title: Gas-phase fragmentation of protonated C60-pyrimidine derivatives.
abstract: Electrospray ionization mass spectrometry/mass spectrometry (ESI/MS/MS) and multiple stage mass spectrometry (MSn, n > 2) were used in the positive ion mode, with two different types of mass spectrometers, a quadrupole time-of-flight and an ion trap, to characterize two sets of different types of C60-aminopyrimidine exohedral derivatives. In one set, the pyrimidine moiety bears an amino acid methyl ester residue, and in the other the pyrimidine ring is part of a nucleoside-type moiety, the latter existing as two separated diastereoisomers.We have found that retro-cycloaddition processes occur for the closed shell protonated species formed by electrospraying C60 derivatives synthesized by Diels-Alder reactions, whereas for the C60 derivatives synthesized via 1,3-dipolar cycloadditions, these processes did not occur. Formation of diagnostic ions allowed the differentiation between the two groups of fullerene derivatives, and between the diastereoisomers of C60 derivatives with a nucleoside-type moiety. In general, the fragmentation processes are strongly dependent on the protonation sites and on the structure of the exohedral moieties.
authors.affiliation: Mass Spectrometry Laboratory, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Catarina I V
authors.initials: CI
authors.lastname: Ramos
authors.forename: M G
authors.initials: MG
authors.lastname: Santana-Marques
authors.forename: Roger F
authors.initials: RF
authors.lastname: Enes
authors.forename: Augusto C
authors.initials: AC
authors.lastname: Tomé
authors.forename: José A S
authors.initials: JA
authors.lastname: Cavaleiro
authors.forename: Manuel
authors.initials: M
authors.lastname: Nogueras
mesh_terms: D005563:Formic Acid Esters / Q000737:chemistry; D037741:Fullerenes / Q000032:analysis / Q000737:chemistry*; D015394:Molecular Structure; D011522:Protons; D011743:Pyrimidines / Q000032:analysis / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D005563:Formic Acid Esters; D037741:Fullerenes; D011522:Protons; D011743:Pyrimidines; C025468:methyl formate; C030986:pyrimidine; C069837:fullerene C60