Vibrational spectra of phenylacetate and phenylglycinate ions

Castro, José L.; Ramírez, María Rosa López; López‐Tocón, Isabel; Otero, Juan C.

doi:10.1016/s0022-2860(03)00116-9

Cited by 7 publications

(7 citation statements)

References 11 publications

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“…As shown in Figure , phenylacetic acid, sodium phenylacetate, and the PAA-Na-PAA cocrystal product exhibited significant differences in the fingerprint region of their infrared absorption spectra that provides information regarding the nature of the interactions in the cocrystals. Other than an ab initio study of the vibrational modes of the phenylacetate ion, little guidance is available in the literature to facilitate a complete assignment of the infrared absorption bands of phenylacetic acid and its derivatives. However, since this species differs from benzoic acid only by the presence of a single methylene group bridging the carboxylic acid and phenyl groups, the important spectra bands were assigned by guidance from authoritative sources − and analogy to the benzoic acid assignments.…”

Section: Resultsmentioning

confidence: 99%

Vibrational Spectroscopic Studies of Cocrystals and Salts. 3. Cocrystal Products Formed by Benzenecarboxylic Acids and Their Sodium Salts

Brittain¹

2010

Crystal Growth & Design

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X-ray powder diffraction, differential scanning calorimetry, infrared absorption spectroscopy, and Raman spectroscopy have been used to study the phenomenon of salt formation in four benzenecarboxylic acids (benzoic acid, phenylacetic acid, hydrocinnamic acid, and 4-phenylbutanoic acid), and in the 1:1 stoichiometric products formed by the cocrystallization of a free acid and a sodium salt. Assignments were derived for the observed peaks in both infrared absorption and Raman spectra of the reactants and their products. In all instances, it was observed that the energy of the antisymmetric stretching mode of the carbonyl group of the free benzenecarboxylic acid invariably shifted to higher energies when that acid formed a cocrystal with a sodium salt of another benzenecarboxylic acid. In addition, the symmetric stretching mode of the benzenecarboxylic acid carbonyl group disappeared in the Raman spectrum of its sodium salt and was also absent in the Raman spectrum of the cocrystal product. It was also found that the antisymmetric carboxylate anion stretching mode, the symmetric carboxylate anion stretching mode, the out-of-plane carboxylate deformation mode, and the vibrational modes associated with the phenyl ring and alkane side chains were not useful spectroscopic tools to differentiate cocrystal and sodium salt, as the observed differences of these vibrational modes did not exhibit significantly consistent differences between the various forms.

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Section: Resultsmentioning

confidence: 99%

Vibrational Spectroscopic Studies of Cocrystals and Salts. 3. Cocrystal Products Formed by Benzenecarboxylic Acids and Their Sodium Salts

Brittain¹

2010

Crystal Growth & Design

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“…In order to have a reliable assignment of the vibrational spectrum of Bz − , the B3LYP/6-31+G* force field of the ground state has been scaled following the quantum mechanical force field (SQMFF) methodology of Pulay et al , The scale factors corresponding to internal coordinates of the same character were kept identical, as done in previous works. , The selected set of independent internal coordinates and their respective fitted scale factors are submitted as Supporting Information (Figure S1 and Table S1).…”

Section: Resultsmentioning

confidence: 99%

Surface-Enhanced Raman Scattering of Benzoate Anion Adsorbed on Silver Nanoclusters: Evidence of the Transient Formation of the Radical Dianion

et al. 2010

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Surface-enhanced Raman scattering (SERS) of benzoate recorded on silver electrode have been analyzed on the basis of a charge transfer (CT) enhancement mechanism similar to a resonance Raman (RR) process where a photoinduced electron transfer between a metal and an adsorbate takes place. Given that benzoic acid (BzH) is adsorbed on silver as benzoate anion (Bz -), this resonant CT process implies the transient formation of the corresponding radical dianion (Bz •2-). The dependence of the relative SERS intensities on the electrode potential has been analyzed on the basis of ab initio calculations of the electronic properties of the isolated adsorbate in its ground and excited CT states (Bz -and Bz •2-, respectively). Moreover, configuration interaction singles (CIS) calculations have also been carried out for the Ag 2 -benzoate (Ag 2 -Bz -) supermolecule, which shows two excited singlets, namely CT 0 ; 1 B 1 and CT 1 ; 1 A 2 , where the properties of the adsorbate are quite similar to those of the radical dianion of the isolated species. The theoretical calculations predict the selective enhancement of modes 8a and ν s (CO 2 -) under CT resonant conditions in close agreement with the SERS results. This confirms once again the relevance of resonant CT processes in the SERS of aromatic molecules and the usefulness of this technique in the study of very unstable species such as radical anions or dianions of aromatic adsorbates.

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“…As shown in Figure , benzylamine, benzylammonium chloride, and the BZA-Cl-BZA salt-cocrystal exhibited several significant differences in the fingerprint region of their FTIR spectra that are consistent with formation of the salt-cocrystal product. In order fully interpret the spectra, the molecular vibrational modes of the major absorbance bands of benzylamine and benzylammonium chloride were assigned through the use of published compilations − and works conducted specifically on phenylalkylamines and their derivatives. − Assignments for the absorption bands of the salt-cocrystal were made whenever possible by extrapolation. The results of this analysis are provided in Table .…”

Section: Resultsmentioning

confidence: 99%

“…The vibrational origins of the major absorbance bands observed in the various FTIR spectra were derived as before, namely, using published compilations − and works conducted specifically on phenylalkylamines and their derivatives − to obtain the assignments collected in Table . As noted with the benzylamine series, the most important effects evident in the spectra were associated with the protonation of the free amine to yield the chloride salt.…”

Section: Resultsmentioning

confidence: 99%

Vibrational Spectroscopic Studies of Cocrystals and Salts. 4. Cocrystal Products formed by Benzylamine, α-Methylbenzylamine, and their Chloride Salts

Brittain¹

2011

Crystal Growth & Design

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The chloride salts formed by benzylamine and Rmethylbenzylamine have been characterized using X-ray powder diffraction, differential scanning calorimetry, and infrared absorption spectroscopy. In addition, X-ray powder diffraction and differential scanning calorimetry have been used to establish formation or lack of formation of the 1:1 stoichiometric salt-cocrystal products containing the chloride salts and their respective free bases. For R-methylbenzylamine (which contains a single dissymmetric center), the chiral identities of the free bases and chloride salts were found to play a determining role as to whether a salt-cocrystal product could or could not be formed. It was found that a salt-cocrystal product could only be formed if the salt and free base were of opposite absolute configurations. For those systems where the existence of cocrystals was demonstrated, assignments were derived for the observed peaks in the infrared absorption spectra of the reactants and their products.

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Vibrational spectra of phenylacetate and phenylglycinate ions

Cited by 7 publications

References 11 publications

Vibrational Spectroscopic Studies of Cocrystals and Salts. 3. Cocrystal Products Formed by Benzenecarboxylic Acids and Their Sodium Salts

Vibrational Spectroscopic Studies of Cocrystals and Salts. 3. Cocrystal Products Formed by Benzenecarboxylic Acids and Their Sodium Salts

Surface-Enhanced Raman Scattering of Benzoate Anion Adsorbed on Silver Nanoclusters: Evidence of the Transient Formation of the Radical Dianion

Vibrational Spectroscopic Studies of Cocrystals and Salts. 4. Cocrystal Products formed by Benzylamine, α-Methylbenzylamine, and their Chloride Salts

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