A series of five zeolitic imidazolate frameworks (ZIFs) have been synthesized using zinc(II) acetate and five different 4,5-functionalized imidazole units, namely ZIF-25, -71, -93, -96, and -97. These 3-D porous frameworks have the same underlying topology (RHO) with Brunauer-Emmet-Teller surface areas ranging from 564 to 1110 m(2)/g. The only variation in structure arises from the functional groups that are directed into the pores of these materials, which include -CH(3), -OH, -Cl, -CN, -CHO, and -NH(2); therefore these 3-D frameworks are ideal for the study of the effect of functionality on CO(2) uptake. Experimental results show CO(2) uptake at approximately 800 Torr and 298 K ranging from 0.65 mmol g(-1) in ZIF-71 to 2.18 mmol g(-1) in ZIF-96. Molecular modeling calculations reproduce the pronounced dependence of the equilibrium adsorption on functionalization and suggest that polarizability and symmetry of the functionalization on the imidazolate are key factors leading to high CO(2) uptake.
Bismuth chalcogenides Bi 2 Se 3 and Bi 2 Te 3 are semiconductors which can be both thermoelectric materials (TE) and topological insulators (TI). Lattice defects arising from vacancies, impurities, or dopants in these materials are important in that they provide the charge carriers in TE applications and compromise the performance of these materials as TIs. We present the first solid-state nuclear magnetic resonance (NMR) study of the 77
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.