Nanoscale self assembly of cyclodextrin capped 4-aminobenzophenone via non-covalent interactions

Abstract

Formation of nanoscale self-assemblies of 4-aminobenzophenone (4ABP) with α-CD and β-CD was analyzed by spectral and morphological techniques. 4ABP:CD inclusion complexes are analyzed by SEM, TEM, FT-IR, DSC, XRD, and 1H NMR methods. TEM images show that both 4ABP:α-CD and 4ABP:β-CD inclusion complexes formed nanovesicles and nanorods respectively. Upfield chemical shift observed for ‘A’ ring protons reveals that phenyl ring (without amino group substitution ring) entered into the CD cavities and the aniline ring of 4ABP present in the exterior part of the CD cavities. Absorbance and emission fluorescence spectral shifts of 4ABP with α-CD and β-CD indicate the formation of supramolecular assemblies in an aqueous solution. The spectral results shows that (i) 4ABP is partially incorporated into the CD nanocavities and (ii) “A” ring of 4ABP is deeply present in the β-CD cavity than in α-CD. Molecular modeling offered better approaching of the noncovalent interactions on the inclusion complex 4ABP:CDs. The negative ΔH and ΔS values specified that the inclusion process was an exothermic and thermodynamically much favorable.