Association phenomena of a chiral perylene derivative in solution and in poly(ethylene) dispersion

In this work, the aggregation behaviour of a chiral perylene derivative, that is, N,N′-bis-(R)-(1′-phenylethyl)-perylene-3,4,9,10-tetracarboxyldiimide (R-Pery), was studied by means of 1H NMR (including DOSY techniques), circular dichroism, UV-Vis and fluorescence spectroscopies in various conditions. The acquired data demonstrate that R-Pery tends to aggregate in pure solvents at high concentrations (>10−5 M in DMSO and >10−3 M in CHCl3), whereas aggregation occurred at lower concentrations by adding a poor solvent, such as water (to DMSO) or CH3CN (to chloroform). Interesting results were obtained studying the optical behaviour of R-Pery when dispersed into a linear low-density polyethylene matrix (LLDPE). In particular, the aggregation extent of R-Pery into LLDPE was investigated by means of UV-Vis, fluorescence and CD spectroscopies as a function of dye concentration as well as thermal stimuli. The optical responsiveness of R-Pery (both in absorption and in emission) versus moderate temperature changes (i.e., for T > 35 °C) suggests applications of polymer dispersions as smart and reversible indicators to thermal solicitations.