Tuning the Size of Metal-Organic Framework Crystals by Decoupling Nucleation and Growth Processes

A group of scientists from Tsinghua University in China have made a breakthrough in enhancing the controllability of the metal-organic framework (MOF) crystal size.

MOF represents a family of microporous crystals consisting of metal node-organic ligand coordination networks. They have shown potential in versatile applications including hydrogen storage, catalysis and electrochemical energy storage. Since their performance strongly correlates to the crystal size, synthesizing MOF crystals with tunable sizes and high yields is necessary to allow fundamental studies on the size-performance relationship. Unfortunately, the conventional size-controlling methods either require complex operations or exhibit low yields.

Now in ChemComm, Tiefeng Wang and coworkers demonstrate a method that can easily tune the size of MOF crystals. The mechanism is based on decoupling nucleation and growth processes. Unlike traditional strategies that mingle all metal precursors and organic ligands together in a solvent, this newly developed protocol initially mixes only a small portion of metal precursors with organic ligands. The metal precursors quickly coordinate with surrounding ligands to form small MOF clusters (the “nucleation” stage). Due to the limited supply of the metal precursors, the growth of these clusters into large crystals is unfavorable. Subsequently, the remaining metal precursors are introduced into the cluster-containing solution. The clusters then continue to grow into MOF crystals (the “growth” stage). Because the crystals develop directly from the small clusters (i.e. the seeds), the number of the seeds and the total concentration of the added metal precursors control the resulting MOF crystal size (Figure 1).

 

Figure 1. A schematic illustration of the growth of MOF crystals via a typical conventional method (top) and the reported decoupling method (down).

Using this method, the authors prepared a series of Pt@ZIF-8 MOF crystals (with sizes ranging from 45 nm to 440 nm) and investigated their ability to catalyze the reaction of 1-hexene hydrogenation. The catalytic activity of different sized crystals was quantified, with a linear correlation observed between the size and the activity (Figure 2).

Figure 2. The linear relationship between the Pt@ZIF-8 MOF size (r) and the hydrogenation reaction rate (D). r0 and D0 represent the size and the reaction rate of the smallest MOF (45 nm).

This reported approach is expected to be applicable for synthesizing MOF crystals other than Pt@ZIF-8. The availability of size-tunable MOFs will facilitate mechanistic studies in determining the optimal crystal size for different applications.

To find out more please read:

A General and Facile Strategy for Precisely Controlling the Crystal Size of Monodispersed Metal-Organic Frameworks via Separating the Nucleation and Growth

Xiaocheng Lan, Ning Huang, Jinfu Wang and Tiefeng Wang

Chem. Commun. 2017, DOI: 10.1039/c7cc08244d

About the blogger:

Tianyu Liu obtained his Ph.D. (2017) in Physical Chemistry from University of California, Santa Cruz in United States. He is passionate about scientific communication to introduce cutting-edge research to both the general public and scientists with diverse research expertise. He is an online blog writer for Chem. Commun. and Chem. Sci. More information about him can be found at http://liutianyuresearch.weebly.com/.

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ChemComm Emerging Investigators 2018 – Call for Papers

Profiling the very best research from scientists in the early stages of their independent careers

We were delighted to publish the 2017 ChemComm Emerging Investigators issue last year and we continue to be overwhelmed by the community’s positive response. We are now excited to announce the forthcoming 2018 ChemComm Emerging Investigators issue.

This special issue, now on its eighth year, showcases high quality research being carried out by international researchers in the early stages of their independent careers. This annual issue features principal investigators whose work has the potential to influence future directions in science or result in new and exciting developments.

If you are interested in submitting to this issue please contact the ChemComm Editorial Office in the first instance and please take a look at the excellent research and Feature articles published by your peers in our previous issues in 20112012, 2013, 2014, 2015 and 2016.

Please note that authors must not have featured in a previous ChemComm Emerging Investigators issue. The deadline for submission to this issue is 27 March 2018.

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Molecular box treats chemists to a strained surprise

Introducing pillar[4]pyridinium – the first of a new family of macrocycles

Pillar[4]pyridinium
Source: Grzegorz Sobczak Oksana Danylyuk and Volodymyr Sashuk

Scientists in Poland have made the most compact multiply charged macrocycle to date. Pillar[4]pyridinium is a cyclic tetramer consisting of four pyridyl units with methylene bridges between their nitrogens and para carbons. The quadruply charged molecule has a very symmetrical and incredibly strained structure. It represents a new class of cationic macrocycles, the pillar[n]pyridiniums.

Read the full story by Jennifer Newton on Chemistry World.

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ChemComm Prizewinners at the 44th Symposium on Main Group Element Chemistry

The 44th Symposium on Main Group Element Chemistry took place on the 7th to 9th December at the Tokyo Institute of Technology. Over 250 delegates attended the symposium which was chaired by Prof Kei Goto (TITech).

ChemComm was proud to sponsor two prizes, which were chosen out of 60 oral presentations and 108 poster presentations.

The winner of the ChemComm oral presentation was Mr Shogo Morisako (Graduate School of Science, Hiroshima University) who presented on ‘Syntheses and Reactivities of New Multiple Bond Boron Compounds’.

