The speciation and hydrolysis of beryllium ions in an aqueous solution of its sulfate salt have been studied over a pH range of 2.5-6.0 by using electrospray ionisation mass spectrometry (ESI-MS). Ions observed by ESI-MS revealed that the highly charged beryllium hydroxido species in solution were preserved into the gas phase by pairing with the sulfate ion. The pH-dependent hydrolytic tendencies of the Be 2+ cation presented as an ESI-MS speciation diagram were in good agreement with previous speciation data, suggesting the ability of [a] Chemistry,
Electrospray ionization
mass spectrometry (ESI MS) is a powerful
technique for the study of coordination complexes because of its ability
to analyze solution systems involving very low concentrations of metal
complexes. In this work, the coordination chemistry of Be ions with
a selection of well-known 1,3-diketone and related 1,2-diketone ligands
has been investigated using ESI MS. With acetylacetone (Hacac), a
range of acac-containing ions is observed, including [Be(acac)2H]+, [Be(acac)(MeOH)
n
]+ (n = 1, 2), and polynuclear species
such as the dinuclear [Be2(acac)3]+ and trinuclear [Be3O(acac)3]+.
Density functional theory calculations indicate that the latter species
has a central Be3(μ3-O) core, with each
Be chelated (as opposed to being bridged) by an acac ligand. The effect
of changing the substituents on 1,3-diketone was explored by an investigation
of mixtures of Be2+ with other 1,3-diketones such as dibenzoylmethane
(Hdbm), where the [Be(dbm)2H]+ ion showed a
lesser tendency to undergo fragmentation and aggregation processes.
Comparisons with the corresponding aluminum acetylacetone system were
also made. In contrast, mixtures of Be2+ and the 1,2-diketones
diacetyl and phenanthrenequinone showed poor metal–ligand interactions.
Be2+ interacted with the 1,2-diketone benzil [PhC(O)C(O)Ph],
forming the [Be(benzil)
n
]2+ (n = 2–4) ions. The synthesis (from BeCl2) and X-ray structures of the dibenzoylmethanato (dbm) complex
Be(dbm)2 and the benzil complex [BeCl2(benzil)]
are also reported.
A fundamental issue in beryllium research is the search for suitable chelating ligands for environmental and biomedical application. In this paper, the speciation of beryllium ions with several multidentate aminopolycarboxylic acids, which are well‐known commercial and biomedical chelating agents, has been investigated using electrospray ionisation mass spectrometry (ESI MS). Stoichiometric information, which was readily obtained from the ESI mass spectra, was found to be effective for the preliminary screening of potential encapsulation by tetradentate coordination from a single ligand. Ions observed by ESI MS revealed that the pre‐existing solution species and binding affinity trends were preserved into the gas phase in good agreement with previous solution speciation data, suggesting the ability of ESI MS to be developed as a quick, sensitive and safe screening technique to observe beryllium speciation with ligands of interest at low concentrations. The disruption of beryllium‐ligand binding by addition of other di‐ or trivalent metal cations is also reported.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.