Puigcerver J, Alajarin M, Martinez-Cuezva A, Berna J. Modulating the shuttling motion of [2]rotaxanes built of
p-xylylenediamine units through permethylation at the benzylic positions of the ring.
Org Biomol Chem 2023;
21:9070-9075. [PMID:
37938860 DOI:
10.1039/d3ob01611k]
[Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2023]
Abstract
In this study, we show the effect of the gem-dimethyl substitution at the four benzylic carbons of the ring on the internal dynamics of two-station [2]rotaxanes. Such structural modification of the polyamide macrocycles promotes a drastic change of the internal dynamics as shown by variable-temperature (VT) 1H NMR experiments. We determined that the shuttling rates of the octamethylated macrocycle along a series of symmetrical threads were significantly faster compared to the non-substituted ring. This effect was particularly pronounced in the fumaramide-based system, in which the rate was 27 times faster than that of the model system.
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