Infrared Study of the Interaction Between Caffeine and Hydroxylic Derivatives

Taeye, J. De; Zeegers‐Huyskens, Th.

doi:10.1002/jps.2600740616

Cited by 16 publications

(6 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A less intense third band, at about 1560 cm-', is due to C=N and C = C stretching vibrations of the purine ring and will not be discussed further. These vibrational band assignments for caffeine are well established (12). Changes of peak position, peak absorptivity, and halfwidth with concentration are recorded in Table 1.…”

Section: Methodsmentioning

confidence: 63%

Self-association of caffeine in aqueous solution: an FT-IR study

Falk¹,

Gil²,

Iza³

1990

Can. J. Chem.

View full text Add to dashboard Cite

MICHAEL FALK, MANUEL GIL, and NEREA IZA. Can. J. Chem. 68, 1293 (1990). Spectra of caffeine in DzO solution (0.003 to 0.129 M) were studied by Fourier-transform infrared spectroscopy. Spectral changes in the carbonyl stretching region were interpreted in terms of the self-association equilibria resulting from the stacking of caffeine molecules. Absence of isosbestic points indicated the occurrence of more than two spectroscopically distinct caffeine species. A simple monomer-dimer-polymer model was employed, in which the successive equilibria are governed by two association constants, Kd for the formation of dimers and K, for the formation of trimers and larger polymers. The value Kd = 158.1 L mol-I was taken from a recent ultraviolet study by Iza et al. and the value K, = 27 L mol-' was derived from the analysis of infrared band profiles sharpened by Fourier self-deconvolution. From these values of Kd and K,, the weight fractions of monomers, dimers, and polymers were calculated for every caffeine concentration and their individual molar absorptivity spectra were derived. In agreement with the earlier work of Maevsky and Sukhorukov, it was found that stacking association causes shifts of both C=O stretching fundamentals to higher wavenumbers. The monomer-dimer shifts are smaller than the dimerpolymer shifts. Analogous shifts were observed for the stacking self-association of 1,3-dimethyluracil in D 2 0 . The shifts to higher wavenumbers are probably caused by the diminished hydrogen bonding of water to C=O groups of the stacked bases.Key words: caffeine, self association, infrared spectroscopy, base stacking.MICHAEL FALK, MANUEL GIL et NEREA IZA. Can. J. Chem. 68, 1293 (1990). Nous avons CtudiC les spectres de la cafkine dans des solutions de D 2 0 (0.003 ? I 0.129 M) par la spectroscopie infrarouge 5 transformke de Fourier. La variation des spectres dans la region de vibration de valence des groupes C=O a Ctk interpret6 en termes des Cquilibres impliquant l'auto-association par empilage de molkcules de cafkine. L'absence de points isosbestiques a indiquC l'existence d'au moins trois espkces distinctes de cafkine. Nous avons employ6 un modkle monomkre-dimkrepolymkre, dans lequel les Cquilibres successifs sont controlks par deux constantes d'association, Kd pour la dimkrization et K , pour la formation de trimkres et de polymkres plus grands. La valeur Kd = 158.1 L mol-I a CtC prise de 1'Ctude rCcente faite par Iza et al., tandis que la valeur K, = 27 L mol-' a CtC derivke de l'analyse des profiles de bandes infrarouges obtenues par auto-dCconvolution. A partir des valeurs de Kd et K,, nous avons calculk la fraction en poids des monomkres, dimkres et polymkres pour chaque concentration de cafCine, ce qui nous a permis de calculer leurs spectres individuels. En accord avec les travaux antCrieurs de Maevsky et Sukhorukov, nous avons trouvC que l'association par empilage cause des dCplacements de vibrations de valence des groupes C=O vers les hautes frkquences. Les dkplacements monomkre-dimkre sont moins grands que...

show abstract

Section: Methodsmentioning

confidence: 63%

Self-association of caffeine in aqueous solution: an FT-IR study

Falk¹,

Gil²,

Iza³

1990

Can. J. Chem.

