Estudo DFT em Pares de Lewis Frustrados (FLP) para a ativação de CO2

Abstract

The research presented in this dissertation work is important to know the properties and structural and electronic aspects of some systems that are of interest in CO2 capture processes. capture of CO2. The emission of carbon dioxide (CO2 ) in the atmosphere, when done in large scale, is considered as the most serious cause of environmental problems globally. Due to the current global awareness of the issue, the major polluting sectors responsible are reducing emissions by are reducing emissions by capturing these pollutants, especially CO2 , usually done by absorbing the pollutant in specific solvents. In light of this, much research has focused on finding and improving techniques for such a purpose, among which, frustrated Lewis pair reactivity, one of the important concepts in the chemistry of Frustrated Lewis Pairs (FLPs) systems, has attracted considerable attention from both theoretical and experimental chemists. However, the combination of system and reactivity for activation or the capture of CO2 is widely explored. Here, we report a density functional theory (DFT) study using the functional and the CAMB3LYP/6-311++G(d,p) basis set on the CO2 capture process promoted by FLP-type systems. Different combinations B/N, B/P, Al/N and Al/P between the acid-base pairs were structured in geminal and vicinal type system, calculations performed in gas phase and solvation effect solvation effect with water solvent and toluene solvent. In the CO2 capture process, groups attached to the acidic center that tend to make this center more acidic, can contribute to the formation the system to be more stable, and on the other hand bulky groups attached to one of the one of the centers contribute to the steric hindrance, thus hindering the interaction between the acidic center (AL) and basic center (BL). Other aspects that we investigated was the possibility formation of dimer structures for the different systems under study. Further investigations related to the distortion interaction calculations revealed that the lowest stress as well as the highest as well as the higher interaction between the distorted FLP and CO2 reactants is more significant when strong electron-withdrawing groups are present in the center (AL), leading to lower activation barriers activation barriers compared to weak electron-withdrawing groups. These approaches may be useful for designing new FLP systems for CO2 capture.