| Abstract
| - Laser-induced fluorescence (LIF), dispersed fluorescence (DF), mass-resolved one-color resonance enhancedtwo-photon ionization (RE2PI) and UV−UV hole-burning spectra of 2-aminoindan (2-AI) were measured ina supersonic jet. The hole-burning spectra demonstrated that the congested vibronic structures observed inthe LIF excitation spectrum were responsible for three conformers of 2-AI. The origins of the conformerswere observed at 36931, 36934, and 36955 cm-1. The DF spectra obtained by exciting the band origins ofthe three conformers showed quite similar vibrational structures, with the exception of the bands around600−900 cm-1. The molecular structures of the three conformers were assigned with the aid of ab initiocalculations at the MP2/6-311+G(d,p) level. An amino hydrogen of the most stable conformer points towardthe benzene ring. The stability of the most stable conformer was attributed to an intramolecular N−H···πhydrogen bonding between the hydrogen atom and the π-electron of the benzene ring. The other twoconformers, devoid of intramolecular hydrogen bonding, were also identified for 2-AI. This suggests weakhydrogen bonding in the most stable conformer. The intramolecular N−H···π hydrogen bonding in 2-AI wasdiscussed in comparison with other weak hydrogen-bonding systems.
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