Studies on two coordination polymers [M(μ4-pz25dc)]n (M=Cd or Zn, pz25dc=pyrazine-2,5-dicarboxylato) with three-dimensional pillared-layer three-nodal framework: Synthesis, structural characterization, strong optical non-linearities and optical limiting properties

Nonlinear optical properties, upconversion and lasing in metal–organic frameworks

The building block modular approach that lies behind coordination polymers (CPs) and metal–organic frameworks (MOFs) results not only in a plethora of materials that can be obtained but also in a vast array of nonlinear optical properties that could be aimed at.

Poly[di-μ-aqua-μ(4)-(pyrazine-2,5-dicarboxyl-ato)-dilithium(I)]

In the title coordination polymer, [Li(2)(C(6)H(2)N(2)O(2))(H(2)O)(2)](n) the pyrazine-2,5-dicarboxyl-ate dianionic ligand bridges two symmetry-independent Li(+) ions using both its N,O-chelating sites. The carboxyl-ate O atom of one of them also bridges to another Li(+) ion, while the second O atom of this group is bonded to another Li(+) ion. Two symmetry-independent water O atoms participate also in the bridging system, which gives rise to a polymeric three-dimensional framework. Both Li(+) ions show distorted trigonal-bipyramidal LiNO(4) coordination geometries, with the N atom in an axial site in both cases. The packing is consolidated by O-H⋯O hydrogen bonds, which occur between water mol-ecules as donors and carboxyl-ate O atoms as acceptors.