Measuring the Elasticity of Poly‐<scp>l</scp>‐Proline Helices with Terahertz Spectroscopy

Ruggiero, Michael T.; Šibík, Juraj; Orlando, Roberto; Zeitler, J. Axel; Korter, Timothy M.

doi:10.1002/ange.201602268

Cited by 13 publications

(18 citation statements)

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“…Low-frequency vibrational spectroscopy of polymers have been studied in far-infrared and THz frequency regions, and the relationship between THz spectral features and polymer structures and properties has been studied. [9][10][11][12][13][14][15] In our previous studies, the THz spectra of polyesters [16][17][18][19][20] and polyamides 21,22 were studied. In order to assign the spectra, the vibrational dipole moments were determined using polarized THz spectroscopy on stretched samples, 16,17 and the experimental THz spectra was compared with low-frequency Raman spectra in order to uncover the origins of the vibrational modes.…”

Section:  Introductionmentioning

confidence: 99%

Exploring the Dynamics of Bound Water in Nylon Polymers with Terahertz Spectroscopy

2019

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Exploring the Dynamics of Bound Water in Nylon Polymers with Terahertz Spectroscopy. ChemRxiv. Preprint. Terahertz (THz) spectroscopy was used to observe adsorbed water structure and dynamics within polymer films, ultimately providing a strong rationale for the observed rates of water desorption. The THz absorption spectra of nylon-6 films undergoes drastic changes during the hydration and drying process. Additionally, the structural change from g to a crystals, induced by the hydration, was observed by the characteristic band of a-nylon-6 at 6.5 THz. Importantly, the THz spectra of adsorbed water, as well as deuterated water, within in the nylon films were observed by the continuous measurement of a-nylon during dehydration. The differential spectra clearly show three absorption bands of water molecules named Peak I, II and III, which behaved differently between the H 2 O and D 2 O materials. The spectra were assigned using a combination of ab initio molecular dynamics simulations and solid-state density functional theory calculations, and were compared to previous spectral assignments of bulk water. The results show that the inclusion of H 2 O and D 2 O into polymer films results in a distinct set of spectral features that, while similar in frequencies to the dynamics of bulk water, represent significantly different motions owing to the unique chemical environment within the material. These results highlight the significant utility of using THz spectroscopy to study the hydration dynamics and spectral signature of bound water in this important class of materials. File list (4) download file view on ChemRxiv 20191018_Nylon_final.docx (1.02 MiB) download file view on ChemRxiv Peak3.gif (16.32 MiB) download file view on ChemRxiv Peak2.gif (16.78 MiB) download file view on ChemRxiv Peak1.gif (18.27 MiB)

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Section:  Introductionmentioning

confidence: 99%

Exploring the Dynamics of Bound Water in Nylon Polymers with Terahertz Spectroscopy

2019

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“…interactions that are perturbed during mechanical processes. [28][29][30] Therefore, the successful modeling of the low-frequency dynamics as a function of temperature implies that the associated elastic response would be equally well-modeled by the theory.…”

Section: Temperature Evolutionmentioning

confidence: 99%

Thermoelasticity in Organic Semiconductors Determined with Terahertz Spectroscopy and Quantum Quasi-Harmonic Simulations

Banks¹,

Maul²,

Mancini³

et al. 2020

Preprint

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The thermomechanical response of organic semiconducting solids is an essential aspect to consider in the design of materials for advanced applications, and in particular, flexible electronics. The non-covalent intermolecular forces that exist in organic solids not only result in a diverse set of mechanical properties, but also a critical dependence of those same properties on temperature. However, studying the thermoelastic response of solids is experimentally challenging, often requiring large single-crystals and sensitive experimental apparatus. An alternative contactless approach involves using low-frequency vibrational spectroscopy to characterize the underlying intermolecular forces, and then combining this information with solid-state density functional theory simulations to retrieve the mechanical response of materials. This methodology leverages recent advances in the quasi-harmonic approximation to predict the temperature evolution of crystalline structures, dynamics, and associated forces, and then utilizes this information to determine the elastic tensor as a function of temperature. Here, this methodology is illustrated for two prototypical organic semiconducting crystals, rubrene and BTBT, and suggests a new alternative means to characterizing the thermoelastic response of organic materials.

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“…This system has been recently investigated with DFT simulations by us, as a single polymer, 32 and in interaction with hydroxyl-apatite surface, 33 and, by others, with the same methodology adopted here, in its crystal form. 34…”

Section: Poly-proline Type II Helix (Ppii)mentioning

confidence: 99%

Decoding Collagen Triple Helix Stability by Means of Hybrid DFT Simulations

2019

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Collagen is a protein family defined by a triple helix motif, which comprises roughly one-third of the total human protein content. Decoding the reasons underlying the stability of the collagen triple helix is of both fundamental and applicative relevance, for instance, to guide collagen protein engineering. In principle, full quantum mechanical approaches based on density functional theory (DFT) are ideal to study the subtle physico-chemical features of collagen. Unfortunately, the huge size of the protein prevents the straightforward application of DFT to realistic collagen protein models. In this paper, we propose a new realistic model of the collagen protein based on a periodic approach. The protein model exploits the intrinsic symmetry of the collagen triple helix, dramatically lowering the cost of the simulations. This allows using accurate hybrid DFT simulations (B3LYP-D/TZP) for systematic studies of the collagen protein features. We have tested the proposed model/level-of-theory combination to analyze the well-known proline-conformation/collagen-stability relationship. For this purpose, we have performed an extensive conformational analysis of proline ring within the protein, clarifying some of the reasons linking specific ring conformations to helix positions. Throughout our data analysis, we have also obtained "for free" the collagen inter-strand binding energy. Simulation results demonstrate that London dispersion interactions play the dominant role in the whole helix stability. The good agreement with the experimental data validates the use of the proposed model/level-of-theory to assist the active field of collagen-like peptide synthesis.

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Measuring the Elasticity of Poly‐l‐Proline Helices with Terahertz Spectroscopy

Cited by 13 publications

References 56 publications

Exploring the Dynamics of Bound Water in Nylon Polymers with Terahertz Spectroscopy

Exploring the Dynamics of Bound Water in Nylon Polymers with Terahertz Spectroscopy

Thermoelasticity in Organic Semiconductors Determined with Terahertz Spectroscopy and Quantum Quasi-Harmonic Simulations

Decoding Collagen Triple Helix Stability by Means of Hybrid DFT Simulations

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