A new chiral bridging ligand, 2,2'-pentaethylene glycol-1,1'-binaphthyl-6,6'-bis(phosphonic acid), was synthesized in 40.7% overall yield in five steps and used to generate single crystals of the first porous lanthanide phosphonates with chiral crown ether pillars. Single-crystal and powder X-ray crystallography established that these chiral crown ether decorated lamellar solids retain their framework structures after the removal of their included guest molecules and serve as structural models for porous solids that are exploitable for bulk chiral separations.
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http://dx.doi.org/10.1021/ja027892i | DOI Listing |
ACS Nano
January 2025
School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, P. R. China.
Crown ethers (CEs), macrocyclic polyethers, have attracted significant attention in supramolecular chemistry. It is known that they have many isomers due to their flexibility. It is challenging to select some exact conformation and tune the following self-assembly structure of CEs, and it has rarely been reported to date.
View Article and Find Full Text PDFPrecis Chem
December 2024
Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
Dual control of the molecular weight and tacticity in proton transfer anionic polymerization (PTAP) of methyl methacrylate (MMA) was investigated by using various ligands in the presence of a bulky potassium base catalyst and an organic compound with a weakly acidic C-H bond as dormant species in toluene at 0 °C. The tacticity of the resulting poly(MMA) (PMMA) produced without ligands was nearly atactic (// = 22/54/24). However, the use of 18-crown-6 as a ligand afforded predominantly syndiotactic PMMA ( ≈ 58%), whereas the use of chiral bis(oxazoline) ligands gave slightly isotactic-rich PMMA ( ≈ 32%).
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
School of Materials Science and Engineering, Tianjin Key Laboratory of Metal and Molecular Materials Chemistry, Frontiers Science Center for New Organic Matter, Nankai University, Tongyan Road 38, Tianjin, 300350, P. R. China.
Chiral hybrid organic-inorganic metal halides (HOMHs) hold great promise in broad applications ranging from ferroelectrics, spintronics to nonlinear optics, owing to their broken inversion symmetry and tunable chiroptoelectronic properties. Typically, chiral HOMHs are constructed by chiral organic cations and metal anion polyhedra, with the latter regarded as optoelectronic active units. However, the primary design approaches are largely constrained to regulation of general components within structural formula.
View Article and Find Full Text PDFSmall
November 2024
Department of Materials Science, Chiba University, 1-33 Yayoi-Cho, Inage-Ku, Chiba, 263-8522, Japan.
Artificial molecular machines, especially when based on wheel-and-axle complexes, can generate mechanical motions in response to external stimuli. Ferrocene (Fc) is a key component, but it decomposes at 300 K on metal surfaces. Here, a novel method is presented to construct and control the molecular complex composed of ammonium-linked ferrocene (Fc-amm) and tetrabrominated crown ether (BrCR) on a Cu(111) surface.
View Article and Find Full Text PDFChem Sci
December 2024
CNRS, LCC (Laboratoire de Chimie de Coordination), Université de Toulouse, UPS, INPT 205 Route de Narbonne, BP 44099, F-31077 Toulouse Cedex 4 France +33-561553003 +33-561333174.
Catalytic asymmetric hydrogenation of ketones is an important approach to prepare valuable chiral alcohols. Understanding how transition metals promote these reactions is key to the rational design of more active, selective and sustainable catalysts. A highly unusual mechanism for asymmetric hydrogenation of acetophenone catalysed by an anionic Ir hydride system, including a strong counterion dependence on catalyst activity, is explored and rationalised here.
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