A Family
of Rare Earth Porous Coordination Polymers with Different Flexibility
for CO<sub>2</sub>/C<sub>2</sub>H<sub>4</sub> and CO<sub>2</sub>/C<sub>2</sub>H<sub>6</sub> Separation
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Abstract
A family of new porous coordination
polymers (PCPs) were prepared by the reaction of an acylamide modified
ligand (H<sub>3</sub>L) and RE(NO)<sub>3</sub>·<i>x</i>H<sub>2</sub>O (RE = Y, La, Ce, Nd, Eu, Tb, Dy, Ho, and
Tm). PXRD and single-crystal X-ray analyses of them revealed that,
besides the La PCP, all other rare earth members gave isomorphous
structures. The two types of structural toplogies obtained, although
similar, differ in their alignment of acylamide functional groups
and structural flexibility. Adsorption experiments and in situ DRIFT
spectra showed that rigid frameworks have the typical microporous
behavior and poor selective capture of CO<sub>2</sub> over C<sub>2</sub>H<sub>4</sub> and C<sub>2</sub>H<sub>6</sub>; however, the unique
La-PCP with structural flexibility and close-packed acylamide groups
has a high selective capture of CO<sub>2</sub> with respect to C<sub>2</sub>H<sub>6</sub> or C<sub>2</sub>H<sub>4</sub> at 273 K, especially
at the ambient pressure area (0.1–1 bar)
