Reinvestigation of the Raman spectrum of benzophenone using a He-Ne laser

Mathur, M. S.; Frenzel, C. A.; Bradley, E. B.

doi:10.1016/0584-8539(70)80093-9

Cited by 12 publications

(6 citation statements)

References 8 publications

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“…It may be observed that the wavenumber of maximum absorption in both mechanical mixtures is 1651 cm -1 , similar to that for benzophenone crystals. 30,31 The small band at 1627 cm -1 , assigned to CdC coupled to CdO stretching modes of benzophenone, may also be observed in these samples.…”

Section: Adsorption Of Benzophenonementioning

confidence: 81%

“…29 As do other diarylketones, it has an extended conjugated system when the molecule is planar; as a consequence, its IR spectrum shows a particularly low wavenumber for the carbonyl stretching mode in the crystalline phase (1650 cm -1 ). However, in solution or molten phase, rotation is free around the C 1 sC and C′ 1 sC bonds and favored by steric hindrance of H 2 and H′ 2 atoms, 30 with the correspondent loss of coplanarity in the molecule. This restricts resonance to the isolated phenyl groups, enhancing the CdO double-bond character and therefore shifting the band to higher wavenumbers.…”

Section: Introductionmentioning

confidence: 99%

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Infrared Approach to the Study of Adsorption on Cellulose: Influence of Cellulose Crystallinity on the Adsorption of Benzophenone

Ilharco¹,

García²,

Silva³

et al. 1997

Langmuir

131

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The structures of different celluloses (microcrystalline and native) were characterized by diffuse reflectance infrared spectroscopy (DRIFT), analyzing the bands due to O−H stretching, C−O stretching, and C−H bending modes. The respective crystallinities were determined as 73 ± 2% and 40 ± 2%, and the crystalline structure in both was characterized as type Iβ. A comparative study of adsorption of an aromatic ketone, benzophenone, on these two substrates was made, using the same technique. Through the modifications observed in the carbonyl stretching band of benzophenone, it was possible to distinguish adsorption in three different environments: entrapped between the glycosidic chains in crystalline domains, in amorphous domains, and as crystallites adsorbed at the cellulose surface. By deconvolution of spectra and subsequent analysis of the main components' relative intensities, it has been possible to calculate the approximate amounts of entrapped molecules per gram of cellulose as a function of total benzophenone concentration. These results show that, for low benzophenone concentrations, adsorption occurs preferentially in crystalline domains of cellulose, independently from its crystallinity. On the contrary, as concentration is increased, crystallinity has a determinant role on the total amount of adsorbed benzophenone and on its molecular distribution in the different domains of cellulose.

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Section: Adsorption Of Benzophenonementioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Infrared Approach to the Study of Adsorption on Cellulose: Influence of Cellulose Crystallinity on the Adsorption of Benzophenone

Ilharco¹,

García²,

Silva³

et al. 1997

Langmuir

131

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“…Under the point of view of infrared spectroscopy, benzophenone may be an interesting probe, as the carbonyl stretching band is very strong and sensitive to any interactions in which it may be involved. For the planar molecule (crystalline phase), the conjugated π system is extended to the whole molecule and the wavenumber of the carbonyl stretching vibration is particularly low (1650 cm -1 ) …”

Section: Introductionmentioning

confidence: 99%

“…For the planar molecule (crystalline phase), the conjugated π system is extended to the whole molecule and the wavenumber of the carbonyl stretching vibration is particularly low (1650 cm -1 ). 8 When rotation is free around the C-(CdO) bonds (in solution or molten phase), the molecule loses coplanarity, the CdO double bond character is reinforced, and the correspondent mode shifts to higher wavenumbers (1667 cm -1 in cyclohexane, for instance). However, if the carbonyl group is involved in strong interactions, such as hydrogen bonds, this effect is partially compensated, and the band shifts back a few wavenumbers.…”

Section: Introductionmentioning

confidence: 99%

Ultraviolet−Visible and Fourier Transform Infrared Diffuse Reflectance Studies of Benzophenone and Fluorenone Adsorbed onto Microcrystalline Cellulose

