Investigation of ground state charge transfer complex between paracetamol and p-chloranil through DFT and UV–visible studies

The present report deals with the theoretical investigation on ground state structure and charge transfer (CT) transitions in paracetamol (PA)/p-chloranil (CA) complex using Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TD-DFT) method. It is found that CO bond length of p-chloranil increases on complexation with paracetamol along with considerable amount of charge transfer from PA to CA. TD-DFT calculations have been performed to analyse the observed UV–visible spectrum of PA–CA charge transferred complex. Interestingly, in addition to expected CT transition, a weak symmetry relieved π–π* transition in the chloranil is also observed.

► The first report of theoretical calculation on paracetamol/p-chloranil CT complex. ► It highlights t the importance of studies of dipole moment and Mulliken charges for CT complex. ► Molecular Electrostatic Potential plot clearly indicates the charge transfer from PA to CA.