Syntheses and structural studies of calix[4]arene-nucleoside and calix[4]arene-oligonucleotide hybrids.

We have synthesized three types of calix[4]arene-nucleoside hybrids efficiently by amide bond formation between the amine functional groups of 1,3-diamino-calix[4]arene and the carboxyl groups of thymidine nucleoside derivatives. X-Ray crystallography of a homocoupled calix[4]arene-nucleoside hybrid revealed an interesting hydrogen bonding pattern between thymine bases and the amide linkages. We designed the calix[4]arene-oligonucleotide hybrids to be V-shaped oligodeoxyribonucleotides and synthesized them by using a calix[4]arene-nucleoside hybrid as a key building block. Thermal denaturation experiments, monitored by UV spectroscopy at 260 and 284 nm, and circular dichroism spectra of the calix[4]arene-oligonucleotide hybrids suggest that the modified oligonucleotides indeed adopt V-shaped conformations, making them suitable for use as building blocks in the construction of programmed oligonucleotide nanostructures.