Superficial and Fundamental Correspondences in the Terahertz/IR (6–15 THz) Absorption Spectra of Aspirin and Benzoic Acid

Lepodise, Lucia M.; Horvat, J.; Lewis, R. A.

doi:10.1021/acs.jpca.8b05393

Cited by 6 publications

(7 citation statements)

References 33 publications

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“…DFT theoretical calculations have been over years used in the interpretation of the THz spectra of materials and have proven to be a very successful technique for assigning the vibrational modes to experimental absorption peaks. 11,34–36 We obtained a maximum deviation between DFT calculation and the experimental values of the peak energies as 15 cm –1 (0.45 THz), which is well within the error estimate of Orca calculations. It was observed that despite a good agreement between the theoretical and experimental energies, there is a mismatch in the intensities.…”

Section: Resultssupporting

confidence: 81%

“…This sparsely studied THz frequency range is accessible using the conventional Fourier transform infrared (FT-IR) technique. The few studies that exist have however revealed characteristic absorption peaks in this frequency range 11,12 which can be used to identify or even characterize materials. The studied 6–15 THz region lies within the frequency range that is often also called far-infrared (FIR) range.…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopic Studies of BA Class Liquid Crystals in the 6–15 THz Range Using the Fourier Transform Infrared (FT-IR) Method

Lepodise

Horvat²

2022

Appl Spectrosc

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Fourier transform infrared spectroscopy was performed for two structurally similar liquid crystals in 6-15 THz range: 4-octyloxybenzoic acid and 4-decyloxybenzoic acid. Density functional theory modelling at PBE0/def2-TZVPP level was used to assign the vibrational modes to each observed absorption peak. We observed 6 peaks that are common for both liquid crystals, assigned to the same vibrational modes and appearing at similar energies. Each of the samples also had additional peaks unique to itself. A strong absorption peak appears at about 280 cm-1 for both samples, however it corresponds to different vibrational modes for the two samples. This work shows that the spectroscopy in this often neglected frequency range can easily distinguish structurally similar compounds.

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Section: Resultssupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Spectroscopic Studies of BA Class Liquid Crystals in the 6–15 THz Range Using the Fourier Transform Infrared (FT-IR) Method

Lepodise

Horvat²

2022

Appl Spectrosc

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“…Its corresponding theoretical line was obtained at 220 cm −1 and it is also confirmed by modeling of the BA crystal with another method. 45…”

Section: Resultsmentioning

confidence: 99%

“…Similar conclusion was obtained earlier when comparing the modes of aspirin and BA. 45 This implies that each absorption band of terra preta samples cannot be necessarily assigned to one particular vibrational mode of the aromatic compounds these samples contain.…”

Section: Resultsmentioning

confidence: 99%

Characteristic Spectral Features of Terra Preta (TP) in the 5–15 Terahertz Range

et al. 2022

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Terra preta is a fertile anthropogenic soil found in the Amazon basin. One of the most significant differences between the terra preta and surrounding soils is that terra preta is rich in aromatic carbons. Previous infrared investigations of terra preta were reported at energies above 1000 cm−1 where many other forms of carbon also have absorption lines. No measurements have been reported below 800 cm−1, where many absorptions associated with aromatic carbons occur in the absence of aliphatic carbon lines. We employ Fourier transform infrared spectroscopy between 150 cm−1 and 500 cm−1. A comparison was made between the spectra of terra preta, several pure aromatic compounds, organic fertilizers developed to replicate terra preta and several Australian soils, some of which containing char from bushfires. The spectra in the 150–500 cm−1 range were very similar between terra preta and the organic fertilizers, while they were very different for the natural soils. These findings indicate that the content of aromatic carbons in terra preta and organic fertilizers is different than in natural soils containing the bushfire chars, but also soils produced entirely by bacterial and fungal activities. This point to the importance of the preparation conditions of the biochars, which are essential ingredients of terra preta and organic fertilizers used in this study.

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“…During the past few decades, the THz spectroscopy technique has been used to analyze wide range of substancesfrom DNA, [19] over explosive materials to several active pharmaceutical ingredients (API). [20][21][22][23][24] The spectrum in THz region of electromagnetic radiation (sub 200 cm À 1 ) provides information about low energy vibrational modes, which arise from interactions based on both intra-and inter-molecular characters. [25] Despite the fact that covalent intramolecular interactions are much stronger than hydrogen bonds or any other dispersion forces, intermolecular interactions characterize overall three-dimensional structure of a system.…”

Section: Introductionmentioning

confidence: 99%

Low Energy Vibrations and Crystalline Structure of Ambroxol Hydrochloride by THz Spectroscopy and DFT Calculations

Uhlíková,

Šlechtová,

Koucký

et al. 2023

ChemistrySelect

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The widely used drug ambroxol hydrochloride (A‐HCl), was subjected to analysis by terahertz time domain (THz‐TDS) spectroscopy and quantum chemistry calculations. The performed X‐ray measurement confirmed the C2/c crystallographic group for A‐HCl. On the contrary, the presented theoretical calculations, achieved by solid‐state density functional theory (ss‐DFT), determined the structure in the global minima on potential energy surface which belong to the Cc crystallographic group. In the frame of this symmetric group, the ss‐DFT calculations resulted in 40 vibrational normal modes up to wavenumber 110 cm−1. The three different functionals (B3LYP, PBE, and PW1PW) were applied and all of them provided similar results. In the same range of wavenumbers (10–110 cm−1) the THz spectrum was measured at two different temperatures (room and cryogenic). Thanks to the very good correspondence of the experiment and calculations in both position and intensities of the peaks, we were able to analyze each peak from percentage contributions of inter‐ and intra‐molecular movements point of view and trivial nomenclature for such complex normal modes was suggested as well.

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Superficial and Fundamental Correspondences in the Terahertz/IR (6–15 THz) Absorption Spectra of Aspirin and Benzoic Acid

Cited by 6 publications

References 33 publications

Spectroscopic Studies of BA Class Liquid Crystals in the 6–15 THz Range Using the Fourier Transform Infrared (FT-IR) Method

Spectroscopic Studies of BA Class Liquid Crystals in the 6–15 THz Range Using the Fourier Transform Infrared (FT-IR) Method

Characteristic Spectral Features of Terra Preta (TP) in the 5–15 Terahertz Range

Low Energy Vibrations and Crystalline Structure of Ambroxol Hydrochloride by THz Spectroscopy and DFT Calculations

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