Two New Copper Borates with Mesoscale Cubic Supramolecular Cages Assembled from {Cu4 @B20 } Clusters.

Two new copper borates, namely H6 [(μ4 -O)Cu4 @B20 O32 (OH)8 ]⋅25 H2 O (1) and H6 [(μ4 -O)Cu4 @B20 O32 (OH)8 ]⋅34 H2 O⋅8 H3 BO3 (2), with 3D supramolecular framework have been made under solvothermal conditions, which built by novel cubic supramolecular cages with mesoscale cavities via the H-bondings. Interestingly, the cage is assembled by [(μ4 -O)Cu4 @B20 O32 (OH)8 ] ({Cu4 @B20 }) cluster units with different point-group symmetry. Owing to extra H3 BO3 molecules participated in building the supramolecular framework, 2 has a larger cubic cage size and higher non-framework volume, leading to the cage size extended to mesoporous size set as a version of ''1 plus".