Bis(nitrate)diaquauranyl(VI) synthon to generate [1 x 2+1 x 1] and [1 x 1+1 x 1] co-crystalized 3d center dot center dot center dot 5f self-assemblies

The syntheses, characterization and crystal structures of four copper(II)/nickel(II)center dot center dot center dot uranyl(VI)self-assemblies of composition [{(NiL1)-L-II}(2)center dot{((UO2)-O-VI)(NO3)(2)(H2O)(2)}] (1), [{(CuL2)-L-II}(2)center dot{((UO2)-O-VI)(NO3)(2)(H2O)(2)}]center dot 0.68H(2)O (2), [{(NiL2)-L-II}(2)center dot{((UO2)-O-VI)(NO3)(2)(H2O)(2)}] (3) and [{(CuL3)-L-II}center dot{((UO2)-O-VI)(NO3)(2)(H2O)(2)}](n) (4) are described in this investigation (H2L1, H2L2 and H2L3 are the Schiff base ligands obtained on condensing 3-ethoxysalicylaldehyde with ethylenediamine, o-phenylenediamine and trans-1,2-diaminocyclohexane, respectively). Compounds 1 and 4 crystallized in the monoclinic P2(1)/n and C2/c space groups, respectively, while compounds 2 and 3 crystallized in the triclinic space group P (1) over bar. Two water molecules of the [((UO2)-O-VI)(NO3)(2)(H2O)(2)] moiety in 1-4, have a linear H2O-U-OH2 arrangement. Each of these two water molecules in 1-3 interacts with the O(phenoxo)(2)O(ethoxy)(2) compartment of a mononuclear copper(II) or nickel(II) moiety due to the formation of bifurcated hydrogen bonds between each of the two water hydrogen atoms and a pair of one phenoxo and one ethoxy oxygen atoms resulting in the interlinking of the two mononuclear 3d units by the [((UO2)-O-VI)(NO3)(2)(H2O)(2)] synthon and therefore these three compounds may be considered as supramolecular dimers. Compounds 1-3 are also two component [1 x 2 + 1 x 1] co-crystals consisting of two mononuclear copper(II) or nickel(II) units and one [((UO2)-O-VI)(NO3)(2)(H2O)(2)] moiety. On the other hand, in 4, two water molecules, from two different [((UO2)-O-VI)(NO3)(2)(H2O)(2)] moieties, interact with one O(phenoxo)(2)O(ethoxy)(2) compartment resulting in the formation of a self-assembled one-dimensional topology. Again, since one mononuclear copper(II) unit and one [((UO2)-O-VI)(NO3)(2)(H2O)(2)] moiety exist in a single crystal in 4, this compound is a two component [1 x 1 + 1 x 1] co-crystal. The outcomes of the present study utilize [((UO2)-O-VI)(NO3)(2)(H2O)(2)] synthon to derive 3d center dot center dot center dot 5f co-crystals, provide the first observation of the interaction of two water molecules with one O(phenoxo)(2)O(ethoxy)(2) compartment, demonstrate the formation of supramolecular dimers and show the first example of a one-dimensional self-assembly resulting from water/O-4 compartment hydrogen bonds, and the first example of [1 x 2 + 1 x 1] co-crystals in 3-ethoxysalicylaldehyde-diamine ligand system.