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A method to produce picolinate ligand in situ under hydrothermal conditions has been used to synthesize four uranyl hydroxyl, oxo- and oxohydroxyl picolinato complexes. (UO 2 )(OH)(Pic) ( 1 ) (HPic = picolinic acid) contains 7-fold coordinated uranyl hydroxyl dimers linked through μ 2 -bridging Pic ligands forming a one-dimensional (1D) polymer. (NH 4 )[(UO 2 ) 3 (O) 2 (OH)(Pic) 2 ] ( 2 ) consists of 7-fold coordinated uranyl oxohydroxyl trinuclear units linked through both μ 2 - and μ 3 -Pic ligands forming a 1D polymer. (NH 4 )[(UO 2 ) 2 (O) 2 (Pic)] ( 3 ) is constructed with 7-fold coordinated uranyl oxo-dinuclear units linked through oxo- and μ 3 -Pic ligands forming a 1D polymer. (NH 4 )[(UO 2 ) 4 (O) 2 (OH) 2 (Pic) 2 (INT)]·H 2 O ( 4 ) (HINT = isonicotinic acid) is made of 7-fold coordinated uranyl oxohydroxyl tetranuclear units linked through both Pic and INT ligands forming a 1D polymer. All four polymers are thermal robust to 350 °C. Raman spectroscopy confirmed the presence of uranyl ion and Pic ligand. In addition, red enhanced fluorescence emissions have been observed for both 1 and 4 . The synthesis method, with the advantage of controlling uranyl hydrolysis and generating ligand in situ , provides a more reliable way to make new coordination polymers of carboxylate ligands with various uranyl hydrolysis species. [ABSTRACT FROM AUTHOR]

Three neodymium (Nd) coordination polymers with propionate, succinate and mixed succinate–oxalate ligands have been synthesized and structurally characterized. Nd 2 (C 3 H 5 O 2 ) 6 (H 2 O) 3 ·3H 2 O ( 1 ) has a 1D polymeric structure built with both ninefold and ten-fold coordinated neodymium polyhedra linked through μ 2 -bridging propionate ligands. Nd 2 (C 4 H 4 O 4 ) 3 (H 2 O) 2 ( 2 ) has a 3D polymeric structure constructed with two distinct ninefold coordinated neodymium polyhedra linked through three types of succinate ligands, two in μ 4 - and one in μ 3 -coordination modes. Nd 2 (C 4 H 4 O 4 ) 2 (C 2 O 4 )(H 2 O) 4 ·3H 2 O ( 3 ) is built with two types of ten-fold coordinated neodymium polyhedra linked through μ 4 -succinate ligands into 2D undulating layers which are further connected through μ 2 -oxalate ligands forming a 3D network with channels. Their vibrational modes and thermal stabilities have been further investigated. [ABSTRACT FROM AUTHOR]

Great effort has been made to synthesize larger uranyl peroxide clusters whilst the understanding of the basic construction units for these clusters still needs to be further explored. Two small uranyl peroxide clusters stabilized by simple dicarboxylate ligands have been synthesized and characterized. Na 10 [(UO 2 )(O 2 )(C 3 H 2 O 4 )] 5 ·20H 2 O ( 1 ) has a pentagonal ring stabilized by malonate and [Na 4 K 2 (UO 2 ) 2 (O 2 )(C 2 O 4 ) 4 ]·6H 2 O ( 2 ) has a dimer stabilized by oxalate. Cation-cation interactions between uranyl and alkali metal ions exist in both 1 and 2 , leading to the observation of elongated U O −yl bonds. Vibrational modes of uranyl ion, peroxide and malonate/oxalate ligands have been confirmed by Raman spectroscopy. The presence of malonate ligands prevents the pentagonal uranyl peroxide rings further assembling into larger clusters whilst the excess oxalate ligands inhibit the dimers further linking to nearby uranyl centers. [ABSTRACT FROM AUTHOR]

The reaction of uranium(VI) or thorium(IV) nitrate with p -toluenesulfonic acid (PTSA) in aqueous solutions at room temperature led to the formation of U(VI)/Th(IV) coordination polymers (CPs) with deprotonated μ 2 -bridging PTS anions. Both [(UO 2 )(PTS) 2 (PTSA)]·4H 2 O ( 1 ) and Th(PTS) 4 (H 2 O) 3 ( 2 ) have one-dimensional (1D) undulating polymeric structures built with pentagonal bipyramidal uranyl polyhedrons and 9-fold coordinated thorium polyhedrons, respectively, linked through μ 2 -bridging PTS anions. Both CPs have similar thermal decomposition patterns as they have similar structural type in the presence of the same ligand. Vibrational modes have been investigated and the structural features have been discussed together with relevant structures. [ABSTRACT FROM AUTHOR]