Mr Shogo Morisako

Mr Shogo Morisako (left) being presented his award by Dr Hiromitsu Urakami (right) on behalf of Chemical Communications

The winner of the ChemComm poster presentation was Mr. Tomoyuki Kosai (Graduate School of Science, Tohoku University) who presented on ‘Activation of Dihydrogen Using Disilenes Bearing Amino and Boryl Groups’.

Tomoyuki Kosai

Mr Tomoyuki Kosai (left) being presented his award by Dr Hiromitsu Urakami (right) on behalf of Chemical Communications

Congratulations to both Mr Morisako and Mr Kosai, we wish you both the best for the future!

 

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Suzuki–Miyaura–hydrogenation targets 3D drugs

Scientists in the UK have unveiled a way to make pharmaceutical molecules with increased 3D characteristics. The single pot Suzuki–Miyaura–hydrogenation reaction results in sp2–sp3 linked pharmaceutically relevant molecules.

Source: Royal Society of Chemistry
A single pot Suzuki–Miyaura-hydrogenation can be used to furnish lead and fragment-like products in good to excellent yields

The number of tetrahedral carbon atoms, or how 3D a molecule is, is one factor that determines the success of a molecule in clinical drug trials. Molecules with a high sp3 fraction are in demand, however current methods to make them suffer drawbacks. The Suzuki–Miyaura reaction is common for the cross-coupling of sp2–sp3 systems, but alkyl boron or alkyl halides are prone to β-elimination and other side reactions, producing mixtures of products.

Read the full story by Suzanne Howson on Chemistry World.

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In-Vivo Visualization of Glucose Metabolism with a Two-Color Imaging Technique

A group of scientists from Columbia University in United States have developed a state-of-the-art probing technique that can simultaneously map glucose uptake and incorporation activities in living cells.

Glucose is a ubiquitous “fuel” for most living organisms. Its metabolism, including uptake and incorporation, is vital to sustain the energy consumption of living organisms. Visualization of glucose metabolism is of critical importance for clinical diagnostics and fundamental biological researches. However, current imaging techniques are destructive to living cells, poorly resolved or incapable of probing uptake and incorporation at the same time.

Now in ChemComm, Prof. Min Wei’s research team demonstrates a breakthrough based on a vibrational imaging technique coupled with stimulated Raman scattering microscopy. This technique utilizes two glucose analogues to present the glucose metabolism, the 13C-labelled 3-O-propargyl-D-glucose (3-OPG-13C3) for glucose uptake and the D7-glucose for glucose incorporation. Conventional Raman spectroscopy is unable to distinguish the aforementioned two species due to their overlapping Raman peaks. The authors addressed this challenge by labelling 3-OPG with 13C that exhibits a blue shifted Raman peak, thus separating it from the peak of D7-glucose. Decoupling of the two peaks allows in-vivo imaging and simultaneous observation of glucose uptake and incorporation in cells with sub-cellular resolution.

Figure 1 shows the two-color mapping images collected for human cancer cells, PC-3. The blue (panel a) and red (panel b) areas display the regions where glucose incorporation and uptake are taking place, respectively. The two images can be easily obtained by tuning the wavenumber of the incident light to match with corresponding Raman peak positions. Use of light with other wavenumbers results in the black image (panel c) containing virtually no colored regions, showing the excellent selectivity of the technique. Additionally, this approach differentiates between cancer cells and healthy cells by comparing the blue to red color intensity ratio.

This novel and versatile imaging technique is expected to serve as a useful tool in advanced bio-imaging and future cancer diagnostics.

Figure 1. Two-color mapping images of PC-3 cells highlighting the (a) glucose-incorporation regions (Raman peak: 2133 cm-1) and (b) glucose-uptake regions (Raman peak: 2053 cm-1). (c) An image collected with a wavenumber (2000 cm-1) that does not match with either of the Raman peaks. Scale bar: 20 µm.

 

To find out more please read:

Two-color Vibrational Imaging of Glucose Metabolism Using Stimulated Raman Scattering

Rong Long, Luyuan Zhang, Lingyan Shi, Yihui Shen, Fanghao Hu, Chen Zeng and Wei Min

Chem. Commun. 2018, DOI: 10.1039/C7CC08217G

About the blogger:

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

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Binder-free Integration of Bismuth Nanoflakes onto Nickel Foams for Sodium-ion Batteries

A new type of bismuth-based electrode material for sodium-ion batteries has been synthesized. This electrode consists of bismuth metal nanoflakes seamlessly integrated onto nickel foams. The electrode contains no polymer binders, a crucial component required to retain the structural integrity of most battery electrodes. This binder-free feature improves the amount of charge being stored (i.e. capacity) at fast charging rates.

Sodium-ion batteries are attracting worldwide research efforts as electric energy storage devices, in addition to the prevalent lithium-ion batteries, due to the abundance of sodium. Similar to the preparation of other battery electrodes, fabricating sodium-ion battery electrodes generally requires binders, e.g. polyvinylidene fluoride (PVDF), to hold powdered electrode materials together and glue them to metal supporting substrates. However, the electrically insulating nature of the binders impedes fast electron transport between electrode materials and supporting substrates, consequently degrading the capacity of the batteries at fast charging rates.

