Guest-Host Inclusion Complex Formation of 2-, 3-, and 4-Aminobenzoic Acids with Native and Modified Cyclodextrins

Abstract

The inclusion complexation of 2-aminobenzoic acid (2ABA), 3-aminobenzoic acid (3ABA), and 4-aminobenzoic acid (4ABA) with α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), hydroxypropyl-α-cyclodextrin (HP-α-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) were studied in buffer solutions of different pHs (pH~1 and pH~7) and it was carried out using UV-Visible, steady-state and time-resolved fluorescence. Dual fluorescence was observed for all the compounds in aqueous and CD medium. All the ABAs forms 1:1 inclusion complex at pH ~ 1 solution and mixture of 1:1 and 1:2 inclusion complex at pH ~7. With CDs, dual luminescence appeared at pH ~ 1 indicates, both NH3+ and COOH groups are present in the interior of the CDs cavities. FT-IR, 1H NMR, results suggest ABAs formed a stable inclusion complex with the CDs.