View full text Add to dashboard Cite

show abstract

“…Moreover, we observed that the slight shift of the band in the region of 1285 cm −1 is probably due to various interactions of caffeine's internal vibration υ (CH 3 ). Referring to the work of Taeye et al (1985), regarding hydrogen bonding via proton donors, we know that when hydrogen bonds occur at an exocyclic atom of a polyfunctional base, the in-plane and out-of-plane ring modes are not shifted by more than 2 cm −1 [43]. However, hydrogen bond complexes between nitrogen or oxygen were not observed.…”

Section: Analysis Of Cellulose After Reaction With Caffeinementioning

confidence: 76%

Chemical Changes of Wood Treated with Caffeine

et al. 2021

View full text Add to dashboard Cite

Earlier studies have revealed that wood treated with caffeine was effectively protected against decay fungi and molds. However, there is a need to establish how the caffeine molecule behaves after wood impregnation and how it can protect wood. The objective of the research was to characterize the interaction between caffeine and Scots pine (Pinus sylvestris L.) wood as well as to assess the stability of the alkaloid molecule in lignocellulosic material. For this purpose, an elementary analyzer was used to assess the nitrogen concentration in the treated wood. The results showed that caffeine is easily removed from the wood structure through large amounts of water. The changes occurring in the wood structure after impregnation were evaluated with regard to the results obtained by Fourier transform infrared (FTIR) spectroscopy of two model mixtures with caffeine and cellulose or lignin for the purpose of conducting a comparison with the spectrum of impregnated and non-impregnated samples. The observed changes in FTIR spectra involve the intensity of the C=O(6) caffeine carbonyl group and signals from guaiacyl units. It might indicate favorable interactions between caffeine and lignin. Additionally, molecular simulation of the caffeine’s interaction with the guaiacyl β-O-4 lignin model compound characteristic for the lignin structure using computational studies was performed. Consequently, all analyses confirmed that caffeine may interact with the methylene group derived from the aromatic rings of the guaiacyl group of lignin. In summary, scanning electron microscope (SEM) observations suggest that caffeine was accumulated in the lignin-rich areas of the primary walls.

show abstract

“…The spectrum of caffeine consists of two major vibrations within the 1620–1720 cm –1 window. Previous infrared studies on caffeine have assigned the peak at ∼1700 cm –1 to the stretching of the isolated carbonyl CO(2) and the peak at ∼1640 cm –1 to the stretching of conjugated carbonyl CO(6). ,− Some of these works pointed out that the conjugated carbonyl vibration is probably coupled with the ring C4C5 stretching. , Also, other infrared studies on the guanine ring in nucleic acids suggest that the conjugated carbonyl peak may be coupled with the ring stretching modes from C4C5 and C5–C6. , As shown in Figure a, the intensity of both infrared bands increases with increasing caffeine concentration as expected. The increase in intensity is also accompanied by changes in the frequency of both peaks.…”

Section: Resultsmentioning

confidence: 94%

Anion–Caffeine Interactions Studied by ¹³C and ¹H NMR and ATR–FTIR Spectroscopy

et al. 2017

View full text Add to dashboard Cite

This work investigates the interactions of a series of 11 anions with caffeine by utilizing C andH NMR and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The aim of this study is to elucidate the molecular mechanisms of ion interactions with caffeine and to study how these interactions affect caffeine aggregation in aqueous solution. The chemical shift changes of caffeine C andH in the presence of salts provide a measure for anions' salting-out/salting-in abilities on individual carbon and hydrogen atoms in caffeine. The relative influences of anions on the chemical shift of individual atoms in the caffeine molecule are quantified. It is observed that strongly hydrated anions are excluded from the carbons on the six-member ring in caffeine and promote caffeine aggregation. On the other hand, weakly hydrated anions decrease caffeine aggregation by accumulating around the periphery of the caffeine molecule and binding to the ring structure. The ATR-FTIR results demonstrate that strongly hydrated anions desolvate the caffeine molecule and increase aggregation, while weakly hydrated anions have the opposite effects and salt caffeine into solution.

show abstract

Infrared Study of the Interaction Between Caffeine and Hydroxylic Derivatives

Cited by 16 publications

References 18 publications

Self-association of caffeine in aqueous solution: an FT-IR study

Self-association of caffeine in aqueous solution: an FT-IR study

Chemical Changes of Wood Treated with Caffeine

Anion–Caffeine Interactions Studied by ¹³C and ¹H NMR and ATR–FTIR Spectroscopy

Contact Info

Product

Resources

About

Infrared Study of the Interaction Between Caffeine and Hydroxylic Derivatives

Cited by 16 publications

References 18 publications

Self-association of caffeine in aqueous solution: an FT-IR study

Self-association of caffeine in aqueous solution: an FT-IR study

Chemical Changes of Wood Treated with Caffeine

Anion–Caffeine Interactions Studied by 13C and 1H NMR and ATR–FTIR Spectroscopy

Contact Info

Product

Resources

About

Anion–Caffeine Interactions Studied by ¹³C and ¹H NMR and ATR–FTIR Spectroscopy