Now in ChemComm, researchers from Nankai University & the Collaborative Innovation Center of Chemical Science and Engineering in China demonstrate a bismuth-based electrode material that does not involve a binder. This characteristic is realized by the in-situ growth of bismuth nanoflakes onto nickel foams through a solution-based replacement reaction (Figure 1). Because the nanoflakes grow directly from the nickel foam surface and firmly anchor onto nickel (Figure 2a), the resultant Bi/Ni composite can be directly used as an electrode. Specifically, the bismuth nanoflakes and nickel foam serve as the active material and supporting substrate, respectively.

The Bi/Ni composite exhibited excellent electrochemical performance. It achieved a high capacity of 377.1 mAh/g at a current density of 20 mA/g. Significantly, when the current density increased 100-fold, its capacity could still retain 206.4 mAh/g, which is more than half of the capacity obtained at 20 mA/g (Figure 2b). This outstanding capacity retention is a benefit of the binder-free characteristic that reduces the resistance of electron transport.

The authors then elucidated the working mechanism of the bismuth nanoflakes by in-situ Raman spectroscopy. They concluded that a two-step alloying process was responsible for the charge storage activity.

Figure 1. A schematic illustration showing the synthetic process of the binder-free Bi/Ni electrode. By inserting a piece of nickel foam into an ethylene glycol (EG) solution containing bismuth(III) nitrate, Bi3+ can replace Ni metal, be reduced to Bi metal and deposit on the Ni metal surface.

 

Figure 2. (a) A scanning electron microscopy image of the bismuth nanoflakes. (b) A plot showing the capacity of the Bi/Ni electrode at different current densities.

 

The successful synthesis of the binder-free electrode is expected to encourage future works on the design and synthesis of integrated electrode materials to advance the performance of sodium-ion batteries.

 

To find out more please read:

In situ Synthesis of Bi Nanoflakes on Ni Foam for Sodium-ion Batteries

Liubin Wang, Chenchen Wang, Fujun Li, Fangyi Cheng and Jun Chen

Chem. Commun. 2017, DOI: 10.1039/c7cc08341f

About the blogger:

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

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Tactile alternative to colour changes

Many instrument-free analytical methods, such as pH test strips and home pregnancy tests, indicate their results with a colour change. Now scientists in the US have devised a system that outputs a signal you can feel as well as see.

Source: Royal Society of Chemistry
Visual and tactile detection of ATP – gel shapes indicate a positive result.

Read the full story by Jennifer Newton on Chemistry World.

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Telescope arrangement puts a twist on organic synthesis

Scientists have adapted a technique more commonly used for making crisps and mixing polymers so that it can perform complex multi-component organic reactions in a single step without the need for a solvent.

Source: Royal Society of Chemistry, Laboratory-scale twin screw extruder

Fine chemicals such as drugs, food additives and fragrances are typically made through complex processes with many intricate reaction steps. These steps can be time-consuming and expensive, and often require solvents that are harmful to the environment. But mechanochemistry, where mechanical forces initiate chemical reactions, could side-step such problems.

Read the full story by Thomas Foley on Chemistry World.

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ChemComm poster prize winners at the Pan Africa Chemistry Network Congress

The Pan Africa Chemistry Network (PACN) Congress was held on 7 – 9 November in Accra, Ghana and was attended by approximately 250 researchers and policy-makers.

The PACN Congress is the flagship annual event for the PACN, which seeks to create a self-sustaining science based in Africa, helping to build capacity, solve local challenges and contribute to global knowledge. The topic for this year’s Congress was ‘Sustainable Agriculture: how the chemical sciences can contribute to food security for a growing population’.

ChemComm is proud to have supported the poster prizes for this wonderful event and the 1st prize was awarded to Francis Asiam, from KNUST in Ghana, for his poster entitled ‘Collection, distribution, extraction and characterisation of vegetable oils from 40 varieties of high yielding Allanblackia parviflora in Ghana’. A full list of the poster prize recipients and poster titles can be found below.

Well done to all of the well-deserved winners!

 

PACN Prize 1st place: Francis Asiam (KNUST, Ghana) for ‘Collection, distribution, extraction and characterisation of vegetable oils from 40 varieties of high yielding Allanblackia parviflora in Ghana

PACN Prize 2nd place: EA Asamoah (KNUST, Ghana) for ‘Development of Rabbit Meat Sausages’

PACN Prize, 3rd place: Ray Voegborlo (KNUST, Ghana) for ‘Human Exposure Assessment of Ochratoxin A through consumption of cocoa beans’

Agilent supported prize: Nkechinyere Isienyi (Forestry Research Institute of Nigeria) for ‘Impact of heavy metal on soil near Lapite dumpsite in Ibadan, Nigeria’

Syngenta supported prize: Flaure Essoung (ICIPE, Kenya) for ‘Welwitschianol A and B: Two cyclohexene derivatives and other insecticidal constituents of Caesalpinia Welwitschiana’

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