Peer-reviewed Publications |
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Alata, I., Bert, J., Broquier, M., Dedonder, C., Feraud, G., Gregoire, G., Soorkia, S., Marceca, E., & Jouvet, C. (2013). Electronic Spectra of the Protonated Indole Chromophore in the Gas Phase. J. Phys. Chem. A, 117, 4420–4427.
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Altnöder J., B. A., Lee J.J., Otto K.E., Suhm M.A., Zehnacker-Rentien A. (2013). Chirality-dependent balance between hydrogen bonding and London dispersion in isolated (±)-1-indanol clusters. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 15, 10167–10180.
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Barry, C. S., Cocinero, E. J., Carcabal, P., Gamblin, D. P., Stanca-Kaposta, E. C., Remmert, S. M., Fernandez-Alonso, M. C., Rudic, S., Simons, J. P., & Davis, B. G. (2013). 'Naked' and Hydrated Conformers of the Conserved Core Pentasaccharide of N-linked Glycoproteins and Its Building Blocks. Journal Of The American Chemical Society, 135(45), 16895–16903.
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Capello, M. C., Broquier, M., Dedonder-Lardeux, C., Jouvet, C., & Pino, G. A. (2013). Fast excited state dynamics in the isolated 7-azaindole-phenol H-bonded complex. J Chem Phys, 138(5), 054304.
Résumé: The excited state dynamics of the H-bonded 7-azaindole-phenol complex (7AI-PhOH) has been studied by combination of picosecond pump and probe experiments, LIF measurements on the nanosecond time scale and ab initio calculations. A very short S(1) excited state lifetime (30 ps) has been measured for the complex upon excitation of the 0(0)(0) transition and the lifetime remains unchanged when the nu(6) vibrational mode (0(0)(0) + 127 cm(-1)) is excited. In addition, no UV-visible fluorescence was observed by exciting the complex with nanosecond pulses. Two possible deactivation channels have been investigated by ab initio calculations: first an excited state tautomerization assisted by a concerted double proton transfer (CDPT) and second an excited state concerted proton electron transfer (CPET) that leads to the formation of a radical pair (hydrogenated 7AIH() radical and phenoxy PhO() radical). Both channels, CDPT and CPET, seem to be opened according to the ab initio calculations. However, the analysis of the ensemble of experimental and theoretical evidence indicates that the excited state tautomerization assisted by CDPT is quite unlikely to be responsible for the fast S(1) state deactivation. In contrast, the CPET mechanism is suggested to be the non-radiative process deactivating the S(1) state of the complex. In this mechanism, the lengthening of the OH distance of the PhOH molecule induces an electron transfer from PhOH to 7AI that is followed by a proton transfer in the same kinetic step. This process leads to the formation of the radical pair (7AIH()...PhO()) in the electronically excited state through a very low barrier or to the ion pair (7AIH(+)...PhO(-)) in the ground state. Moreover, it should be noted that, according to the calculations the pisigma* state, which is responsible for the H loss in the free PhOH molecule, does not seem to be involved at all in the quenching process of the 7AI-PhOH complex.
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Carcabal, P., Cocinero, E. J., & Simons, J. P. (2013). Binding energies of micro-hydrated carbohydrates: measurements and interpretation. CHEMICAL SCIENCE, 4(4), 1830–1836.
Résumé: The strength of the interaction between three monosaccharides (O-phenyl-beta-D-gluco-, beta-D-galacto-and alpha-D-mannopyranoside) and a single water molecule has been investigated experimentally in the gas phase by means of 2-colour UV-UV ionisation and dissociation threshold measurements. Their binding energies have also been calculated using dispersion corrected DFT methods and the resolution of identity approximation. The calculated and experimental relative binding energies are in good correspondence at all considered levels of theory, and the RI-B97D+ disp/ TZVPP level of theory in particular, provides very good agreement with a considerable reduction in computational time. Although these systems experience some conformational changes upon photo-ionisation, the experimental measurements lead to reliable estimates of the binding energies of the different conformers of the monosaccharide-water complexes and their relative values reflect their structural differences.
