Studies on the Solvent Effect and Assignment of Bands of the Absorption Spectra of some Phenol Betaines. Part I

Absorption spectra of N-methyl-2-(p-hydroxy phenyl) quinolinium hydroxide anhydro-salt has been studied in different solvents in the region 200-600 mμ. Four bands at 20830, 27400, 32470, and 42020 cm^-1 have been observed in its ethanolic solution. A marked relation between the absorption spectra and hydrogen bonding capacity of the solvent has been observed in the case of the anhydro-salt characteristic absorption band in the region of longer wave-lengths. Based on available evidences, the band at 20830 cm-¹ has been assigned to an intra-molecular charge-transfer band. Bands at 27400, 32470 and 42020 cm^-1 have been assigned to ¹L_b→¹A, ¹L_a →¹A and ¹B_b → ¹A transitions respectively.