Self-assembly of pseudo-rotaxane and rotaxane complexes using an electrostatic slippage approach

Catalán, Aldo C; Tiburcio, Jorge

doi:10.1039/c6cc04619c

Cited by 22 publications

(36 citation statements)

References 29 publications

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“…Additional efforts to assess the limit of the combined operation of the EASA and the usage of a flexible macrocyclic ring were undertaken by investigating a guest featuring a positively charged eight‐membered ring (azocanium) as an end‐group, [ Azo ⋅ H ] 2+ . For this guest, no complex was observed with [ DB24C8 ] even at 333 K and despite the operation of EASA [12] …”

Section: Resultsmentioning

confidence: 93%

“…However, a protonated azepanium‐containing guest could slip through [ DB24C8 ]’s cavity with an energy barrier of

{Δ G}_{o n}^{\neq}

=92.8 kJ⋅mol −1 , which implies an 18.0 kJ⋅mol −1 increment with respect to the one observed for piperidinium. We could not obtain evidence of the slippage of [ DB24C8 ] through a cationic eight‐membered ring (azocanium), even at elevated temperature (333 K) [12] …”

Section: Introductionmentioning

confidence: 80%

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An Operative Electrostatic Slipping Mechanism along Macrocycle Flexibility Accelerates Guest Sliding during pseudo‐Rotaxane Formation

et al. 2022

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A pseudo-rotaxane is a hostÀ guest complex composed of a linear molecule encircled by a macrocyclic ring. These complexes can be assembled by sliding the host over the guest terminal groups. If there is a close match between the molecular volume of the flanking groups on the guest and the cavity size of the macrocycle, the slipping might occur slowly or even become completely hindered. We have previously shown that it is possible to overcome the restraints imposed by steric effects on the sliding process by integrating electrostatic attractive interactions during the slipping step. In this work, we extend our electrostatically assisted slipping approach (EASA) to a new hostÀ guest system featuring a flexible macrocyclic ring and a series of asymmetric guests containing a cyclic tertiary ammonium group. Compelling evidence for pseudo-rotaxane formation is presented, along with thermodynamic and kinetic data. Experimental results suggests that the higher conformational flexibility of 24-crown-8 significantly increases the sliding rate, compared with the more rigid dibenzo-24-crown-8, without affecting complex stability. Furthermore, by combining the EASA and macrocycle flexibility, we were capable to slip a large eight-membered cyclic group across the 24-crown-8 annulus, setting a new limit on the ring molecular size that can pass through a 24-membered crown ether.

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Section: Resultsmentioning

confidence: 93%

“…However, a protonated azepanium‐containing guest could slip through [ DB24C8 ]’s cavity with an energy barrier of

{Δ G}_{o n}^{\neq}

Section: Introductionmentioning

confidence: 80%

An Operative Electrostatic Slipping Mechanism along Macrocycle Flexibility Accelerates Guest Sliding during pseudo‐Rotaxane Formation

et al. 2022

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“…The N−H⋅⋅⋅N hydrogen bond formed between H‐bpy + cations affords a one‐dimensional (1D) polymer structure . Dibenzo‐24‐crown‐8 (DB‐24‐crown‐8), which can include whole heteroaromatic rings because of a larger ring size compared with 15‐crown‐4 and 18‐crown‐6, was selected as the “shuttle” part of the rotaxane. In addition to the large ring size, π–π interactions between the phenylene rings of DB‐24‐crown‐8 and the pyridyl rings of H‐bpy + should stabilize the pseudo‐polyrotaxane crystal.…”

Section: Introductionmentioning

confidence: 99%

“…The NÀH···N hydrogen bond formed between H-bpy + cations affords ao ne-dimensional (1D) polymer structure. [14] Dibenzo-24-crown-8 (DB-24-crown-8), which can include whole heteroaromatic rings because of al arger ring size compared with 15-crown-4 and 18-crown-6, [15][16][17][18] wass elected as the "shuttle" part of the rotaxane. In addition to the large ring size, p-p interactions betweent he phenylene rings of DB-24-crown-8 and the pyridyl rings of H-bpy + shouldstabilize the pseudo-polyrotaxanec rystal.C ompared with covalent bonds, hydrogen bonds have greater freedom in terms of bond lengtha nd angles, and the hydrogen bonds between Hbpy + lend flexibility to the crystal.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen‐Bonded Polyrotaxane Cation Structure in Nickel Dithiolate Anion Radical Salts: Ferromagnetic and Semiconducting Behavior Associated with Structural Phase Transition

