ja9829867_si_001.cif (26.01 kB)
Thin-Film Molecular Materials Based on Tetrametallic “Squares”: Nanoscale Porosity and Size-Selective Guest Transport Characteristics
dataset
posted on 1999-01-12, 00:00 authored by Suzanne Bélanger, Joseph T. Hupp, Charlotte L. Stern, Robert V. Slone, David F. Watson, Thomas G. CarrellDescribed are the preparation and functional characterization of nanocrystalline and/or amorphous
thin films comprising of neutral “molecular squares” of the form [Re(CO)3(Cl)(μ-L)]4 (L = difunctional imine
or azine ligand). The films are strongly adherent, stable in aqueous media, and characterized by comparatively
few pinhole defects. Electrochemical transport experiments show that the materials are exceptionally porous
with respect to sufficiently small solution-phase permeants but blocking toward larger permeants. Related
thin-film experiments based on monometallic “corner” materials indicate efficient exclusion of all candidate
permeant molecules evaluated. For the title materials, these experiments, together with additional electrochemical
probe experiments, indicate that (1) membranelike permeation via pores or tunnels of about nanometer diameter
is the primary mode of transport of molecular and ionic species through thin films and (2) the transport-relevant pore or tunnel diameter is defined by the cavity dimensions for the component molecular square. The
crystal structure of a single isomer of [Re(CO)3(Cl)(μ-4,4‘-bipyridine)]4 is also reported. A packing view down
the c axis of the tetragonal unit cell shows that the molecules, which are significantly puckered in the crystalline
state, are arranged with cavities aligned to generate infinite zeolite-like channels.