A Switchable bis-Branched Rotaxane featuring Dual-Mode Molecular Motions and Tunable Molecular Aggregation
2014 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 21, 18921-18929 p.Article in journal (Refereed) Published
A multifunctional bis-branched rotaxane containing a perylene bisimide (PBI) core and two identical bistablerotaxane arms terminated with ferrocene units was prepared and characterized by H-1 NMR, C-13 NMR, and 2D ROESY NMR spectroscopies and by HR-ESI spectrometry. The system is shown to possess several key features: (1) In acetone solution, external acid base stimuli can result in relative mechanical movements of its ring and thread, which can induce extension and contraction movements of the whole system accompanied by a rotational movement of the ferrocene units, thus realizing dual-mode molecular motions, and the optimized conformations at different states are obtained through molecular dynamics simulations employing the general Amber force field. (2) The introduction of PBI enables the system fluorescence encoding through distance-dependent photoinduced electron transfer process from the ferrocene units to the PBI fluorophore. (3) The addition of Zn2+ can increase the degree of aggregation of the system, while adding base hinders aggregation because of the movement of the macrocyde. The tunable aggregated nanostructural morphologies of rotaxane were examined by scanning electron microscopy. These results can pave the way to achieve precise control of integrated and coupling nanomechanical motions at a single-molecule level and provide more insight into controlling the aggregate behavior of switchable mechanically interlocked molecules.
Place, publisher, year, edition, pages
2014. Vol. 6, no 21, 18921-18929 p.
bistable rotaxanes, perylene bisimide, fluorescence, dual-mode motions, tunable aggregation
IdentifiersURN: urn:nbn:se:kth:diva-158823DOI: 10.1021/am506283gISI: 000344978200070ScopusID: 2-s2.0-84910147231OAI: oai:DiVA.org:kth-158823DiVA: diva2:783784
QC 201501272015-01-272015-01-122015-01-27Bibliographically approved