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Conformational flexibility of hybrid [3]- and [4]-rotaxanes

DOI: 10.1021/jacs.0c06547 DOI Help

Authors: Selena J. Lockyer (The University of Manchester) , Selina Nawaz (The University of Manchester) , Adam Brookfield (The University of Manchester) , Alistair J. Fielding (Liverpool John Moores University) , Inigo J. Vitórica-yrezábal (The University of Manchester) , Grigore A. Timco (The University of Manchester) , Neil A. Burton (The University of Manchester) , Alice M. Bowen (The University of Manchester) , Richard E. P. Winpenny (The University of Manchester) , Eric J. L. Mcinnes (The University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of The American Chemical Society

State: Published (Approved)
Published: August 2020
Diamond Proposal Number(s): 17379

Abstract: The synthesis, structures and properties of [4]- and [3]-rotaxane complexes are reported where [2]rotaxanes, formed from het-erometallic {Cr7Ni} rings, are bound to a fluoride-centered {CrNi2} triangle. The compounds have been characterized by sin-gle crystal X-ray diffraction and have the formulae [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 (SAXS) and atomistic molecular dynamic simulations (AMDS) show that the structure of 3 is similar to that found in the crystal but that 4 has a different conformation to the crystal. C.w. and pulsed EPR spectroscopy were 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 confor-mations.

Subject Areas: Chemistry

Instruments: I19-Small Molecule Single Crystal Diffraction