Coordinated Axial Ligand and d‐π Conjugated Network Makes the Difference: Engineered 2D Mn‐Based Antioxidase Mimic for Enhancing Stem Cell Protection

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Coordinated Axial Ligand and d-π Conjugated Network Makes the Difference: Engineered 2D Mn-Based Antioxidase Mimic for Enhancing Stem Cell Protection

This highlight features a recently reported rational construction of antioxidase-like active site, Mn-N5, having axial ligands and 2D d-π-conjugated network that robustly scavenge reactive oxygen species and provide cytoprotection to stem cells and transcription of osteogenesis-related genes.


Abstract

Reactive oxygen species (ROS) refer to various partially reduced oxygen moieties that are naturally generated due to biochemical processes. Elevated formation of ROS leads to damage to biomolecules, resulting in oxidative stress and cell death. The increased level of ROS also affects therapeutics based on stem cell transplantation. Nanomaterials-based enzyme mimetics have attracted immense attention, but there are several challenges to be addressed in terms of selectivity, efficiency, and biocompatibility. This highlight focuses on a recent investigation by Cheng and coworkers, who engineered an Mn-superoxide dismutase (Mn-SOD)-inspired material with Mn-N5 sites having an axial ligand and 2D d-π-conjugated network. This engineering approach enhances antioxidase-like function and effectively rescues stem cells from ROS. In addition, it also protects osteogenesis-related gene transcription, ensuring survival rates and osteogenic differentiation of hMSCs under ROS environment. This versatile and robust artificial antioxidase holds promise for stem cell therapies and ROS-originated diseases.

Study on the sensing characteristics of two‐dimensional material WTe2 to toxic gases HF and Cl2

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Study on the sensing characteristics of two-dimensional material WTe2 to toxic gases HF and Cl2

The gas sensing characteristics of monolayer WTe2 to toxic gases are studied by doping atoms, applying vertical electric field and drawing current–voltage curve, which provides important reference value for the development of gas sensors and the detection and recovery of toxic gases in the future.


Abstract

The adsorption characteristics of gas molecules HF and Cl2 on monolayer WTe2 surface are studied by first-principles calculation method. The results show that monolayer WTe2 is more sensitive to gas molecule Cl2. The adsorption performance of monolayer WTe2 to gas molecule HF cannot be improved by doping atoms. When the upward vertical electric field is applied, the sensitivity of monolayer WTe2 to gas molecule Cl2 is improved, and when the downward vertical electric field is applied, the monolayer WTe2 shows an obvious desorption trend to gas molecule Cl2. The vertical electric field cannot significantly enhance the interaction between gas molecule HF and Ag-doped monolayer WTe2. Our research confirms that monolayer WTe2 is more sensitive to gas molecule Cl2 and can be improved or desorbed by the vertical electric field, while that of monolayer WTe2 for gas molecule HF cannot significantly change. Furthermore, the electrical transport characteristics of monolayer WTe2 and Cl2-WTe2 system are studied to better explain the reason for the higher sensitivity to gas molecule Cl2. The research results of this paper provide theoretical guidance for the experimental preparation of high sensitivity gas sensor based on two-dimensional transition metal dichalcogenide WTe2.

Macroporous Hydrogels Prepared By Ice Templating: Developments And Challenges

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Macroporous Hydrogels Prepared By Ice Templating: Developments And Challenges†

This review expects to give an overview on macroporous hydrogels prepared by the ice templating, namely, cryogels. Recent progresses on emerging cryo-porogenation methods are introduced. Future opportunities on the application of cryogels are prospected. More importantly, the fundamental understanding concerning the behavior of the polymer chains during the formation of ice is proposed.


Comprehensive Summary

Macroporous hydrogels are water-swollen polymer networks with porous structures beyond the mesh size. They provide high specific surface areas and hieratical mass transfer channels which are desired for emerging applications including cell culturing, bio-separation, and drug delivery. A variety of approaches have been developed to fabricate macroporous hydrogels, including gas foaming, porogen templating, phase separation, 3D printing, etc. Alternatively, ice templating utilizes the crystallization of water as the porogenation mechanism which doesn't need the leaching of porogens. The porous structures can be easily manipulated by controlling the morphology of ice (size, orientation, etc.) upon freezing. In addition, mechanical properties of obtained porous hydrogels are commonly better than those of other macroporous hydrogels since the pore walls are made up of concentrated polymers through the freezing step. These three characteristics, that is, the green process, the highly tunable morphology, and the enhanced mechanical strength make the ice templating a superior porogenation method. This review expects to give an overview on macroporous hydrogels prepared by the ice templating, namely, cryogels. Recent progresses on emerging cryo-porogenation methods are introduced. Fundamental understanding concerning the behavior of the polymer chains during the formation of ice is proposed. Future opportunities on the application of cryogels are prospected.

