Dimerisation and vibrational spectroscopic properties of (RS)-phenylsuccinic acid

Abstract

Single crystals of (RS)-phenylsuccinic acid (RSPSA) were grown by the slow evaporation technique and vibrational spectral analysis was carried out using near-IR Fourier transform Raman and Fourier transform IR spectroscopy. The density functional theoretical (DFT) computations were also performed at the B3LYP/6-31G(d) level to derive the equilibrium geometry, vibrational wavenumbers, intensities and atomic charges. Vibrational spectral investigation confirmed the formation of cyclic dimers in the crystal, with the carboxyl groups of each acid molecule being hydrogen bonded to those of the adjacent molecules. Each molecule is connected to two other molecules, forming infinite chains. The wavenumber difference observed between the carbonyl modes in the IR and Raman spectra might be attributed to the intramolecular association based on C O· · ·H type hydrogen bonding in the molecule. In a hydrogenbonded carbonyl, resonance can occur, which places a partial negative charge on the oxygen atom accepting the hydrogen bond and a positive charge on the atom donating the hydrogen. The resulting partial 'transfer of allegiance' of the proton enhances resonance and lowers the carbonyl stretching wavenumber. The O-H stretching vibrational wavenumber is red-shifted owing to the formation of strong O-H· · ·O hydrogen bonds by hyperconjugation between carbonyl oxygen lone electron pairs and O-H s * antibonding orbitals. Vibrational analysis was used to investigate the C-H· · ·O interaction and electronic effects, induction of the methylene group by an adjacent electronegative atom and the resulting increase of stretching mode wavenumbers and decrease of infrared intensities.

NIR-FT Raman, FT-IR and surface-enhanced Raman scattering and DFT based theoretical studies on the adsorption behaviour of (S)-phenylsuccinic acid on silver nanoparticles

“…The broadening in the O-H stretching of SPSA is due to combination bands between the low wavenumber vibrations and ν O-H and between the ring vibrations and excited binary combination of δ COH and ν C-O . The weak bands in infrared spectrum 2700-2500 cm -1 region, correspond to overtones and combinations of the 1322 and 1423 cm -1 bands due to interacting C-O stretch and O-H deformation vibrations 19,[27][28][29][30][31][32][33][34][35][36]. The very strong Raman peak at 1292 cm -1 is due to the O-H in-plane deformation mode as expected.…”

“…Owing to its rather rigid structure, benzoic acid can be regarded as a good model compound in the investigation of interaction of carboxylic acids with metal surfaces. 8 Vibrational and SERS spectral investigations of (RS)-phenylsuccinic acid 19,20 supported by ab initio density functional theory studies have been reported. Though the crystal structure of the title compound, (S)-phenylsuccinic acid (SPSA) has been reported, 21 the vibrational spectral features of SPSA crystal have not been subject of detailed analysis so far.…”

Chemical modification and surface reactions on carbon fibers studied by SERS

“…Peaks at 1110, 1149, 1202 and 1757 cm 1 can be assigned to the stretching vibration of O-H and C-O, while peaks at 1336, 1520, 1589 and 2219 cm 1 correspond to the C C vibration in the aromatic ring. 15,16 Earlier Raman spectroscopic studies revealed that the Raman spectra of pristine carbon fiber consist of characteristic peaks at ¾1350 and 1580 cm 1 . The notable differences found on the sample CF are believed to be due to the sizing on the fiber surface applied by the manufacturer.…”

Density functional study on the structural conformations and intramolecular charge transfer from the vibrational spectra of the anticancer drug combretastatin‐A2

“…Vibrational spectroscopy has been extensively used to understand the factors contributing to the vibrational modes in organic materials and to obtain deeper knowledge regarding intermolecular interactions. [17,18] NIR FT-Raman and FT-IR spectra, combined with density functional theoretical computations, have recently been successfully employed in the vibrational spectral analysis of drug molecules, biological compounds and natural products, since fluorescence-free Raman spectra and computed results help in the unambiguous identification of vibrational modes and provide deeper insight into the bonding and structural features of complex organic molecular systems. [19 -21] The present work describes the geometrical optimization and vibrational spectral investigations on the relationship between the molecular structural features of the CA2 molecule, with special emphasis on the role of the ICT mechanism in such organic materials.…”