RESOLUTION OF OVERLAPPING BANDS IN THE NEAR‐UV ABSORPTION SPECTRUM OF INDOLE DERIVATIVES

Abstract— The second derivative spectra of tryptophan in water and in ethylene glycol at 22°C have been integrated in order to obtain the corresponding primitive functions. The integration was carried out by making use of Tchebychev polynomials. The results show that the integrated primitive functions do not correspond to the original absorption spectra of tryptophan in various solvents, but they reflect only the contributions of the 1Lb bands of the indolic chromophore. The identification of the electronic component, which generates the second derivative spectrum, was based on the solvent insensitivity of the derivative peaks. The comparison between the absorption spectra reported in this paper and those calculated for the 1Lb←1A electronic transition of indole confirmed the assumption that the derivation process eliminates the broad, although more intense, contributions coming from the 1La←1A electronic transition. Copyright © 1985, Wiley Blackwell. All rights reserved