Supramolecular structures of Mn2+, Co2+ and Zn2+ complexes containing 1,3-bis(4-pyridyl)propane and aminosalicylate anion

In this study, the synthesis, spectroscopic properties and crystal structures of three new supramolecular compounds named [Mn2(bpp)4(H2O)4](AS)4·H2O (1), [Co2(bpp)4(H2O)4](AS)4·H2O (2) and [Zn(bpp)(AS)2] (3), have been described, where bpp is 1,3-bis(4-pyridil)propane and AS−  is aminosalicylate anion. By analysing the similarities between the X-ray powder diffraction results, it has been observed that compounds 1 and 2 are isomorphous, exhibiting an orthorhombic system with space group Pccn; for compound 3, another orthorhombic system was observed, with space group Aba2, which displays coordination between the Zn2+ metal ion and the aminosalicylate anion; this can be considered the first case in the literature involving the direct coordination to the metal ion. The vibrational spectra of compounds 1 and 2 are very similar. In the Raman spectra, the main bands are observed at ca. 1625 and 1020 cm− 1, referring to the − O–C = O and CC/CN stretching modes of AS−  and bpp ligands, respectively.