Archive for July, 2017

A warm welcome to Sandeep Verma, our new ChemComm Associate Editor

We are excited to welcome new Associate Editor Sandeep Verma (Indian Institute of Technology Kanpur) to the ChemComm Editorial Board

Professor Sandeep Verma

Sandeep Verma holds the positions of Professor of Chemistry and Shri Deva Raj Endowed Chair Professor at the Department of Chemistry, Indian Institute of Technology Kanpur, which he joined in 1997. His work has been recognized by numerous awards such as Swarnajayanti Fellowship (2005), Shanti Swarup Bhatnagar Prize in Chemical Sciences (2010), Department of Atomic Energy-Science Research Council Outstanding Investigator Award (2012), Ranbaxy Research Award in Pharmaceutical Sciences (2013), J C Bose National Fellowship (2013), Silver Medal, Chemical Research Society of India (2017), and National Prize for Research on Interfaces between Chemistry and Biology (2017).

His main research interests include peptide/protein assemblies for disease modeling, soft biomaterials, bioimaging, and surface chemistry of metal complexes. In particular, his group focuses on heterogeneous catalysts designed by developing polymeric templates based on nucleobase frameworks for application to interesting chemical and biochemical reactions. His work also focuses on the construction of architectures mimicking biological assemblies and metal-organic frameworks.

As a ChemComm, Sandeep will be handling submissions to the journal in the above areas. Why not submit your next paper to his Editorial Office?

Read Professor Verma’s recent articles published in ChemComm and its sister journals:

Chemical sensing in two dimensional porous covalent organic nanosheets
Gobinda Das, Bishnu P. Biswal, Sharath Kandambeth, V. Venkatesh, Gagandeep Kaur, Matthew Addicoat, Thomas Heine, Sandeep Verma and Rahul Banerjee
Chem. Sci., 2015, 6, 3931-3939

Organostannoxane-supported nucleobase arrays: synthesis and supramolecular structures of polymeric and molecular organotin complexes containing guanine, uracil and 2-aminopurine
Subrata Kundu, N. Nagapradeep, Balaram Mohapatra, Sourav Biswas, Sandeep Verma and Vadapalli Chandrasekharn
CrystEngComm, 2016, 18, 4807-4817

Assembly, postsynthetic modification and hepatocyte targeting by multiantennary, galactosylated soft structures
Anisha Thomas, Akansha Shukla, Sri Sivakumarb and Sandeep Verma
Chem. Commun., 2014, 50, 15752-15755

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Releasing A Pungent Anti-cancer Reagent with A Trisulfide Linker Inspired by Garlic

People who love the taste of garlic are often annoyed by its lingering smell. While there are various tips to get rid of this unpleasant odor, have you ever thought that this garlic aroma brings you chemical compounds that are potent anti-cancer reagents?

Diallyl trisulfide, one of the natural occurring components rendering the flavor of garlic, is able to release hydrogen sulfide (H2S) upon contacting with thiol compounds (i.e., organic molecules with –SH functional groups). H2S is a pungent gas that one might never forget after sniffing a rotten egg. However, this “notorious” gas, when at low concentrations, is reported to be friendly to our bodies. It relaxes vascular smooth muscle, reduces blood pressure, lowers risk associated with cancer as well as protects gastrointestinal, nervous and immune systems. All the aforementioned benefits of H2S have aroused worldwide efforts in developing H2S-releasing and bio-compatible materials that mimic the natural products for pharmaceutical applications.

Davis, Quinn and co-workers from Monash University, Australia and University of Warwick, United Kingdom, recently published a paper in Chemical Communications that reports a trisulfide-linked organic polymer capable of releasing H2S when meets –SH groups. As shown in the scheme below, the synthesized polymer is composed of three parts: a polyethylene glycol (PEG) unit on the left (in blue), a cholesterol (CHOL) group on the right (in orange), and a linker (in black) joining the two ends. PEG and CHOL are chosen mainly due to their bio-compatibility. By changing the structure of the middle linker, the authors obtained three types of polymers that behave differently when mixing with thiol compounds. The trisulfide linker (denoted as T) enables release of H2S gas and initiates polymer degradation. The disulfide linker (denoted as D) allows polymer degradation only. The amide linker (denoted as C) containing no sulfide atoms is inert to the thiol exposure.

Scheme. The chemical structure of the synthesized polymers with different linkers.

Experiments showed that the T-linked polymers are capable of releasing H2S both in vitro and in vivo.

