Cubic and rhombohedral heterobimetallic networks constructed from uranium, transition metals, and phosphonoacetate: new methods for constructing porous materials

摘要

Four heterobimetallic U(vi)/M(ii) (M = Mn, Co, Cd) carboxy-phosphonates have been synthesized. M_2I(UO_2)_6 (PO_3CH_2CO_2)_3O_3(OH)(H_2O)_2] 16H_2O (M = Mn(n), Co(n), and Cd(n)) adopt cubic three-dimensional network structures with large cavities approximately 16 A in diameter that are filled with co-crystallized water molecules. [Cd_3(UO_2)_6 (PO_3CH_2CO_2)_6(H_2O)_(13)) 6H_2O forms a rhombohedral channel structure with hydrated Cd(n) within the channels. The cubic compound (Co) displays differential gas absorption with a surface area for CO_2 uptake of 40 m~2 g~(-1) at 273 K, and no uptake of N_2 at 77 K.