By tuning the steric environment and free porespace in metal−organic frameworks, a large variety of rotordynamics of the organic linkers can appear. NitrofunctionalizedMIL-53 is a terephthalate-linker-based MOF that shows coupledrotor dynamics between the neighboring linkers along the poredirection. Here, we use classical molecular dynamics up to 6 × 2 ×2 supercells to investigate the range of the correlated linkerdynamics. Interestingly, we observe an PNPNPNPN... conforma-tional arrangement (P = nearly planar and N = nonplanar) for theconformations of the linkers in a row along the pore direction inthe MOF. We identified correlated linker dynamics emergingamong the direct and next nearest neighboring linkers along thepore. Due to 180° rotational flips of the planar linkers along the pore, (1) a change in the width of librations in their direct neighbors(PN) is observed; (2) intriguingly, their next nearest planar neighbors (PP) rotate between 0° and ±180° to reattain aligned (0°, 0°)or (±180°, ±180°) conformations. The presence of correlated dynamics in such linkers over long-length scales occurring atnanoseconds time scales is desirable for applications like ferroelectric switching or diffusion control via geared linker rotation, andthis work provides insight into the design for such applications.
Abstract