Izquierdo Raul A, Barros Cristina M, Santana-Marques M Graça, Ferrer-Correia A J, Silva Eduarda M P, Giuntini Francesca, Faustino Maria A F, Tomé João P C, Tomé Augusto C, Silva Artur M S, Neves Graça P M S, Cavaleiro J A S, Peixoto Andreia F, Pereira Mariette M, Pais Alberto A C C
Mass Spectrometry Laboratory, Department of Chemistry, University of Aveiro, Campus de Santiago, Aveiro, Portugal.
J Am Soc Mass Spectrom. 2007 Feb;18(2):218-25. doi: 10.1016/j.jasms.2006.09.010. Epub 2006 Oct 27.
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.
