The Intercalation Reaction of 1,10-Phenanthroline with Layered Compound FePS3

The intercalation reaction of 1,10-phenanthroline with FePS₃ in ethanol and in the presence of anilinium chloride has been monitored in detail with the X-ray powder diffraction (XRD) method to study the reaction mechanism. It is revealed that during the intercalation period there are three phases: the 001 phase (corresponding to the perpendicular orientation of the 1,10-phenanthroline ring with the layer of the host FePS₃), the 001′ phase (standing for the parallel orientation of the 1,10-phenanthroline ring with the layer), and the 001″ phase (pristine FePS₃), but as the period of the reaction is prolonged, the 001′ and 001″ phases diminish gradually and finally disappear, and the 001 phase is intensified and a complete intercalate is obtained for Series A, in which excess 1,10-phenanthroline is used. However, for Series B in which the optimum amount of 1,10-phenanthroline is used, the 001 and 001″ phases diminish gradually, and another intercalate is obtained that exhibits the 001′ phase. Moreover, if the amount of phenanthroline used in the reaction is more than that in Series B but not in excess, another intercalate containing 001 and 001′ phases is obtained. In these intercalation reactions, the results of IR spectroscopy indicate that anilinium chloride serves only as the source of protons for 1,10-phenanthroline, but 1,10-phenanthroline acts as both the complexing agent of Fe²⁺ ions removed from FePS₃, confirmed by UV spectra of the filtrates, and the inserted guest, some of which exists in the form of protonated cation to maintain the charge balance of the intercalates. From the experimental evidence we find that the arranged orientation of 1,10-phenanthroline between the layers is controlled by the amount of guest used in the reaction, and a possible intercalation mechanism is proposed for the reaction.