Self-assembled conjugated thiophene-based rotaxane architectures: structure, modelling and spectroscopy

Leszek Zalewski, Sergio Brovelli, Massimo Bonini, Jeffrey M. Mativetsky, Michael Wykes, Emanuele Orgiu, Thomas Breiner, Marcel Kastler, Florian Dötz, Francesco Meinardi, Harry L. Anderson, David Beljonne, Franco Cacialli, Paolo Samorì, Weinheim (2011)

We report a comparative study on the self-assembly at a variety of surfaces of a dithiophene rotaxane 1β-CD and its corresponding dumbbell 1 by means of Atomic Force Microscopy (AFM) imaging and Scanning Tunneling Microscopy (STM) imaging on the micrometer and nanometer scale, respectively. We found that the dumbbell has a greater propensity to form ordered supramolecular assemblies, as a result of π-π interactions between dithiophenes belonging to adjacent molecules, which are hindered in the rotaxane. The interpretation of the fine molecular structure determined by STM was corroborated by molecular modelling. The optical properties of both rotaxane and dumbbell in the solid state were investigated by steadystate and time-resolved PL experiments on spin-cast films and diluted solutions. The comparison between the optical features of the threaded and unthreaded systems reveals an effective role of encapsulation in reducing aggregation and exciton migration for the rotaxanes with respect to the dumbbells, thus leading to higher PL quantum efficiency and preserved single molecule photophysics for longer times after excitation in the threaded oligomers.

Partners : UMons, UCL, UdS

Place of Publication : Weinheim

Date of Publication : 2010/12/13

Additional Data : Advanced Functional Materials Volume 21, Issue 5, pages 834–844, March 8, 2011

Link to the online version of the article.