Mixing of intermolecular and intramolecular vibrations in optical phonon modes: terahertz spectroscopy and solid‐state density functional theory

Zhang, Feng; Wang, Houng-Wei; Tominaga, Kazuhiro; Hayashi, M.

doi:10.1002/wcms.1256

Cited by 53 publications

(45 citation statements)

References 125 publications

(303 reference statements)

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“…We focus on reproducing the frequencies, as well as IR and Raman activities, in the low-frequency spectral range. It is currently being intensively studied [29,65,66], since various intermolecular vibrations can be observed in it, in particular, because of the presence of intermolecular H-bonds [36,[67][68][69]. The double harmonic approximation provides a reasonable description of the IR/Raman spectra of organic crystals in the low-frequency spectral range [29,30,70,71].…”

Section: Ir Spectrum In the Low-frequency Regionmentioning

confidence: 99%

Combined X-ray Crystallographic, IR/Raman Spectroscopic, and Periodic DFT Investigations of New Multicomponent Crystalline Forms of Anthelmintic Drugs: A Case Study of Carbendazim Maleate

et al. 2020

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Synthesis of multicomponent solid forms is an important method of modifying and fine-tuning the most critical physicochemical properties of drug compounds. The design of new multicomponent pharmaceutical materials requires reliable information about the supramolecular arrangement of molecules and detailed description of the intermolecular interactions in the crystal structure. It implies the use of a combination of different experimental and theoretical investigation methods. Organic salts present new challenges for those who develop theoretical approaches describing the structure, spectral properties, and lattice energy Elatt. These crystals consist of closed-shell organic ions interacting through relatively strong hydrogen bonds, which leads to Elatt > 200 kJ/mol. Some technical problems that a user of periodic (solid-state) density functional theory (DFT) programs encounters when calculating the properties of these crystals still remain unsolved, for example, the influence of cell parameter optimization on the Elatt value, wave numbers, relative intensity of Raman-active vibrations in the low-frequency region, etc. In this work, various properties of a new two-component carbendazim maleate crystal were experimentally investigated, and the applicability of different DFT functionals and empirical Grimme corrections to the description of the obtained structural and spectroscopic properties was tested. Based on this, practical recommendations were developed for further theoretical studies of multicomponent organic pharmaceutical crystals.

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Section: Ir Spectrum In the Low-frequency Regionmentioning

confidence: 99%

Combined X-ray Crystallographic, IR/Raman Spectroscopic, and Periodic DFT Investigations of New Multicomponent Crystalline Forms of Anthelmintic Drugs: A Case Study of Carbendazim Maleate

et al. 2020

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“…The samples were made of sheets and placed on the terahertz test plate. After the vacuum processing, the interference was removed from the cellulose test in the terahertz band spectrum [32][33][34][35]. Because the absorption intensity of pure cellulose samples might be larger, an appropriate preparation of samples with different thicknesses and different PE blending ratios were discussed.…”

Section: Terahertz Spectroscopy Analysismentioning

confidence: 99%

“…At the current stage, this task was, however, formidable to be achieve at the ab initio level. For having a preliminary trial towards the final solution, the low-frequency vibrations of the building unit, cellobiose, of cellulose were explicitly examined [35,36,39]. The calculation was performed using a combination of the B3LYP functional and the Gaussian-type 6-31G (d, p) basis set in the Gaussian16 software package.…”

Section: Calculation Of Cellulose Molecular Vibration Modelmentioning

confidence: 99%

Novel Terahertz Spectroscopy Technology for Crystallinity and Crystal Structure Analysis of Cellulose

et al. 2020

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Crystallinity is an essential indicator for evaluating the quality of fiber materials. Terahertz spectroscopy technology has excellent penetrability, no harmful substances, and commendable detection capability of absorption characteristics. The terahertz spectroscopy technology has great application potential in the field of fiber material research, especially for the characterization of the crystallinity of cellulose. In this work, the absorption peak of wood cellulose, microcrystalline cellulose, wood nano cellulose, and cotton nano cellulose were probed in the terahertz band to calculate the crystallinity, and the result compared with XRD and FT-IR analysis. The vibration model of cellulose molecular motion was obtained by density functional theory. The results showed that the average length of wood cellulose (WC) single fiber was 300 μm. The microcrystalline cellulose (MCC) was bar-like, and the average length was 20 μm. The cotton cellulose nanofiber (C-CNF) was a single fibrous substance with a length of 50 μm, while the wood cellulose nanofiber (W-CNF) was with a length of 250 μm. The crystallinity of cellulose samples in THz was calculated as follows: 73% for WC, 78% for MCC, 85% for W-CNF, and 90% for C-CNF. The crystallinity values were obtained by the three methods which were different to some extent. The absorption peak of the terahertz spectra was most obvious when the samples thickness was 1 mm and mixed mass ratio of the polyethylene and cellulose was 1:1. The degree of crystallinity was proportional to the terahertz absorption coefficients of cellulose, the five-movement models of cellulose molecules corresponded to the five absorption peak positions of cellulose.

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“…Conversely, vibrational modes at higher frequencies (far-IR) are rather straightforward to calculate, because the contribution of intramolecular motion becomes dominant [23,24]. Some of the bands can be simulated by considering a small number of atoms.…”

Section: Resultsmentioning

confidence: 99%

Terahertz Spectroscopy for Characterization of Hydrogen Bonding and Cross-linked Structure Dynamics in Polyurethane

Hoshina

Saito

Furuhashi

et al. 2020

J Infrared Milli Terahz Waves

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Terahertz (THz) absorption spectra of cross-linked polyurethane films were observed at 30-180°C. The obtained spectra displayed characteristic absorption bands. A band observed at 2.6 THz was assigned to the C=O•••N-H hydrogen bond vibration using previously reported data. DFT calculation results confirmed that a band at 7.5 THz arises owing to the torsional vibration of cross-linked molecules containing urethane bonds. The slight changes in the temperature-dependent spectra were analyzed by the first derivative of absorption intensity with temperature. The thermal behavior of absorption intensities indicates the dynamics of hydrogen bonds and cross-linked structures in polyurethane films.

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Mixing of intermolecular and intramolecular vibrations in optical phonon modes: terahertz spectroscopy and solid‐state density functional theory

Cited by 53 publications

References 125 publications

Combined X-ray Crystallographic, IR/Raman Spectroscopic, and Periodic DFT Investigations of New Multicomponent Crystalline Forms of Anthelmintic Drugs: A Case Study of Carbendazim Maleate

Combined X-ray Crystallographic, IR/Raman Spectroscopic, and Periodic DFT Investigations of New Multicomponent Crystalline Forms of Anthelmintic Drugs: A Case Study of Carbendazim Maleate

Novel Terahertz Spectroscopy Technology for Crystallinity and Crystal Structure Analysis of Cellulose

Terahertz Spectroscopy for Characterization of Hydrogen Bonding and Cross-linked Structure Dynamics in Polyurethane

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