Syntheses, Structures, Luminescence, and Photocatalytic Properties of a Series of Uranyl Coordination Polymers

A new
series of uranium coordination polymers have been hydrothermally
synthesized by using 4,4′-oxidiphthalic acid (H4L) in the presence of N-bearing species, namely, (H2dpa)­UO2L·3H2O (1), (H2dib)­UO2L·H2O (2), (H2bbi)­(UO2)­L·3H2O (3), (H2dib)­(dib)0.5[UO2L­(dib)]·3H2O (4), (H2bbi)­(U2O5)­L·2H2O (5), and (Hbpi)2(UO2F)2L (6) [dpa = di­(pyridin-4-yl)­amine, dib = 1,4-di­(1H-imidazol-1-yl)­benzene, bbi = 1,1′-(1,4-butanediyl)­bis­(imidazole),
and bpi = 1-(biphenyl-4-yl)-1H-imidazole]. Compounds 1–3 exhibit the ribbon structures with dpa, dib, and
bbi as the templates, respectively. Compound 4 represents
a one-dimensional chain assembly of uranyl centers, L ligands, and
coordinated dib molecules. Compound 5 contains the tetranuclear
motifs of edge-sharing of two UO7 pentagonal and two UO8 hexagonal bipyramids, which are linked by L ligands forming
a layered structure with bbi as the template. Compound 6 forms a two-dimensional arrangement, in which the chain structures
of edge-sharing UO5F2 pentagonal bipyramids
are pillared by L ligands. Luminescence studies reveal the characterized
green light emission from uranyl centers for these uranyl carboxylates.
Moreover, the excellent visible light photodegradation activities
for RhB are displayed by these coordination polymers.