Cu(II) bifunctional (N,O,O') coordination polymer : a case study for complex ab-initio crystal structure determination from PXRD data

The synthesis of a novel Cu(II) bifunctional (N,O,O′) coordination polymer, the Cu(PzHP) compound, has been carried out by coupling Cu(II) salts and the newely synthesized H2(PzHP) organic linker (H2(PzHP) = 1-[4-(1H) -pyrazolyl]-2-methyl-3-hydroxy-4(1H)-pyridinone). Despite to the numerous attempts done for the growth of suitable single crystals and to the synthetic trials carried out to ameliorate the crystallinity of the Cu(PzHP) coordination polymer, its diffraction pattern was always characterized by a discouraging, less-than-ideal, crystallinity. Notwithstanding the extended disorder, leading to a higher than required space group symmetry, we succeeded in the description of its relevant structural features by following an unconventional route to ab-initio structure solution. In this process consideration on the coordination ability of the ligand and on the space group symmetry have been taken into account to ‘manually’ achieve the initial structural model, highlighting that, in some cases, it is still possible to ascertain by PXRD the crystal structure of a material that shows challenging, broad, PXRD pattern.