Michler's Ketone: β-Cyclodextrin Host-Guest Inclusion Complex for Enhancing the Ultraviolet Protection Factor of...

Michler's ketone (4,4' bis(N,N-dimethylamino)benzophenone) mk is a potential ultraviolet radiation (UVR) absorber in various materials. In this study, we have tested the UVR filtering ability of mk on cotton fabric. The beta-cyclodextrin (β-CD) inclusion complex of mk enhances ultraviolet protection factor (UPF) drastically. The impact of β-CD on the UVR filtering of mk are demonstrated by investigating the guest (mk:absorbers)-host (β-CD:enhancer) inclusion complex. Spectral and molecular docking analysis of mk:β-CD complex infers the vertical insertion of the guest molecule by positioning -C=O group of mk at the center of the host molecule with the exclusion of the terminal atoms of guest molecule outside the β-CD cavity. Thus, the host; β-CD renders an inflexible fit to the guest:mk. The inflexible fit of mk into the β-CD cavity enhances the UVR dissipation when it is incorporated on the poplin cotton fabric. With UPF = 46 mk:β-CD complex is proposed as a potential UVR absorber suitable for manufacturing sun protective textiles. The holding of mk by β-CD enhances the UVR dissipation and hence facilitates the native red-shifted emission and non-radiative relaxation by the formation of twisted intramolecular charge transfer in mk.