Complexes of Diquat with Dibenzo‐24‐Crown‐8

Li, Shijun; Huang, Feihe; Slebodnick, Carla; Ashraf‐Khorassani, Mehdi; Gibson, Harry W.

doi:10.1002/cjoc.200990299

Cited by 6 publications

(5 citation statements)

References 48 publications

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“…Simple crown ethers form responsive complexes with small organic guests, and some of them exhibit pseudorotaxane-type geometries. For example, dibenzo-24-crown-8 (DB24C8, 1 ) forms pH-responsive pseudorotaxanes with secondary ammonium salts (e.g., 5 ) and 2:1 inclusion complexes with paraquat ( N , N ′-dimethyl-4,4′-bipyridinium, 6a ) and diquat (1,1′-ethylene-2,2′-bipyridinium, 7 ). , The complexation between bis( m -phenylene)-26-crown-8 (BMP26C8, 2 ) and paraquat is not K + -responsive, but a BMP26C8-based lariat ether displays K + -responsive binding affinities with paraquat derivatives. , Bis( m -phenylene)-32-crown-10 (BMP32C10) derivatives, such as 3a and 3b , exhibit redox-responsive binding affinities with paraquat derivatives and diquat 7 , but in the solid state, the complexes are found to be mostly sandwich-type structures (“taco complexes”), in which the guest molecules are enveloped within the folded host. , Two exceptions reported to date involve paraquat salts 6b and 6a that form pseudorotaxanes with the urea derivative 3c and the biscarbazyl derivative 3d , respectively. , Bis( p -phenylene)-34-crown-10 (BPP34C10, 4 ) forms pseudorotaxanes with paraquat derivatives …”

Section: Pseudorotaxanesmentioning

confidence: 99%

“…For example, dibenzo-24crown-8 (DB24C8, 1) forms pH-responsive pseudorotaxanes with secondary ammonium salts 19 (e.g., 5) and 2:1 inclusion complexes with paraquat (N,N′-dimethyl-4,4′-bipyridinium, 6a) and diquat (1,1′-ethylene-2,2′-bipyridinium, 7). 20,21 The complexation between bis(m-phenylene)-26-crown-8 (BMP26C8, 2) and paraquat is not K + -responsive, but a BMP26C8-based lariat ether displays K + -responsive binding affinities with paraquat derivatives. 22,23 Bis(m-phenylene)-32crown-10 (BMP32C10) derivatives, 24 such as 3a and 3b, exhibit redox-responsive binding affinities with paraquat derivatives and diquat 7, but in the solid state, the complexes are found to be mostly sandwich-type structures ("taco complexes"), in which the guest molecules are enveloped within the folded host.…”

Section: ■ Pseudorotaxanesmentioning

confidence: 99%

“…30 In cryptand complexes, we mainly focused on paraquat-based systems not only because they are widely used precursors for the construction of rotaxanes, catenanes, and even metal− organic frameworks but also because their interesting redox properties make them good building blocks for molecular machines, nanocontainers, and molecular devices. Cryptands are also wonderful hosts for other organic guests such as diquat (7), 39,42,43 diazapyrenium (12), 44 monopyridinium (13), 45 bispyridinium ( 14), 46 trispyridinium (15), 47 bisimidazolium ( 16), 48 bisparaquat (17), 49 1,2-bis(pyridinium)ethane ( 18), 50 vinylogous viologen ( 19), 51 and tropylium salts (20). 52 Due to the preorganization and additional or optimized binding sites, the cryptand complexes all display better stabilities than the corresponding simple crown ether-based analogues.…”

Section: ■ Pseudorotaxanesmentioning

confidence: 99%

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Stimuli-Responsive Host–Guest Systems Based on the Recognition of Cryptands by Organic Guests

et al. 2014

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CONSPECTUS: As the star compounds in host-guest chemistry, the syntheses of crown ethers proclaimed the birth of supramolecular chemistry. Crown ether-based host-guest systems have attracted great attention in self-assembly processes because of their good selectivity, high efficiency, and convenient responsiveness, enabling their facile application to the "bottom-up" approach for construction of functional molecular aggregates, such as artificial molecular machines, drug delivery materials, and supramolecular polymers. Cryptands, as preorganized derivatives of crown ethers, not only possess the above-mentioned properties but also have three-dimensional spatial structures and higher association constants compared with crown ethers. More importantly, the introduction of the additional arms makes cryptand-based host-guest systems responsive to more stimuli, which is crucial for the construction of adaptive or smart materials. In the past decade, we designed and synthesized crown ether-based cryptands as a new type of host for small organic guests with the purpose of greatly increasing the stabilities of the host-guest complexes and preparing mechanically interlocked structures and large supramolecular systems more efficiently while retaining or increasing their stimuli-responsiveness. Organic molecules such as paraquat derivatives and secondary ammonium salts have been widely used in the fabrication of functional supramolecular aggregates. Many host molecules including crown ethers, cyclodextrins, calixarenes, cucurbiturils, pillararenes, and cryptands have been used in the preparation of self-assembled structures with these guest molecules, but among them cryptands exhibit the best stabilities with paraquat derivatives in organic solvents due to their preorganization and additional and optimized binding sites. They enable the construction of sophisticated molecules or supramolecules in high yields, affording a very efficient way to fabricate stimuli-responsive functional supramolecular systems. This Account mainly focuses on the application of cryptands in the construction of mechanically interlocked molecules such as rotaxanes and catenanes, and stimuli-responsive host-guest systems such as molecular switches and supramolecular polymers due to their good host-guest properties. These cryptands are bicyclic derivatives of crown ethers, including dibenzo-24-crown-8, bis(m-phenylene)-26-crown-8, dibenzo-30-crown-10, and bis(m-phenylene)-32-crown-10. The length of the third arm has a very important influence on the binding strength of these cryptands with organic guests, because it affects not only the size fit between the host and the guest but also the distances and angles that govern the strengths of the noncovalent interactions between the host and the guest. For example, for bis(m-phenylene)-32-crown-10-based cryptands, a third arm of nine atoms is the best. The environmental responsiveness of these cryptand-based host-guest systems arises from either the crown ether units or the third arms. For example, a dibenzo...

