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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

Preparation of a mannosyl pH-sensitive [2]rotaxane molecular machine. Reagents and conditions: a) DB24C8 (2 equiv), CH2Cl2, RT; b) 2,6-lutidine, Cu(MeCN)4PF6, CH2Cl2, RT, 24 h, 72 %; c) 1) CH3I, 2) NH4PF6, quantitative; d) DIEA; e) 1) HCl/Et2O, 2) NH4PF6.
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sch01: Preparation of a mannosyl pH-sensitive [2]rotaxane molecular machine. Reagents and conditions: a) DB24C8 (2 equiv), CH2Cl2, RT; b) 2,6-lutidine, Cu(MeCN)4PF6, CH2Cl2, RT, 24 h, 72 %; c) 1) CH3I, 2) NH4PF6, quantitative; d) DIEA; e) 1) HCl/Et2O, 2) NH4PF6.

Mentions: We reported the first example of a pH-sensitive [2]rotaxane molecular machine possessing a triazolium molecular station for the DB24C8 in 2008 (Scheme 1).13 Its synthesis appeared quite straightforward and efficient, and the molecular machinery easy to drive and characterize. The targeted DB24C8-based [2]rotaxane 4 consists of an encircled axle which contains an anilinium and a N-methyltriazolium molecular stations. Two bulky extremities have been chosen for the thread in order to prevent the macrocycle from any unthreading. One extremity is a mannose derivative, whereas the other one is a di-tert-butyl anilinium moiety. The anilinium was chosen as the pH-dependent station and as the template to drive the rotaxane formation. The triazolium serves as the second station of much poorer affinity for the DB24C8. The preparation of the [2]rotaxane molecular architecture was achieved according to the threading and end-capping strategy described in Section 2.1. The anilinium alkyne 1 was able to thread quite instantaneously through the DB24C8 because of the hydrogen-bonding and ion–dipole interactions between the oxygen atoms of the crown ether and both the ammonium charge and the hydrogen atoms H14 and H15. The obtained semi-rotaxane 2 was then capped at its alkyne extremity using CuAAC click chemistry with the mannosyl azide derivative. The subsequent methylation of the triazole revealed the triazolium station and afforded the pH-sensitive [2]rotaxane molecular machine 4. After deprotonation of the anilinium station, the DB24C8 has no reason to sit anymore over the aniline because it has no more interaction with it. Therefore, the DB24C8 moves toward the N-methyltriazolium and interacts with it. Protonation of 5 inverts the translational process of the DB24C8 toward the anilinium.


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

Coutrot F - ChemistryOpen (2015)

Preparation of a mannosyl pH-sensitive [2]rotaxane molecular machine. Reagents and conditions: a) DB24C8 (2 equiv), CH2Cl2, RT; b) 2,6-lutidine, Cu(MeCN)4PF6, CH2Cl2, RT, 24 h, 72 %; c) 1) CH3I, 2) NH4PF6, quantitative; d) DIEA; e) 1) HCl/Et2O, 2) NH4PF6.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

sch01: Preparation of a mannosyl pH-sensitive [2]rotaxane molecular machine. Reagents and conditions: a) DB24C8 (2 equiv), CH2Cl2, RT; b) 2,6-lutidine, Cu(MeCN)4PF6, CH2Cl2, RT, 24 h, 72 %; c) 1) CH3I, 2) NH4PF6, quantitative; d) DIEA; e) 1) HCl/Et2O, 2) NH4PF6.
Mentions: We reported the first example of a pH-sensitive [2]rotaxane molecular machine possessing a triazolium molecular station for the DB24C8 in 2008 (Scheme 1).13 Its synthesis appeared quite straightforward and efficient, and the molecular machinery easy to drive and characterize. The targeted DB24C8-based [2]rotaxane 4 consists of an encircled axle which contains an anilinium and a N-methyltriazolium molecular stations. Two bulky extremities have been chosen for the thread in order to prevent the macrocycle from any unthreading. One extremity is a mannose derivative, whereas the other one is a di-tert-butyl anilinium moiety. The anilinium was chosen as the pH-dependent station and as the template to drive the rotaxane formation. The triazolium serves as the second station of much poorer affinity for the DB24C8. The preparation of the [2]rotaxane molecular architecture was achieved according to the threading and end-capping strategy described in Section 2.1. The anilinium alkyne 1 was able to thread quite instantaneously through the DB24C8 because of the hydrogen-bonding and ion–dipole interactions between the oxygen atoms of the crown ether and both the ammonium charge and the hydrogen atoms H14 and H15. The obtained semi-rotaxane 2 was then capped at its alkyne extremity using CuAAC click chemistry with the mannosyl azide derivative. The subsequent methylation of the triazole revealed the triazolium station and afforded the pH-sensitive [2]rotaxane molecular machine 4. After deprotonation of the anilinium station, the DB24C8 has no reason to sit anymore over the aniline because it has no more interaction with it. Therefore, the DB24C8 moves toward the N-methyltriazolium and interacts with it. Protonation of 5 inverts the translational process of the DB24C8 toward the anilinium.

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