NEW ALIPHATIC BORONATE LIGANDS FOR AFFINITY-CHROMATOGRAPHY

Aliphatic boronates have not been used as ligands in boronate affinity chromatography, possibly because of their low stability. To fill this void, we have prepared three different boronate esters: 1-chloro-5-(3-dimethylaminophenoxy)pentane-1-boronate, 1-thiourea-5-(3-dimethylaminophenoxy)pentane-1-boronate and 1-acetamido-5-(3-dimethylaminophenoxy)pentane-1-boronate, the latter two of which have a hetero atom coordinated with the boron, creating a tetrahedral boronate. These were coupled to the hydroxylic matrix and their ability to interact with various catechols was tested. Chloroboronate gel bound a number of catechol derivatives, except DL-DOPA, quantitatively, but was rather unstable. Thiourea-boronate gel, on the other hand, was relatively stable, although chromatography using it failed. Acetamido-boronate gel did not bind catechol derivatives quantitatively, but did retard them differentially, a property which could be used for their separation. Acetamido-boronate gel was also more stable than chloro-boronate gel, although it was not stable enough for unlimited application.