Water‐Insoluble Ag–U–Organic Assemblies with Photocatalytic Activity

Abstract

Two metal-organic coordination polymers [Ag(bipy)(UO(2))(bdc)(1.5)] (bipy=2,2'-bipyridyl, bdc=1,4-benzenedicarboxylate) and [Ag(2)(phen)(2)UO(2)(btec)] (phen=1,10-phenanthroline, btec=1,2,4,5-benzenetetracarboxylate) were obtained by hydrothermal assembly of the d(10) metal silver and the 5f metal uranium with mixed ligands. Both compounds form two-dimensional networks with pi-pi overlap interactions between the aromatic fragments in the neighboring layers. In aqueous suspension the two water-insoluble materials show photocatalytic degradation performance superior to that of commercial TiO(2) (Degussa P-25) when tested on nonbiodegradable rhodamine B (RhB) as model pollutant. The relationship between the structure of the photocatalysts and the photocatalytic activity was also elucidated. On the basis of the monitored intermediate species and the final mineralized products, it is proposed that the possible reaction mechanism for the photodegradation (oxidation) of RhB in aqueous solution catalyzed by the two assembly compounds involves photoexcitation of uranyl centers and molecular oxygen.

Solid‐State Luminescence and π‐Stacking in Crystalline Uranyl Dipicolinates

“…[26] Even more recently, [32] some uranyl complexes of isomeric (2,4-and 3,4-)pyridine dicarboxylates, though of different stoichiometry to the present materials, have also been described as luminescent due to uranyl centre emission. Though stacking of the pyridine units is extended in these solids, the ring atom separations are relatively large (ca.…”

Single-site photocatalysts with a porous structure

“…This waterinsoluble MOF material exhibits UV-and visible-light photocatalytic activities superior to those of commercial TiO 2 (Degussa P-25) for the degradation of rhodamine B (RhB). Through the same strategy, another Ag-U-organic compound [Ag 2 (phen) 2 UO 2 (btec)] (structure 2 in figure 2) in the presence of 1,10-phenanthroline (phen) and 1,2,4,5-benzenetetracarboxylate (btec) was obtained (Yu et al 2005). This uranyl-organic extended structure also exhibits photocatalytic activity for the RhB degradation.…”

“…Recently, a metal-organic extended structure [Ag(bipy)(UO 2 )(bdc) 1.5 ] (structure 1 in figure 2) with a two-dimensional network was prepared using 2,2 -bipyridyl (bipy) and 1,4-benzenedicarboxylate (bdc) as mixed ligands (Yu et al 2005). In the structure of 1, the uranyl units are connected by bridging bdc ligands to produce chains, which are then cross-linked by additional bdc groups to form a two-dimensional network decorated with [Ag(bipy)] + subunits.…”

New photocatalysts based on mixed-metal pyridine dicarboxylates

“…On the other hand, it is also important to search for new materials with improved photocatalytic properties. In this context, the photocatalytic studies of mixed-metal (d)f) hybrid compounds are just beginning to emerge [13,14]. The synthesis of such mixed-metal systems pose some difficulty for the following reasons: (a) the high coordination and low stereochemical preferences of the lanthanides, which limit their selective introduction into a highly ordered structure and (b) competitive reactions between 3d and 4f metals bonding to the same ligand, which often results in homometallic compounds rather than a hetero-metallic ones.…”