Vibrational self-trapping in beta-sheet structures observed with femtosecond nonlinear infrared spectroscopy

Abstract

Vibrational self-trapping in beta-sheet structures observed with femtosecond nonlinear infrared spectroscopy Bodis, P.; Schwartz, E.; Koepf, M.; Cornelissen, J.L.M.; Rowan, A.E.; Nolte, R.J.M.; Woutersen, S. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Download date: 12 May 2018Vibrational self-trapping in beta-sheet structures observed with femtosecond nonlinear infrared spectroscopy Self-trapping of NH-stretch vibrational excitations in synthetic ␤-sheet helices is observed using femtosecond infrared pump-probe spectroscopy. In a dialanine-based ␤-sheet helix, the transient-absorption change upon exciting the NH-stretch mode exhibits a negative absorption change at the fundamental frequency and two positive peaks at lower frequencies. These two induced-absorption peaks are characteristic for a state in which the vibrational excitation is self-trapped on essentially a single NH-group in the hydrogen-bonded NH¯OC chain, forming a small ͑Holstein͒ vibrational polaron. By engineering the structure of the polymer we can disrupt the hydrogen-bonded NH¯OC chain, allowing us to eliminate the self-trapping, as is confirmed from the NH-stretch pump-probe response. We also investigate a trialanine-based ␤-sheet helix, where each side chain participates in two NH¯OC chains with different hydrogen-bond lengths. The chain with short hydrogen bonds shows the same self-trapping behavior as the dialanine-based ␤-sheet helix, whereas in the chain with long hydrogen bonds the self-trapping is too weak to be observable.

Helical poly(isocyanides): past, present and future

“…95,96 In polyisocyanopeptides vibrational self-trapping was evidenced for polymers possessing a well-defined hydrogen bonded network along the side chain, however, when the hydrogen bonding network was disrupted by the incorporation of the non-hydrogen bonding monomer in the polymer chain, the resulting copolymer showed no evidence for self-trapping. 97,98 As previously shown by Millich for several aliphatic isocyanides, 16 the isocyanopeptide polymerisation can be initiated by Brønsted acids. In this case remarkably long polymers chains with lengths up to 14 mm can be grown.…”

Simulated IR, Isotropic and Anisotropic Raman, and Vibrational Circular Dichroism Amide I Band Profiles of Stacked β-Sheets

“…It should be mentioned that anharmonic and nonadiabatic coupling between different vibrational states can cause dephasing, satellite bands, and substantial broadening, which all could reduce the VCD signal. , Indeed, the spectra in Figure suggest that such broadening effects occur.…”

Phonon anharmonicity-induced decoherence slowing down in exciton–phonon systems

“…Moreover, although the present model is rather general, it will be applied to situations in which the lattice temperature plays a crucial role, being typically equal to or higher than the phonon cutoff frequency. Such situations are rather common and they can mimic, for instance, the vibron dynamics in α-helices [4][5][6][7][8][9][10][11][12]. In such lattices, peptide units H-N-C=O are regularly distributed and neighboring units are linked by an H bond.…”

“…The knowledge of the coupling correlation function ( 9) allows us to compute the relaxation operator in both real space (equation ( 7)) and Bloch space (equation ( 13)). Consequently, it is straightforward to determine the Bloch transform σ k (t) (12) and to compute the local coherences σ x (t) (11). This procedure is illustrated in the following section where special attention is paid to characterize the space and time evolution of the coherences.…”

“…Atom, charge and energy transfers between atomic subunits in large molecules and crystals play a key role in understanding various phenomena in both physics, chemistry and biology [1][2][3]. Examples among many are vibron propagation in αhelices [4][5][6][7][8][9][10][11][12][13], exciton dynamics in photosynthetic antenna and semiconducting polymers [14][15][16][17][18][19], vibrational energy flow in adsorbed nanostructures [20][21][22][23] and self-diffusion of light atoms on metallic surfaces [24,25].…”