Limits...
A Focus on Triazolium as a Multipurpose Molecular Station for pH-Sensitive Interlocked Crown-Ether-Based Molecular Machines.

Coutrot F - ChemistryOpen (2015)

Bottom Line: This can result in variations of physical or chemical properties.It also served as a molecular barrier in order to lock interlaced structures or to compartmentalize interlocked molecular machines.This review describes the recently reported examples of pH-sensitive triazolium-containing molecular machines and their peculiar features.

View Article: PubMed Central - PubMed

Affiliation: Supramolecular Machines and Architectures Team, Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 Cnrs, Faculté des Sciences, Université Montpellier, ENSCM Bâtiment Chimie (17), 3ème étage, Place Eugène Bataillon, case courrier 1706, 34095, Montpellier cedex 5, France.

ABSTRACT
The control of motion of one element with respect to others in an interlocked architecture allows for different co-conformational states of a molecule. This can result in variations of physical or chemical properties. The increase of knowledge in the field of molecular interactions led to the design, the synthesis, and the study of various systems of molecular machinery in a wide range of interlocked architectures. In this field, the discovery of new molecular stations for macrocycles is an attractive way to conceive original molecular machines. In the very recent past, the triazolium moiety proved to interact with crown ethers in interlocked molecules, so that it could be used as an ideal molecular station. It also served as a molecular barrier in order to lock interlaced structures or to compartmentalize interlocked molecular machines. This review describes the recently reported examples of pH-sensitive triazolium-containing molecular machines and their peculiar features.

No MeSH data available.


Related in: MedlinePlus

SchemeA triazolium-containing bis-branched [1]rotaxane with reversible fluorescence, stretching/contraction motion, and reversible aggregation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4608521&req=5

sch13: SchemeA triazolium-containing bis-branched [1]rotaxane with reversible fluorescence, stretching/contraction motion, and reversible aggregation.

Mentions: The authors then explored the possible dual pH- and redox-dependent output signal after oxidizing/reducing the ferrocene unit, using respectively Fe(ClO4)3 or ascorbic acid. In rotaxane 29, after that the ferrocene unit of rotaxane 27 is oxidized, the fluorescence is dramatically restored to its original level. Furthermore, the oxidation of the protonated fluorescent rotaxane 26 leads to compound 28 without any significant change of emission intensity. These two last results can be ascribed to the fact that oxidation of the ferrocene units obviously affects its electron-donating ability, thus not allowing efficient PET in this case, whatever the distance between the considered moieties. Reducing the ferrocene unit with ascorbic acid gave rise to the controllable pH-switchable fluorescence output signal (rotaxanes 26/27). In summary, this molecular machine proved to operate upon a pH variation through the motion of the macrocycle along the threaded axle. The fluorescent output signal was found to be both pH- and redox-dependent. Quenching the fluorescence could be achieved using a pH stimulus (deprotonation) through actuation of the machinery, whereas restoring the original level of fluorescence was possible either by oxidation or by protonation. The authors present their system as an INHIBIT logic gate combining a “silent” and an “active” signal output which could be of real interest for the conception of logic circuits with memories or sequential functions. The same group extended this work to the synthesis and the study of two pH-sensitive star-shaped [1](n)rotaxane molecular machines with tri and tetrabranched cores that are linked to triazolium stations.32 Using the features of the two previously reported examples, 24 and 26, Qu et al. recently published an appealing bis-branched [1]rotaxane that can combine dual-mode molecular motions and tunable nanostructural morphologies (Scheme 13).33


A Focus on Triazolium as a Multipurpose Molecular Station for pH-Sensitive Interlocked Crown-Ether-Based Molecular Machines.

Coutrot F - ChemistryOpen (2015)

SchemeA triazolium-containing bis-branched [1]rotaxane with reversible fluorescence, stretching/contraction motion, and reversible aggregation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608521&req=5

sch13: SchemeA triazolium-containing bis-branched [1]rotaxane with reversible fluorescence, stretching/contraction motion, and reversible aggregation.
Mentions: The authors then explored the possible dual pH- and redox-dependent output signal after oxidizing/reducing the ferrocene unit, using respectively Fe(ClO4)3 or ascorbic acid. In rotaxane 29, after that the ferrocene unit of rotaxane 27 is oxidized, the fluorescence is dramatically restored to its original level. Furthermore, the oxidation of the protonated fluorescent rotaxane 26 leads to compound 28 without any significant change of emission intensity. These two last results can be ascribed to the fact that oxidation of the ferrocene units obviously affects its electron-donating ability, thus not allowing efficient PET in this case, whatever the distance between the considered moieties. Reducing the ferrocene unit with ascorbic acid gave rise to the controllable pH-switchable fluorescence output signal (rotaxanes 26/27). In summary, this molecular machine proved to operate upon a pH variation through the motion of the macrocycle along the threaded axle. The fluorescent output signal was found to be both pH- and redox-dependent. Quenching the fluorescence could be achieved using a pH stimulus (deprotonation) through actuation of the machinery, whereas restoring the original level of fluorescence was possible either by oxidation or by protonation. The authors present their system as an INHIBIT logic gate combining a “silent” and an “active” signal output which could be of real interest for the conception of logic circuits with memories or sequential functions. The same group extended this work to the synthesis and the study of two pH-sensitive star-shaped [1](n)rotaxane molecular machines with tri and tetrabranched cores that are linked to triazolium stations.32 Using the features of the two previously reported examples, 24 and 26, Qu et al. recently published an appealing bis-branched [1]rotaxane that can combine dual-mode molecular motions and tunable nanostructural morphologies (Scheme 13).33

Bottom Line: This can result in variations of physical or chemical properties.It also served as a molecular barrier in order to lock interlaced structures or to compartmentalize interlocked molecular machines.This review describes the recently reported examples of pH-sensitive triazolium-containing molecular machines and their peculiar features.

View Article: PubMed Central - PubMed

Affiliation: Supramolecular Machines and Architectures Team, Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 Cnrs, Faculté des Sciences, Université Montpellier, ENSCM Bâtiment Chimie (17), 3ème étage, Place Eugène Bataillon, case courrier 1706, 34095, Montpellier cedex 5, France.

ABSTRACT
The control of motion of one element with respect to others in an interlocked architecture allows for different co-conformational states of a molecule. This can result in variations of physical or chemical properties. The increase of knowledge in the field of molecular interactions led to the design, the synthesis, and the study of various systems of molecular machinery in a wide range of interlocked architectures. In this field, the discovery of new molecular stations for macrocycles is an attractive way to conceive original molecular machines. In the very recent past, the triazolium moiety proved to interact with crown ethers in interlocked molecules, so that it could be used as an ideal molecular station. It also served as a molecular barrier in order to lock interlaced structures or to compartmentalize interlocked molecular machines. This review describes the recently reported examples of pH-sensitive triazolium-containing molecular machines and their peculiar features.

No MeSH data available.


Related in: MedlinePlus