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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]

With the coordination of dimethylformamide (DMF), two new uranium(VI) complexes with either 4-hydroxybenzoic acid (H 2 phb) or terephthalic acid (H 2 tph) have been synthesized under solvothermal conditions and structurally characterized. [(UO 2 ) 2 (Hphb) 2 (phb)(DMF)(H 2 O) 3 ]·4H 2 O ( 1 ) has a dinuclear structure constructed with both pentagonal and hexagonal bipyramidal uranium polyhedra linked through a µ 2 -bridging ligand via both chelating carboxylate arm and alcohol oxygen bonding, first observation of such a coordination mode of 4-hydroxybenzoate for 5 f ions. [(UO 2 )(tph)(DMF)] ( 2 ) has a three-dimensional (3D) framework built with pentagonal bipyramidal uranium polyhedra linked with µ 4 -terephthalate ligands. The 3D channeled structure is facilitated by the unique carboxylate bonding with nearly linear C–O–U angles and the coordination of DMF molecules. The presence of phb ligands in different coordination modes, uranyl ions in diverse environments and DMF in complex 1 , and tph ligand, DMF and uranyl ion in complex 2 has been confirmed by Raman spectroscopy. In addition, their thermal stability and photoluminescence properties have been 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]

Four dysprosium (Dy) single carboxylates, a formate, a propionate, a butyrate and an oxalate have been synthesized and structurally characterized. The structure of Dy(HCO 2 ) 3 ( 1 ) contains nine-fold coordinated Dy polyhedra in perfect tricapped trigonal prisms. They are linked through trigonal O atoms forming 1D pillars which are further linked together through tricapped O atoms into a 3D pillared metal organic framework. The network structure is stable up to 360 °C. The structure of [Dy 2 (C 2 O 4 ) 3 (H 2 O) 6 ]·2.5H 2 O ( 2 ) contains nine-fold coordinated Dy polyhedra linking together through μ 2 -bridging oxalate anions into a 2D hexagonal layered structure. Both [Dy 2 (Pr) 6 (H 2 O) 4 ]·(HPr) 0.5 ( 3 ) [Pr=(C 2 H 5 CO 2 ) −1 ] and [Dy 2 (Bu) 6 (H 2 O) 4 ] ( 4 ) [Bu=(C 3 H 7 CO 2 ) −1 ] have similar di-nuclear structures. The Raman vibration modes of the complexes have been investigated. [ABSTRACT FROM AUTHOR]