Self-organizing lariat ether derivatives ordered by hydrogen-bonded and stacked nucleotide bases
作者:Otto F. Schall、George W. Gokel
DOI:10.1039/c39920000748
日期:——
A novel bibracchial lariat ether based upon 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (A2O3T3A) has been prepared which has CH2CH2adenine (2A) and CH2CH2CH2thymineOCH2CH2adenine (3T3A) side-arms; the terminal adenine in the 3T3A side-arm folds parallel to and π-stacks with the thymine in the same side-arm while the adenines in opposite side-arms form a single hydrogen bond as judged by two-dimensional NOESY studies.
Molecular Boxes Derived from Crown Ethers and Nucleotide Bases: Probes for Hoogsteen vs Watson-Crick H-Bonding and Other Base-Base Interactions in Self-Assembly Processes
作者:Otto F. Schall、George W. Gokel
DOI:10.1021/ja00093a005
日期:1994.7
Bibracchial lariat ethers based upon 4, 13-diaza-18-crown-6 having -(CH2)(3)-sidearms terminated in adenine or thymine have been prepared and characterized. The three structures are as follows: adenine-(CH2)(3)-(N18N)(CH2)(3)-adenine (A-O-A), thymine-(CH2)(3)-(N18N)-(CH2)(3)-thymine (T-O-T), and adenine-(CH2)(3)-(N18N)-(CH2)(3)-thymine (A-O-T). Association of the nucleotide bases was expected to afford molecular boxes or other aggregates that would be stabilized by interactions between or among the nucleotide bases. These compounds have been studied in solution by H-1-NMR spectroscopy and by vapor pressure osmometry to determine the extent of association as well as what interactions occur between the bases. The H-1-NMR solution studies involved both temperature and concentration dependence and NOE studies. Several lines of evidence make clear that association does occur in CDCl3 with an association constant for A-O-A with T-O-T of 855 M(-1). Both intra- and intermolecular H-bonding interactions are detected. Hoogsteen binding modes appear to play a very important role in these flexible systems. The A-O-A.T-O-T box may also comprise a ditopic receptor system in which the sides of the box are Ade::Thy pairs and the ends are crown ethers. We have studied such systems in the presence of decanediyldiammonium and dodecanediyldiammonium salts and report evidence for a ternary induced-fit receptor complex.
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作者:Stephen L. De Wall、Leonard J. Barbour、Otto F. Schall、George W. Gokel
DOI:10.1023/a:1009534904760
日期:——
Hydrogen Bonding and π-Stacking Interactions as Organizing Elements in Lariat Ethers Containing Nucleotide Bases
作者:Otto F. Schall、George W. Gokel
DOI:10.1021/jo951959l
日期:1996.1.1
Two new bibracchial lariat ethers have been prepared as flexible model systems for nucleotide H-bonding and pi-stacking interactions. In both compounds, nucleotide bases terminate side arms attached at the nitrogen atoms of a diaza-18-crown-6 macroring. Each side arm is terminated by one or more nucleotide bases. The unsymmetrical structure is ade-CH2CH2CH2CH2CH2-thy-CH2CH2-ade (A-O-T-A). The symmetrical compound is ade-CH2CH2-thy-CH2CH2CH2CH2CH2CH2-thy-CH2CH2-ade (A-T-O-T-A). NMR studies show that the thy-ade side arm organizes by pi-stacking in both A-O-T-A and A-T-O-T-A. Both compounds exhibit hydrogen bonding between the stacked base pair and the opposite adenine. A-O-T-A exhibits a stronger interaction resulting from the enforced interplay of noncovalent forces, as evidenced by one- and two-dimensional NMR experiments. This compound also presented the opportunity to detect and examine single hydrogen-bonded interactions between two adenine bases. The effects of conformational rigidity, side arm orientation, metal ion complexation, and variations in solvent were assessed for both compounds. The results presented here indicate that an increase in the medium's dielectric constant or complexation of metal cations appear to modulate the interplay between hydrogen bonding and stacking interactions.