Designing lower critical solution temperature behavior into a discotic small molecule

Design and analysis of amphiphilic small molecules exhibiting lower critical solution temperature (LCST) behavior is reported. 2,3,6,7,10,11- Hexakis[2-(N,N-dialkylamino)ethoxy] triphenylenes containing hydrophilic groups attached at their discotic core were prepared, and the LCST behavior of their solutions was studied using fluorescence spectrophotometry and ¹H NMR spectroscopy. ¹H NMR spin-lattice relaxation times were used to assess the rotational mobility of molecules below and above the clouding point. The impact on the LCST of supramolecular π-π stacking forces introduced by the triphenylene (TP) core was studied. The operation of the LCST phenomenon was found not to depend significantly on stacking of TP moieties. This process in small molecular species offers several advantages over the polymer-originated phenomenon. For instance, enabling an analogue of the LCST transition in dye molecules might allow the design of novel optical devices by permitting previously unavailable specific aggregated states.