reactivity of the vinyl functions was next explored and hydrosilylations of 3 were successfully achieved with three different silanes in the presence of a small amount of Pt catalyst (0.025 mol% of Pt per vinyl function) in each case. The resulting laddersiloxanes were isolated in high yields (76 to 99%) after straightforward work-ups and fully characterized. With its high thermal stability (Td 5 = 372 °C) and chemical versatility, 3 thus appears as a promising precursor for building hybrid materials. [Display omitted] [ABSTRACT FROM AUTHOR]

A vinyl-functionalized all-cis-tetrasiloxycyclotetrasiloxane [ViSi(OSiMe2H)O]4 (Vi = vinyl group) Janus precursor was prepared from potassium cyclotetrasiloxane silanolate. The Janus precursor was selectively modified at its dimethylhydrosilyl groups [–SiMe2H] via the Piers–Rubinsztajn reaction to obtain a family of new tetravinyl-substituted Janus rings [ViSi(OR')O]4 containing various functional groups in moderate yields. Remarkably, the tetravinyl groups on the structure remained intact after modification by the Piers–Rubinsztajn reaction. Since these synthesized compounds possess multiple functional groups (up to eight per molecule), they are potential precursors for advanced hybrid organic-inorganic functional materials. [ABSTRACT FROM AUTHOR]

Der Janus ‐ Würfel ist gelandet ‐ ‐ vielleicht folgt ein großer Schritt für die Materialwissenschaften. In ihrer Zuschrift auf S. 9482 ff. berichten M. Unno und Mitarbeiter über die Synthese und Röntgen ‐ Kristallstruktur eines Octasilsesquioxans mit zwei verschiedenen Substituentenarten, das einem nanoskaligen Janus ‐ Partikel entspricht. Die beiden Würfelhälften, ein Natriumcyclosiloxanolat und ein cyclisches Fluorsiloxan, werden durch eine neuartige Kreuzkupplung verknüpft. [ABSTRACT FROM AUTHOR]