A new type of 3D "strongly" self-catenated metal-organic framework (SDU-9) has been constructed from [Cu-2(COO)(4)] paddlewheel secondary building units and a tripodal carboxylate linker. SDU-9 ([Cu-6(H2O)(6)L-4]center dot 24H(2)O, where [H3L = 4,4',4 ''-(hydroxysilanetriyl)tris(triphenyl-4-carboxylic acid), represents a rare example of a highly symmetrical coordination network and extremely tight self-catenation. To the best of our knowledge, SDU-9 has the highest topological density among all known 3,4-coordinated nets.