| Popis: |
The vibrational spectrum of 2,6-naphthyridine (point group C 2 h ) has been measured; the fundamentals are assigned. The electronic spectrum is recorded to 210 nm in solution, and the first two absorption regions studied in further detail. The first transition (onset 400 nm) is very weak (⨍ ∼1.5 × 10 −5 ), and is assigned as a forbidden B g ← A g π*← n , transition as predicted by theory. Its spectrum in naphthalene host shows uniform polarization, parallel to the shorter in-plane molecular axis. The second absorption region at 330 nm contains the first π*←π system ( B u ← A g ). In the vapor it shows a sparsely “tangled” spectrum indicative of a resonance between the π, π* and some other state of only slightly lower energy. The complexities due to this resonance are not seen in durene host crystal. We conclude that a second n , π* state ( A u ) lies just below the first π,π* state in the vapor, and that these two states reverse their order in durene. |
