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Rotamer‐Induced Dynamic Nature of a [2]Rotaxane and Control of the Dynamics by External Stimuli
Author(s) -
Santra Saikat,
Ghosh Pradyut
Publication year - 2017
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201601525
Subject(s) - chemistry , conformational isomerism , rotaxane , moiety , alkyne , amide , azide , cycloaddition , atropisomer , nuclear magnetic resonance spectroscopy , stereochemistry , polymer chemistry , photochemistry , supramolecular chemistry , molecule , organic chemistry , catalysis
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.