Organosilicon platforms: bridging homogeneous, heterogeneous, and bioinspired catalysis

Kung, Mayfair C.; Riofski, Mark V.; Missaghi, Michael N.; Kung, Harold H.

doi:10.1039/c3cc48766k

Cited by 41 publications

(18 citation statements)

References 112 publications

(119 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Specific representatives of cage metallacomplexes, namely cagelike metallasilsesquioxanes (CLMSs), are being intensely studied as (pre)catalysts for numerous chemical processes of high relevance . Cage metallasilsesquioxanes were found to be active in alkene polymerization, epoxidation or epoxide ring opening, metathesis, hydroformylation, Ullmann–Goldberg condensation and amidation .…”

Section: Introductionmentioning

confidence: 99%

Heptanuclear Cage Cu^II‐Silsesquioxanes: Synthesis, Structure and Catalytic Activity

et al. 2018

View full text Add to dashboard Cite

Two prismatic phenyl-(PhSiO 1.5 ) 14 (CuO) 7 (1, 29 % yield) and methyl-(MeSiO 1.5 ) 14 (CuO) 7 (2, 19 % yield) heptacoppersilsesquioxanes were obtained by the interaction of Cu,Na-based cage silsesquioxanes [(RSiO 1.5 ) 12 (CuO) 4 (NaO 0.5 ) 4 ] (R = Ph, Me) with 4,4′-bipyridine and pyrazine, respectively, acting as "silent witness" ligands. Unusual molecular topologies of both compounds 1 and 2, which are the first representatives of [a] Nesmeyanov Institute of Organoelement Compounds,

show abstract

Section: Introductionmentioning

confidence: 99%

Heptanuclear Cage Cu^II‐Silsesquioxanes: Synthesis, Structure and Catalytic Activity

et al. 2018

View full text Add to dashboard Cite

show abstract

“…They are commonly used in the form of polysiloxane "silicone" polymers as components of industrial and consumer products for a variety of purposes such as bulking agents, separation media, protective coatings, lubricants, emulsifiers, and adhesives (1)(2)(3). Their use as auxiliaries in the chemical synthesis of complex molecules is also long-established (4)(5)(6).…”

mentioning

confidence: 99%

Recombinant silicateins as model biocatalysts in organosiloxane chemistry

Dakhili

Caslin

Faponle

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The family of silicatein enzymes from marine sponges (phylum Porifera) is unique in nature for catalyzing the formation of inorganic silica structures, which the organisms incorporate into their skeleton. However, the synthesis of organosiloxanes catalyzed by these enzymes has thus far remained largely unexplored. To investigate the reactivity of these enzymes in relation to this important class of compounds, their catalysis of Si-O bond hydrolysis and condensation was investigated with a range of model organosilanols and silyl ethers. The enzymes' kinetic parameters were obtained by a high-throughput colorimetric assay based on the hydrolysis of 4-nitrophenyl silyl ethers. These assays showed unambiguous catalysis with k cat /K m values on the order of 2-50 min. Condensation reactions were also demonstrated by the generation of silyl ethers from their corresponding silanols and alcohols. Notably, when presented with a substrate bearing both aliphatic and aromatic hydroxy groups the enzyme preferentially silylates the latter group, in clear contrast to nonenzymatic silylations. Furthermore, the silicateins are able to catalyze transetherifications, where the silyl group from one silyl ether may be transferred to a recipient alcohol. Despite close sequence homology to the protease cathepsin L, the silicateins seem to exhibit no significant protease or esterase activity when tested against analogous substrates. Overall, these results suggest the silicateins are promising candidates for future elaboration into efficient and selective biocatalysts for organosiloxane chemistry.silicatein | biocatalysis | organosilicon | organosiloxane | silyl ether T he organosiloxanes, compounds containing C-Si-O moieties, represent a class of compounds with a truly diverse range of applications. They are commonly used in the form of polysiloxane "silicone" polymers as components of industrial and consumer products for a variety of purposes such as bulking agents, separation media, protective coatings, lubricants, emulsifiers, and adhesives (1-3). Their use as auxiliaries in the chemical synthesis of complex molecules is also long-established (4-6). However, the production and synthetic manipulation of these compounds are almost entirely dependent on chlorosilane feedstocks, which are environmentally undesirable and energyintensive to produce (7,8). Furthermore, organosiloxanes, which are entirely anthropogenic in origin, are now known to be persistent environmental contaminants because little attempt is made to recover and recycle them (3). Synthetic routes that use, and ultimately recycle, siloxanes and silanols as alternatives would in principle be more environmentally sound.One possible strategy toward improved sustainability is to harness enzymes for chemical processing. Such biocatalysts are attractive because they offer highly efficient synthesis in terms of yields and regio-and stereospecificity, together with an ability to promote reactions under mild conditions and a minimal reliance on halogenated or metallic feedstocks (...

show abstract

“…More versatile building blocks could offer possibility of new advances in this direction. Silicon compounds constitute an underutilized class of building blocks . Compared with C—O—C bonds, the Si—O—Si bond angles are more flexible, which result in higher degrees of conformational flexibility of siloxane polymers.…”

Section: Discussionmentioning

confidence: 99%

New materials for catalysis and energy storage devices

Kung

2016

AIChE Journal

Self Cite

View full text Add to dashboard Cite

surfactant molecule possessing a cleavable carbamate bond; B. Micelle formed from A; C. Resulting nanocage with tethered interior amino groups after cleavage of carbamate bond and release of cleaved fragments. (D-E): D. Fourth generation dendrimer using cleavable carbamate bond for generation growth; inset shows the repeating units on the left and the periphery unit on the right; E. Nanoparticle formed by cross-linking the periphery C5C bond in D by hydrosilylation; F. Nanocage with interior alcohol groups after cleaving the carbamate bonds in E. (G-I): G. Core containing silyl ester bonds only at the periphery; H. Nanoparticle formed by cross-linking the periphery C5C bonds in G; inset shows the silane cross-linking agent; I. A segment of the core-shell nanocage after cleaving the silyl ester bonds in H; core remained, resulting in carboxylic acid-silanol pairs in the cavity. a Reaction conditions: Catalyst weight 5 350 mg except 5.5 mg Au/TiO 2 , C 3 H 8 :O 2 :H 2 :He 5 5:5:5:85, total flow rate 5 30 mL min 21 , data shown were collected after 4.5 h time-on-stream at 2208C. Ti (wt %) were determined by ICP-AES. b (MO x )/[Au/SiO 2 ] denotes MO x patches decorating a Au/SiO 2 catalyst. Au loading 0.5 wt %, Ti loadings for the three samples were 0, 0.7, and 1.5 wt %. c Average Au particle diameter after catalytic testing estimated from STEM images. d Small amounts (4-6%) each of isopropanol and acetaldehyde also detected, but no propene. e From Ref. 26. f 11% acetaldehyde also detected.

show abstract

Organosilicon platforms: bridging homogeneous, heterogeneous, and bioinspired catalysis

Cited by 41 publications

References 112 publications

Heptanuclear Cage Cu^II‐Silsesquioxanes: Synthesis, Structure and Catalytic Activity

Heptanuclear Cage Cu^II‐Silsesquioxanes: Synthesis, Structure and Catalytic Activity

Recombinant silicateins as model biocatalysts in organosiloxane chemistry

New materials for catalysis and energy storage devices

Contact Info

Product

Resources

About

Organosilicon platforms: bridging homogeneous, heterogeneous, and bioinspired catalysis

Cited by 41 publications

References 112 publications

Heptanuclear Cage CuII‐Silsesquioxanes: Synthesis, Structure and Catalytic Activity

Heptanuclear Cage CuII‐Silsesquioxanes: Synthesis, Structure and Catalytic Activity

Recombinant silicateins as model biocatalysts in organosiloxane chemistry

New materials for catalysis and energy storage devices

Contact Info

Product

Resources

About

Heptanuclear Cage Cu^II‐Silsesquioxanes: Synthesis, Structure and Catalytic Activity

Heptanuclear Cage Cu^II‐Silsesquioxanes: Synthesis, Structure and Catalytic Activity