Treatments of lanthanide nitrate or perchlorate and C-2-symmetric 2,2'-hydroxy-1,1'-binaphthalene-6,6'-dicarboxylic acid (6,6'-H(2)BDA) led to diastereoselective self-assembly of nanoscale, porous molecular adamantanoids [Ln(4)(BDA)(6)(H2O)(12)].12DMF (Ln = Gd, La, 1a,b). These adamantanoid clusters possess perfect T symmetry as a result of the C-2-symmetric nature of BDA bridging ligands and C-3-symmetric nature of lanthanide ions. Face-to-face intercluster hydrogen bonds formed between 2,2'-dihydroxyl groups of BDA ligands and carboxylate oxygen atoms direct the assembly of 3D polycages based on chiral molecular adamantanoid building blocks which possess two different types of open channels.