The electronic spectra of N-heteroaromatic systems. IX. n → π transitions of polycyclic azines was written by Mason, S. F.. And the article was included in Journal of the Chemical Society in 1962.Reference of 322-46-3 This article mentions the following:
The visible and ultraviolet spectra of some polycyclic azines were measured in hydrocarbon and hydroxylic solvents. The frequencies of the n → π bands are determined primarily by the energy of the lowest unoccupied orbital in the corresponding aromatic hydrocarbon and the 1-electron charge ds. in that orbital at the positions occupied by N atoms, together with ground-state interaction between the lone pair orbitals in the ortho diazines. The intensities of the diazine n → π bands increase with the sum of the 1-electron charge ds. at the N positions of the lowest unoccupied π orbital. Compounds investigated are quinoline, quinoxaline, 1,5- and 1,8-naphthyridine, cinnoline, quinazoline, phthalazine, 1,2,4-, 1,4,5-, and 1,4,6-triazanaphthalene, 1,3,5,8-and 1,4,5,8-tetraazanaphthalene, and phenazine. In the experiment, the researchers used many compounds, for example, Pyrido[2,3-b]pyrazine (cas: 322-46-3Reference of 322-46-3).
Pyrido[2,3-b]pyrazine (cas: 322-46-3) belongs to pyrazine derivatives. Pyrazinesare six-membered aromatic heterocyclic organic compounds with two nitrogen atoms at 1,4-positions. Pyrazine is a weaker base (pKb = 13.4) than pyridine (pKb = 8.8), pyrimidine (pKb = 12.7). A number of pyrazine-based derivatives were used as dyes or fluorescent probes.Reference of 322-46-3