Chemical Science Blog

We are happy to present a selection of our HOT articles for January. To see all of our HOT referee-recommended articles from 2019, please find the collection here.

As always, Chemical Science articles are free to access.

Enantioselective [1,3] O-to-C rearrangement: dearomatization of alkyl 2-allyloxy/benzyloxy-1/3-naphthoates catalyzed by a chiral π–Cu(II) complex

Lu Yao, Kazuaki Ishihara*

Chem. Sci., 2019, 10, 2259-2263

DOI: 10.1039/C8SC05601C, Edge Article

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Through-space charge transfer hexaarylbenzene dendrimers with thermally activated delayed fluorescence and aggregation-induced emission for efficient solution-processed OLEDs

Xingdong Wang, Shumeng Wang, Jianhong Lv, Shiyang Shao,* Lixiang Wang,* Xiabin Jing and Fosong Wang

Chem. Sci., 2019, Advance Article

DOI: 10.1039/C8SC04991B, Edge Article

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Heterolytic bond activation at gold: evidence for gold(III) H–B, H–Si complexes, H–H and H–C cleavage

Luca Rocchigiani,* Peter H. M. Budzelaar* and Manfred Bochmann*

Chem. Sci., 2019, 10, 2633-2642

DOI: 10.1039/C8SC05229H, Edge Article

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Insights into mechanochemical reactions at the molecular level: simulated indentations of aspirin and meloxicam crystals

Michael Ferguson, M. Silvina Moyano, Gareth A. Tribello, Deborah E. Crawford, Eduardo M. Bringa, Stuart L. James,* Jorge Kohanoff* and Mario G. Del Pópolo*

Chem. Sci., 2019, Advance Article

DOI: 10.1039/C8SC04971H, Edge Article

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Structure revision of cryptosporioptides and determination of the genetic basis for dimeric xanthone biosynthesis in fungi

Claudio Greco, Kate de Mattos-Shipley, Andrew M. Bailey, Nicholas P. Mulholland, Jason L. Vincent, Christine L. Willis, Russell J. Cox* and Thomas J. Simpson*

Chem. Sci., 2019, Advance Article

DOI: 10.1039/C8SC05126G, Edge Article

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From nano-balls to nano-bowls

Helena Brake, Eugenia Peresypkina, Claudia Heindl, Alexander V. Virovets, Werner Kremer and Manfred Scheer*

Chem. Sci., 2019, Advance Article

DOI: 10.1039/C8SC05471A, Edge Article

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Sunlight-assisted water splitting represents a sustainable way to convert solar energy into chemical energy in hydrogen and oxygen gases. Due to its high activation energy, the oxygen evolution reaction (OER) requires large overpotential for initiation. Developing suitable OER catalysts to reduce the overpotential thus becomes instrumental for the feasibility of solar energy harvesting.

Recently, a group of scientists led by Rui Cao from Renmin University of China, and Shaanxi Normal University, China, has developed a water-soluble Cu(II)-porphyrin complex as a high-performance OER catalyst. This breakthrough has been published in Chemical Science (DOI: 10.1039/C8SC04529A).

Inspired by the molecular structure of a natural OER catalyst in the photosynthesis system – photosystem II (PSII), the researchers designed a Cu²⁺-coordination compound with a porphyrin ligand, tetrakis(4-N-methylpyridyl)porphyrin (Figure 1a), which mimics the structure of PSII. This biomimetic Cu²⁺-complex exhibits outstanding catalytic OER activity in a phosphate buffer solution at pH=7.0. The current of the cyclic voltammogram of the Cu²⁺-complex increases sharply (due to O₂ evolution) at an onset potential of 1.13 V vs. normal hydrogen electrode (Figure 1b), corresponding to an OER overpotential of 310 mV. For comparison, the cyclic voltammograms of a blank buffer solution and a CuSO₄-containing buffer solution show no pronounced current enhancement (Figure 1b), indicating the electrolyte itself and the un-coordinated Cu²⁺ cannot generate O₂ within the tested potential range. The 310 mV overpotential is approximately two times smaller than the typical values exhibited by previously reported Cu complexes.

Figure 1. (a) The molecular structure of Cu²⁺-tetrakis(4-N-methylpyridyl)porphyrin complex. (b) Cyclic voltammograms of 1 mM Cu²⁺-tetrakis(4-N-methylpyridyl)porphyrin (red), bare buffer solution (black) and buffer solution containing 1 mM CuSO₄ (green). The electrode is a piece of fluorine-doped tin oxide glass slide.

The authors ascribed the ultra-small OER overpotential to the formation of an oxidized form of the Cu²⁺-porphyrin complex. This oxidized species is generated after the complex loses one electron, and is active for O-O bond formation and subsequent O₂ evolution. The energy barrier of this one-electron-oxidation pathway is expected to be much lower than those of conventional processes involving higher-valent Cu species (e.g., Cu⁴⁺-oxo), which facilitates OER at small overpotential.

With the complete catalytic cycle of water oxidation by the Cu²⁺-porphyrin complex being fully revealed, OER will become more efficient and energy-saving.

To find out more please read:

Low Overpotential Water Oxidation at Neutral pH Catalyzed by A Copper(II) Porphyrin

Yanju Liu, Yongzhen Han, Zongyao Zhang, Wei Zhang, Wenzhen Lai, Yong Wang and Rui Cao

Chem. Sci., 2019, DOI: 10.1039/C8SC04529A

About the blogger:

Tianyu Liu obtained his Ph.D. (2017) in Chemistry from University of California, Santa Cruz in the 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 blog writer for Chem. Commun. and Chem. Sci. More information about him can be found at http://liutianyuresearch.weebly.com/.