Thermoanalytical and spectral study of zinc(II) complexes containing theophylline

Treatment of theophylline (Tph) and zinc(II) acetate in various reaction media is studied in this paper. The synthesis, spectral and thermal properties of four theophyllinato complexes, namely [Zn(NH3)2(Tph−)2] (Tph−=theophyllinato monoanion), [Zn(mea)2(Tph−)2] (mea=ethanolamine), [Zn(ipa)2(Tph−)2] (ipa=isopropylamine) and [Zn2(OH)(CH3COO)(Tph−)2] are reported. For successful reaction basic media (acetonitrile, methanol, liquid ammonia, ethanolamine, isopropylamine) were needed. No reaction was found in neutral or acidic water solutions. Differences in the thermal decompositions of the complexes containing one (NH3, ipa) and two-donor-atom ligands (mea) were observed. Spectroscopic studies suggested that carboxylato and hydroxo bridges connect the zinc atoms in the complex [Zn2(OH)(CH3COO)(Tph−)2].