- Effects of Molecular Geometry on the STM Image Contrast of Methyl- and Bromo-Substituted Alkanes and Alkanols on Graphite
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Scanning tunneling microscopy (STM) images have been collected for a series of substituted alkanes and alkanols that form ordered overlayers at room temperature on highly ordered pyrolytic graphite surfaces. Molecules that have been imaged possess an internal bromide, with or without terminal alcohol groups (HO-(CH2)9CHBr(CH2)10OH and H3C(CH2)16CHBr(CH2) 16CH3), an internal -OH group (H3C(CH2)16CHOH(CH2) 16-CH3), and an internal methyl group (H3C(CH2)16CHCH3(CH 2)16CH3). These data allow comparison to the STM image contrast reported previously for molecules in which -OH, -Br, and -CH3 groups were located in terminal positions of alkane chains adsorbed onto graphite surfaces. When the functional groups were in gauche positions relative to the alkyl chain, and thus produced molecular features that protruded toward the tip, the functional groups were observed to produce bright regions in a constant current STM image, regardless of the STM contrast behavior observed for these same functional groups when they were in terminal positions of adsorbed alkyl chains. These observations are in excellent agreement with theoretical predictions of the STM behavior of such systems. Additionally, several interesting packing structures have been observed that have yielded insight into the intermolecular forces that control the packing displayed by these overlayers.
- Claypool, Christopher L.,Faglioni, Francesco,Matzger, Adam J.,Goddard III, William A.,Lewis, Nathan S.
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- Lipids, lipid compositions, and methods of using them
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Disclosed are formulation and optimization protocols for delivery of therapeutically effective amounts of biologically active agents to liver, tumors, and/or other cells or tissues. Also provided are compositions and uses for cationic lipid compounds of formula (I). The invention also relates to compositions and uses for stealth lipids of formula (XI). Also provided are processes for making such compounds, compositions, and formulations, plus methods and uses of such compounds, compositions, and formulations to deliver biologically active agents to cells and/or tissues.
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Page/Page column 123
(2016/05/02)
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- Hydrophobically assisted separation-friendly Mitsunobu reaction
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A separation-friendly Mitsunobu reaction using hydrophobic-tagged acids is reported. Commercially available or simply prepared and recyclable hydrophobic-tagged acids can react with various alcohols to afford the target products in high yield with easy purification based on C-18 silica solid-phase extraction or normal silica gel filtration. Georg Thieme Verlag Stuttgart · New York.
- Guo, Jian,Lu, Yu-Jiao,Zhang, Li,Ye, Xin-Shan
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supporting information; experimental part
p. 1696 - 1700
(2012/07/17)
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- Carbamate-based cationic lipids
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The present invention provides novel carbamate-based cationic lipids of the general structure: or a salt, or solvate, or enantiomers thereof, wherein (a) R1 is a lipophilic moiety; (b) R2 is a positively charged moiety; (c) n is an integer from 1 to 8; (d) X is an anion or polyanion; and (e) m is an integer from 0 to a number equivalent to the positive charge(s) present on the lipid. The present invention further provides compositions of these lipids with polyanionic macromolecules, methods for interfering with protein expression in a cell utilizing these compositions, and a kit for preparing the same.
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- Phosphonic acid-based cationic lipids
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The present invention provides novel phosphonic acid-based cationic lipids of the general structure: STR1 or a salt, or solvate, or enantiomers thereof wherein; (a) R1 is a lipophilic moiety; (b) R2 is a positively charged moiety; (c) R3 is a lipophilic moiety of 1 to about 24 carbon atoms, a positively charged moiety, or a negatively charged moiety; (d) n is an integer from 0 to 8; (e) X- is an anion or polyanion; (f) Y is N or O, and (g) m is an integer from 0 to a number equivalent to the positive charge(s) present on the lipid. The present invention further provides compositions of these lipids with polyanionic macromolecules, methods for interfering with protein expression in a cell utilizing these compositions and a kit for preparing the same.
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