Nucleoside-based organogelators: gelation by the G-G base pair formation of alkylsilylated guanosine derivatives

2',3'-O-Isopropylideneguanosine derivatives 1a-c having a bulky alkylsilyl moiety showed excellent gelation ability in alkane solvents. IR spectra of the gel clearly showed the absence of hydrogen bonding interaction at the C(6)=O position and, together with a CD study, a G-G base pair formation by double N(2)H center dot center dot center dot N(3) and additional N(2)H center dot center dot center dot O(2') hydrogen bonds was indicated. X-ray diffraction and SEM studies of the xerogel and AFM observation of the transferred gel suggested the formation of a two-dimensional supramolecular assembly 2 nm in thickness. The G-G base pair formation is discussed in terms of the molecular packing in the two-dimensional assemblies. (c) 2007 Elsevier Ltd. All rights reserved.