Oligonucleotide Analogues with Integrated Bases and Backbones. Part 25: Structural Effects on the Gelation of Self-Complementary A*[s]U Dinucleosides

Abstract

The ability of A*[s]U dinucleosides to gel organic solvents and water is modulated by changing the nature of the substituents at O-C(2′) and O-C(3′), as evidenced by comparing the gelation of the dinucleosides 7–9 and the properties of the gels. A mere extension of the hydrophobic moiety, by replacing the isopropylidene groups of 2 by cyclohexylidene groups, as in 7, has a small effect, while changing the conformation of the ribose ring and reducing the size of the hydrophobic moiety, as in 8, has a strong effect on the scope of gelation, the minimum gelation concentration, as low as 0.07% for pentanol and decanol, and the properties of the gel. The fully deprotected dinucleoside 9 gels water at a minimal gelation concentration of 0.6%. A TEM of the corresponding xerogel shows the formation of fibers with a diameter of ca. 30 to 90 nm. © 2010 Verlag Helvetica Chimica Acta