Study by DFT of the functionalization of amylose/amylopectin with glycerin monoacetate: Characterization by FTIR, electronic and adsorption properties

Abstract

Based on the Density Functional Theory (DFT) calculations, in this work is studied the electronic and vibrational characterization of different molecular complexes formed by a molecule of glycerol monoacetate (or monoacetin) and short chains of the starch polymer (amylose or amylopectin). The computational calculations were performed using the B3LYP functional and the 6-31G basis set. All systems studied have a neutral charge and a singlet multiplicity. In this work we propose two different forms of interaction: molecules that interact laterally (Models 1.1 and 2.1) and linearly (Models 1.2 and 2.2). All the complexes showed to be energetically stable, whose adsorption processes are exothermic. The analysis of the thermodynamic functions and the global quantum-molecular descriptors indicate that the complex formed between monoacetin and amylose tetramer (Model 2.1) is the most stable, with a spontaneous chemisorption process. FT-IR theoretical spectra of these molecular complexes are obtained, which may be used in the future studies as theoretical identifiers.