Rigidtritopic linkers of different sizes were used to buildporous U-(IV) and Th-(IV) 3D frameworks. The charge of the polymerscould be tuned by reaction conditions such as the temperature, pH,solvent, ligand, or metal precursor, yielding a series of neutralor positively or negatively charged frameworks. Postsynthetic solventsubstitution revealed a rare crystal-to-crystal transformation froma cationic to a neutral framework.

Ninenew coordination polymers based on U-(IV) and Th-(IV)were synthesizedsolvothermally utilizing four different trianionic carboxylates (H3BHTC = biphenyl-3,4 ',5-tricarboxylic acid, H3NTB = 4,4 ',4 ''-nitrilotribenzoic acid, H3BTB = 4,4 ',4 ''-benzene-1,3,5-triyl-tris-(benzoic acid),H3BTE = 4,4 ',4 ''-(1,3,5-benzenetriyltri-2,1-ethynediyl)-trisbenzoicacid). The influence of the ligand architecture, the pH, the stoichiometry,the nature of the metal, and the concentration on the structure anddimensionality of the final actinide assembly is discussed. The H3BHTC ligand allowed the synthesis of a cationic three-dimensional(3D) framework [U-(BHTC)-(DMF)(3)]I (1), whichis the first example of a cationic U-(IV) polymer. The H3NTB ligand yielded the 3D neutral polymer [U-3(NTB)(4)] (2) or the two-dimensional (2D) cationic polymer[U-(NTB)-(NMP)(3)]I (3), depending on the solvent.When conditions leading to (2) were used with a Th-(IV)precursor, the 2D neutral polymer [Th-(NTB)-(DMF)(3)Cl] (4) was obtained. The ligand H3BTB allowed the synthesisof two 3D cationic networks [U-(BTB)-(DMF)(2)]I (5) and [U-(BTB)-(DMF)(3)]I (7) or the neutral3D analogue [U-3(BTB)(4)] (6), dependingon the precursor's oxidation state and the acidity of the reactionmixture. The ligand H3BTE allowed the synthesis of theanionic 3D [(CH3)(2)NH2]-[U-2(BTE)(3)] (8) framework featuring large accessiblepores, and under the same conditions, an isostructural Th-(IV) wasalso obtained [(CH3)(2)NH2]-[Th-2(BTE)(3)] (8-Th). All isolated coordinationpolymers were characterized by single-crystal X-ray diffraction (SCXRD).The Langmuir surface areas of the U-(IV) polymers (2),(7), and (8) increased from 140 to 310 m(2)/g owing to the increasing size of the linker, with polymer(8) showing a value that is comparable to the highestsurface area reported to date. The effect of the postsynthetic solventsubstitution was also studied, revealing a crystal-to-crystal transformationof the cationic framework (7) to the neutral framework[U-(BTB)-(THF)-I] (7c).