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Carré B., Poisson, L., Shafizadeh, N., & Soep, B. (2013). Stereodynamics of Chemical Reactions. Journal of Chemical Physics A, 117, 8093–8094.
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Dehon, C., Soorkia, S., Pedrazzani, M., Jouvet, C., Barat, M., Fayeton, J. A., & Lucas, B. (2013). Photofragmentation at 263 nm of small peptides containing tyrosine: role of the charge transfer on CO. Phys. Chem. Chem. Phys., 15, 8779–8788.
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Ha-Thi M.H, Shafizadeh N., Poisson, L., & Soep, B. (2013). An Efficient Indirect Mechanism for the Ultrafast Intersystem Crossing in Copper Porphyrins. Journal of Chemical Physics A, 117, 8111–8118.
Résumé: The ultrafast dynamics of copper tetraphenylporphyrin (CuTPP), copper octaethylporphyrin (CuOEP) and of the free base tetraphenylporphyrin (H2TPP), excited in the S2. state have been investigated in the gas phase by femtosecond pump/probe experiments. The porphyrins were excited in the Soret band at 400 nm. Strikingly, the S2.-S1. internal conversion in H2TPP is very rapid (110 fs), as compared to that of ZnTPP (600 fs), previously observed. In turn, CuTPP and CuOEP, excited in S2., follow a different relaxation pathway from that of other open-shell metalloporphyrins. These two molecules exhibit a four-step decay ending on a slow evolution in the nanosecond range 2S2.→ 2CT→ 2T→ 2Ground State. This latter evolution is linked to the formation of the 2T, Tripdoublet state in CuTPP, observed in the condensed phase. It is shown that an intermediate charge transfer state plays a crucial role in linking the porphyrin centered 1ππ* and 3ππ* configurations. A simple model is presented that allows a rapid evolution between these two configurations, via coupling with the free d electron on the copper, getting around the spin orbit coupling in the porphyrin π.
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Mahjoub, A., Le Barbu-Debus, K., & Zehnacker, A. (2013). Structural Rearrangement in the Formation of Jet-Cooled Complexes of Chiral (S)-1,2,3,4-Tetrahydro-3-isoquinolinemethanol with Methyl Lactate: Chirality Effect in Conformer Selection. JOURNAL OF PHYSICAL CHEMISTRY A, 117(14), 2952–60.
Résumé: The jet-cooled complexes between the two enantiomers of methyl lactate (ML) and (S)-1,2,3,4-tetrahydro-3-isoquinolinemethanol (THIQM) are studied by double resonance spectroscopy combined with ab initio calculations. Both diastereomer complexes exist in different isomers, involving either direct addition of THIQM on ML with no structural rearrangement of the subunits or formation of very stable structures involving multiple intermolecular hydrogen bonds and extensive deformation of the subunits. Competition between these two processes and its dependence upon chirality are discussed. It is shown that the most stable form of the chromophore (THIQMI with an OH···N hydrogen bond) prefers to directly stick to ML to form the addition complex whereas the second conformer (THIQMII with NH···O hydrogen bond) rearranges to form a strongly bound structure. The two structures are formed for the homochiral as well the heterochiral complex, however with different relative abundance. This shows an enantioselective binding preference of ML for one of the conformers of the chromophore.
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Miyazaki, M., Kawanishi, A., Nielsen, I., Alata, I., Ishiuchi, S. -ichi, Dedonder, C., Jouvet, C., & Fujii, M. (2013). Ground state proton transfer in phenol-(NH3)(n) (n </= 11) clusters studied by mid-IR spectroscopy in 3-10 mum range. J Phys Chem A, 117(7), 1522–1530.
Résumé: The infrared (IR) spectra of size-selected phenol-ammonia clusters, PhOH-(NH(3))(n) (n </= 11) in the 3-10 mum wavelength region were measured to investigate the critical number of solvent molecules necessary to promote the ground state proton transfer (GSPT) reaction. While the N-H stretching vibrations did not provide clear information, characteristic changes that are assigned to the GSPT reaction were observed in the skeletal vibrational region. The production of phenolate anion (PhO(-)), which is a product of the GSPT reaction, was established from the appearance of characteristic bands assignable to C-C stretching and C-H bending vibrations of PhO(-) and from the corresponding disappearance of C-O-H bending vibration of PhOH at n = 9. The mid-IR spectroscopy directly proves the structural change induced by the deprotonation from the O-H bond and thus establishes the GSPT reaction as complete at n = 9. No such absorptions were observed for n </= 5 in line with a previous report. For n = 6-8, both the proton transferred and the nontransferred signatures were observed in the spectra, showing coexistence of both species for the first time.
