Oligonucleotide has been used as functional molecule such as recording device, or catalyst for chemical reaction. However, that utility has been limited, because it is only soluble in water. Recently, we succeeded in making chemically modified DNA which is clearly soluble in organic solvent. Using this technique, G-quadruplex was constructed in non-polar organic solvent such as 1,2-dichloroethane. The structure was analyzed by CD spectra.