Laser studies of pyridylindoles in supersonic jets

One- and two-photon spectroscopy has been used to study jet-cooled 2-(2′-pyridyl)indole (PyIn-0) and 3,3′-dimethylene-2-(2′-pyridyl)indole (PyIn-2). The laser-induced fluorescence and resonance-enhanced photoionisation spectra of PyIn-2 are congested due to the flexibility of the ethylene chain. Single vibronic level fluorescence spectra allow identification of equivalent modes in the ground and electronically excited states. Deuteration at nitrogen reveals a 4 cm−1 red shift of the origin. Ab initio calculations were conducted at the TD B3LYP/6-31G(d,p) level of theory. We were able to reproduce the energies of pure electronic transitions both in PyIn-0 and PyIn-2. The properties of pyridylindoles in supersonic jets are compared with those for indole and 2-phenylindole.