Oligonucleotide Analogues with Integrated Bases and Backbones. Part 25

Abstract

The ability of A*[s]U dinucleosides to gel organic solvents and water is modulated by changing the nature of the substituents at OÀC(2') and OÀC(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.

Functional π-Gelators and Their Applications

“…The guanosine base pair formation promoted gelation of alkylsilylated guanosine derivatives 435a – c (Chart ) . Dinucleosides 436a – e (Chart ) form thermoreversible gels in organic solvents due to base pairing assisted linear aggregate formation followed by desolvation of the nucleobases. , …”

“…898 Dinucleosides 436a−e (Chart 107) form thermoreversible gels in organic solvents due to base pairing assisted linear aggregate formation followed by desolvation of the nucleobases. 899,900 The binary mixtures of 5′-guanosine monophosphate and guanosine form stable gels at neutral pH over a temperature range that can be tuned by varying the relative proportions of the hydrophobic guanosine and the hydrophilic 5′-guanosine monophosphate in the mixture. 901 The transformation of gel fibres into precipitates upon aging was accompanied by a change in the photoluminescence intensity and was ascribed to as a consequence of Ostwald ripening process.…”

Supramolecular gels made from nucleobase, nucleoside and nucleotide analogs

“…14). 80,81 Gels formed with these derivatives depend on the linear self-association of the nucleobases A and U via hydrogen bonding. While, altering the identity of the protecting group from isopropylidene 19 to cyclohexylidene 20 had little impact on the properties of the organogels, gels formed with the dimethylated derivative 21 had consistently lower minimum gelation concentrations and generally higher gel-sol transition temperatures than 19 and 20.…”