Postsynthetic Modification of a Metal–Organic Framework for Stabilization of a Hemiaminal and Ammonia Uptake

다국어 초록 (Multilingual Abstract)

<P>In our study, we show by solid-state <SUP>15</SUP>N NMR measurements that an important zirconium metal–organic framework (UiO-66) with amino-functionalized links is composed of a mixture of amino and −NH<SUB>3</SUB><SUP>+</SUP>Cl<SUP>–</SUP> salt functionalities rather than all amino functionality to give a composition of Zr<SUB>6</SUB>O<SUB>4</SUB>(OH)<SUB>4</SUB>(BDC-NH<SUB>2</SUB>)<SUB>4</SUB>(BDC-NH<SUB>3</SUB><SUP>+</SUP>Cl<SUP>–</SUP>)<SUB>2</SUB> (UiO-66-A). UiO-66-A was postsynthetically modified to form a mixture of three functionalities, where the hemiaminal functionality is the majority species in UiO-66-B and aziridine is the majority functionality in UiO-66-C. UiO-66-A–C are all porous with surface areas ranging from 780 to 820 m<SUP>2</SUP>/g and have chemical stability, as evidenced by reversible ammonia uptake and release showing capacities ranging from 134 to 193 cm<SUP>3</SUP>/g.</P><P>Zr<SUB>6</SUB>O<SUB>4</SUB>(OH)<SUB>4</SUB>(BDC-NH<SUB>2</SUB>)<SUB>4</SUB>(BDC-NH<SUB>3</SUB><SUP>+</SUP>Cl<SUP>−</SUP>)<SUB>2</SUB> (UiO-66-A), a crystalline porous framework, is synthesized as a result of the reaction of ZrCl<SUB>4</SUB> and 2-aminoterephthalic acid (H<SUB>2</SUB>BDCNH<SUB>2</SUB>). UiO-66-A was postsynthetically modified to form a mixture of three functionalities, where the hemiaminal functionality is the majority species in UiO-66-B and aziridine is the majority functionality in UiO-66-C. Furthermore, investigation of ammonia adsorption in UiO-66-A−C shows reversible ammonia adsorption in each framework, with the highest uptake observed in UiO-66-C.</P><P><B>Graphic Abstract</B>
<IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/inocaj/2011/inocaj.2011.50.issue-15/ic200744y/production/images/medium/ic-2011-00744y_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ic200744y'>ACS Electronic Supporting Info</A></P>