Absorption spectra and nature of electron transitions in azomethine dyes as 6-derivatives of 2H-2-chromenone

Abstract

One of the main problems in expanding the application of the coumarin derivatives is a search of new ways for deeping the color and increasing the intensity of the spectral bands. A series of 6-derivatives of 2H-2-chromenone were synthesized. The UV–VIS, 1H NMR spectra of azomethine dyes in the region 220–450 nm have been recorded. Quantum-chemical calculations and the nature of the electronic excitation process were carried out using the PPP and AM1 approximations. Dependence of long wavelength band intensity on the donor strength of the end groups was investigated. The spectral and quantum-chemical investigations show that the azomethine dyes based on the 2H-2-chromenone could be an effective way to influence spectral properties of their derivatives, particularly, position and intensity of the long wavelength absorption bands.