Fig. 5

Investigation of the mechanism of separation of C6 alkane isomers in compounds 1 and 2. a Energy barriers calculated from ab initio molecular dynamics (AIMD) simulations in compound 1 to highlight vast differences in kinetic energy barrier between the linear and branched C6 alkanes. Barriers range from 0 (no barrier) to 450 kJ/mol and are broken into 50 kJ/mol increments. The size of each circle corresponds to the amount of AIMD trajectory time in that increment. A larger circle thus indicates more AIMD time steps with a barrier in that increment range. As expected, a higher degree of branching results in higher barriers. These results confirm the kinetically-driven sieving mechanism at play in compound 1. b IR spectra of compound 2 upon adsorption of three C6 alkane isomers after 3 min under 10 torr at 30 °C. All spectra are normalized by the reference spectra recorded prior to the adsorption