183 research outputs found

    Molecule of the month: Cryptatium, the first "Elementoid"

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    Electrochemical reduction of a cryptate yielded a neutral species with the properties of an expanded atom

    The seven component coupling: a new world record by Ivar Ugi and co-workers

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    This article does not have an abstract

    A new bile acid-derived lariat-ether: design, synthesis and cation binding properties

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    A new chola lariat ether (1, a 21-crown-6) was constructed fromreadily available precursors. The association constant of compound 1 with alkali metal picrates was measured using Cram's extraction protocol. Evidence is presented for the involvement of the 3-methoxy group for the complexation. Energy minimised structures show that the A-ring gets slightly distorted upon metal ion binding

    Synthesis and in vitro cholesterol dissolution by 23- and 24-phosphonobile acids

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    A new class of 23- and 24-phosphonobile acids have been synthesized from bile acid and their in vitro cholesterol-dissolving efficiency have been estimated. 24-Phosphonobile salts (PBSs) are slightly more efficient in solubilizing cholesterol than 23-PBSs and natural bile salts. The cholesterol solubilizing power is influenced by the structure of PBSs, and is considerably reduced with an increase in the bulk pH

    Organic reaction mechanisms

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    This article does not have an abstract

    Facially amphiphilic thiol capped gold and silver nanoparticles

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    A series of bile acid-derived facially amphiphilic thiols have been used to cap sliver and gold nanoparticles. The self-assembling properties of these steroid-capped nanoparticles have been investigated and reported in this article

    Use of isotopes for studying reaction mechanisms. 4. Distinguishing between single minima and rapidly equilibrating structures

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    The method of isotopic perturbation of equilibrium is described. In conjunction with nuclear magnetic resonance spectroscopy, the procedure can be used to distinguish between double well and single minimum potential energy surfaces. Some representative studies on classical and non-classical carbocations are discussed

    Chemistry and biology of bile acids

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    This review makes an attempt to combine the insights gained into the biochemistry and physiology of bile acids with the elegant supramolecular systems designed from them. Bile acids are cholesterol-derived facial amphiphiles responsible for the solubilization of cholesterol and fat through mixed micelle formation with phospholipids. An intriguing aspect of bile acids is that their chemical structure has been postulated to correlate with vertebrate evolution. However, the etiology of molecular evolution of bile acids is still poorly understood. There has been a steady progress in the studies aimed at elucidating physiological functions and developing pharmacological applications of bile acids. In recent years, bile acids and their analogues have been extensively utilized as supramolecular receptors for various types of guest molecules and ions. Under certain defined conditions, the supramolecular association of bile acids and their derivatives leads to gel formation. Thus, modified bile acids might find use in the design of futuristic materials

    Supramolecular gels: functions and uses

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    In recent years there has been immense interest in studying gels derived from low molecular mass gelators (supramolecular, or simply molecular gels). The motivation for this is not only to understand the fundamental aggregate structures in the gels at different length scales, but also to explore their potential for futuristic technological applications. Gels have been made sensitive to external stimuli like light and chemical entities by incorporating a spectroscopically active or a receptor unit as part of the gelator molecule. This makes them suitable for applications such as sensing and actuating. The diversity of gel structural architectures has allowed them to be utilized as templates to prepare novel inorganic superstructures for possible applications in catalysis and separation. Gels derived from liquid crystals (anisotropy gels) that can act as dynamically functional materials have been prepared, for example, for (re-writable) information recording. Supramolecular gels can be important in controlled release applications, in oil recovery, for gelling cryogenic fuels etc. They can also serve as media for a range of applications. This tutorial review highlights some of the instructive work done by various groups to develop smart and functional gels, and covers a wide spectrum of scientific interest ranging from medicine to materials science
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