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Conformational Flexibility of Hybrid [3]- and [4]-Rotaxanes

Lockyer, SJ, Nawaz, S, Brookfield, A, Fielding, AJ, Vitorica-Yrezabal, IJ, Timco, GA, Burton, NA, Bowen, AM, Winpenny, REP and McInnes, EJL (2020) Conformational Flexibility of Hybrid [3]- and [4]-Rotaxanes. Journal of the American Chemical Society, 142 (37). pp. 15941-15949. ISSN 0002-7863

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Abstract

The synthesis, structures, and properties of [4]- and [3]-rotaxane complexes are reported where [2]-rotaxanes, formed from heterometallic {Cr7Ni} rings, are bound to a fluoride-centered {CrNi2} triangle. The compounds have been characterized by single-crystal X-ray diffraction and have the formulas [CrNi2(F)(O2CtBu)6]{(BH)[Cr7NiF8(O2CtBu)16]}3 (3) and [CrNi2(F)(O2CtBu)6(THF)]{(BH)[Cr7NiF8(O2CtBu)16]}2 (4), where B = py-CH2CH2NHCH2C6H4SCH3. The [4]-rotaxane 3 is an isosceles triangle of three [2]-rotaxanes bound to the central triangle while the [3]-rotaxane 4 contains only two [2]-rotaxanes bound to the central triangle. Studies of the behavior of 3 and 4 in solution by small-angle X-ray scattering and atomistic molecular dynamic simulations show that the structure of 3 is similar to that found in the crystal but that 4 has a different conformation to the crystal. Continuous wave and pulsed electron paramagnetic resonance spectroscopy was used to study the structures present and demonstrate that in frozen solutions (at 5 K) 4 forms more extended molecules than 3 and with a wider range of conformations.

Item Type: Article
Uncontrolled Keywords: 03 Chemical Sciences
Subjects: Q Science > QD Chemistry
Divisions: Pharmacy & Biomolecular Sciences
Publisher: American Chemical Society
Date Deposited: 16 Sep 2020 10:06
Last Modified: 04 Sep 2021 06:41
DOI or ID number: 10.1021/jacs.0c06547
URI: https://researchonline.ljmu.ac.uk/id/eprint/13645
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