Acid‐Base Switchable [2]‐ and [3]Rotaxane Molecular Shuttles with Benzimidazolium and Bis(pyridinium) Recognition Sites. Issue 22 (13th October 2016)

• Record Type: Journal Article
• Authors: Zhu, Kelong; Vukotic, V. Nicholas; Loeb, Stephen J.
• Is Part Of: Chemistry, an Asian journal. Volume 11:Issue 22(2016)
• Page Start: 3258
• Page End: 3266
• Publication Date: 2016-10-13
• Subjects: benzimidazole -- molecular shuttles -- molecular switches -- rotaxanes -- supramolecular chemistry; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/asia.201601179
• Languages: English
• ISSNs: 1861-4728

Abstract

Abstract: For the purpose of developing higher level mechanically interlocked molecules (MIMs), such as molecular switches and machines, a new rotaxane system was designed in which both the 1, 2‐bis(pyridinium)ethane and benzimidazolium recognition templating motifs were combined. These two very different recognition sites were successfully incorporated into [2]rotaxane and [3]rotaxane molecular shuttles which were fully characterized by 1 H NMR, 2D EXSY, single‐crystal X‐ray diffraction and VT NMR analysis. By utilizing benzimidazolium as both a recognition site and stoppering group it was possible to create not only an acid/base switchable [2]rotaxane molecular shuttle (energy barrier 20.9 kcal⋅mol −1 ) but also a [3]rotaxane molecular shuttle that displays unique dynamic behavior involving the simultaneous motion of two macrocyclic wheels on a single dumbbell. This study provides new insights into the design of switchable molecular shuttles. Due to the unique properties of benzimidazoles, such as fluorescence and metal coordination, this new type of molecular shuttle may find further applications in developing functional molecular machines and materials. Abstract : [3]Rotaxane molecular shuttle : Translocating two macrocyclic wheels simultaneously on one single dumbbell‐shaped axle.