Ilharco¹,

García²,

Silva³

et al. 1997

Langmuir

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Benzophenone and fluorenone, which have a nonrigid and a rigid structure, respectively, were used as probes to study the nature of the adsorption process onto microcrystalline cellulose. Diffuse reflectance techniques were used in the UV−vis and infrared regions. Luminescence studies revealed that whenever fluorenone or benzophenone are entrapped into the natural polymer chains and in close contact with the substrate, a strong quenching effect exists for both probe's luminescence at room temperature. For fluorenone, the fluorescence quantum yields (ΦF) determined were about 0.10 when dichloromethane, cyclohexane, and benzene (solvents which do not swell cellulose) were used for sample preparation, while for dioxane, acetone, ethanol, and methanol (solvents which efficiently swell cellulose) ΦF was approximately 0.01. These values are about 1 order of magnitude higher than those obtained in solution, showing the importance of the rigid dry matrix in reducing the nonradiative pathways of deactivation of the (π,π*) fluorenone first excited singlet state. Complementary, infrared studies showed that the carbonyl group of benzophenone is affected by entrapment (when the solvents used induce the swelling of cellulose), whereas in fluorenone the same band is insensitive to the adsorption process, not allowing the differentiation between entrapped molecules and surface crystallites of this ketone. These observations implied that benzophenone is entrapped between the chains of the polymer forming hydrogen bonds between the carbonyl and the hydroxyl groups of the glycosidic chains, while the rigidity of fluorenone apparently restrains the ketone−substrate interactions to the aromatic rings. Through the modifications observed in the carbonyl stretching band of benzophenone, it was possible to establish a swelling effect scale for the solvents, which is compared with previous results.

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“…30,50,51 While most Raman active modes of benzophenone exhibit no dependence on solvent structure, there are two features which are an exception to this rule. These modes comprise the carbonyl stretch, denoted ν(C=O), which is found over a relatively broad region around 1662.8 ± 7.2 cm −1 and the aromatic stretching modes ν i (C-H) in the vicinity of ∼3066 cm −1 (Fig.…”

Section: A Solvatochromic Shiftsmentioning

confidence: 90%

Solvatochromism and the solvation structure of benzophenone

Elenewski

Hackett

2013

The Journal of Chemical Physics

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Many complex molecular phenomena, including macromolecular association, protein folding, and chemical reactivity, are determined by the nuances of their electrostatic landscapes. The measurement of such electrostatic effects is nonetheless difficult, and is typically accomplished by exploiting a spectroscopic probe within the system of interest, such as through the vibrational Stark effect. Raman spectroscopy and solvatochromism afford an alternative to this method, circumventing the limitations of infrared spectroscopy, providing a lower detection limit, and permitting measurement in a native chemical environment. To explore this possibility, the solvatochromism of the C=O and aromatic C-H stretching modes of benzophenone are investigated using Raman spectroscopy. In conjunction with density functional theory calculations, these observations are sufficient to determine the probe electrostatic environment as well as contributions from halogen and hydrogen bonding. Further analysis using a detailed Kubo-Anderson lineshape model permits the detailed assignment of distinct hydrogen bonding configurations for water in the benzophenone solvation shell. These observations reinforce the use of benzophenone as an effective electrostatic probe for complex chemical systems.

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Reinvestigation of the Raman spectrum of benzophenone using a He-Ne laser

Cited by 12 publications

References 8 publications

Infrared Approach to the Study of Adsorption on Cellulose: Influence of Cellulose Crystallinity on the Adsorption of Benzophenone

Infrared Approach to the Study of Adsorption on Cellulose: Influence of Cellulose Crystallinity on the Adsorption of Benzophenone

Ultraviolet−Visible and Fourier Transform Infrared Diffuse Reflectance Studies of Benzophenone and Fluorenone Adsorbed onto Microcrystalline Cellulose

Solvatochromism and the solvation structure of benzophenone

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