title: Characterization of isomeric cationic porphyrins with beta-pyrrolic substituents by electrospray mass spectrometry: the singular behavior of a potential virus photoinactivator.
abstract: Electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS/MS) have been used to differentiate the 2- and 4-methylpyridyl isomers of free-base and metallated cationic beta-vinylpyridylporphyrins. The analysis by ESI-MS/MS of the deuterated analogs and semiempirical calculations of structural and electronic parameters were also undertaken. The two free-base isomers are easily differentiated by ESI-MS/MS but the presence of a metallic center renders differentiation of the metallated isomers less effective. The data acquired show that of all the studied compounds, the free-base 2-methylpyridyl isomer, which was operative in the in vitro photoinactivation of Herpes simples virus, has a different gas-phase behavior. Local distortion of the macrocycle due to the presence of the beta-vinylpyridyl substituent occurs for all the compounds, but a different electron density distribution can account for the observed gas-phase behavior of this potential virus photoinactivator.
authors.affiliation: Mass Spectrometry Laboratory, Department of Chemistry, University of Aveiro, Campus de Santiago, Aveiro, Portugal.
authors.forename: Raul A
authors.initials: RA
authors.lastname: Izquierdo
authors.forename: Cristina M
authors.initials: CM
authors.lastname: Barros
authors.forename: M Graça
authors.initials: MG
authors.lastname: Santana-Marques
authors.forename: A J
authors.initials: AJ
authors.lastname: Ferrer-Correia
authors.forename: Eduarda M P
authors.initials: EM
authors.lastname: Silva
authors.forename: Francesca
authors.initials: F
authors.lastname: Giuntini
authors.forename: Maria A F
authors.initials: MA
authors.lastname: Faustino
authors.forename: João P C
authors.initials: JP
authors.lastname: Tomé
authors.forename: Augusto C
authors.initials: AC
authors.lastname: Tomé
authors.forename: Artur M S
authors.initials: AM
authors.lastname: Silva
authors.forename: Graça P M S
authors.initials: GP
authors.lastname: Neves
authors.forename: J A S
authors.initials: JA
authors.lastname: Cavaleiro
authors.forename: Andreia F
authors.initials: AF
authors.lastname: Peixoto
authors.forename: Mariette M
authors.initials: MM
authors.lastname: Pereira
authors.forename: Alberto A C C
authors.initials: AA
authors.lastname: Pais
mesh_terms: D000998:Antiviral Agents / Q000032:analysis / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D007536:Isomerism; D010777:Photochemistry; D011166:Porphyrins / Q000032:analysis / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D014753:Vinyl Compounds / Q000032:analysis / Q000737:chemistry*; D038301:Virus Inactivation
chemical_list: D000998:Antiviral Agents; D002412:Cations; D011166:Porphyrins; D014753:Vinyl Compounds; C409084:tetraphenylporphyrin