The helix surface of sugar ring for tetrahydrofuran

The present calculations of three geometry conformation for tetrahydrofuran (THF, C sub(4)H sub(8)O) using density functional theory lead to the energy level sequence E (C sub(1)) < E (C sub(s)) < E (C sub(2v)), where, both the geometry symmetry C sub(2v) and C sub(s )are probably a transition structure. The C sub(1) symmetry is the equilibrium conformation, for its energy is the lowest one and it is only possible without the negative harmonic frequency. In C sub(1) conformation, the 4 of carbon atoms C and oxygen atom O constitute a curved surface or the helix surface. The tetrahydrofuran molecule can be as a simple prototype of deoxyribose and has been reviving a quite deal of interest in radiation damage research. It is well known that the sugar ring of deoxyribose is considered as a plane in most of the references. If the equilibrium conformation of THF is C sub(1) symmetry with the helix surface, and for the same reason, the sugar ring of deoxyribose would be also the helix surface; this probably causes the double helix of DNA. It is hardly believed that the sugar ring is a plane in deoxyribose.