scholarly journals Rotaxanes and catenanes as prototypes of molecular machines and motors

2003 ◽  
Vol 75 (10) ◽  
pp. 1383-1393 ◽  
Author(s):  
C. O. Dietrich-Buchecker ◽  
M. C. Jimenez-Molero ◽  
V. Sartor ◽  
J.-P. Sauvage
Keyword(s):  
Dynamic Properties ◽  
Molecular Machines ◽  
Molecular Assembly ◽  
External Signal ◽  
Metal Exchange ◽  
Metathesis Reaction ◽  
Preparative Scale ◽  
Molecular Systems ◽  
Metal Exchange Reaction ◽  
Stretching Process

In the course of the last 20 years, our view on rotaxanes and catenanes has completely changed. Copper(I)-templated strategies, in particular, have allowed us to prepare catenanes on a real preparative scale, in a few chemical steps from commercially available compounds. A particularly significant improvement was the introduction of the recently developed ring-closing metathesis reaction, using Grubbs catalyst. The dynamic properties of rotaxanes and catenanes has been exploited to construct molecular systems for which one component can be set in motion under the action of an external signal, while the other components can be considered as motionless (artificial molecular “machines ”and “motors ”). A particularly representative example is that of a rotaxane dimer, whose overall length can be controlled chemically: A metal exchange reaction (CuI/ZnII) triggers a reversible contraction/stretching process of the same molecular assembly, in a way reminiscent of the functioning of biological muscles.

The Second Step of the Halogen/Metal Exchange Reaction

2003 ◽  
Vol 5 (3) ◽  
pp. 313-316 ◽  
Author(s):  
Reinhard W. Hoffmann ◽  
Mark Brönstrup ◽  
Michael Müller
Keyword(s):  
Exchange Reaction ◽  
Second Step ◽  
Metal Exchange ◽  
Metal Exchange Reaction

Thermochromism of Metal Exchange Reaction between Zinc(II) and Mercury(II) Porphyrins

1995 ◽  
Vol 50 (4) ◽  
pp. 545-550 ◽  
Author(s):  
Masaaki Tabata ◽  
Masahiro Ide ◽  
Kentaro Kaneko
Keyword(s):  
Aqueous Solution ◽  
Exchange Reaction ◽  
Thermodynamic Parameters ◽  
Distribution Curve ◽  
Equilibrium Constants ◽  
Metal Exchange ◽  
Free Base ◽  
Temperature Range ◽  
Base Form ◽  
Metal Exchange Reaction

Thermochromism was observed for an aqueous solution containing zinc(II) and mercury( II) cations and N-p-nitrobenzyl-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin anion (NO2Bz(Htpps)4-) in the temperature range 10 to 70 °C. The equilibrium constants and the thermodynamic parameters of Zn(NO2Bztpps)3- and Hg(NO2Bztpps)3- have been determined spectrophotometrically to elucidate the thermochromism at 10, 15, 20, 25 and 30 °C in 0.1 mol dm-3 NaNO3. The protonation and metalation constants of NO2Bz(Htpps)4- are defined as K2 = [H2P][H+]-1[HP]-1, K3 = [H3P][H+]-1[H2P]-1 and KMP = [M P][H+][M2+]-1[HP]-1, where HP and MP denote the free base form of the prophyrin and the metalloporphyrins of zinc(II) and mercury(II), respectively. Charges of the prophyrin and metalloporphyrins are omitted for simplicity. The following values were found: logK2 = 7.75 ±0.02 (25 °C), ΔH°/kJmol-1 = -21.2±0.5 and ΔS°/Jmol-1K-1 = 77±1, logK3 = 2.55±0.02 (25 °C), ΔH°/kJmol-1 = -25±0.8 and ΔS°/Jmol-1K-1 = -35±3 and log KZnP = 0.63±0.03 (25 °C), ΔH°/kJmol-1 = 31.0±0.8 and ΔS°/Jmol-1K-1 = 116±3, logKHgP = 6.22±0.03 (25 °C), ΔH°/kJmol-1 = 4.5±0.7 and ΔS°/Jmol-1K-1 = 134±2. The distribution curve calculated from the thermodynamic parameters sufficiently agrees with the observed metal exchange reaction between the metalloporphyrins.

