Metastable doubly threaded [3]rotaxanes with a large macrocycle

Abstract

Multiple metastable doubly threaded [3]rotaxanes using a large 46 atom ring were prepared and fully characterized. Varying the stopper group size gave a range of interlocked stabilities in CDCl3 from a half-life of <1 minute to ca. 6 months.

Doubly Threaded Slide-Ring Polycatenane Networks

“…In targeting the SR-PCNs, a doubly threaded pseudo[3]­rotaxane (P3R) moiety that is stable under the network reaction conditions is required. Metal ion templating is a common route to interlocked molecules, and many different ligands and metal ion combinations have been used to form interlocked compounds under different reaction conditions. − Recently, the terdentate 2,6-bis­( N -alkyl-benzimidazolyl)­pyridine (Bip) , ligand and its derivatives have been used to build doubly threaded mechanically interlocked compounds, such as poly­[ n ]­catenanes − and [3]­rotaxanes . Building on this prior work, the Bip-containing ditopic macrocycle 1 and bis-alkyne thread component 2 were synthesized from their corresponding bis-phenolic Bip derivatives , via Williamson ether synthesis (Schemes S1 and S2).…”

“…Building on this prior work, the Bip-containing ditopic macrocycle 1 and bis-alkyne thread component 2 were synthesized from their corresponding bis-phenolic Bip derivatives , via Williamson ether synthesis (Schemes S1 and S2). The ditopic macrocycle incorporates two Bip ligands joined by rigid naphthalene linkers that prevent both ligands in the ring from binding to the same Zn 2+ ion . As such, the most thermodynamically favorable way for these ligands to form 2:1 Bip/metal complexes is by forming the doubly threaded P3R complex [ 1:2 2 :Zn­(II) 2 , Figure a].…”

“…45−47 Recently, the terdentate 2,6-bis(Nalkyl-benzimidazolyl)pyridine (Bip) 48,49 ligand and its derivatives have been used to build doubly threaded mechanically interlocked compounds, such as poly[n]catenanes 50−52 and [3]rotaxanes. 53 Building on this prior work, the Bip-containing ditopic macrocycle 1 and bis-alkyne thread component 2 were synthesized from their corresponding bis-phenolic Bip derivatives 48,50 via Williamson ether synthesis (Schemes S1 and S2). The ditopic macrocycle incorporates two Bip ligands joined by rigid naphthalene linkers that prevent both ligands in the ring from binding to the same Zn 2+ ion.…”

“…The ditopic macrocycle incorporates two Bip ligands joined by rigid naphthalene linkers that prevent both ligands in the ring from binding to the same Zn 2+ ion. 53 As such, the most thermodynamically favorable way for these ligands to form 2:1 Bip/metal complexes is by forming the doubly threaded P3R complex [1:2 2 :Zn(II) 2 , Figure 2a]. A solution of Zn(NTf 2 ) 2 is titrated into a 2:1 mixture of the ditopic macrocycle 1 and bis-alkyne thread 2 and monitored via 1 H-NMR to achieve the stoichiometry required for the P3R formation (Scheme S3 and Figure S1).…”

The effect of thread-like monomer structure on the synthesis of poly[n]catenanes from metallosupramolecular polymers

“…2b), was synthesized via a ring-closing metathesis reaction of the pre-assembled MSP template. Both monomers (1 and 2(xan-6)) contain two 2,6-bisbenzimidazolylpyridine (Bip) ligands 53,54 which allows them to self-assemble into the MSP template upon addition of metal ions, such as Zn(II). The thread component consists of three distinct regions: the Bip ligand (dark blue, Fig.…”