Shirakawa

Takahashi

Sato

et al. 2019

Chemistry A European J

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The pseudo‐polyrotaxane structure of [(H‐bpy+)‐ (DB‐24‐crown‐8)]∞ (H‐bpy+ = monoprotonated 4,4‐bipyridinium; DB‐24‐crown‐8 = dibenzo‐24‐crown‐8) has been incorporated into the anion radical salt [Ni(dmit)2]− (dmit2− = 1,3‐dithiole‐2‐thione‐4,5‐dithiolate). (H‐bpy+)(DB‐24‐crown‐8)[Ni(dmit)2]− crystallized as two polymorphs, crystals 1 and 2. Crystal 1 was found to have a lower density and looser packing structure in which H‐bpy+ forms a one‐dimensional hydrogen‐bonding chain that passes though the crown ether ring of DB‐24‐crown‐8. DB‐24‐crown‐8 adopts a U‐shaped conformation in which two phenylene rings sandwich one of the pyridyl rings of H‐bpy+ to stabilize the structure. The [Ni(dmit)2]− anions are arranged in a layer parallel to the (10) plane with uniform side‐by‐side interactions. A structural phase transition was observed at 235 K, accompanied by ordering of the polyrotaxane structure. In crystal 1, at 173 K, H‐bpy+ is twisted around the central C−C bond, which perturbs the arrangement of [Ni(dmit)2]− through short C−H⋅⋅⋅S contacts. As a result, the semiconducting behavior, with an activation energy of 0.21 eV, becomes insulating below 235 K. The crystal exhibits ferromagnetic interactions because of the weak side‐by‐side interactions between [Ni(dmit)2]− anions. Crystal 2 has a similar pseudo‐polyrotaxane structure but showed no phase transition. This suggests that the looser crystal packing in crystal 1 induces the structural change of the pseudo‐polyrotaxane, perturbing the electron system of [Ni(dmit)2]−.

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“…Whereas the choice of a certain recognition motif dictates thermodynamic strength of association in host‐guest systems often in an intuitive way, the kinetics of their formation is usually less straight forward to predict. Steric interactions are frequently used for this purpose, although electrostatic repulsion or attraction may also be engaged. Incremental variation of steric factors is often required to reveal design rules for rational adjustment of exchange kinetics .…”

Section: Introductionmentioning

confidence: 99%

Slow Formation of Pseudorotaxanes in Water

et al. 2019

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The synthesis of two water‐soluble oligophenylene‐ethynylene (OPE)‐rods with substituted iso‐ and terephthalate end groups is presented. Both undergo slow association with a Diederich‐type cyclophane in aqueous solution. Formation of [2]pseudorotaxanes occurs with reaction half‐lives of several hours. Characterization of the supermolecules by 1H‐NMR spectroscopy reveals a high thermodynamic stability and kinetic inertness of the pseudorotaxanes. The phthalate precursors are functionalized with peripheral azide groups, which make them modular precursors for construction of mechanically interlocked molecules in water.

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Self-assembly of pseudo-rotaxane and rotaxane complexes using an electrostatic slippage approach

Cited by 22 publications

References 29 publications

An Operative Electrostatic Slipping Mechanism along Macrocycle Flexibility Accelerates Guest Sliding during pseudo‐Rotaxane Formation

An Operative Electrostatic Slipping Mechanism along Macrocycle Flexibility Accelerates Guest Sliding during pseudo‐Rotaxane Formation

Hydrogen‐Bonded Polyrotaxane Cation Structure in Nickel Dithiolate Anion Radical Salts: Ferromagnetic and Semiconducting Behavior Associated with Structural Phase Transition

Slow Formation of Pseudorotaxanes in Water

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