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

Abstract

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.

Keywords:

• supramolecular chemistry
• 1,3-bis(4-pyridil)propane
• aminosalicylate anion

Acknowledgements

The authors thank CNPq, CAPES, FAPEMIG (PRONEX 04370/10, CEX-APQ-01740-11) and FINEP (PROINFRA 1124/06) for financial support and also LabCri (Departamento de Física – UFMG) and LDRX (Instituto de Física – UFF) for the X-ray facilities.