Diffusional and conformational behaviour of hexadecane-1,16-diol and hexadecane enclathration in three-dimensional nanoporous urea inclusion compound model systems via molecular dynamics simulation

Abstract

Diffusion and molecular conformation are essential characteristics that could be employed to comprehend the dynamics behaviour of molecules in a nanoporous host-guest system. We have performed here a molecular dynamics simulation on hexadecane-1,16-diol and hexadecane guests in the three-dimensional hexagonal nanoporous structure of urea inclusion compound model system and compared the findings with that of one-dimensional urea model system. The guests’ along urea tunnel exhibited slower diffusion with the value correlating well with experimental findings, as the size of the model systems tend to mimic more the real system. The asymmetrical G- and G+ distortion along the guests’ conformational energies, demonstrated that the influence of urea chirality on the guests was notable on hexadecane-1,16-diol as compared to hexadecane. The variation in the diffusional and conformational properties evaluated in each phase of model systems addressed the significant role of the guests’ functional groups. Rationalisation on the factors affecting the guests’ behavioural properties found that the urea confinement had an important role in manipulating the guests’ conformational properties. The intrinsic conformational property, i.e., the steric constraint associated with hydroxyl and alkyl functional groups of hexadecane-1,16-diol and hexadecane, respectively, was found to have a minor role.