Deoxyribonucleic acid (DNA) is the genetic material of living organisms. In the past, double-stranded DNA (dsDNA) with its ubiquitous architecture has not been regarded as a catalytic species, since the duplex structure precludes the formation of catalytically competent tertiary structures.[1] To date, although no naturally occurring catalytic DNA has been reported, DNA for nonbiological applications has aroused much interest in chemists for applications in areas such as catalysis, encoding, and stereocontrol.[2] Among these applications, a series of DNA-based asymmetric catalysis have been developed, which use a hybrid catalyst composed of dsDNA and a copper(II) complex.[3] This same strategy was later applied to G-quadruplex DNA (G4DNA) and modest enantioselectivities in the Diels-Alder (D-A) reaction were obtained.[4] Very recently, a G4DNA metalloenzyme composed of G4DNA and copper(II) ions has been reported to be able to catalyze an enantioselective Friedel-Crafts reaction. [5] This biology/chemistry interface is an attractive area of research and awaits further extensive exploration. Herein, we report an enantioselective D-A reaction achieved through the use of human telomeric G4DNA-based catalysts. We show that the absolute configuration of the products can be reversed when the conformation of the G4DNA is switched from antiparallel to parallel. Furthermore, both the reaction rate and the enantioselectivity of the reaction were found to be dependent on the DNA sequence.The D-A reaction is an important carbon-carbon bond forming reaction in organic synthesis. In the past few decades, it has received much attention in the development of innovative catalytic strategies to control the creation of the new carbon-carbon bonds and stereocenters. Among those strategies, biological molecules have been viewed as interesting and promising catalysts.[6] Herein, human telomeric G4DNA (ODN-1, 5'-G 3 (T 2 AG 3 ) 3 -3') was selected owing to its tunable conformation. As an initial attempt, a model D-A reaction [7] between aza-chalcone (1 a) and cyclopentadiene (2) was chosen to probe the catalytic performance of ODN-1. We found that ODN-1 alone in its antiparallel conformation [8] could promote the D-A reaction and the enantiomeric excess of the endo isomer of product 3 a is 17 % (Table 1, entry 2).The enantioselectivity of the ODN-1 promoted D-A reaction is significantly higher than that of the uncatalyzed reaction (Table 1, entry 2 vs. entry 1), which suggests that ODN-1 might function as an enantioselective catalyst for the D-A reaction.We assembled a complex between Cu(NO 3 ) 2 and ODN-1 (ODN-1-Cu 2+ ) and tested its ability to enantioselectively catalyze the D-A reaction. ODN-1-Cu 2+ provides a significant enhancement in the reaction rate ( entry 3). We also observed an excellent diastereoselectivity for product 3 a (endo/exo of 98:2) and a good enantioselectivity (74 % ee). These results suggest that ODN-1-Cu 2+ can serve as a potent catalyst, providing stereoselectivity and enhancement in reaction rates. To furthe...

Electrochemical nitrogen reduction to ammonia is proposed as a promising alternative to the Haber-Bosch process because it can be driven by renewable electricity at ambient conditions. Currently, the development of such a process is hampered by the lack of efficient electrocatalysts for the nitrogen reduction reaction (NRR). Herein, we report a super-rapid approach for the synthesis of flower-like Au microstructures (Au flowers) within 5 s. The obtained Au structures are assembled by staggered nanoplates as building blocks, which provide abundant electrocatalytically active sites for the NRR. The Au flowers achieve a high performance (NH yield: 25.57 μg h mg ; faradaic efficiency: 6.05 %), 100 % selectivity (no N H production), and long-term durability toward the electrochemical ammonia production. The work is highly valuable for the rapid synthesis of active catalysts for the NRR.

