C O M M U N I C A T I O N S
Table 1. Structural Factors Determining the Effective Size of the
Pore Openings, A (Excluding van der Waals Radius of H)
on the remarkable differences in their diffusion rates through the
pore systems. The effective size of the pore opening is believed to
be the controlling factor determining the separation capability. In-
depth studies to assess the full separation capability of these
materials, e.g., the breakthrough performance, process efficiency,
and cost simulations, etc., are currently underway.
θ (deg)
d (Å)
Φ (deg)
L (Å)
A (Å)
1
2
3
142.62
144.35
144.77
1.983
1.995
1.984
5.328
7.032
10.764
6.004
6.032
6.015
3.37
3.54
3.26
Acknowledgment. The authors gratefully acknowledge the
financial support from DoE (Grant No. DE-FG02-08ER46491). J.L.
is a Cheung Kong Scholar associated with South China University
of Technology.
thermodynamic separation seems impractical, the rates of adsorption
are markedly different (Figure 2). At 30 °C, the ratio of their
o
diffusion rate coefficients, D(C3 )/D(C3)), is 125, suggesting that
3 has great potential for the kinetic separation of these two very
similar molecules. Adsorption rate measurements for 1 have also
yielded the relative adsorption rates of propene and propane. At
30 °C the ratio of their diffusion rates is 60, approximately one-
half that of 3 (Figure 2).
Supporting Information Available: Syntheses of 2-cim; crystal
growths and selected crystallographic data of 1, 2, and 3; adsorption
measurement procedures and additional figures. These materials are
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Figure 2. Propene and propane uptake by 3 (left) and 1 (right) as a function
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