Uranyl Tricarballylate Triperiodic and Nanotubular Species. Counterion Control of Nanotube Diameter.

Tricarballylic acid (propane-1,2,3-tricarboxylic acid, H tca) was reacted with uranyl nitrate hexahydrate under solvo-hydrothermal conditions and in the presence of different additional cations, yielding four complexes which have been crystallographically characterized. [(UO)Ba(tca)(HO)] (), isomorphous to the Pb analogue previously reported, crystallizes as a triperiodic framework in which diperiodic uranyl-tca subunits with the (honeycomb) topology are linked by carboxylate-bound Ba cations. Triperiodic polymerization is also found in [(UO)(tca)Ni(cyclam)] () and [(UO)(tca)Cu(-Mecyclam)] (), but here the diperiodic uranyl-tca subunits have the (square lattice) topology, and the frameworks formed through bridging by Ni or Cu cations have different topologies, in and in . [Co(en)][UO(tca)]·2HO () crystallizes as a monoperiodic coordination polymer with the topology and a nanotubular geometry. In contrast to the square-section nanotubules previously found in [NH][(UO)Pb(tca)(NO)(bipy)] (bipy = 2,2'-bipyridine), those in have a hexagonal section with a width of ∼7 Å. The structure-directing role of the hydrogen bonded counterions in these nanotubular species, either NH located within the nanotubule cavity or [Co(en)] located outside, is discussed. Emission spectra in the solid state display the usual vibronic fine structure for and , while uranyl emission is quenched in .