Rotamer‐Induced Dynamic Nature of a [2]Rotaxane and Control of the Dynamics by External Stimuli. Issue 12 (27th March 2017)

• Record Type: Journal Article
• Authors: Santra, Saikat; Ghosh, Pradyut
• Is Part Of: European journal of organic chemistry. Issue 12(2017)
• Page Start: 1583
• Page End: 1593
• Publication Date: 2017-03-27
• Subjects: Rotaxanes -- Rotamers -- Amides -- Click chemistry -- Crown compounds; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.201601525
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract : A Cu I ‐catalyzed azide–alkyne cycloaddition reaction between an azide‐terminated Ni II ‐templated [2]pseudorotaxane with an oxy‐ether tris(amino) macrocycle (MC) and an alkyne‐terminated triphenylene stopper unit produces a new [2]rotaxane (ROT) with multiple functional groups. A detailed mass spectrometry study and various 1D and 2D NMR spectroscopy studies confirm the interpenetration of the axle in the macrocycle of ROT. The tri‐acetylation of the tris(amine) moiety of ROT produces AcROT with three tertiary amide functionalities. Prior to this selection, a detailed study of the dynamic properties was undertaken with the tertiary amide functionalized macrocycle MC1 and the tri‐methylated derivative of MC, MC2. A 1 H NMR study of AcROT at room temp. reveals multiple signals for most of the protons owing to the existence of multiple conformers and co‐conformers in solution through tertiary amide bond rotations. Furthermore, the ethereal pocket of the heteroditopic macrocycle was explored to demonstrate the reversible locking and unlocking of the dynamic behaviour of AcROT through the addition and removal, respectively, of alkali‐metal ions. Abstract : A new [2]rotaxane based on a tris(amino) ether macrocyclic wheel is functionalized with three tertiary amide groups and exhibits dynamic behaviour through rotamer formation as well as locking and unlocking properties in the presence of Na + ions and 18‐crown‐6 inputs, respectively.