Communication between Components in Metal‐Directed Assemblies of Oriented Calix[6]arene‐Based Pseudorotaxanes and Rotaxanes

Abstract

International audienc

Plugging a Bipyridinium Axle into Multichromophoric Calix[6]arene Wheels Bearing Naphthyl Units at Different Rims

“…The inclusion of DOV ×2 TsO into either 7 or 10 causes a large negative shift of the first reduction potential, although the second process occurs at the same potential as for the free guest (see Figure and the Supporting Information). These results indicate that 1) the bipyridinium unit becomes more difficult to reduce because it is stabilized inside the calixarene wheel, and 2) the one‐electron reduction of DOV ×2 TsO promotes its dethreading from the host, in line with the behavior of several related bipyridinium‐containing pseudorotaxanes . The large peak‐to‐peak separation and the scan‐rate dependence of the first reduction process of the 7 ⊃ DOV ×2 TsO and 10 ⊃ DOV ×2 TsO complexes indicate that the complexation/decomplexation reactions occur on the voltammetric timescale; these aspects have been discussed in detail elsewhere …”

“…These results indicatet hat 1) the bipyridinium unit becomes more difficult to reduce because it is stabilized inside the calixarenew heel,a nd 2) the one-electronr eductiono fDOV 2TsO promotes its dethreading from the host, in line with the behavior of several related bipyridiniumcontaining pseudorotaxanes. [23,25,[41][42][43] The large peak-to-peak separation and the scan-rate dependence of the first reduction process of the 7'DOV 2TsO and 10'DOV 2TsO complexes indicatet hat the complexation/decomplexation reactions occur on the voltammetric timescale;t hese aspects have been discussed in detail elsewhere. [23]…”

“…In this context, we have demonstrated that calix[6]arene 1 (Figure ) acts as three‐dimensional and heteroditopic wheel that, in low polarity media, forms oriented pseudorotaxanes and rotaxanes with dialkylviologen salts as axles . A peculiar property of 1 is that suitable bipyridinium axles can unidirectionally transit through the calixarene annulus under the action of external stimulation . Owing to the possibility of functionalizing the two chemically different rims, wheel 1 is also attractive as a scaffold for the construction of multicomponent species bearing covalently linked molecular subunits.…”

“…[21][22][23] Ap eculiar property of 1 is that suitable bipyridinium axles can unidirectionally transit through the calixarene annulus under the action of externals timulation. [24][25][26][27] Owing to the possibility of functionalizing the two chemically different rims, wheel 1 is also attractive as as caffold for the construction of multicomponent speciesbearing covalently linked molecular subunits.…”

Rotaxanes and pseudorotaxanes with threads containing viologen units

“…25,26 Pseudorotaxanes are also intensively studied, they are prototypes of molecular machines [27][28][29] and serve as building blocks for interlocked supramolecular assemblies, 30 some of them are promising in preparation of molecular sensors 31 and in drug delivery. 32 There should be mentioned here also rotaxanes and pseudorotaxanes containing cyclodextrins, [33][34][35] calixarenes 36,37 or cucurbiturils. 38,39 Today many works concerning viologen-based rotaxanes and pseudorotaxanes appear, [40][41][42][43][44][45] in these systems viologens are components of a thread [45][46][47][48][49] or are present as parts of the tetracationic cyclophane serving as a ring.…”