scholarly journals DNA Origami Nanomachines

Molecules ◽  
2018 ◽  
Vol 23 (7) ◽  
pp. 1766 ◽  
Author(s):  
Masayuki Endo ◽  
Hiroshi Sugiyama
Keyword(s):  
Dna Sequences ◽  
Molecular Motors ◽  
Molecular Machines ◽  
Dna Origami ◽  
Dna Nanostructures ◽  
Molecular Systems ◽  
Nanoscale Structures ◽  
Research Fields ◽  
Dna Strands ◽  
External Stimuli

DNA can assemble various molecules and nanomaterials in a programmed fashion and is a powerful tool in the nanotechnology and biology research fields. DNA also allows the construction of desired nanoscale structures via the design of DNA sequences. Structural nanotechnology, especially DNA origami, is widely used to design and create functionalized nanostructures and devices. In addition, DNA molecular machines have been created and are operated by specific DNA strands and external stimuli to perform linear, rotational, and reciprocating movements. Furthermore, complicated molecular systems have been created on DNA nanostructures by arranging multiple molecules and molecular machines precisely to mimic biological systems. Currently, DNA nanomachines, such as molecular motors, are operated on DNA nanostructures. Dynamic DNA nanostructures that have a mechanically controllable system have also been developed. In this review, we describe recent research on new DNA nanomachines and nanosystems that were built on designed DNA nanostructures.

scholarly journals On the mechanism of rapid metal exchange between thiolate-protected gold and gold/silver clusters: a time-resolved in situ XAFS study

2018 ◽  
Vol 20 (7) ◽  
pp. 5312-5318 ◽  
Author(s):  
Bei Zhang ◽  
Olga V. Safonova ◽  
Stephan Pollitt ◽  
Giovanni Salassa ◽  
Annelies Sels ◽  
...  
Keyword(s):  
Exchange Reaction ◽  
Silver Clusters ◽  
Metal Exchange ◽  
Time Resolved ◽  
X Ray ◽  
Gold Silver ◽  
In Situ Xafs ◽  
Metal Exchange Reaction ◽  
X Ray Absorption

The fast metal exchange reaction between Au38 and AgxAu38−x nanoclusters has been studied by time resolved in situ X-ray absorption spectroscopy.

Dynamic Properties of Self-Reproducing Molecular Systems: Theoretical Analysis

1996 ◽  
pp. 11-37
Author(s):  
Vadim A. Ratner ◽  
Andrey A. Zharkikh ◽  
Nikolay Kolchanov ◽  
Sergey N. Rodin ◽  
Viktor V. Solovyov ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Dynamic Properties ◽  
Molecular Systems

Molecular assembly at surfaces: progress and challenges

2017 ◽  
Vol 204 ◽  
pp. 9-33 ◽  
Author(s):  
R. Raval
Keyword(s):  
Building Blocks ◽  
Covalent Bonding ◽  
Molecular Assembly ◽  
Theoretical Modelling ◽  
Top Down ◽  
Molecular Systems ◽  
Natural Systems ◽  
Surfaces And Interfaces ◽  
Macromolecular Systems ◽  
Determine System

Molecules provide versatile building blocks, with a vast palette of functionalities and an ability to assemble via supramolecular and covalent bonding to generate remarkably diverse macromolecular systems. This is abundantly displayed by natural systems that have evolved on Earth, which exploit both supramolecular and covalent protocols to create the machinery of life. Importantly, these molecular assemblies deliver functions that are reproducible, adaptable, finessed and responsive. There is now a real need to translate complex molecular systems to surfaces and interfaces in order to engineer 21st century nanotechnology. ‘Top-down’ and ‘bottom-up’ approaches, and utilisation of supramolecular and covalent assembly, are currently being used to create a range of molecular architectures and functionalities at surfaces. In parallel, advanced tools developed for interrogating surfaces and interfaces have been deployed to capture the complexities of molecular behaviour at interfaces from the nanoscale to the macroscale, while advances in theoretical modelling are delivering insights into the balance of interactions that determine system behaviour. A few examples are provided here that outline molecular behaviour at surfaces, and the level of complexity that is inherent in such systems.

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