High-Resolution Laser-Induced Fluorescence Spectra of 7-Azaindole−Water Complexes and 7-Azaindole Dimer

The geometric structures of 7-azaindole−water complexes, (7-AzI)-(H2O) n (n = 1−3), and 7-AzI dimer were investigated by laser-induced fluorescence (LIF) spectroscopy with high resolution (∼0.01 cm-1). For the 7-AzI−(H2O) n complexes (n = 1−3), the LIF spectra show partially resolved rotational structure, which has been analyzed in combination with theoretical calculations. This analysis yields the rotational constants and characterizes the structures. In 7-AzI−(H2O)1, the H2O molecule is located in the molecular plane, forming a six-membered ring with two hydrogen bonds. Analyses for 7-AzI−(H2O)2 and −(H2O)3 show, furthermore, that both the second and the third H2O are located in the molecular plane of 7-AzI, forming a network ring of hydrogen bonds. For the 7-AzI dimer, the LIF spectrum shows an unresolved rotational envelope. The rotational contour has been analyzed, and we discuss the dimer's likely structure.