“…Further, their properties (e.g., lipophilicity) needs to differ somehow to enable separation of congeners by column chromatography. Separation of the mixture is performed either in the form of metal complexes [52,178,232,234,243] if the differences in the R f values between congeners are sufficiently big or in the form of metal free TPyzPzs [132,162,164,167]. Metal complexes are usually strongly tailing on silica, but this is not the case of metal free TPyzPz that, on the other hand, may suffer from lower solubility [166].…”