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Relevant academic research and scientific papers

Corner- and Side-Opened Cage Silsesquioxanes: Structural Effects on the Materials Properties

Open-cage silsesquioxane, in which traditional closed-cage silsesquioxane is partially hydrolyzed, is a promising class of building blocks for constructing organic-inorganic hybrids. It has advantages of high thermal stability, low crystallinity, transparency, designability, etc. Although the structural effects of closed-cage silsesquioxanes have been elucidated in detail so far, those of open-cages have never been studied. Herein, we synthesized corner- and side-opened cage silsesquioxanes having carbazole units at the open moieties. The former was amorphous in the solid state and polymer matrix, while the latter formed crystalline structures. These different packing structures caused significant difference in the performance as an emission layer of organic light emitting device.

Synthesis of an Open-Cage Structure POSS Containing Various Functional Groups and Their Effect on the Formation and Properties of Langmuir Monolayers

Recently, silsesquioxanes have been recognized as a new group of film-forming materials. This study has been aimed at determining the effect of the kind of functional groups present in two different open-cage structure POSS molecules on the possibility of the formation of Langmuir monolayers and their properties. To achieve this goal, two new POSS derivatives (of open-cage structures) containing polyether and fluoroalkyl functional groups have been synthesized on the basis of a hydrosilylation process. An optimization of the process was performed, which makes it possible to obtain the above-mentioned derivatives with high yields. In the next step, the Langmuir technique was applied to measurements of the surface pressure (π) ? the mean molecular area (A) isotherms during the compression of monolayers formed by molecules of the two POSS derivatives considered. Subsequently, the monolayers were transferred onto quartz plates according to the Langmuir–Blodgett technique. Both derivatives are able to form insoluble Langmuir films at the air–water interface, which can be transferred onto a solid substrate and effectively change its wetting properties.

Synthesis of Functionalized Silsesquioxane Nanomaterials by Rhodium-Catalyzed Carbene Insertion into Si?H Bonds

We report carbene insertion into Si?H bonds of polyhedral oligomeric silsesquioxanes (POSS) for the synthesis of highly functionalized siloxane nanomaterials. Dirhodium(II) carboxylates catalyze insertion of aryl-diazoacetates as carbene precursors to afford POSS structures containing both ester and aryl groups as orthogonal functional handles for further derivatization of POSS materials. Four diverse and structurally varied silsesquioxane core scaffolds with one, three, or eight Si?H bonds were evaluated with diazo reactants to produce a total of 20 new POSS compounds. Novel diazo compounds containing a fluorinated octyl group and boron-dipyrromethene (BODIPY) chromophore demonstrate the use of highly functionalized substrates. Transformations of aryl(ester)-functionalized POSS compounds derived from this method are demonstrated, including ester hydrolysis and Suzuki–Miyaura cross-coupling.

A Highly Effective Route to Si?O?Si Moieties through O-Silylation of Silanols and Polyhedral Oligomeric Silsesquioxane Silanols with Disilazanes

A simple and highly practical catalyst-free O-silylation of silanols with commercially available disilazanes has been developed under mild conditions. In the case of polyhedral oligomeric silsesquioxane (POSS) silanols and some other silanols, it was necessary to use catalytic amounts of inexpensive Bi(OTf)3 as additional catalyst. This efficient chlorine-free protocol involves the synthesis of a wide range of important organosilicon derivatives such as unsymmetrical disiloxanes and functionalized silsesquioxanes.

Highly Efficient Catalytic Route for the Synthesis of Functionalized Silsesquioxanes

Silsesquioxanes (POSS) have recently become the subject of growing interest in many branches of materials chemistry. Despite this great interest, no direct metal-catalyzed method to cap the corner of the POSS molecules has yet been proposed. In this report, we present a highly efficient method for the synthesis of functionalized silsesquioxanes mediated by scandium(III) triflate, which opens up the possibility of introducing a wide variety of functional groups into this class of organosilicon compounds under mild conditions with excellent yields. We also investigated the differences in the activity of the Lewis acid (Sc(OTf)3) and the hidden Br?nsted acid (TfOH) generated in situ from triflates as catalysts in the functionalization of silsesquioxanes. What is more, this solution provides an efficient corner-capping reaction and other functionalizations to obtain silsesquioxane derivatives which are often not possible to synthesize with good yields, efficiency, and chemoselectivity using conventional methods.

SILICON COMPOUND

A large part of conventional organic-inorganic composite materials is obtained by mechanical blending silsesquioxanes with organic polymers, and therefore it has been very difficult to control the structure thereof as the molecular aggregate of the composite materials. An object of the present invention is to provide a novel silicon compound having a living radical polymerization-initiating ability for an addition-polymerizable monomer and a polymer obtained using the same to thereby solve the problem described above regarding the conventional organic-inorganic composite materials. The present inventors have found that a novel silsesquioxane derivative to which a group having an ability to initiate polymerization of a monomer is useful as means for solving the problem described above. That is, the silsesquioxane derivative of the present invention is represented by Formula (1): wherein R1 is hydrogen, alkyl, aryl or arylalkyl; R2 and R3 are alkyl, phenyl or cyclohexyl; and A is a group having an ability to initiate polymerization of a monomer.