Conceptual DFT study of the local chemical reactivity of the dilysyldipyrrolones A and B intermediate melanoidins

This computational study assessed 11 density functionals related to Def2TZVP basis sets, namely CAM-B3LYP, LC-omega PBE, M11, M11L, MN12L, MN12SX, N12, N12SX, omega B97, omega B97X, and omega B97XD, and the SMD solvation model for calculating the molecular properties and structures of the intermediate melanoidin pigments, dilysyldipyrrolone A (XL-W1) and dilysyldipyrrolone B (XL-W2). The global and local chemical reactivity descriptors for the systems were calculated via conceptual density functional theory (DFT). The active sites applicable to nucleophilic, electrophilic, and radical attacks were chosen by connecting them with Fukui function indices, electrophilic Parr functions, and condensed dual descriptor Delta f(r) over the atomic sites. The predicted maximum absorption wavelength obtained directly from the HOMO-LUMO was more accurate relative to the experimental values of the MN12SX and N12SX density functionals than those obtained with TDDFT calculations. This study found the MN12SX and N12SX density functionals to be most appropriate for predicting the chemical reactivity of the molecules under study.