Spectrophotometric studies on some hydroxy nitrosocoumarins

ABSTRACT

The UV and visible absorption spectra of some hydroxy nitrosocoumarins have been studied in organic solvents of varying polarities. The dependence of the band shift on the nature of substituent, dielectric effect and specific solvation was studied. The acid dissociation constants of the different ionizable groups were determined using the half- height and the modified limiting absorbance methods. The observed transition energy and oscillator strengths were correlated with those calculated from the SCF PPP CI method for molecular orbitals