Protocols for the in-silico screening of the perceived color of industrial dyes: Anthraquinones and indigos as study cases

Abstract

Being able to accurately predict the perceived color of industrially relevant dyes is still a challenge for current theoretical approaches, especially when aiming at keeping a low computational cost and user input. In this work focusing on time-dependent density functional theory as the underlying quantum method of choice, we have analyzed the performance of different integrated approaches to reproduce the perceived color of selected anthraquinones and indigo derivatives. To reconstruct absorption spectra band shape both fully empirical approaches and different vibronic coupling approaches have been tested. The results obtained show how empirical broadening methods, and particularly the pseudo-Voigt model, provide good agreement with experiment in perceived colors but need parametrization and validation for each family of molecules. On the other hand, vibronic coupling models represent a possible powerful alternative, especially in the case of simplified models, though intrinsically limited to rigid dyes.