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

Photophysics of Caffeic, Ferulic and Sinapic Acids with α- and β-Cyclodextrins: Spectral and Molecular Modeling Studies

“…72 The above results showed that, the guest molecules were transferred from more protic environments (bulk aqueous phase) to less protic CD cavity environments [1][2][3][4][5][6][7][8][9][10][26][27][28][29][30][31]. Similar spectral shifts of all the HCAs showed that same type of the functional group is encapsulated and this functional group is interacted with the secondary hydroxyl groups of the CD.…”

“…It is well known fact that deprotonation of COOH group gives blue shifted absorption and emission maxima whereas deprotonation of hydroxyl group gives red shifted absorption and emission maxima [27][28][29][30][31]. In the HCA molecules, unusual blue shift noticed in the hydroxyl anion indicating that carboxy monoanion decrease the interaction between the ionic substituent and the aromatic ring [26][27][28][29][30][31].…”

Photophysics of Caffeic, Ferulic and Sinapic Acids with α- and β-Cyclodextrins: Spectral and Molecular Modeling Studies

“…With addition of α-CD and β-CD, the increase in absorbance along with red shift indicating the formation of guest:CD inclusion complex. The above results showed that, the guest molecules were transferred from more protic environments (bulk aqueous phase) to less protic CD cavity environments [1][2][3][4][5][6][7][8][9][10][26][27][28][29][30][31]. Similar spectral shifts of all the HCAs showed that same type of the functional group is encapsulated and this functional group is interacted with the secondary hydroxyl groups of the CD.…”

“…The reciprocal of the absorbance/fluorescence intensity of the inclusion complex versus the reciprocal of CD concentration is excellent, because the formation constant and stoichiometry can be simultaneously obtained from the plot. Benesi-Hildebrand relation [26][27][28][29][30][31] should give a straight indicates 1:1 inclusion complex to be formed in the ground and excited state.…”

“…It is well known fact that deprotonation of COOH group gives blue shifted absorption and emission maxima whereas deprotonation of hydroxyl group gives red shifted absorption and emission maxima [27][28][29][30][31]. In the HCA molecules, unusual blue shift noticed in the hydroxyl anion indicating that carboxy monoanion decrease the interaction between the ionic substituent and the aromatic ring [26][27][28][29][30][31]. q-Quenching, w -weakly fluorescent…”