Theoretical study of the inclusion complexation of TCDD with cucurbit[n]urils

Dioxins are a group of persistent organic pollutants which cause extreme harm to animals and human beings. There is great significance in developing fast and effective methods for enriching (capturing) and detecting dioxins. In this work, molecular dynamics (MD) simulations and quantum chemistry (QM) calculations have been used to study the inclusion complexation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic dioxin, with cucurbit[n]urils (CBn, n = 6, 7, and 8), a group of well-known host complexes applied in the study of host-guest interactions. The inclusion of TCDD with all three CBn hosts is found to be an energetically favorable process without remarkable energy barriers. In general, the host and guest form stable 1 : 1 complexes (TCDD-CBn), as indicated by calculated large complexation energies and small deformation energies of the host and guest. Moreover, the 1 : 2 host-guest complex (2TCDD-CB8) can be formed for CB8 due to its relatively larger cavity. The characteristic infrared (IR) and Raman peaks of TCDD are recognizable in the corresponding spectra of TCDD-CBn complexes. Based on the theoretical results, CBn are believed to be capable of including TCDD, and the TCDD in the inclusion complexes can be detected using both IR and Raman techniques. The results shown in this work are expected to be informative to the relevant experimental researchers.