A series of new lanthanide coordination polymers has been synthesized and structurally characterized; [Ln4(TTHA)2(pzac)(H3O)2(H2O)]·5H2O (Ln = Pr (1a) and Nd (1b)), [Sm8(TTHA)4(pzac)0.5(H3O)(H2O)7.5]·4H2O (2), [Ln4(HTTHA)2(SO4)(H2O)4]·5H2O (Ln = Pr (3a) and Nd (3b)), where H6TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid, and H2pzac = 2,5-dioxo-piperazine-1,4-diacetic acid. The compounds feature 3-D frameworks comprising the deprotonated H6TTHA as the primary ligand and either the in situ generated pzac2- or sulfate as the secondary ligands. The influence of the deprotonated H6TTHA in directing the framework structures through preferential coordination modes and molecular conformation is described. The effect of the secondary ligands in increasing the compactness of the frameworks and in the alternation of the framework topologies based on the four-connected pts type is described.