Angewandte Chemie最新文献

We report in this paper the first total synthesis of discobahamin A, a 24-membered macrocyclopeptide containing an α-keto amide functional group. We assign the absolute configuration of 2-hydroxy-3-methylpentanoic acid (Hmp), the side chain capping the N-terminus of the macrocycle, as the (2S, 3S) stereoisomer. A novel macrocyclization strategy was developed, utilizing an intramolecular Passerini reaction between ω-isocyano aldehyde and acetic acid. Notably, this macrocyclization proceeds via C(sp³)-C(sp²) bond formation and de novo generation of an α-keto amide functional group. Furthermore, we synthesized both the proposed structure of discobahamin B and its diastereomer. However, the spectroscopic data for these two compounds do not fully align with those reported for discobahamin B.

“My favorite molecule is thioctic acid… The scientific challenge that I am dreaming to overcome is to make life-like macromolecular machines with abiological molecules…” Find out more about Qi Zhang in his Introducing… Profile.

Solar-driven hydrogen production is regarded as one of the most ideal methods to achieve a sustainable society. In order to artificially establish efficient photosynthetic systems, efforts have been made to develop single-molecular photocatalysts capable of serving both as a photosensitizer (PS) and a catalyst (Cat) in hydrogen evolution reaction (HER). Although examples of such hybrid molecular photocatalysts have been demonstrated in the literature, their solar energy conversion efficiencies still remain quite limited. Here we demonstrate that a new dinuclear platinum(II) complex Pt₂(bpia)Cl₃ (bpia=bis(2-pyridylimidoyl)amido) serves as a single-molecular photocatalyst for HER with its performance significantly higher than that of the PtCl(tpy)- and PtCl₂(bpy)-type photocatalysts developed in our group (tpy=2,2':6′,2''-terpyridine, bpy=2,2′-bipyridine). The outstanding feature is that Pt₂(bpia)Cl₃ can produce H₂ even by irradiating the lower-energy light above 500 nm, which is rationalized due to the direct population of triplet states via singlet-to-triplet transitions (i.e., S-T transitions) accelerated by the diplatinum core. To the best of our knowledge, Pt₂(bpia)Cl₃ is the first example of a single-molecular photocatalyst enabling hydrogen production from water via the S-T transitions using lower-energy light (>580 nm).

“The advice I wish I had received is that coming up with research ideas is a skill like any other. Practice makes perfect!… The most exciting thing about my research is being the first person in the world to discover something…” Find out more about Natalie Boehnke in her Introducing… Profile.

In their Research Article (e202419688), André Schäfer and co-workers report the synthesis and structures of pentaisopropylcyclopentadienyl gallium(I), -indium(I) and -thallium(I) and explore their donor ability in the formation of heterobimetallic complexes. A series of tungsten pentacarbonyl complexes, as well as a heterobimetallic polydecker were isolated.

Prediction of a liquidus state with lower entropy than the corresponding solid at Kauzmann temperature (T_k), and associated entropy catastrophe/paradox, remains an enigma. Despite efforts to resolve this paradox for nearly 80 years, no unifying resolution has been reported. Potential resolutions to the Kauzmann paradox rely on an ideal glass transition, however, this limits the interpretation of T_k as an equilibrium critical point rather than an instability. Focusing on entropy, statistical mechanics and non-equilibrium dynamics becomes a key tenet in resolving this paradox. Expansion in phase space beyond 2D and consideration of T_k as a non-equilibrium critical point is necessary to understand the extent of liquid relaxation beyond T_k. In this review, we provide an entropic perspective of the relaxation behavior of supercooled liquids, associated expanded phase diagram, and the potential resolution to the Kauzmann paradox. This work integrates the historical evolution of our understanding of entropy/thermodynamics with modern interpretation of quantum states through renormalization group and thermodynamic speed limits.

A revised Supporting Information (SI) file for this manuscript has been provided correcting the following issue: All the calculations supporting the experimental observations have been carried out for toluene as the solvent (which was the solvent in the experiments). In the main manuscript this was correctly stated but in the SI we accidentally stated THF as the solvent considered for the calculations. This mistake was now corrected throughout the whole SI.

