98%
921
2 minutes
20
Classical electromagnetic theory applied to infrared (IR) and vibrational circular dichroism (VCD) spectra of chiral compounds can provide useful insights, such as the fact that the area of all bands of wavenumber-normalized absorbance above zero must be the same as the area below zero. Additionally, dispersion analysis based on wave optics and dispersion theory, which was extended by Born and Kuhn to include chiral substances, can be used to quantitatively describe the dielectric function and the chiral admittance functions that shape IR and VCD spectra. For dispersion analysis, pairs of coupled oscillators, with five different kinds of parameters, namely oscillator strength, damping, oscillator position, vertical distance between coupled oscillators, and the coupling constant are used to model the dielectric functions and chiral admittance functions. We report the results of such an analysis for α-Pinene and Propylene oxide. For most bands, the oscillator model using two coupled oscillators is sufficient to achieve a good correspondence between experimental and modelled data.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1016/j.saa.2023.123549 | DOI Listing |
Angew Chem Int Ed Engl
August 2025
Dipartimento di Chimica Industriale "Toso Montanari", Università di Bologna, Via P. Gobetti 85-40129, Bologna, Italy.
We present a straightforward and versatile synthetic route to FeC carbide carbonyl clusters containing organosulfur ligands, including the chiral amino acid L- and D-cysteine. Reaction of the reduced cluster [NEt][FeC(CO)] (1) with thiols (RSH) or disulfides (RSSR) affords novel functionalized hexa-iron carbide clusters [NEt][FeC(CO)(SR)] (R = CH, 2; CH, 3; p-CHCH, 4; L-cysteine, L-5; D-cysteine, D-5). Compounds 2-5 have been characterized by Fourier transform infrared (FT-IR), H and C{H} nuclear magnetic resonance (NMR) spectroscopy, and the molecular structures of 2-4 have been determined by single-crystal X-ray diffraction (SC-XRD).
View Article and Find Full Text PDFChem Commun (Camb)
August 2025
Ruhr-Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, 44801 Bochum, Germany.
Using VCD spectroscopy in combination with the matrix isolation technique, we investigate 4-azido-paracyclophane and its photochemical reaction products. We demonstrate that the isomers of the benzazirine and ketenimine photoproducts, although basically indistinguishable in the IR spectra, can be easily differentiated by VCD spectroscopy. The triplet nitrene cannot be identified unambiguously in the IR and VCD spectra of the irradiated sample.
View Article and Find Full Text PDFJ Phys Chem A
July 2025
Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, Brescia 25123, Italy.
The vibrational circular dichroism (VCD) spectra in the CD-stretching region of ()-(-)-neopentyl-1d-halides (Cl and Br), ()-(+)-1-exo-d-camphor, and ()-(+)-1-phenylethane-1-d (and ()-(+)-1-phenylethane-1,2,2,2-d) are correctly interpreted by properly including anharmonicity, both mechanical and electrical, with DFT calculations. This result is noteworthy, since the spectroscopic range containing the CD-stretching transitions is always rich in features attributed to overtone and combination transitions. The importance of the reported simulations is thought to go beyond the cases discussed here and to be applicable to other molecules containing the HC*D fragment and, more generally, CD, a point that is rising in importance after the FDA's approval of deuterated drugs.
View Article and Find Full Text PDFPhys Chem Chem Phys
July 2025
Faculty of Medicine, Toho University, Tokyo, 143-8540, Japan.
Observation of hornet hindwings using scanning electron microscopy revealed a coating composed of helically wound hairs of approximately 10 μm in diameter and 100 μm in length. A strict enantiomeric relationship in the organ morphology existed in the area closest to the leading edge of the wings: the hairs on the right wing exhibited left-handedness, whereas those on the left wing exhibited right-handedness. Evaluation of microscopic vibration circular dichroism spectra indicated that both sides of the wings comprised β-sheets.
View Article and Find Full Text PDFJ Chem Phys
June 2025
Department of Chemistry, Indian Institute of Technology Jammu, Jammu 181221, India.
Theoretical investigation of the vibrational circular dichroism (VCD) spectrum requires computationally demanding construction of Hessian matrix elements along with atomic polar- and atomic axial-tensors. The fragmentation-based method, molecular tailoring approach (MTA) [Sahu et al., Acc.
View Article and Find Full Text PDF