J. Parsch et Jw. Engels, Synthesis of fluorobenzene and benzimidazole nucleic-acid analogues and their influence on stability of RNA duplexes, HELV CHIM A, 83(8), 2000, pp. 1791-1808
Six different ribonucleoside phosphoramidites with fluorobenzenes or fluoro
benzimidazoles as base analogues, one abasic site, and inosine were synthes
ized and incorporated into oligoribonucleotides. The oligomers were investi
gated by means of UV and CD spectroscopy to assess the contribution of H-bo
nding, base stacking, and solvation to the stability of the RNA duplex. CD
Spectra show that the incorporation of modified nucleosides does not lead t
o changes in the structure of RNA. The T-m differences determined are based
on changes in base stacking and solvation. Individual contributions of bas
e stacking and solvation of the modified nucleosides could be determined. I
n fluorobenzene . fluorobenzimidazole-modified base pairs, a duplex-stabili
zing force was found that points to a weak F ... H H-bond.