A fluorescent probe, which can be reduced by H2S and becomes fluorescent, is applied to detect the existence of H2S. As shown in Figure a, the trisulfide linked polymers tested in vitro exhibited the highest fluorescence when mixing with L-cysteine (a thiol compound to trigger H2S generation). For the in vivo measurements, the authors incubated HEK293 cells with the polymers and the probe. Similar as the in vitro results, the fluorescence intensity of the cells containing the T-linked polymers is the highest (Figure b). Both the in vitro and in vivo results unambiguously proved that the presence of the T-linker was responsible for generating H2S. Additionally, another set of tests using Nile Red confirmed the biodegradability of the T-linked polymers.

Figure. (a) Fluorescence spectra collected from different systems in vitro. The inset shows the chemical reaction between the probe (SF4) and H2S that displays fluorescence. (b) Fluorescence intensity of different polymers over time in HEK293 cells.

The developed tri-sulfide linker may allow the mimicry of endogenous biosynthesis, the initiation of discrete signaling events and the synthesis of next-generation pharmaceutical excipients.

 

To find out more please read:

Garlic-inspired Trisulfide Linkers for Thiol-stimulated H2S Release
Francesca Ercole, Michael R. Whittaker, Michelle L. Halls, Ben J. Boyd, Thomas P. Davis and John F. Quinn
DOI: 10.1039/c7cc03820h

About the author:

Tianyu Liu is a Ph.D. in chemistry graduated from University of California-Santa Cruz. He is passionate about scientific communication to introduce cutting-edge researches to both the general public and the scientists with diverse research expertise. He is a web writer for the Chem. Commun. and Chem. Sci. blog websites. More information about him can be found at http://liutianyuresearch.weebly.com/.

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Simplified structure eases antibiotic synthesis

New analogues of the potent antibiotic teixobactin could be instrumental in the fight against multi-drug resistant pathogens.

By replacing a rare amino acid in the structure of teixobactin, UK researchers have unlocked the door to cheaper and easier-to-manufacture forms of this potent antibiotic.

(Left) Teixobactin. (Right) General structure of teixobactin analogues with the hydrophilic/charged residues shown in red, hydrophobic residues shown in black and structural differences shown in blue.

Scientists in the US reported their discovery of teixobactin in 2015. It works against multi-drug resistant pathogens, but as it contains a rare and difficult to manufacture amino acid it is hard to make.

Read the full story by Tabitha Watson on Chemistry World.

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A Promising Cathode Material for Magnesium-ion Batteries Has Been Identified

Research associated with batteries is gaining increasing attention and extensive efforts in recently decades, partly due to the development of sustainable energy to combat a series of problems including fossil fuel depletion, environmental pollution and global warming. Batteries are indispensable energy storage devices for the utilization of sustainable energy (e.g., solar and wind energy). One of the battery’s cutting-edge research topics is to achieve novel batteries with higher capacity (a figure-of-merit to measure how much electrical energy a battery can store) and better reliability than the lithium-ion batteries that currently dominate the battery market.

In the past decade, batteries based on magnesium ions, termed as magnesium-ion batteries, are emerging. The magnesium-ion batteries possess at least two advantages over lithium-ion batteries. Firstly, their typical anode material, magnesium metal, has a theoretical capacity of 3833 mAh/cm3. This value is much higher than that of graphite, a conventional anode material for lithium-ion batteries. Secondly, the formation of metal dendrite on anode surface can be avoided by replacing lithium metal with magnesium metal. Metal dendrites grow from anodes can eventually touch cathodes, causing electric short circuits and triggering fire and explosion. Therefore, magnesium-ion batteries are safer than lithium-ion batteries. However, nothing can be perfect. The limited mobility of Mg2+ of cathode materials greatly reduces the capacity (particularly at fast charging rates) and practicability of the magnesium-ion batteries.

Now Rong et al. has published an article in Chemical Communications stating that a promising cathode material capable of fast conducting Mg2+ for magnesium-ion batteries has been identified. The material is a molybdenum phosphate compound with a chemical formula of Mo3(PO4)3O. It is composed of several edge-sharing MoO6 octahedra, corner-sharing MoO5 trigonal bipyramids, MoO4 tetrahedra, and PO4 tetrahedra. Using advanced simulation and computation techniques (i.e., the first-principles density functional theory), the authors first proved that Mg2+ can stably reside in some interstitial sites among the aforementioned polyhedra, indicating the identified compound is active for Mg2+ storage. In addition, the authors plotted two possible pathways for Mg2+ diffusion during charge and discharge processes (shown in the Figure). As illustrated in Figure a1, the first one is an inner-channel path along the b-axis. The second one is an inter-channel path along the c-axis.

