Formation and thermal stability of supramolecular complexes of dibromosubstituted zinc(II) dipyrromethenate with ethanol and N,N – dimethylformamide

Abstract

Crystal solvates of zinc(II) 3,3′,5,5′-tetramethyl-4,4′-dibromo-dipyrromethenate [ZnL2] form supramolecular complexes [ZnL2(C2H5OH)2] and [ZnL2(DMF)2] with molecules of ethanol and DMF. Such complexes are stable up to ∼ 150 and 111 °C, respectively. According to the quantum chemical calculations, [ZnL2(DMF)2] is formed due to the additional coordination of molecular ligands by the zinc atom (Znδ+ ⟵: O). In the case of [ZnL2(C2H5OH)2], along with weak coordination interactions of the hydroxyl group oxygen with the zinc ion, the main contribution to the suprastructure formation is made by hydrogen bonds (C2H5OH ⟵ :N≤), which makes both the destruction onset temperature and the total enthalpy (ΔHΣ) of the intermolecular interactions in [ZnL2(C2H5OH)2] much higher than in [ZnL2(DMF)2]. The obtained results are interesting for the development of new [ZnL2] fluorescent sensors of N- and O-containing analytes.