title: Entropically Driven Self-Assembly of Bolaamphiphilic Perylene Dyes in Water.
abstract: The specific hydrophobic effect involved in the self-assembly of a bolaamphiphilic perylene bisimide (PBI) dye bearing oligoethylene glycol (OEG) chains has been identified. In pure water, the self-assembly is entropically driven and enthalpically disfavored, as explored by optical spectroscopy and isothermal titration calorimetry studies. Besides strong π-π interactions between the PBI units that are primarily of enthalpic nature, the major contribution to the self-assembly is the gain of entropy by release of confined water molecules from the hydration shell of the hydrophilic OEG moieties. Both contributions favor self-assembly, but their countervailing thermodynamic parameters are reflected in an uncommon temperature dependence, which can be inverted upon gradual addition of an organic cosolvent that makes the π-π interaction increasingly dominant.
authors: Universität Würzburg, Institut für Organische Chemie and Center for Nanosystems Chemistry (CNC) and Bavarian Polymer Institute (BPI), Am Hubland, 97074, Würzburg, Germany.
authors: Daniel
authors: D
authors: Görl
authors: Universität Würzburg, Institut für Organische Chemie and Center for Nanosystems Chemistry (CNC) and Bavarian Polymer Institute (BPI), Am Hubland, 97074, Würzburg, Germany. wuerthner@chemie.uni-wuerzburg.de.
authors: Frank
authors: F
authors: Würthner
keywords: entropy; hydrophobic effect; perylene bisimides; self-assembly; π-π stacking