Knowledge Bank

The geometric structures of 7-azaindole (7-AzI), its dimer, and $7-AzI-H2O$ complexes were investigated by laserinduced fluorescence (LIF) with high resolution $(-0.01cm-1)$. For the 7-AzI dimer, the LIF spectrum shows unresolved rotational envelope due to lifetime broadening, and the rotational contour has been analyzed to T-shaped structure. The structure obtained is consistent with the fact that the dimer shows no proton-transfer reaction. For the $7-AzI-(H2O)n$ complexes (n=1-3), the LIF spectra show partially resolved rotational structure, which has been analyzed. This analysis yields the rotational constants and the structure; the $H2O$ molecule is located in the molecular plane, forming a hydrogen bond with both N and H(-N) atoms. The structure is similar to that of phenol-water complex, where the interaction through hydrogen bonds plays an important role in the complex $formation1$. A preliminary analysis for $7-AzI-(H2O)2$ and $-(H2O)3$, furthermore, shows that the second and third $H2O$ are located in the molecular plane of 7-AzI, forming a network of hydrogen bonds.