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Section: Pseudorotaxanesmentioning

confidence: 99%

Section: ■ Pseudorotaxanesmentioning

confidence: 99%

Section: ■ Pseudorotaxanesmentioning

confidence: 99%

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Stimuli-Responsive Host–Guest Systems Based on the Recognition of Cryptands by Organic Guests

et al. 2014

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“…In particular, the interior of the molecular squid was expected to share some of the binding characteristics of the parent CPP and calixarene motifs, displaying an affinity for electron-deficient and positively charged π-conjugated guests. The four guests used for further study (Chart ), namely anthraquinone (AQ), − 10-methylacridinium (MA + ), − diquat (DQ 2+ ), − and its phenanthroline-derived benzologue PQ 2+ , − were selected on the basis of their established utility in supramolecular chemistry. As we found, crystals of an inclusion complex could be successfully grown from a dichloromethane solution of 1 and 4 equiv of anthraquinone (AQ) by slow diffusion of methanol vapors.…”

Section: Resultsmentioning

confidence: 99%

Feeding a Molecular Squid: A Pliable Nanocarbon Receptor for Electron-Poor Aromatics

et al. 2020

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A hybrid nanocarbon receptor consisting of a calix[4]arene and a bent oligophenylene loop (“molecular squid”), was obtained in an efficient, scalable synthesis. The system contains an electron-rich cavity with an adaptable shape, which can serve as a host for electron deficient guests, such as diquat, 10-methylacridinium, and anthraquinone. The new receptor forms inclusion complexes in the solid state and in solution, showing a dependence of the observed binding strength on the shape of the guest species and its charge. The interaction with the methylacridinium cation in solution was interpreted in terms of a 2:1 binding model, with K 11 = 5.92(7) × 10 3 M –1 . The solid receptor is porous to gases and vapors, yielding an uptake of ca. 4 mmol/g for methanol at 293 K. In solution, the receptor shows cyan fluorescence (λ max em = 485 nm, Φ F = 33%), which is partly quenched upon binding of guests. Methylacridinium and anthraquinone adducts show red-shifted emission in the solid state, attributable to the charge-transfer character of these inclusion complexes.

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“…Crown ethers [7][8][9][10][11][12][13], cryptands [14][15][16][17][18], cyclodextrins [19][20][21][22], cucurbit[n]urils [23][24][25], and calix[n]arenes [26,27] have been universally used as hosts to fabricate various supramolecular assemblies, which have great potential in molecular devices, chemosensors, and nano materials. Paraquat ( Figure 1) and its derivatives (N,N′-dialkyl-4,4′-bipyridinium salts) are common guests in the field of pseudorotaxanes and rotaxanes [28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

A new cryptand/paraquat [2]pseudorotaxane

Zheng

Huang

et al. 2010

Sci. China Chem.

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A new cryptand/paraquat [2]pseudorotaxane and its crown ether analog were synthesized and characterized by proton NMR, mass spectrometry, and single crystal X-ray analysis. The Job plots based on proton NMR data demonstrated that both the complex between cryptand 1 and paraquat derivative 2a and the complex between bis(p-phenylene)-34-crown-10 (3) and paraquat derivative 2b have 1:1 stoichiometry in solution. The apparent association constants (K a,exp ) of 1·2a and 3·2b calculated for 1:1 complexes were 1.4 ( 0.2)  10 4 and 4.7 ( 0.5)  10 2 M 1 , respectively. X-ray analysis showed that 1·2a is stabilized by ten hydrogen bonds and face-to-face -stacking interactions in the solid state, while 3·2b is stabilized by four hydrogen bonds and face-to-face -stacking interactions. As well as in the X-ray structure of 1·2c, a water molecule acts as a hydrogen bridge between the -pyridinium protons of 2a and the ether oxygen atoms of 1 in 1·2a. The successful preparation of 1·2a demonstrated that the tert-butyl group is not big enough to be a stopper for rotaxanes based on 1. host-guest system, self-assembly, pseudorotaxane, cryptand, paraquat

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Complexes of Diquat with Dibenzo‐24‐Crown‐8

Cited by 6 publications

References 48 publications

Stimuli-Responsive Host–Guest Systems Based on the Recognition of Cryptands by Organic Guests

Stimuli-Responsive Host–Guest Systems Based on the Recognition of Cryptands by Organic Guests

Feeding a Molecular Squid: A Pliable Nanocarbon Receptor for Electron-Poor Aromatics

A new cryptand/paraquat [2]pseudorotaxane

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