Zinc(II) metal–organic framework
(MOF) materials were prepared
using a porphyrin-based tetracarboxylate linker and pyridine-terminated
[2]rotaxane linkers as pillars. Two pillaring rotaxanes (R = H or
CH3 at pyridine 2-position) were used to create two MOFs α-UWDM-6 and α-UWDM-7, and their
structures were determined by single-crystal X-ray diffraction. Both
MOFs undergo reversible phase transitions upon solvent removal to
generate γ-UWDM-6 and β-UWDM-7. The dynamics of the 24-membered macrocycle ([24]crown-6) inside
each MOF phase was studied using variable-temperature 2H solid-state NMR spectroscopy. Interestingly, only solvated α-UWDM-7 demonstrates unrestricted rotation of the macrocycle
inside the MOF pores; studies on α-UWDM-7 with
various solvents showed that the dynamics of the wheel is essentially
independent of the solvent.
[5]Rotaxanes prepared in a one-pot reaction via simultaneous threading-followed-by-stoppering and condensation can be used to generate different co-conformational states making these systems potential multi-state switches.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.