title: Protonation Sites, Tandem Mass Spectrometry and Computational Calculations of o-Carbonyl Carbazolequinone Derivatives.
abstract: A series of a new type of tetracyclic carbazolequinones incorporating a carbonyl group at the ortho position relative to the quinone moiety was synthesized and analyzed by tandem electrospray ionization mass spectrometry (ESI/MS-MS), using Collision-Induced Dissociation (CID) to dissociate the protonated species. Theoretical parameters such as molecular electrostatic potential (MEP), local Fukui functions and local Parr function for electrophilic attack as well as proton affinity (PA) and gas phase basicity (GB), were used to explain the preferred protonation sites. Transition states of some main fragmentation routes were obtained and the energies calculated at density functional theory (DFT) B3LYP level were compared with the obtained by ab initio quadratic configuration interaction with single and double excitation (QCISD). The results are in accordance with the observed distribution of ions. The nature of the substituents in the aromatic ring has a notable impact on the fragmentation routes of the molecules.
authors.affiliation: Programa Institucional de Fomento a la Investigaci&#243;n, Desarrollo e Innovaci&#243;n, Universidad Tecnol&#243;gica Metropolitana, Las Palmeras 3360, Casilla 9845, Santiago 7800003, Chile. mmartinez@utem.cl.
authors.forename: Maximiliano
authors.initials: M
authors.lastname: Martínez-Cifuentes
authors.affiliation: Departamento de Qu&#237;mica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago 7800003, Chile. gracielaclavijo@gmail.com.
authors.forename: Graciela
authors.initials: G
authors.lastname: Clavijo-Allancan
authors.affiliation: Departamento de Qu&#237;mica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago 7800003, Chile. pamela.zuniga@ug.uchile.cl.
authors.forename: Pamela
authors.initials: P
authors.lastname: Zuñiga-Hormazabal
authors.affiliation: Departamento de Qu&#237;mica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago 7800003, Chile. braulio.aranda.z@gmail.com.
authors.forename: Braulio
authors.initials: B
authors.lastname: Aranda
authors.affiliation: Unidad de Espectrometr&#237;a de Masas, Facultad de Ciencias Qu&#237;micas y Farmac&#233;uticas, Universidad de Chile, Santos Dumont 964, Casilla 233, Santiago 8380494, Chile. anbarr@gmail.com.
authors.forename: Andrés
authors.initials: A
authors.lastname: Barriga
authors.affiliation: Departamento de Qu&#237;mica, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653, Santiago 7800003, Chile. bweiss@uchile.cl.
authors.forename: Boris
authors.initials: B
authors.lastname: Weiss-López
authors.affiliation: Instituto de Qu&#237;mica de Recursos Naturales, Universidad de Talca, Av. Lircay s/n, Casilla 747, Talca 3460000, Chile. raraya@utalca.cl.
authors.forename: Ramiro
authors.initials: R
authors.lastname: Araya-Maturana
mesh_terms: D016227:Benzoquinones / Q000032:analysis / Q000138:chemical synthesis / Q000737:chemistry*; D005740:Gases / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D007659:Ketones / Q000737:chemistry*; D011522:Protons; D021241:Spectrometry, Mass, Electrospray Ionization; D013816:Thermodynamics
chemical_list: D016227:Benzoquinones; D005740:Gases; D007477:Ions; D007659:Ketones; D011522:Protons; C004532:quinone
keywords: DFT; QCISD; carbazole; mass spectrometry; quinones