نتایج جستجو برای: crown ethers

تعداد نتایج: 25024  

Journal: :Chemical communications 2011
Joseph W Tucker Jagan M R Narayanam Pinkey S Shah Corey R J Stephenson

Herein we report an advancement in the application of visible light photoredox catalysts in the oxidation of electron-rich arenes resulting in the selective deprotection of para-methoxybenzyl (PMB) ethers. This method is highlighted by excellent functional group tolerance, protecting group orthogonality, mild reaction conditions and avoidance of stoichiometric redox byproducts.

Journal: :Langmuir : the ACS journal of surfaces and colloids 2014
Tea Mihelj Vlasta Tomašić Nikola Biliškov

18-Crown-6, one of the most relevant crown ethers, and sodium cholate, a steroidal surfactant classified as a natural bile salt, are components of a novel, synthesized coordination complex: 18-crown-6-sodium cholate (18C6·NaCh). Like crown ethers, bile salts act as building blocks in supramolecular chemistry to design new functionalized materials with a desired structure and properties. In orde...

Journal: :Macromolecular Chemistry and Physics 2022

Abstract In‐depth understanding of copolymerization kinetics and the resulting polymer microstructure is crucial for design materials with well‐defined properties. Further, insights regarding impact solvents on allows precisely tuned materials. In this regard, in situ 1 H NMR spectroscopy enables precise monitoring living anionic ring‐opening (AROP) ethylene oxide (EO) glycidyl ethers allyl eth...

Journal: :Catalysts 2023

We review crown ether-facilitated nucleophilic reactions using metal salts, presenting the studies kinetic measurements and quantum chemical methods. focus on mechanistic features, specifically contact ion-pair (CIP) mechanism of salts for processes promoted by ethers derivatives. Experimental verification CIP form salt CsF complexed with [18-Crown-6] H-NMR spectroscopy is described. The use ch...

Journal: :Organic & biomolecular chemistry 2006
Edzard M Geertsema Anne Marie Schoevaars Auke Meetsma Ben L Feringa

The concept of bisthioxanthylidene biscrown ethers as potential stereodivergent chiral ligands in asymmetric synthesis is introduced. Substituted bisthioxanthylidenes may be chiral and can exist as stable enantiomers due to their folded structure. As a result, both a right-handed helix (P) and left-handed helix (M) are present in this type of molecule. This offers the unique possibility to cons...

2017
Małgorzata Jóźwiak

The enthalpies of solution of the cyclic ethers 1,4-dioxane, 12-crown-4 and 18-crown-6 in mixtures of ethanol and water have been measured within the whole mole fraction range at T = 298.15 K. The enthalpy of solvation has been calculated. In pure ethanol and pure water, the solvation enthalpy of the investigated cyclic ethers depends linearity on the number of -CH2CH2- groups in the cyclic eth...

Journal: :The journal of physical chemistry. B 2006
Jaakko Akola Kari Rytkönen Matti Manninen

Possible ways for manipulating carbon nanotubes (CNTs) with cyclic supermolecules are studied using density functional theory. Electronic structure calculations with structure optimizations have been performed for the (4,4) and (8,0) single-walled carbon nanotubes (SWNTs) complexed with crown ethers as well as for the (4,0) SWNT with beta-cyclodextrin. A slight polarization of charge in both th...

2015
Maryna I. Bodnarchuk Sergii Yakunin Laura Piveteau Maksym V. Kovalenko

Colloidal inorganic nanocrystals (NCs), functionalized with inorganic capping ligands, such as metal chalcogenide complexes (MCCs), have recently emerged as versatile optoelectronic materials. As-prepared, highly charged MCC-capped NCs are dispersible only in highly polar solvents, and lack the ability to form long-range ordered NC superlattices. Here we report a simple and general methodology,...

2011
Mikio Ouchi

The synthesis and cation-binding properties of a series of Calixarene derivatives possessing alkyl chain groups, ester groups and crown ether rings have been investigated. The syntheses of Calix[4]arene crown ethers and Calix[6]arene derivatives possessing alkyl chain, ester group and crown ether ring have been described. In order to evaluate their monovalent cation binding abilities, solvent e...

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