Coordination chemistry of Be2+ ions with chelating oxygen donor ligands: further insights using electrospray mass spectrometry

The electrospray ionisation mass spectrometric (ESI-MS) behaviour of various complexes of beryllium have been investigated in the work described in this paper. These beryllium complexes were analysed in situ on a small scale by preparing appropriate molar mixtures of the Be2+ ion with ligands in a range of solvent systems. In view of the toxicity of beryllium compounds, this combinatorial type screening, involving miniscule amounts of material in solution, proved to be a safe strategy to pursue the coordination chemistry of beryllium. A variety of beryllium complexes were generated with various ligands in solutions and subjected to detailed characterisation by ESI-MS. These ligands, containing functional groups or architecture of interest, varied from simple ligands such as the acetate ion to more common beryllium chelators including hydroxy keto ligands (maltol, tropolone), malonic acid, chromotropic acid and citric acid. Generally, there was excellent correlation between the species observed in the mass spectrum and those confirmed to exist in solution by other techniques. This lent strong credence to the ESI-MS methodology used as an efficient analytical technique for the easy screening of a diverse range of potential ligands for the divalent beryllium ion.