Archive for February, 2015

Biochemical Logic Systems – closed-loop “Sense/Act” operations

When research in a particular area reaches saturation point, the question of future applications becomes critically important. This recent Feature Article in ChemComm considers molecular logic gates, which have not yet achieved pure computational applications (with their hoped for advantages) due to limitations caused by noise build-up and cross-talk between various biomolecular elements. Thus they are unable to compete with electronic computing devices. The authors ask the question: what potential applications are there that justify the continued research in this field?

Evgeny Katz from the Department of Chemistry and Biomolecular Science at Clarkson University with Sergiy Minko from the Nanostructured Materials Lab at the University of Georgia lead the reader through a short overview of potential answers. These include “smart” switchable membranes, electrodes, biofuel cells and drug-releasing systems.
 
The use of biochemical data processing to produce a yes/no answer provides the opportunity for direct coupling with signal-responsive materials to produce a closed-loop “sense/act” operation. This ability has the potential to transform the field of biosensors and bioactuators.

(A) A biocatalytic cascade activated by enzyme–substrate inputs and resulting in the in situ produced pH changes. (B) The logic circuitry equivalent to the biocatalytic cascade. (C) pH-switchable electrode interface modified with a polymeric brush.

The authors could be considered brave to ask the question of such a popular focus of research, but this article provides an opportunity for reflection and thought about what biochemical computing research can uniquely achieve. Having read this article I was left with a sense of excitement at the specific in vivo sensing possibilities that biochemical computing provides. To find out if you think the opportunities are exciting too, read the article today!

To read the details, check out the ChemComm article in full:
Enzyme-based logic systems interfaced with signal-responsive materials and electrodes
Evgeny Katz and Sergiy Minko
Chem. Commun., 2015, 51, Advance Article
DOI: 10.1039/C4CC09851J

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Ring closing highlights hydrogen bonding

The discolouration rate of a fluorescent dye can act as a visual marker for changes in hydrogen bonding environment, new research shows.

Colourless spiropyrans undergo ring opening to form brightly coloured merocyanines on exposure to UV light. Merocyanines are thermally unstable and relax back to the colourless spiropyrans over time. The merocyanines designed by Simone Ciampi, from the University of Wollongong, Australia, and his colleagues contain a catechol group that can form intramolecular hydrogen bonds, which stabilises the open form and slows down discolouration. However, polar solvents can out-compete intramolecular hydrogen bond formation, and speed up discolouration. In this way, Ciampi’s team were able to visualise the hydrogen bonding character of solvents by adding their dye and observing the rate at which it discoloured.


Read the full article in Chemistry World»

Read the original journal article in ChemComm:
Decoloration rates of a photomerocyanine dye as a visual probe into hydrogen bonding interactions
Simone Ciampi, Paul K. Eggers, Naomi L. Haworth, Nadim Darwish, Pawel Wagner, Michelle L. Coote, Gordon G. Wallace and Colin L. Raston  
Chem. Commun., 2015, Advance Article
DOI: 10.1039/C4CC09857A, Communication

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Unexpected success with luminescent liquid crystals

A simple and effective procedure to incorporate strongly-emitting inorganic clusters into nematic liquid crystals has been reported by a team from France. By combining the supramolecular paradigms of host–guest chemistry and electrostatic interactions the team have overcome previously insurmountable limitations of liquid crystalline materials.

Liquid crystals, which exhibit long-range directional order but also flow like a liquid, are a prominent feature of modern technology. They are commonly used as temperature sensors and their nematic phase is an integral component in liquid crystal display (LCD) technology.


Read the full article in Chemistry World»

Read the original journal article in ChemComm – it’s free to access until 19th March:
From metallic cluster-based ceramics to nematic hybrid liquid crystals: a double supramolecular approach
Susanta K. Nayak, Maria Amela-Cortes, Claire Roiland, Stéphane Cordier and Yann Molard  
Chem. Commun., 2015, Advance Article
DOI: 10.1039/C4CC10085A, Communication

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Exploiting the chirality of DNA

Scientists in France and Germany have made use of DNA as part of a catalytic system for various enantioselective alkylations and addition reactions.

