Inclusion of thymol into cucurbiturils: density functional theory approach with dispersion correction and natural bond orbital analysis

Stability of inclusion complexes of thymol (a natural flavour) with cucurbit[n]urils was interpreted by using density functional theory with dispersion correction and natural bond orbital analysis. Density functional tight binding computations showed that among different cucurbit[n = 5–8]urils, some inverted diastereoisomers of cucurbit[7]uril can form relatively stable inclusion complexes with thymol in water. From density functional theory computations, it can be seen that non-covalent interaction and electron transfer between thymol and CB[7] offer more stability to the inclusion complex. Theoretically calculated dipole moments and electronic spectra of thymol and the its inclusion complex showed that the inclusion complex can have better solubility and photo-resistance than free thymol.

Graphical abstract

Thymol inclusion into CB[n]: Inclusion of thymol into cucurbit[n]urils (CB[n]) was studied by DFTB + and DFT computations. The doubly-inverted CB[7] (i2-CB[7]) can form more stable inclusion complex (thymol@i2-CB[7]) with thymol than other CB[n].(see figure)