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<DIV align=center><FONT face=Arial size=2><FONT size=4>Seminarios DQIAQF -
INQUIMAE, 9 de agosto de 2010- 13 h</FONT>s.<BR> <BR>Aula de
Seminarios INQUIMAE - DQIAQF<BR>Facultad de Ciencias Exactas y
Naturales<BR>Ciudad Universitaria - Pab. 2 - Piso 3<BR><BR><FONT
size=4>Structure of reactive species in the gas phase using Infrared
spectroscopy coupled with tandem mass spectrometry<BR></FONT> <BR>Philippe
Maître</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Laboratoire de Chimie Physique, UMR8000
CNRS/Université Paris Sud 11,<BR>Faculté des Sciences, bâtiment 350, 91405 Orsay
Cedex, France<BR> </FONT></DIV>
<DIV><FONT face=Arial size=2> <BR>Resumen:<BR>Gas phase mid-infrared
spectroscopy of molecular ions can nowadays be performed with high performance
tandem mass spectrometers, thus offering an interesting opportunity for the
direct 3D structural characterization of mass-selected ions.[1] The
free-electron lasers (FELs) are particularly interesting since they produce
tunable mid-IR radiation in a broad wavenumber range covering the so-called
molecular fingerprint region (typically 600-2000 cm-1), and their high intensity
makes them very suitable for IRMPD spectroscopy of gas phase molecular ions.
<BR>Experiments are performed using a quadrupole ion-trap (QIT)[2] or a 7 teslas
Fourier Transform Ion Cyclotron Resonance (FT-ICR)[3] mass spectrometer coupled
with the IR FEL based in Orsay, France. In addition, IR spectra recorded in the
NH and OH stretching region using an optical parametric oscillator/amplifier
(OPO/OPA) laser system will also be presented.[4, 5] Comparison of the
experimental spectrum with calculated IR absorption spectra of the low-lying
isomers allows for an unambiguous characterization of the molecular
structure.[1] <BR>Two types of applications will be given. Examples of
characterization of organometallic reactive intermediates will be first
presented.[1] Two examples of palladium catalyzed reactions will be presented.
We will then turn our attention on the structure of N-terminal CID fragments of
peptides, [6, 7] with a special focus on doubly protonated tryptic peptides
whose fragmentation behaviours are of particular interest. We will see that the
1600-2000 cm-1 spectral range is the most diagnostically useful part of the IR
spectrum, especially for distinguishing oxazolone from other isomers of bn+
ions. Whereas it has been suggested that b2+ fragments of doubly protonated
tryptic peptides may have a diketopiperazine structure, we will provide
spectroscopic evidence of an oxazolone structure. IR spectra of larger bn+ ions
will also be presented providing evidence of the formation of a macro-cyclic
structure competing with oxazolone as in the case of the b5+ fragment of G5RH+
which has been characterized as a 15-membered ring cyclic.[7] In addition to IR
fingerprint spectra, we will also present IR spectra of b2+ recorded in the NH
and OH stretching region which may allow for the characterization of the
protonation site of oxazolone.</FONT></DIV>
<DIV><FONT size=1></FONT> </DIV>
<DIV><FONT face=Arial size=1>1. MacAleese, L.; Maitre, P., Infrared spectroscopy
of organometallic ions in the gas phase: From model to real world complexes.
Mass Spectrom. Rev. 2007, 26, (4), 583-605.<BR>2. Mac Aleese, L.; Simon, A.;
McMahon, T. B.; Ortega, J. M.; Scuderi, D.; Lemaire, J.; Maitre, P., Mid-IR
spectroscopy of protonated leucine methyl ester performed with an FTICR or a
Paul type ion-trap. Int. J. Mass Spectrom. 2006, 249, 14-20.<BR>3. Bakker, J.
M.; Besson, T.; Lemaire, J.; Scuderi, D.; Maitre, P., Gas-phase structure of a
p-allyl-palladium complex: Efficient infrared Spectroscopy in a 7 T Fourier
transform mass spectrometer. J. Phys. Chem. A 2007, 111, (51),
13415-13424.<BR>4. Bakker, J. M.; Sinha, R. K.; Besson, T.; Brugnara, M.; Tosi,
P.; Salpin, J. Y.; Maitre, P., Tautomerism of Uracil Probed via Infrared
Spectroscopy of Singly Hydrated Protonated Uracil. J. Phys. Chem. A 2008, 112,
(48), 12393-12400.<BR>5. Bakker, J. M.; Salpin, J. Y.; Maitre, P., Tautomerism
of cytosine probed by gas phase IR spectroscopy. Int. J. Mass Spectrom. 2009,
283, (1-3), 214-221.<BR>6. Bythell, B. J.; Erlekam, U.; Paizs, B.; Maitre, P.,
Infrared Spectroscopy of Fragments from Doubly Protonated Tryptic Peptides.
ChemPhysChem 2009, 10, (6), 883-885.<BR>7. Erlekam, U.; Bythell, B. J.; Scuderi,
D.; Van Stipdonk, M.; Paizs, B.; Maitre, P., Infrared Spectroscopy of Fragments
of Protonated Peptides: Direct Evidence for Macrocyclic Structures of b(5) Ions.
J. Am. Chem. Soc. 2009, 131, (32), 11503-11508.</FONT></DIV></BODY></HTML>