Dipolar molecular rotors in the metal-organic framework crystal IRMOF-2

Phys Chem Chem Phys. 2008 Sep 14;10(34):5188-91. doi: 10.1039/b808104b. Epub 2008 Jul 15.

Abstract

Rotating polar linker groups in the cubic metal-organic framework single crystal known as IRMOF-2 were investigated for freedom of motion, response to an external electric field, and effects of dipole-dipole interactions. The crystals consist of octahedrally coordinated zinc oxide clusters linked by the bromoterephthalate group, which contains a rotatable bromo-p-phenylene moiety. We confirmed the rotation by dielectric spectroscopy and found a 7.3 kcal mol(-1) barrier. The non-polar analog, IRMOF-1, containing terephthalic acid, was used as a control system. DFT and MP2 computations of the rotational barrier yield results in agreement with the observation, with B3LYP/SDD being the best. A Monte Carlo analysis of the equilibrium polarization fluctuations was used to assess the possibility of polar ordering and the potential for electro-optic applications.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.