Photophysical behaviour of 4-hydroxy-3,5-dimethoxybenzoic acid in different solvents, pH and β-cyclodextrin

Inclusion of chrysin in β-cyclodextrin nanocavity and its effect on antioxidant potential of chrysin: A spectroscopic and molecular modeling approach

“…The higher wavelength peak is more red shifted than the lower one, further confirming strong pÀp à character of the B-ring and reflects greater delocalization of the p-cloud of the aromatic B-ring with the carbonyl group in the C-ring of chrysin [27]. Moreover, the spectral shifts observed in the absorption spectrum of chrysin in protic and aprotic solvents are consistent with the characteristic behaviour of hydroxyl groups [51][52][53][54][55].…”

Encapsulation of 4-hydroxy-3-methoxy benzoic acid and 4-hydroxy-3,5-dimethoxy benzoic acid with native and modified cyclodextrins

“…A clear isosbestic point was observed in the absorption spectra and the changes were observed in the absorbance are very small. Further, no changes were observed in the absorbance of these solutions when recorded after 12 h. In general, the existence of an isosbestic point in the absorption spectra is indicative of the formation of well defined 1:1 complex [13][14][15][16][17][18][19][20][21][22][23][24][25]. With the addition of all the four CDs, the increase in absorbance along with a spectral shift indicates the formation of 1:1 HMBA/CD inclusion complexes.…”

“…The formation constants are very sensitive to change of pH supported the selective inclusion associated with the HDMBA and HMBA (neutral, carboxylic anion and hydroxy anion) species. Of the three species, we should note that all the CDs can readily include the neutral species as compared to the anionic species because the CDs cavity favor the neutral form of the benzoic acid derivatives [13,14]. The higher binding constant in pH $ 1 implies that the COOH group is encapsulated in the interior of the CD cavity when compared to carboxylic anion.…”

“…In addition, CDs can mediate many organic reactions in which CDs represent a good model of mimicking enzymes [6,7] and have molecular recognition property to identify the small differences between compounds [8,9]. Due to the limitations of the experimental methods, in recent times molecular modeling has become very popular in CD chemistry [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25].…”

“…In the last few years, we have been examining amino, hydroxyl, aldehyde and COOH group substituted benzenes in various environments [13][14][15][16][17][18][19][20]. It has been observed that the photophysical characteristics of these molecules are largely influenced by the nature of substituents in the para position of the phenyl rings.…”