The most striking feature of the path #1 is its ultra-low activation barrier (i.e., the highest potential energy that a Mg2+ need to overcome when diffusing) of only ~80 meV (Figure a2). Such a low diffusion barrier is expected to allow facile Mg2+ diffusion within the bulk of Mo3(PO4)3O, which can boost the capacity of the magnesium-ion batteries particularly at elevated charging rates. On the contrary, the activation barrier of the path #2 is as high as ~1200 meV. The authors claimed that the Mg2+ diffusion along the path #2 “should be ~1018 times less frequent than” the path #1.

 

 

Figure (a1) schematic of the Mg2+ diffusion path #1 and (a2) its corresponding diffusion potential barrier distribution along the way. (b1) Schematic of the Mg2+ diffusion path #2 and (a2) its corresponding diffusion potential barrier distribution along the way.

 

At last, the authors estimated the theoretical average potential that Mo3(PO4)3O can reach is 1.98 V, corresponding to a promising energy density of 173 Wh/kg. Although the proposed phosphate is hypothetical, the investigation of its stability reveals the possibility that this material can be experimentally synthesized.

To find out more please read:

Fast Mg2+ Diffusion in Mo3(PO4)3O for Mg Batteries
Ziqin Rong, Penghao Xiao, Miao Liu, Wenxuan Huang, Daniel C. Hannah, William Scullin, Kristin A. Persson and Gerbrand Ceder
DOI: 10.1039/c7cc02903a

About the author:

Tianyu Liu is a Ph.D. in chemistry graduated from University of California-Santa Cruz. He is passionate about scientific communication to introduce cutting-edge researches to both the general public and the scientists with diverse research expertise. He is a web writer for the Chem. Commun. and Chem. Sci. blog websites. More information about him can be found at http://liutianyuresearch.weebly.com/.

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A “Cube-in-tube” Carbon-Metal Oxide Lithium-ion Battery Composite Electrode with Outstanding Capacity and Durability

Lithium-ion batteries are indispensable for powering a number of electronics (e.g. cell phones, laptops and even electric vehicles) used in the modern society. The key components of a lithium-ion battery are its two electrodes (anode and cathode) because they largely dictate the amount of electrical energy (measured by a parameter called “capacity”) the battery can hold. Increasing the capacity as well as prolonging the lifetime of lithium-ion batteries are practically desirable. Material scientists worldwide are searching for electrode materials to achieve the goal.

In the past decade, a diverse array of metal oxides has been developed as lithium-ion battery anodes with promising performance. These anodes have exhibited considerably higher capacity (~1000 mAh/g) than the current commercial anode material, graphite (372 mAh/g). However, two major drawbacks of metal oxides, namely the limited electrical conductivity and the short lifetime, impede their feasibility for practical applications. While the poor electrical conductivity is an intrinsic physical property of most metal oxides, their short life time is caused by the large volumetric deformation during charge and discharge processes. The deformation will eventually trigger pulverization of electrodes and lead to loss of capacity. Therefore, developing novel strategies that manage to turn metal oxides to viable electrode candidates with satisfying lifetime becomes necessary.

Now writing in Chemical Communications, a research group led by Professor Liqiang Mai and Professor Qi Li from Wuhan University of Technology, China demonstrated a metal oxide-carbon composite anode that exhibited both high capacity and super-long lifetime. The structure of this composite is a “cube-in-tube” configuration (Figure 1): the manganese oxide nanoparticle-embedded carbon “tubes” encapsulate the CoSnO3 (a binary metal oxide) “cubes”. This unique composite electrode delivered a maximal capacity of 960 mAh/g at a current density of 0.1 A/g (Figure 2a), around three times higher than the theoretical capacity of graphite. More impressively, as shown in Figure 2b, the electrode displayed outstanding stability with ~99% of capacity retained after 1500 consecutive charge and discharge cycles (roughly equivalent to four years’ use), much higher than those of the current commercial products and other laboratory-developed composites.

Figure 1. Schematic of the synthesis strategy and the morphology of the “cube-in-tube” metal oxide-carbon composite lithium-ion battery electrode.

