Self-assembling metal rotaxane complexes of .alpha.-cyclodextrin

Wylie, R. Stephen; Macartney, Donal H.

doi:10.1021/ja00034a069

Cited by 159 publications

(54 citation statements)

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“…Following previous work on the kinetics of α-CD with 1,1''-(α,ω-alkanediyl)bis(4,4'-bipyridinium) [341,342] Assuming a 1:1 binding stoichiometry between surfactant and cyclodextrin, the rate constants for the formation "on", k on , and dissociation "off", k off , processes can be represented by the following equation (27) Several aspects must be considered in the kinetic analysis. As pointed out by Park [343] the rate constants k on and k off in fact each depends on two microscopic rate constants.…”

Section: Kinetic Controlled Association Complexesmentioning

confidence: 99%

The formation of host–guest complexes between surfactants and cyclodextrins

Valente

Söderman

2014

Advances in Colloid and Interface Science

184

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Cyclodextrins are able to act as host molecules in supramolecular chemistry with applications ranging from pharmaceutics to detergency. Among guest molecules surfactants play an important role with both fundamental and practical applications. The formation of cyclodextrin/surfactant host-guest compounds leads to an increase in the critical micelle concentration and in the solubility of surfactants. The possibility of changing the balance between several intermolecular forces, and thus allowing the study of, e.g., dehydration and steric hindrance effects upon association, makes surfactants ideal guest molecules for fundamental studies. Therefore, these systems allow for obtaining a deep insight into the host-guest association mechanism. In this paper, we review the influence on the thermodynamic properties of CD-surfactant association by highlighting the effect of different surfactant architectures (single tail, double-tailed, gemini and bolaform), with special emphasis on cationic surfactants. This is complemented with an assessment of the most common analytical techniques used to follow the association process. The applied methods for computation of the association stoichiometry and stability constants are also reviewed and discussed; this is an important point since there are significant discrepancies and scattered data for similar systems in the literature.In general, the surfactant-cyclodextrin association is treated without reference to the kinetics of the process. However, there are several examples where the kinetics of the process can be investigated, in particular those where volumes of the CD cavity and surfactant (either the tail or in special cases the head group) are similar in magnitude.This will also be critically reviewed.

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Section: Kinetic Controlled Association Complexesmentioning

confidence: 99%

The formation of host–guest complexes between surfactants and cyclodextrins

Valente

Söderman

2014

Advances in Colloid and Interface Science

184

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“…With special structures of the hydrophobic inner cavity and hydrophilic outer surface, CD is one of the most significant host molecules in supramolecular chemistry. A large number of novel, ordered supramolecular materials [1][2][3] as well as rotaxane [4], polyrotaxane [5], catenane [6], molecular necklaces [7] and other supramolecular assemblies have been constructed. Among all of these, the study of CD nanotubes has attracted great attention [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Formation of nanotubes and secondary assemblies of cyclodextrins induced by BBOT

Zhang

Shen

et al. 2010

Sci. China Chem.

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The study of cyclodextrin nanotubes is a significant topic among the self-assembly behaviors of cyclodextrins. We report herein the interaction of 2,5-bis(5′-tert-butyl-2-benzoxazoyl)thiophene (BBOT) with -, -, -cyclodextrins (CDs). It has been discovered that the reaction patterns of BBOT with CDs are remarkably different. -CD forms a simple inclusion complex with BBOT in a stoichiometry of 1:2 (guest:host). -CD forms a 1:1 inclusion complex with BBOT at its low concentration. At higher concentration of BBOT, the nanotube and secondary assembly of -CD are formed. As for -CD, the nanotube and secondary assembly are formed within the whole concentration range of BBOT studied. The structure of -CD nanotubes is different from that of -CD nanotubes to a certain extent.

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“…Significant attention has recently been given to coordination chemistry, which has found applications in the construction of complicated or nano-sized structures, catenanes, 1,2 rotaxanes, [3][4][5] helices, 6,7 molecular squares, [8][9][10] tetrahedral hosts, [11][12][13][14][15][16] and so on. [17][18][19][20][21] Coordination compounds exist not only as discrete molecules in solution, but also as compounds with infinite periodicity in the crystal state.…”

mentioning

confidence: 99%

Solvent-dependent Assembly of Discrete and Continuous CoCl2 Adamantane-based Ligand Complexes: Observations by CSI–Mass Spectrometry and X-ray Crystallography

et al. 2013

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773Significant attention has recently been given to coordination chemistry, which has found applications in the construction of complicated or nano-sized structures, catenanes, 1,2 rotaxanes, [3][4][5] helices, 6,7 molecular squares, 8-10 tetrahedral hosts, [11][12][13][14][15][16] and so on. 17-21Coordination compounds exist not only as discrete molecules in solution, but also as compounds with infinite periodicity in the crystal state. Coordination polymers (CPs) and metal-organic frameworks (MOFs) are well-known crystals constructed by an organic compound and a metal. Porous CPs (PCPs) and MOFs, in particular, are highly potential materials for gas storage, 22-24 ion exchange, 25-28 heterogeneous catalysis, 29-31 separation, 29,[32][33][34][35][36] and non-linear optics, 37-39 because of the nanospace separated from bulk space.Structure construction with a coordination bond plays a critical role in the formation of a complicated structure and the introduction of functionality into the structure for basic research and industrial applications. In structure control, it is important to adjust the metal-ligand stoichiometry based on the number of coordination sites or the coordination environment. For example, Lehn and coworkers 40 demonstrated the spontaneous formation of a cylindrical complex from five ligands and six metal ions, in which two hexaazatriphenylene derivatives acting as the planar molecule and three bisbipyridyl ligands linked at the 5,5′ positions acting as the pillar molecule were connected by three copper ions. The structure was characterized by 1 H NMR spectroscopy, fast atom bombardment mass spectrometry (MS), and single-crystal X-ray structure analysis. The concept of adjusting metal-ligand stoichiometry has been widely accepted in discrete complexes and CPs, depending on the metal coordination geometry and the ligand binding site. However, complex preparation relies on many factors, such as the temperature, concentration, and the counter ion. For instance, Fujita and coworkers 41 demonstrated the treatment of Pd(NO3)2 and a ditopic bidentate ligand assembled into a mixture of M4L8 and M3L6 box-like structures, depending on the ratio of dimethylsulfoxide to acetonitrile.In such an environment-dependent complex formation, advanced functions, including molecular switching and molecular catch and release, for instance, have been obtained in recent years. However, structure elucidation of obtained complexes is generally difficult by using only 1 H NMR analysis in the case that the numbers of ligands and metals are not known. Therefore, limited studies of environment-dependent complexes have been reported up to the present. [42][43][44][45][46] Conventional MS using electron ionization, chemical ionization, fast atom bombardment, and electro-spray ionization cannot detect large coordination complexes because the weak coordination bonds dissociate during ionization. Cold-spray ionization MS (CSI-MS) is one of the most promising solutions to this problem, 47 as it can detect coordination complexes w...

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Self-assembling metal rotaxane complexes of .alpha.-cyclodextrin

Cited by 159 publications

References 2 publications

The formation of host–guest complexes between surfactants and cyclodextrins

The formation of host–guest complexes between surfactants and cyclodextrins

Formation of nanotubes and secondary assemblies of cyclodextrins induced by BBOT

Solvent-dependent Assembly of Discrete and Continuous CoCl2 Adamantane-based Ligand Complexes: Observations by CSI–Mass Spectrometry and X-ray Crystallography

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