title: Tunable transition metal-ligand complexation for enhanced elucidation of flavonoid diglycosides by electrospray ionization mass spectrometry.
abstract: A tunable ESI-MS/MS strategy for differentiation of flavone and flavanone diglycoside isomers based on metal complexation with auxiliary ligands is reported. The addition of a metal salt and an auxiliary ligand to a flavonoid solution results in the formation of [M(II) (flavonoid-H) auxiliary ligand](+) complexes, where M(II) is a transition metal. A series of auxiliary ligands with electron-withdrawing substituents were synthesized to tailor the relative metal binding affinities of the ligands and thus directly influence the stabilities, and consequently the dissociation pathways, of the complexes. Upon collisionally activated dissociation, the complexes yield fragmentation patterns in which the abundances of key diagnostic ions are enhanced, thus facilitating isomer differentiation.
authors.affiliation: Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712-0165, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Pikulski
authors.forename: Apolonio
authors.initials: A
authors.lastname: Aguilar
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Brodbelt
mesh_terms: D005419:Flavonoids / Q000032:analysis*; D006027:Glycosides / Q000032:analysis*; D008024:Ligands; D008670:Metals / Q000737:chemistry*; D015394:Molecular Structure; D021241:Spectrometry, Mass, Electrospray Ionization; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry
chemical_list: D005419:Flavonoids; D006027:Glycosides; D008024:Ligands; D008670:Metals