Mn(II)-containing layered double hydroxide composites: synthesis, characterization and an application in Ullmann diaryl etherification

Mn(II)-containing layered double hydroxides were prepared having the Mn(II) ions in various positions (i) on the layers as dopants, (ii) in the layers as their constituents and (iii) among the layers in the form of intercalated Mn(II) amino acid complexes. The substances were characterized by a range of instrumental methods (XRD, SEM, SEM–EDX) to indicate the positions of the Mn(II) ions. The catalytic activities of the composites were studied in the Ullmann-type etherification reaction. All materials promoted the reaction actively. However, only those having the Mn(II) ions in the structure of the LDH samples, the latter two, proved to be recyclable, i.e. they were real catalysts; the activity of the one prepared by doping deteriorated rapidly on reuse.