Peer-reviewed Publications |
Ben Nasr, F., Alata, I., Scuderi, D., Lepere, V., Brenner, V., Jaidane, N. E., & Zehnacker, A. (2019). Effects of complexation with sulfuric acid on the photodissociation of protonated Cinchona alkaloids in the gas phase. Physical Chemistry Chemical Physics, 21(28), 15439–15451.
Résumé: The effect of complexation with sulfuric acid on the photo-dissociation of protonated Cinchona alkaloids, namely cinchonidine (Cd), quinine (Qn) and quinidine (Qd), is studied by combining laser spectroscopy with quantum chemical calculations. The protonated complexes are structurally characterized in a room-temperature ion trap by means of infra-red multiple photon dissociation (IRMPD) spectroscopy in the fingerprint and the nu(XH) (X = C, N, O) stretch regions. Comparison with density functional theory calculations including dispersion (DFT-D) unambiguously shows that the complex consists of a doubly protonated Cinchona alkaloid strongly bound to a bisulfate HSO4- anion, which bridges the two protonated sites of the Cinchona alkaloid. UV excitation of the complex does not induce loss of specific photo fragments, in contrast to the protonated monomer or dimer, for which photo-specific fragments were observed. Indeed the UV-induced fragmentation pattern is identical to that observed in collision-induced dissociation experiments. Analysis of the nature of the first electronic transitions at the second order approximate coupled-cluster level (CC2) explains the difference in the behavior of the complex relative to the monomer or dimer towards UV excitation.
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Crépin-Gilbert, C., & Savchenko, E. (2019). Nanostructures and impurity centers in cryogenic environment. Low Temperature Physics, 45(6), 581–582.
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de Pujo, P., Ryan, M., Crépin, C., Mestdagh, J. M., & McCaffrey, J. G. (2019). The role of spin-orbit coupling in the optical spectroscopy of atomic sodium isolated in solid xenon. Low Temperature Physics, 45(7), 715–720.
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Declerck, V., Perez-Mellor, A., Guillot, R., Aitken, D. J., Mons, M., & Zehnacker, A. (2019). Vibrational circular dichroism as a probe of solid-state organisation of derivatives of cyclic beta-amino acids: Cis- and trans-2-aminocyclobutane-1-carboxylic acid. Chirality, 31(8), 547–560.
Résumé: Peptide models built from cis- and trans-2-aminocyclobutane-1-carboxylic acids (ACBCs) are studied in the solid phase by combining Fourier-transform infrared spectroscopy (FTIR) absorption spectroscopy, vibrational circular dichroism (VCD), and quantum chemical calculations using density functional theory (DFT). The studied systems are N-tert-butyloxycarbonyl (Boc) derivatives of 2-aminocyclobutanecarboxylic acid (ACBC) benzylamides, namely Boc-(cis-ACBC)-NH-Bn and Boc-(trans-ACBC)-NH-Bn. These two diastereomers show very different VCD signatures and intensities, which of the trans-ACBC derivative being one order of magnitude larger in the region of the nu (CO) stretch. The spectral signature of the cis-ACBC derivative is satisfactorily reproduced by that of the monomer extracted from the solid-state geometry of related ACBC derivatives, which shows that no long-range effects are implicated for this system. In terms of hydrogen bonds, the geometry of this monomer is intermediate between the C6 and C8 structures (exhibiting a 6- or 8-membered cyclic NHMIDLINE HORIZONTAL ELLIPSISO hydrogen bond) previously evidenced in the gas phase. The benzyl group must be in an extended geometry to reproduce satisfactorily the shape of the VCD spectrum in the nu (CO) range, which qualifies VCD as a potential probe of dispersion interaction. In contrast, reproducing the IR and VCD spectrum of the trans-ACBC derivative requires clusters larger than four units, exhibiting strong intermolecular H-bonding patterns. A qualitative agreement is obtained for a tetramer, although the intensity enhancement is not reproduced. These results underline the sensitivity of VCD to the long-range organisation in the crystal.
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Gutiérrez-Quintanilla A., Chevalier M., Platakyte R., Ceponkus J., & Crépin C. (2019). Selective photoisomerisation of 2- chloromalonaldehyde. J Chem Phys, 150, 034305.
Résumé: Isomerization of 2-chloromalonaldehyde (2-ClMA) is explored giving access to new experimental data on this derivative of malonaldehyde,
not yet studied much. Experiments were performed isolating 2-ClMA in argon, neon, and para-hydrogen matrices.