Paired electrosynthetic technology is of significance to realize the co-production of high-added value chemicals. However, exploiting efficient bifunctional electrocatalyst of the concurrent electrocatalysis to achieve the industrial-level performance is still challenging. Herein, an amorphous Co₂P@MoO_x heterostructure is rationally designed by in situ electrodeposition strategy, which is acted as excellent bifunctional catalysts for the electrocatalytic nitrite reduction reaction (NO₂RR) and glycerol oxidation reaction (GOR). The membrane-electrode assembly (MEA) electrolyzer realizes a low voltage of 1.30 V, robust stability over 200 h at 100 mA cm⁻², high Faraday efficiencies and yield of NH₃ (above 95 %, 49.7 mg h⁻¹ cm⁻²) and formate (above 95 %, 304.4 mg h⁻¹ cm⁻²) at industrial-level current density of 500 mA cm⁻². In situ spectroscopy studies have shown that high-valence CoOOH is the main active material of GOR, and the main catalytic conversion pathway of NO₂RR involves key *NH₂OH reaction intermediates. In addition, theoretical calculations confirm that the Co₂P@MoO_x heterostructure has strong interfacial electronic interaction and optimized reaction energy barriers, which endows its intrinsically high electrocatalytic activity for the co-electrosynthesis of NH₃ and formate.

Charged channels are considered an effective design for achieving efficient monovalent cation transport; however, it remains challenging to establish a direct relationship between charge microenvironments and ionic conductivity within the pores. Herein, we report a series of crystalline covalent organic frameworks (COFs) with identical skeletons but different charge microenvironments and explore their intra-pore charge-driven ion transport performance and mechanism differences. We found that the charged nature determines ion-pair action sites, modes, host-guest interaction, thereby influencing the dissociation efficiency of ion pairs, the hopping ability of cations, and the effective carrier concentration. The order of transport efficiency for Li⁺, Na⁺, and H⁺ follows anion > zwitterion > cation > neutrality. Ionic COFs exhibit up to 11-fold higher ionic conductivity than neutral COFs. Notably, the ionic conductivity of anionic COF achieves 2.0 × 10⁻⁴ S cm⁻¹ for Li⁺ at 30 °C and 3.8 × 10⁻² S cm⁻¹ for H⁺ at 160 °C, surpassing most COF-based ionic conductors. This COF platform for efficient ion migration and stable battery cycling in lithium-metal quasi-solid-state batteries has also been verified as proof of concept. This work offers new insights into the development and structure-activity relationship studies of the next generation of solid-state ionic conductors.

Photocatalytic seawater splitting into hydrogen and hydrogen peroxide (2H₂O→H₂↑ + H₂O₂) offers an ultimate solution for simultaneously generating green fuel and value-added chemicals by the two most earth-abundant resources i.e., solar energy and natural seawater. In this study, Pd nanoparticles are integrated with one-dimensional gallium nitride nanowires (Pd NPs/GaN NWs) on a silicon wafer to produce H₂ and H₂O₂ from seawater powered by sunlight. In situ spectroscopic characterizations combined with computational investigations reveal that in this nanohybrid, Pd NPs function as an efficient hole extractor and *OH alleviator during photocatalysis. Meanwhile, the chloride ions in seawater facilitate the H₂O→ H₂ + H₂O₂ conversion by improving the charge dynamics and lowering the energy barrier of the key *OH self-coupling step over Pd sites in the catalytic system. As a result, the photocatalyst delivers an appreciable hydrogen production rate of 2.5 mmol⋅cm⁻²⋅h⁻¹ with a light-to-hydrogen (LTH) efficiency of 4.38 % in natural seawater under concentrated light irradiation of 3 W⋅cm⁻² without sacrificial agents and external energies. Notably, the water oxidation reaction produces 300 μmol/L of valuable H₂O₂ over a duration of 2 hours under a light intensity of 3 W/cm² using a 20 mL water sample, achieving a light-to-chemical efficiency of 0.53 %. The photocatalyst shows excellent stability for up to 60 hours with a considerable turnover number of 1.42×10⁷ moles H₂ per mole of Pd. The outdoor test further suggests the great potential for solar-driven seawater splitting into green fuels and chemicals.