Figure 2. (a) Plot of capacity at different current densities; (b) The stability performance evaluated at 2 A/g.

The authors attributed the electrode’s excellent durability to two reasons. Firstly, the hollow structures (both the “tube” and the “cube”) provide adequate empty space to accommodate volumetric change of metal oxides. Secondly, the soft nature of carbon renders its ability to serve as a mechanical buffer layer. Both aspects reduce the possibility of structural pulverization and promote long lifetime.

To find out more please read:

Facile Electrospinning Formation of Carbon-confined Metal Oxide Cube-in-tube Nanostructures for Stable Lithium Storage

Ziang Liu, Ruiting Guo, Jiashen Meng, Xiong Liu, Xuanpeng Wang, Qi Li, Liqiang Mai

DOI: 10.1039/C7CC0327A

About the author:

Tianyu Liu is a Ph.D. in chemistry graduated from University of California-Santa Cruz, United States. He is passionate about scientific communication to introduce cutting-edge researches to both the general public and the scientists with diverse research expertise. He is a web writer for the Chem. Commun. and Chem. Sci. blog websites. More information about him can be found at http://liutianyuresearch.weebly.com/.

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HOT ChemComm articles for June

All of the referee-recommended articles below are free to access until 5th August 2017.

Chemically individual armoured bioreporter bacteria used for the in vivo sensing of ultra-trace toxic metal ions
Zhijun Zhang, Enguo Ju, Wei Bing, Zhenzhen Wang, Jinsong Rena and Xiaogang Qu
Chem. Commun., 2017, Advance Article
DOI: 10.1039/C7CC03794E, Communication

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Expeditious synthesis of pyrano[2,3,4-de]quinolines via Rh(III)-catalyzed cascade C–H activation/annulation/lactonization of quinolin-4-ol with alkynes
Gang Liao, Hong Song, Xue-Song Yinab and Bing-Feng Shi
Chem. Commun., 2017, Advance Article
DOI:  10.1039/C7CC04113F, Communication

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Autonomously propelled microscavengers for precious metal recovery
Sarvesh Kumar Srivastava, Mariana Medina-Sáncheza and Oliver G. Schmidta
Chem. Commun., 2017, Advance Article
DOI: 10.1039/C7CC02605F, Communication

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Aromatic stacking – a key step in nucleation
Aurora J. Cruz-Cabeza, Roger J. Davey, Sharlinda Salim Sachithananthan, Rebecca Smith, Sin Kim Tang, Thomas Vetter and Yan Xiao
Chem. Commun., 2017, Advance Article
DOI: 10.1039/C7CC02423A, Communication

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Hexagonal boron nitride nanosheets as a multifunctional background-free matrix to detect small molecules and complicated samples by MALDI mass spectrometry
Jianing Wang, Jie Sun, Jiyun Wang, Huihui Liu, Jinjuan Xue and Zongxiu Nie
Chem. Commun., 2017, Advance Article
DOI: 10.1039/C7CC02957H, Communication

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Faradaic oxygen evolution from SrTiO3 under nano- and femto-second pulsed light excitation
D. J. Aschaffenburg, X. Chen and T. Cuk
Chem. Commun., 2017,53, 7254-7257
DOI: 10.1039/C7CC03061D, Communication

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Bismuth drug structure solved

Crystal structure of bismuth subgallate viewed along (a) [010] and (b) [100]. Bismuth, carbon and oxygen atoms are coloured purple, grey and red, respectively. Hydrogen atoms and water molecules in the pores have been omitted for clarity.

Bismuth subgallate – a widely used pharmaceutical for treating stomach ulcers – is a porous coordination polymer, new research shows. The discovery, made by scientists in Sweden and the UK, settles a long running question over the drug’s structure, which had been frustrated by bismuth subgallate’s tiny crystals and their tendency to break down when exposed to high energy electron beams.

Now, Andrew Kentaro Inge from Stockholm University and his team have overcome these issues. By combining continuous rotational data collection with a cooling technique, they avoided the electron beam damage, poor resolution and diffuse scattering holding them and others back. ‘Continuous rotation electron diffraction is a promising way to elucidate the structures of hard to obtain, or very hard to crystallise, pharmaceutical forms. For this purpose, it’s an up-and-coming method,’ says Tomislav Friŝĉić, an expert in materials chemistry at McGill University in Canada.

Read the full story by Tabitha Watson on Chemistry World.

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