Recently the structure of gas-phase dimer 2-aminopyridine Æ
2-pyridone, the DNA base pair mimic, was investigated
using the technique of rotationally resolved electronic
spectroscopy [33]. According to the structural data, the
two bases are found not being coplanar and a dihedral
angle of between the base planes was 6.1. The present
result obtained by the MP2/6-31G(d,p) optimization is
in a qualitative agreement with the experimental data.