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Sen, A., Le Barbu-Debus, K., Scuderi, D., & Zehnacker-Rentien, A. (2013). Mass Spectrometry Study and Infrared Spectroscopy of the Complex Between Camphor and the Two Enantiomers of Protonated Alanine: The Role of Higher-Energy Conformers in the Enantioselectivity of the Dissociation Rate Constants. Chirality, 25, 436–443.
Résumé: The properties of the protonated complexes built from S camphor and R or S alanine were studied in a Paul ion trap at room temperature by collision-induced dissociation (CID) and infrared multiple-photon dissociation spectroscopy (IRMPD), as well as molecular dynamics and ab initio calculations. While the two diastereomer complexes display very similar vibrational spectra in the fingerprint region, in line with similar structures, and almost identical calculated binding energies, their collision-induced dissociation rates are different. Comparison of the IRMPD results to computed spectra shows that the SS and SR complexes both contain protonated alanine strongly hydrogen-bonded to the keto group of camphor. The floppiness of this structure around the NH+…O = C hydrogen bond results in a complex potential energy surface showing multiple minima. Calculating the dissociation rate constant within the frame of the transition state theory shows that the fragmentation rate larger for the heterochiral SR complex than the homochiral SS complex can be explained in terms of two almost isoenergetic low-energy conformers in the latter that are not present for the former. Chirality 00:000-000, 2013. © 2013 Wiley Periodicals, Inc.
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Sen, A., Lepere, V., Le Barbu-Debus, K., & Zehnacker, A. (2013). How do Pseudoenantiomers Structurally Differ in the Gas Phase? An IR/UV Spectroscopy Study of Jet-Cooled Hydroquinine and Hydroquinidine. CHEMPHYSCHEM, 14(15), 3559–3568.
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Stanca-Kaposta, E. C., Carcabal, P., Cocinero, E. J., Hurtado, P., & Simons, J. P. (2013). Carbohydrate-Aromatic Interactions: Vibrational Spectroscopy and Structural Assignment of Isolated Monosaccharide Complexes with p-Hydroxy Toluene and N-Acetyl L-Tyrosine Methylamide. J. Phys. Chem. B, 117(27), 8135–8142.
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Thon, R., Chin, W., Galaup, J. - P., Ouvrard, A., Bourguignon, B., & Crepin, C. (2013). Vibrational Perturbations of W(CO)(6) Trapped in a Molecular Lattice Probed by Linear and Nonlinear Spectroscopy. J. Phys. Chem. A, 117(34), 8145–8156.
Résumé: Vibrational dynamics of the T-1u CO stretching mode of tungsten hexacarbonyl is explored when the molecule is embedded in a nitrogen matrix at low temperature. Experiments combined infrared (IR) absorption spectroscopy and IR stimulated photon echoes at the femtosecond time scale. W(CO)(6) is found to be trapped in two main families of sites differing by their symmetry (called hereafter O-h and D-2h sites). In O-h sites, the vibrational coherence is strongly temperature dependent, exhibiting a coupling with librational phonons of the nitrogen lattice. Perturbation in D-2h sites results in the splitting of the T-1u band in three components. Each component is inhomogeneously broadened, with dephasing times in the tens of picoseconds, and is weakly coupled to the lattice phonons. Experiments in solid krypton are performed to compare the effect of atomic and diatomic host lattices. Dephasing time in Kr does not depend on temperature and remains in the hundreds of picoseconds, highlighting the molecular origin of the dephasing process in N-2. Additionally, nonlinear signals show oscillations due to quantum beats and polarization interferences between different frequency components of the induced third order polarization, giving information, in particular, on the overtone vibrational transition.
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