Cholesterol-tethered AIEE fluorogens: Formation of self-assembled nanostructures

Design and synthesis of cholesterol conjugated chromophores exhibiting intramolecular charge transfer (ICT) and Aggregation Induced Enhanced Emission (AIEE) is described. Cholesterol conjugated α-cyanostilbene exhibits weak emission in organic solvents but in aqueous media this shows 5-fold intensity increase accompanied by a strong bathochromic emission shift as a consequence of AIEE effect. On the other hand, cholesterol conjugated diene exhibits quenched emission in water with characteristic polarity dependent solvatochromic emission shifts. Under aqueous conditions and in sodium cholate matrix, cholesterol stilbene conjugate self-assembles to form organized nanostructures having distinct morphological differences to the structures observed in the absence of cholesterol tether. The self-assembled structures were characterized using scanning electron microscopy and circular dichroism.