NONCOVALENT HOST-GUEST INTERACTION OF CYANINE DYE WITH CUCURBITURILS: PHOTOPHYSICAL PROPERTIES

Sankhaneel Sarma

M.Sc Chemistry, NIT SiKKIM

Dr. A.C. Bhasikuttan

Scientific Officer (H), RPC Division,Bhabha Atomic Research Centre, Mumbai

Abstract

The noncovalent host-guest interaction of an cyanin dye 3,3'-Diethylthiacarbocyanine iodide(DTC), with cucurbiturils (CB[7] and CB[8]) has been investigated using ground-state optical absorption, steady-state and time-resolved fluorescence measurements. Cucurbiturils are a suitable host for an array of neutral and cationic species. Thus the cationic dye DTC exhibits a strong non covalent ion-dipole interaction. These ion-dipole interactions lead to modulate the photophysical properties of the cyanin dye significantly in the presence of CB[7] and CB[8]. The photostability of the dye DTC is adequately enhanced in the presence of both CB[7] and CB[8] which can be used to increase the biomedical activity including imaging of the dye. DTC shows strong emission enhancement on interaction with CB7. On the other hand, the Jobs plot clearly indicates that DTC formed a 1:1 complex with CB7 and with CB8 formed 1:2. The CB8:DTC complex has been confirmed from the Jobs plot experiment. The strong affinity of CB7 and CB8 leads to the formation of inclusion complexes with macrocyclic hosts that are of great current interest, because they find potential applications in drug delivery, photodynamic therapy, catalysis, and sensor applications.

Keywords: Host Guest interaction, cucurbiturils, fluorescence, inclusion complex