Making hybrid [n]-rotaxanes as supramolecular arrays of molecular electron spin qubits

Abstract

Quantum information processing (QIP) would require that the individual units involved—qubits—communicate to other qubits while retaining their identity. In many ways this resembles the way supramolecular chemistry brings together individual molecules into interlocked structures, where the assembly has one identity but where the individual components are still recognizable. Here a fully modular supramolecular strategy has been to link hybrid organic–inorganic [2]- and [3]-rotaxanes into still larger [4]-, [5]- and [7]-rotaxanes. The ring components are heterometallic octanuclear [Cr7NiF8(O2CtBu)16]– coordination cages and the thread components template the formation of the ring about the organic axle, and are further functionalized to act as a ligand, which leads to large supramolecular arrays of these heterometallic rings. As the rings have been proposed as qubits for QIP, the strategy provides a possible route towards scalable molecular electron spin devices for QIP. Double electron–electron resonance experiments demonstrate inter-qubit interactions suitable for mediating two-qubit quantum logic gates.

Cr7Ni Wheels: Supramolecular Tectons for the Physical Implementation of Quantum Information Processing

“…As well as, a variety of potentially switchable, diamagnetic and paramagnetic linkers of either organic or metalloorganic nature. 6 ], as illustrated in Figure 8 [57]. Interestingly, these [n]-rotaxanes exhibited T M values in the range of 0.70 to 0.80 µs at 2.6 K, and in some of them, two-qubit interactions of the right strength to implement logic quantum gates have been found.…”

“…The requirement of ammonium cations that template the formation of {Cr 7 Ni} wheels have also been exploited by Winpenny's group to create hybrid inorganic-organic rotaxanes [53][54][55][56][57]. They have shown that it is possible to obtain in high yields [2]-and [3]-rotaxanes from the reaction in pivalic acid of chromium(III) trifluoride, a nickel(II) pivalate salt, and a thread with one or two amines, respectively, that would be protonated during the reaction and then act as template cations.…”

Hybrid Organic–Inorganic Rotaxanes, Including a Hetero‐Hybrid [3]Rotaxane Featuring Two Distinct Heterometallic Rings and a Molecular Shuttle

“…Zuschriften broadenings or minor changes in ZFS compared to isolated {Ti 7 M}, [5] nor in that of the hetero- [3]rotaxane 11 (Supporting Information, Figure S3), which comprises as uperposition of features for {Ti 7 Fe}(S = 5/2) and {Cr 7 Ni}(S = 1 = 2 ground state with g = 1.8). [20] Theexchange interactions in the {Cr 7 Ni}ring appear to be unchanged from isolated {Cr 7 Ni}r ings.…”

“…[1,2] They differ from metallocrowns [3] and other metal rings [4] in that the design of the organic template,orthread, is such that bulky groups or stoppers are included to prevent the thread leaving the ring. This allows inclusion of coordinating groups at the end of the threads, building complex structures including [4], [ 5],a nd [7]rotaxanes. [5] It is also possible to add additional paramagnetic centres such as Cu II ions [6] or organic radicals.…”

“…This allows inclusion of coordinating groups at the end of the threads, building complex structures including [4], [ 5],a nd [7]rotaxanes. [5] It is also possible to add additional paramagnetic centres such as Cu II ions [6] or organic radicals. [7] While there are several mechanically interlocked molecules featuring metal ions, [8] they remain unusual.…”