An interesting pseudo-honeycomb supramolecular arrangement obtained from the interaction between 4-aminosalicylic acid, trans-1,2-bis(4-pyridyl)ethylene and transition metal ions

Abstract

In this work, three new compounds containing coordination polymers named [Co(bpe)(H₂O)₄]AS₂·4H₂O (1), [Ni(bpe)(H₂O)₄]AS₂·4H₂O (2) and [Zn(bpe)(H₂O)₄]AS₂·4H₂O (3) (where AS is aminosalicylate anion and bpe is trans-1,2-bis(4-pyridyl)ethylene) were synthesized and characterized by X-ray diffraction and vibrational spectroscopy (infrared and Raman). All complexes are isomorphous, crystallizing in a monoclinic system with space groupP2₁/c. The crystalline arrangement shows the presence of a cavity called pseudo-honeycomb imperfect, parallel to the bc-plane formed through hydrogen bonding between aminosalicylate anions and water molecules of crystallization. The vibrational spectra of the compounds are very similar, in agreement with the crystal data. The Raman spectra show bands for bpe at 1642 and 1614 cm⁻¹, assigned to ν(CC) and ν(CC)/ν(CN), respectively. This study can be considered as the first work in the literature where the aminosalicylate anion is associated with coordination polymers just filling the cavities of pseudo-honeycomb structures.