title: Gas-phase dissociation of 1,4-naphthoquinone derivative anions by electrospray ionization tandem mass spectrometry.
abstract: Gas-phase dissociation pathways of deprotonated 1,4-naphthoquinone (NQ) derivatives have been investigated by electrospray ionization tandem mass spectrometry (ESI-MS/MS). The major decomposition routes have been elucidated on the basis of quantum chemical calculations at the B3LYP/6-31 + G(d,p) level. Deprotonation sites have been indicated by analysis of natural charges and gas-phase acidity. NQ anions underwent an interesting reaction under collision-induced dissociation conditions, which resulted in the radical elimination of the lateral chain, in contrast with the even-electron rule. Possible pathways have been suggested, and their mechanisms have been elucidated on the basis of Gibbs energy and enthalpy values for the anions previously described at each pathway.
authors.affiliation: Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão, Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Vessecchi
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Carollo
authors.forename: José N C
authors.initials: JN
authors.lastname: Lopes
authors.forename: Antonio E M
authors.initials: AE
authors.lastname: Crotti
authors.forename: Norberto P
authors.initials: NP
authors.lastname: Lopes
authors.forename: Sérgio E
authors.initials: SE
authors.lastname: Galembeck
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry*; D015394:Molecular Structure; D009285:Naphthoquinones / Q000737:chemistry*; D010575:Pesticides / Q000737:chemistry*; D044367:Phase Transition; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013816:Thermodynamics
chemical_list: D000970:Antineoplastic Agents; D009285:Naphthoquinones; D010575:Pesticides