Mechanistic Insights into the Self-Assembly of an Acid-Sensitive Photoresponsive Supramolecular Polymer |
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| Authors: | Dr Kalathil K Kartha Dr Naveen Kumar Allampally Prof Dr Shiki Yagai Dr Rodrigo Q Albuquerque Prof Dr Gustavo Fernández |
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| Institution: | 1. Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, Germany;2. Institut für Organische Chemie, Universität Würzburg, am Hubland, 97074 Würzburg, Germany;3. Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, 1-33-Yayoi-cho, Inage-Ku, Chiba, 263-8522 Japan |
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| Abstract: | The supramolecular polymerization of an acid-sensitive pyridyl-based ligand ( L1 ) bearing a photoresponsive azobenzene moiety was elucidated by mechanistic studies. Addition of trifluoroacetic acid (TFA) led to the transformation of the antiparallel H-bonded fibers of L1 in methylcyclohexane into superhelical braid-like fibers stabilized by H-bonding of parallel-stacked monomer units. Interestingly, L1 dimers held together by unconventional pyridine–TFA N⋅⋅⋅H⋅⋅⋅O bridges represent the main structural elements of the assembly. UV-light irradiation caused a strain-driven disassembly and subsequent aggregate reconstruction, which ultimately led to short fibers. The results allowed to understand the mechanism of mutual influence of acid and light stimuli on supramolecular polymerization processes, thus opening up new possibilities to design advanced stimuli-triggered supramolecular systems. |
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| Keywords: | acid-sensitive photoresponsive self-assembly supramolecular polymers π-conjugated systems |
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