UV irradiation of the matrix samples induced isomerization to three open enolic forms including two previously observed along
with the closed enolic form after deposition. IR spectra of these specific conformers were recorded, and a clear assignment
of the observed bands was obtained with the assistance of theoretical calculations. UV spectra of the samples were measured,
showing a blue shift of the absorption with the opening of the internal hydrogen bond of the most stable
enol form. Specific sequences of UV irradiation at different wavelengths allowed us to obtain samples containing only one
enol conformer. The formation of conformers is discussed. The observed selectivity of the process among the enol forms is
analyzed.
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Gutiérrez-Quintanilla,, Briant,, Mengesha,, Gaveau, M. - A., Mestdagh,, Soep,, & Poisson,. (2019). Propyne-water complexes hosted in helium droplets. Low Temperature Physics, 45(6), 634–638.
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Perez-Mellor, A., Alata, I., Lepere, V., & Zehnacker, A. (2019). Conformational Study of the Jet-Cooled Diketopiperazine Peptide Cyclo Tyrosyl-Prolyl. Journal Of Physical Chemistry B, 123(28).
Résumé: The conformational landscape of the diketopiperazine (DKP) dipeptide built on tyrosine and proline, namely, cyclo Tyr-Pro, is studied by combining resonance-enhanced multiphoton ionization, double resonance infrared ultraviolet (IR-UV) spectroscopy, and quantum chemical calculations. Despite the geometrical constraints due the two aliphatic rings, DKP and proline, cyclo Tyr-Pro is a flexible molecule. For both diastereoisomers, cyclo LTyr-LPro and cyclo LTyr-DPro, two structural families coexist under supersonic jet conditions. In the most stable conformation, the aromatic tyrosine substituent is folded over the DKP ring (g(+) geometry of the aromatic ring) as it is in the solid state. The other structure is completely extended (g(-) geometry of the aromatic ring) and resembles that proposed for the vapor phase. IR-UV results are not sufficient for unambiguous assignment of the observed spectra to either folded or extended conformations and the simulation of the vibronic pattern of the S-0-S-1 transition is necessary. Still, the comparison between IR-UV results and anharmonic calculations allows explanation of the minor structural differences between cyclo LTyr-LPro and cyclo LTyr-DPro in terms of different NH center dot center dot center dot pi and CH center dot center dot center dot pi interactions.
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Platakyte, R., Gutiérrez-Quintanilla, A., Sablinskas, V., & Ceponkus, J. (2019). Influence of environment and association with water, to internal structure of trifluoroacetylacetone. Matrix isolation FTIR study. Low Temperature Physics, 45(6), 615–626.
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Rojas-Lorenzo,, Lara-Moreno,, Gutierrez-Quintanilla,, Chevalier,, & Crépin,. (2019). Theoretical study of “trapping sites” in cryogenic rare gas solids doped with β-dicarbonyl molecules. Low Temperature Physics, 45, 363–370.
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Tamura, M., Sekiguchi, T., Ishiuchi, S., Zehnacker-Rentien, A., & Fujii, M. (2019). Can the Partial Peptide SIVSF of the beta(2)-Adrenergic Receptor Recognize Chirality of the Epinephrine Neurotransmitter? Journal Of Physical Chemistry Letters, 10(10), 2470–2474.
Résumé: Chirality plays an essential role in biological molecular recognition, such as neurotransmission. Here, we applied electrospray-cold ion trap spectroscopy to complexes of a partial binding motif SIVSF of a beta(2)-adrenergic receptor pocket with L- and D-epinephrine AdH(+). The ultraviolet spectrum of the SIVSF-AdH(+) complex changed drastically when L-AdH(+) was replaced by its enantiomer. The isomer-selected infrared spectra revealed that D-AdH(+) was bound to SIVSF by its protonated amino-group or a single catechol OH and induced nonhelical secondary structures of SIVSF. This is in sharp contrast to the helical SIVSF complex with L-AdH(+), which is close to the natural binding structure with two catechol OHs binding in the receptor. This shows that a short pentapeptide SIVSF can distinguish the chirality of the ligand AdH(+) as well as the receptor. This stereoselectivity is suggested to arise from an additional interaction involving the hydroxyl group on the chiral carbon.
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Chapitres de Livres |
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Pérez-Mellor A. Zehnacker A. (2019). Chirality Effects in Jet-Cooled Cyclic Dipeptides. In Ebata T. Fujii M. (Ed.), Physical Chemistry of Cold Gas-Phase Functional Molecules and Clusters (pp. 63–87). Singapore: Springer.
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