Probing the pH dependent assembly-disassembly of water-soluble organic capsules with coumarins and anthracene

Abstract Octaacid (OA) and octaamine (OAm) form water-soluble capsules in presence of guest molecules. Using the polarity dependent fluorescence of coumarins (coumarin-1, coumarin-153 and coumarin-480) we have shown that the dynamic OA and OAm capsules can be reversibly disassembled and reassembled by controlling the pH of the solution. Anthracene is a unique guest molecule that forms a 2:2 capsule with both OA and OAm and shows excimer emission when inside the capsule and monomer emission when in water. Reversible pH dependent excimer-monomer emission of anthracene has revealed that the disassembly process is much dependent on the hydrophobicity of the guest. The disassembly of the capsules is slower with anthracene than with the less hydrophobic coumarins. In addition the assembly-disassembly is not 100% with hydrophobic anthracene while quantitative in the case of coumarins.