Helicity Control in the Aggregation of Achiral Squaraine Dyes in Solution and Thin Films |
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Authors: | Andreas T Rösch Dr Qirong Zhu Jorn Robben Dr Francesco Tassinari Dr Stefan C J Meskers Prof?Dr Ron Naaman Prof?Dr Anja R A Palmans Prof?Dr E W Meijer |
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Institution: | 1. Laboratory of Macromolecular and Organic Chemistry, and Institute for Complex Molecular Systems, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600, MB Eindhoven, The Netherlands;2. Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, 76100 Israel;3. Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600, MB Eindhoven, The Netherlands |
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Abstract: | Squaraine dyes are well known for their strong absorption in the visible regime. Reports on chiral squaraine dyes are, however, scarce. To address this gap, we here report two novel chiral squaraine dyes and their achiral counterparts. The presented dyes are aggregated in solution and in thin films. A detailed chiroptical study shows that thin films formed by co-assembling the chiral dye with its achiral counterpart exhibit exceptional photophysical properties. The circular dichroism (CD) of the co-assembled structures reaches a maximum when just 25 % of the chiral dye are present in the mixture. The solid structures with the highest relative CD effect are achieved when the chiral dye is used solely as a director, rather than the structural component. The chiroptical data are further supported by selected spin-filtering measurements using mc-AFM. These findings provide a promising platform for investigating the relationship between the dissymmetry of a supramolecular structure and emerging material properties rather than a comparison between a chiral molecular structure and an achiral counterpart. |
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Keywords: | circular dichroism helical structures self-assembly squaraine dyes supramolecular chemistry |
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