scholarly journals A precise polyrotaxane synthesizer

Science ◽  
2020 ◽  
Vol 368 (6496) ◽  
pp. 1247-1253 ◽  
Author(s):  
Yunyan Qiu ◽  
Bo Song ◽  
Cristian Pezzato ◽  
Dengke Shen ◽  
Wenqi Liu ◽  
...  

Mechanically interlocked molecules are likely candidates for the design and synthesis of artificial molecular machines. Although polyrotaxanes have already found niche applications in exotic materials with specialized mechanical properties, efficient synthetic protocols to produce them with precise numbers of rings encircling their polymer dumbbells are still lacking. We report the assembly line–like emergence of poly[n]rotaxanes with increasingly higher energies by harnessing artificial molecular pumps to deliver rings in pairs by cyclical redox-driven processes. This programmable strategy leads to the precise incorporation of two, four, six, eight, and 10 rings carrying 8+, 16+, 24+, 32+, and 40+ charges, respectively, onto hexacationic polymer dumbbells. This strategy depends precisely on the number of redox cycles applied chemically or electrochemically, in both stepwise and one-pot manners.

2018 ◽  
Vol 57 (44) ◽  
pp. 14967-14976 ◽  
Author(s):  
Cheng Peng ◽  
Jian Liang ◽  
Honggen Peng ◽  
Ran Yan ◽  
Wenming Liu ◽  
...  

Author(s):  
O. Bugera ◽  
A. Netrebchuk ◽  
V. Pivovarenko

Adenosine 5'-triphosphate (ATP) is known as a universal energy source and signaling mediator in numerous biological processes. Among the methods for its determination, molecular fluorescence probes occupy leading positions due to high sensitivity and selectivity. Recently we have shown that 31 of 33 tested flavones and quinolones of various structures give fluorescence response and can be effectively applied as the probes in aqueous solutions for detection of ATP in 1–50,000 μM range of its concentrations. To increase response parameters of a probe in respect to ATP we have synthesized N,N'-(butane-1,4-diyl)bis(2-((2-(4-(dimethylamino)phenyl)-3-hydroxy-4-oxo-4H-chromene-6-yl)oxy)acetamide, the molecular tweezer composed of two flavonol units connected by active linker. On our idea, being equipped by two planar platforms, the tweezershould demonstrate increased affinity and selectivity to ATP in a result of increased number of hydrogen bonds and increased stacking interactions. Having two NH-amide groups the amino acid linker will form hydrogen bonds with the phosphates of ATP, increasing the portion of probe-ATP complex population in the reporting conformation.In the four-step synthesis of this molecular device, starting from methyl 2-(3-acetyl-4-hydroxyphenoxy)acetate and N,N-dimethylaminobenzaldehyde, the conditions for the reaction of one-pot chalcone formation and its oxidative heterocyclization in the presence of an organic base were found, which resulted in the isolation of a target flavonol-amino acid derivative with high yields. We suggest that atmospheric oxygen was an oxidizer in this process. The obtained derivative was converted intotarget compound by dual condensation with 1,4-butane diamine.


2020 ◽  
Vol 22 (15) ◽  
pp. 5839-5843
Author(s):  
Rabi Sankar Das ◽  
Pranab Chandra Saha ◽  
Nayim Sepay ◽  
Ayan Mukherjee ◽  
Sudipta Chatterjee ◽  
...  

2008 ◽  
Vol 80 (1) ◽  
pp. 17-29 ◽  
Author(s):  
Euan R. Kay ◽  
David A. Leigh

Nature uses molecular motors and machines in virtually every significant biological process, but learning how to design and assemble simpler artificial structures that function through controlled molecular-level motion is a major challenge for contemporary physical science. The established engineering principles of the macroscopic world can offer little more than inspiration to the molecular engineer who creates devices for an environment where everything is constantly moving and being buffeted by other atoms and molecules. Rather, experimental designs for working molecular machines must follow principles derived from chemical kinetics, thermodynamics, and nonequilibrium statistical physics. The remarkable characteristics of interlocked molecules make them particularly useful for investigating the control of motion at the molecular level. Yet, the vast majority of synthetic molecular machines studied to date are simple two-state switches. Here we outline recent developments from our laboratory that demonstrate more complex molecular machine functions. This new generation of synthetic molecular machines can move continuously and progressively away from equilibrium, and they may be considered true prototypical molecular motors. The examples discussed exemplify two, fundamentally different, "Brownian ratchet" mechanisms previously developed in theoretical statistical physics and realized experimentally in molecular-level devices for the first time in these systems.


RSC Advances ◽  
2018 ◽  
Vol 8 (13) ◽  
pp. 6789-6797 ◽  
Author(s):  
Xiangong Wang ◽  
Fang Zhao ◽  
Bo Pang ◽  
Xuping Qin ◽  
Shengyu Feng

TN hydrogels with high mechanical properties are prepared and they have potential application in biomaterials.


Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 4953
Author(s):  
Vincent Hervin ◽  
Ritu Arora ◽  
Jyoti Rani ◽  
Srinivasan Ramchandran ◽  
Urmi Bajpai ◽  
...  

The synthesis of hitherto unknown 5′-deoxy-5′-(4-substituted-1,2,3-triazol-1-yl)-uridine and its evaluation, through an one-pot screening assay, against MurA-F enzymes involved in Mycobacterium tuberculosis (Mtb), are described. Starting from UDP-N-acetylmuramic acid (UDP-MurNAc), the natural substrate involved in the peptidoglycan biosynthesis, our strategy was to substitute the diphosphate group of UDP-MurNAc by a 1,2,3-triazolo spacer under copper-catalyzed azide-alkyne cycloaddition conditions. The structure-activity relationship was discussed and among the 23 novel compounds developed, N-acetylglucosamine analogues 11c and 11e emerged as the best inhibitors against the Mtb MurA-F enzymes reconstruction pathway with an inhibitory effect of 56% and 50%, respectively, at 100 μM. Both compounds are selective inhibitors of Mtb MurE, the molecular docking and molecular dynamic simulation suggesting that 11c and 11e are occupying the active site of Mtb MurE ligase.


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