DNA has emerged as an innovative way of controlling the chirality of a reaction product; by binding catalysts in such a way that one enantiomer is preferentially generated. The chiral nature of the helix makes it ideal for asymmetric catalysis. However, this field of research is still in its infancy…


Read the full article in Chemistry World»

Read the original journal article in ChemComm – it’s free to access until 19th March:
DNA-cellulose: an economical, fully recyclable and highly effective chiral biomaterial for asymmetric catalysis
Erica Benedetti, Nicolas Duchemin, Lucas Bethge, Stefan Vonhoff, Sven Klussmann, Jean-Jacques Vasseur, Janine Cossy, Michael Smietana and Stellios Arseniyadis  
Chem. Commun., 2015, Advance Article
DOI: 10.1039/C4CC10190A, Communication

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A sticky way to inspect self-cleaning glass

Reusable colour-changing sticky labels that act as a cheap and easy way to check the activity of photocatalysis-based self-cleaning glass have been designed by scientists in the UK.

Interest in self-cleaning technologies, including semiconductor photocatalysis (SPC), has been on the increase since the commercialisation of self-cleaning glass by Pilkington in 2001. However, SPC, a process by which light activation of a surface coating, usually titanium dioxide, facilitates the breakdown of organic dirt, is difficult to measure as most coatings are invisible to the eye.


Read the full article in Chemistry World»

Read the original journal article in ChemComm – it’s free to access until 12th March:
Smart, reusable labels for assessing self-cleaning films
A. Mills and N. Wells  
Chem. Commun., 2015, Advance Article
DOI: 10.1039/C4CC09734C, Communication

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Graphene looks to doped superbenzene to overcome electronic hurdles

Building graphene from carefully-modified superbenzene segments has been proposed as a way to help graphene overcome a major stumbling block limiting its application in electronic devices – by opening its bandgap to make it a true semiconductor. 

Intrinsically, graphene is a semimetal with no bandgap. Boron nitride can afford graphene the electronic properties desired for atomically thin circuits. However, positioning these boron nitride-groups in just the right places to properly regulate electron flow through graphene is difficult. 

 


Read the full article in Chemistry World» 

Read the original article in ChemComm – it’s free to access until 11th March:
Synthesis, structure and properties of C3-symmetric heterosuperbenzene with three BN units
Xiao-Ye Wang, Fang-Dong Zhuang, Xin-Chang Wang, Xiao-Yu Cao, Jie-Yu Wang and Jian Pei  
Chem. Commun., 2015, Advance Article
DOI: 10.1039/C4CC10105G, Communication

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Accessing Chiral Space with Visible Light

Researchers have made tremendous efforts to unlock stereoselective, catalytic organic transformations. In this recent ChemComm Feature Article, Professor Eric Meggers, one of the pioneers in the field of photoredox catalysis, provides a comprehensive review of the recent advances in asymmetric catalysis driven by visible light.

Asymmetric catalysis has been one of the most attractive yet challenging areas of organic chemistry for the synthesis of unique, biologically active natural products such as Taxol, Rapamycin, or Vinblastine that possess numerous stereocenters.

C4CC09268F gaRecently, visible light, a sustainable and affordable energy resource, gained substantial interest with its capability to selectively access chiral molecules from prochiral substrates without undesirable by-products. Transformations including aldehyde α-functionalization and [2+2] cycloadditions demonstrate the potential of visible light in the presence of a photosensitizer.

These photosensitizers are typically ruthenium or iridium complexes that can facilitate electron/energy transfer upon photoinduction. In most cases, a photoredox catalyst has to be coupled with a chiral co-catalyst to introduce stereocenters in the products.

Notable advances in the Meggers, Melchiorre, and MacMillan research groups have recently demonstrated that photoactivation can be achieved with a single chiral photosensitizer to provide products of high enantiomeric excess and good yield.

This inspirational review was just published in Chemical Communications as a Feature Article. I recommend reading “Asymmetric catalysis activated by visible light” (DOI: 10.1039/c4cc09268f) by Professor Eric Meggers to learn more about the recent advances with mechanistic details and his forecast for one of the rapidly-growing research topics in organic chemistry.

This article is free to access until 17th March.* Download it here:
Asymmetric catalysis activated by visible light
Eric Meggers �
Chem. Commun., 2015, Advance Article
DOI: 10.1039/C4CC09268F, Feature Article


Dr. Tezcan Guney is a guest web writer for Chemical Communications. Dr. Guney received his Ph.D. from the Department of Chemistry at Iowa State University with Prof. George Kraus, where he focused on the synthesis of biologically active polycyclic natural products and multifunctional imaging probes. Currently, he is a postdoctoral research scholar at the Memorial Sloan-Kettering Cancer Center in New York with Prof. Derek Tan, contributing to the efforts to access biologically active small molecules using the diversity-oriented synthetic approach.

*Access is free through a registered RSC account

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