Synthesis of an organic-inorganic hybrid material by solid state intercalation of 2-mercaptopyridine into Na-, Al(III)- and Co(II)-montmorillonite

Abstract

The preparation of an organic-inorganic hybrid material by solid state intercalation of 2-mercaptopyridine (2Mpy) into Na-, Co(II)- and Al(III)-montmorillonite has been studied using a variety of techniques. The extension ofd₀₀₁from XRD proves that the intercalation of 2-mercaptopyridine into Na-, Co(II)- and Al(III)-mont occurs at ambient temperature in 5 mn. When the intercalated samples were heated at different temperatures, we found that the d₀₀₁ gave different values. For instance, for intercalated Al(III)- and Co(II)-, d₀₀₁ remained unchanged for a temperature under 500°C. However, for intercalated Na-mont, it shifted to 14 Å for a temperature of 300° C, the washing of different samples with a methanol solution shifted thed₀₀₁of intercalated Na-mont to 14 Å. However, for intercalated Al(III) and Co(II), it did not change. This proves that in the case of Na-mont, the molecules of 2-mercaptopyridine interact with the clay through hydrogen bindings and physical interactions. However, for Al(III) and Co(II), it forms coordination linking and physical interaction.¹³C NMR and FTIR spectroscopy have been employed for the characterization of the intercalation compounds. Tautomeric equilibrium between thiol and thione species of 2-mercaptopyridine must be taken into account to explain the arrangement of molecular aggregates and their particular orientation in the interlayer space. The isotherm of adsorption-desorption of nitrogen and topographic AFM images prove that intercalation of 2Mpy is accompanied by a total blockage of clay porosity and an increase in roughness.