Developing high-performance electrocatalysts for hydrogen evolution reaction (HER) is crucial for sustainable hydrogen production, yet still challenging. Here, we report boron-modulated osmium (B-Os) aerogels with rich defects and ultra-fine diameter as a pH-universal HER electrocatalyst. The catalyst shows the small overpotentials of 12, 19, and 33 mV at a current density of 10 mA cm−2 in acidic, alkaline, and neutral electrolytes, respectively, as well as excellent stability, surpassing commercial Pt/C. Operando X-ray absorption spectroscopy shows that interventional interstitial B atoms can optimize the electron structure of B-Os aerogels and stabilize Os as active sites in an electron-deficient state under realistic working conditions, and simultaneously reveals the HER catalytic mechanisms of B-Os aerogels in pH-universal electrolytes. The density functional theory calculations also indicate introducing B atoms can tailor the electronic structure of Os, resulting in the reduced water dissociation energy and the improved adsorption/desorption behavior of hydrogen, which synergistically accelerate HER.

The design of effective electrocatalysts is the critical to electrochemical NH 3 production. Although both theoretical and experimental investigations already reveal that noble metals (e.g., Ru, Au, Rh, Pd) are suitable catalysts for the nitrogen reduction reaction (NRR), [14][15][16][17][18][19] it still remains a great challenge to explore active metallic catalysts to produce NH 3 in a high NH 3 yield and Faradaic efficiency (FE). Recently, porous noble metals have been demonstrated to be effective electrocatalysts for electrochemical energy conversions and storages, [20][21][22] which are very promising to be explored for NRR. Traditionally, porous noble metals are prepared by dealloying method and hard template method. [23,24] However, these synthetic procedures are usually very complicated and time-consuming. Moreover, most of porous metallic materials require to be immobilized on electrode surfaces by using polymer binders (e.g., Nafion) for electrocatalysis, [25][26][27][28] which blocks the active sites and reduces the conductivity. To address these issues, the direct fabrication of porous metallic nanostructures on a conductive substrate is a highly promising strategy. In our previous work, we have developed a electrochemical micelle approach by using triblock copolymer (e.g., F127) for synthesis of porous Pt and Pt/Pd films on a flat ITO substrate. [29,30] However, porous Au film supported on a conductive substrate has rarely been demonstrated because of the difficultly in controlling Au growth in triblock copolymer micelles. Moreover, the fabrication porous Au film on 3D porous metallic foam is very promising for the materials to be directly used as a blinder-free electrode, which is rarely been achieved.In this study, we propose a micelle-assisted electrodeposition method for direct fabrication of porous Au film on Ni foam (pAu/NF) by using diblock copolymer poly(1-vinylpyrrolidone-co-styrene) (PVP-co-PS) micelles as soft template. The binder-free pAu/NF exhibits superior performance for NH 3 production ascribed to its self-supported 3D porous architectonics and active Au composition. Results and DiscussionThe pAu/NF is simply fabricated by a one-step micelle-assisted electrodeposition method (Figure 1). The distinct nanopores with an average pore size of 59.5 nm are observed in the entire Electrochemical reduction of N 2 to NH 3 provides an alternative strategy to replace the industrial Haber-Bosch process for facile and sustainable production of NH 3 . The development of efficient electrocatalysts for the nitrogen reduction reaction (NRR) is highly desired. Herein, a micelleassisted electrodeposition method is presented for the direct fabrication of porous Au film on Ni foam (pAu/NF). Benefiting from its interconnected porous architectonics, the pAu/NF exhibits superior NRR performance with a high NH 3 yield rate of 9.42 µg h −1 cm −2 and a superior Faradaic efficiency of 13.36% at −0.2 V versus reversible hydrogen electrode under the neutral electrolyte (0.1 m Na 2 SO 4 ). The proposed micelle-assi...

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A human telomeric G-quadruplex (G4DNA) metalloenzyme, assembled with G4DNA and Cu(2+) ions, can catalyze the enantioselective Friedel-Crafts (F-C) reaction in water with good enantioselectivity (up to 75% ee). Furthermore, we found that the absolute configuration and the enantioselectivity of the product largely depend on the conformation and the sequence of G4DNA.

A very simple one-step synthetic method is developed for fabrication of PdRu tripods for electrochemical nitrogen reduction to ammonia.

In an ad-hoc retrieval task, the query is usually short and the user expects to find the relevant documents in the first several result pages. We explored the possibilities of using Wikipedia's articles as an external corpus to expand ad-hoc queries. Results show promising improvements over measures that emphasize on weak queries.