Generation of Naphthoquinone Radical Anions by Electrospray Ionization: Solution, Gas-Phase, and Computational Chemistry Studies

Autor(es)

Vessecchi, Ricardo ^{[1, 2]} ; Naal, Zeki ^[2] ; Lopes, Jose N. C. ^[2] ; Galembeck, Sergio E. ^[1] ; Lopes, Norberto P. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Fac Filosofia Ciencias & Letras, Dept Quim, BR-14040901 Ribeirao Preto, SP - Brazil

^[2] Univ Sao Paulo, Fac Ciencias Farmaceut, Dept Fis & Quim, BR-14040901 Ribeirao Preto, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Physical Chemistry A; v. 115, n. 21, p. 5453-5460, JUN 2 2011.
• Citações Web of Science: 22

Resumo

Radical anions are present in several chemical processes, and understanding the reactivity of these species may be described by their thermodynamic properties. Over the last years, the formation of radical ions in the gas phase has been an important issue concerning electrospray ionization mass spectrometry studies. In this work, we report on the generation of radical anions of quinonoid compounds (Q) by electrospray ionization mass spectrometry. The balance between radical anion formation and the deprotonated molecule is also analyzed by influence of the experimental parameters (gas-phase acidity, electron affinity, and reduction potential) and solvent system employed. The gas-phase parameters for formation of radical species and deprotonated species were achieved on the basis of computational thermochemistry. The solution effects on the formation of radical anion (Q(center dot-)) and dianion (Q(2-)) were evaluated on the basis of cyclic voltammetry analysis and the reduction potentials compared with calculated electron affinities. The occurrence of unexpected ions {[}Q + 15](-) was described as being a reaction between the solvent system and the radical anion, Q(center dot-).The gas-phase chemistry of the electrosprayed radical anions was obtained by collisional-induced dissociation and compared to the relative energy calculations. These results are important for understanding the formation and reactivity of radical anions and to establish their correlation with the reducing properties by electrospray ionization analyses. (AU)

• Processo FAPESP: 05/01572-1 - A utilização da química computacional em processos químicos relacionados à ionização por eletrospray
• Beneficiário: Ricardo Vessecchi Lourenço
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 09/08281-3 - Reatividade em fase gasosa do lapachol e derivados quinonóides ionizados por electrospray: Sinergismo entre termoquímica computacional e métodos experimentais
• Beneficiário: Ricardo Vessecchi Lourenço
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado