Synthesis, Self-Assembly, and Switching of One-Dimensional Nanostructures from New Crowded Aromatics
摘要:
This study outlines a versatile and expeditious synthesis of the first derivatives of a new class of benzene that is substituted with both three amide and three alkyne substituents. Sparsely covered monolayer films, made through spin-casting, reveal one-dimensional nanostructures that can be visualized with atomic force microscopy. In bulk, synchrotron X-ray diffraction and polarized light microscopy show that these nanostructured columns assemble further into a two-dimensional liquid crystalline phase. The birefringence of this phase can be switched by application of an electric field. The half-time for the liquid crystalline phase to switch is very fast and proportional to the applied voltage.
Process for increasing the tolerance of X-ray contrast media, and
申请人:Guerbet S.A.
公开号:US04474747A1
公开(公告)日:1984-10-02
X-ray contrast media, for which the human body has a greater tolerance than that of contrast media comprising solely iodobenzene compounds, and an opacity of the same order of magnitude as the latter contrast media, comprise mixtures of benzene compounds nuclearly substituted with a plurality of iodine atoms and of benzene compounds nuclearly substituted with a plurality of bromine atoms, the bromobenzene compounds having the mole ratio from 1/2 to 2/1 to the iodobenzene compounds in the mixture.
2D-Covalent Organic Frameworks with Interlayer Hydrogen Bonding Oriented through Designed Nonplanarity
作者:Sampath B. Alahakoon、Kui Tan、Haardik Pandey、Shashini D. Diwakara、Gregory T. McCandless、Daniel I. Grinffiel、Alejandra Durand-Silva、Timo Thonhauser、Ronald A. Smaldone
DOI:10.1021/jacs.0c03409
日期:2020.7.29
We report the synthesis and characterization of a new class of 2D-covalent organic frameworks, called COFamides, whose layers are held together by amide hydrogen bonds. To accomplish this, we have designed monomers with a non-planar structure that arises from steric crowding, forcing the amide side groups out of plane with the COF sheets orienting the hydrogen bonds between the layers. The presence
Supramolecular Reinforcement of a Large-Pore 2D Covalent Organic Framework
作者:Shashini D. Diwakara、Whitney S. Y. Ong、Yalini H. Wijesundara、Robert L. Gearhart、Fabian C. Herbert、Sarah G. Fisher、Gregory T. McCandless、Sampath B. Alahakoon、Jeremiah J. Gassensmith、Sheel C. Dodani、Ronald A. Smaldone
DOI:10.1021/jacs.1c12020
日期:2022.2.16
Two-dimensionalcovalentorganicframeworks (2D-COFs) are a class of crystalline porous organic polymers that consist of covalently linked, two-dimensional sheets that can stack together through noncovalent interactions. Here we report the synthesis of a novel COF, called PyCOFamide, which has an experimentally observed pore size that is greater than 6 nm in diameter. This is among the largest pore