Facile Modification on Buried Interface for Highly Efficient and Stable FASn0.5Pb0.5I3 Perovskite Solar Cells with NiOx Hole‐Transport layers

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Facile Modification on Buried Interface for Highly Efficient and Stable FASn0.5Pb0.5I3 Perovskite Solar Cells with NiOx Hole-Transport layers†

It's reported that a method using alkali metal bromide (NaBr, KBr, CsBr) as a modification layer was used to prepare a highly efficient and stable FA-based Sn-Pb PSC with NiO x HTL and the device with CsBr buffer layer achieved an outstanding PCE of 19.48%.


Comprehensive Summary

Formamidinium (FA)-based Sn-Pb perovskite solar cells (FAPb0.5Sn0.5I3 PSCs) with ideal bandgap and impressive thermal stability have caught enormous attention recently. However, it still suffers from the challenge of realizing high efficiency due to the surface imperfections of the transport materials and the energy-level mismatch between functional contacts. Herein, it is demonstrated that the modification on buried interface with alkali metal salts is a viable strategy to alleviate these issues. We systematically investigate the role of three alkali metal bromide salts (NaBr, KBr, CsBr) by burying them between the NiO x hole transport layer (HTL) and the perovskite light-absorbing layer, which can effectively passivate interface defects, improve energy-level matching and release the internal residual strain in perovskite layers. The device with CsBr buffer layer exhibits the best power conversion efficiency (PCE) approaching 20%, which is one of the highest efficiencies for FA-based Sn-Pb PSCs employing NiO x HTLs. Impressively, the long-term storage stability of the unencapsulated device is also greatly boosted. Our work provides an efficient strategy to prepare desired FA-based ideal-bandgap Sn-Pb PSCs which could be applied in tandem solar cells.

Palladium‐Catalyzed Denitrogenative Self‐carbonylation of Arylhydrazine Using CO and O2 as an Ideal Oxidant

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Palladium-Catalyzed Denitrogenative Self-carbonylation of Arylhydrazine Using CO and O2 as an Ideal Oxidant†

Pd/Cu-catalyzed denitrogenative self-carbonylation of arylhydrazine hydrochlorides to synthesize symmetrical biaryl ketones under CO/O2 pressure has been developed. The arylhydrazine hydrochlorides are used as a green arylating agent which releases nitrogen and water as byproducts. This developed protocol significantly restricts the formation of aryl iodide and azobenzene products even under favorable conditions. Additionally, this protocol provides a series of symmetric carbonylative ketones with a wide variety of functional group tolerance under CO/O2 pressure.


Comprehensive Summary

An efficient Pd/Cu-catalyzed oxidative self-carbonylation of arylhydrazine with CO and molecular oxygen as an oxidant to afford symmetrical biaryl ketones via C—N bond activation has been developed. In this approach, arylhydrazine hydrochlorides are used as a green arylating agent which releases nitrogen and water as byproducts. This developed protocol significantly restricts the formation of aryl iodide and homo-coupled azobenzene products even under favorable conditions. A library of symmetrical biaryl ketones with wide functionalities was synthesized in good yields under mild conditions.

Crystal structures and P–T phase diagrams of SrC2$$ {}_2 $$O5$$ {}_5 $$ and BaC2$$ {}_2 $$O5$$ {}_5 $$

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Abstract

In this study, we present the results of a search for new stable structures of SrC2$$ {}_2 $$O5$$ {}_5 $$ and BaC2$$ {}_2 $$O5$$ {}_5 $$ in the pressure range of 0–100 GPa based on the density functional theory and crystal structure prediction approaches. We have shown that the recently synthesized pyrocarbonate structure SrC2$$ {}_2 $$O5$$ {}_5 $$-P21/c$$ P{2}_1/c $$ is thermodynamically stable for both SrC2$$ {}_2 $$O5$$ {}_5 $$ and BaC2$$ {}_2 $$O5$$ {}_5 $$. Thus, SrC2$$ {}_2 $$O5$$ {}_5 $$-P21/c$$ P{2}_1/c $$ is stable relative to decomposition reaction above 10 GPa, while the lower-pressure stability limit for BaC2$$ {}_2 $$O5$$ {}_5 $$-P21/c$$ P{2}_1/c $$ is 5 GPa, which is the lowest value for the formation of pyrocarbonates. For SrC2$$ {}_2 $$O5$$ {}_5 $$, the following polymorphic transitions were found with increasing pressure: P21/c→Fdd2$$ P{2}_1/c\to Fdd2 $$ at 40 GPa and 1000 K, Fdd2→C2$$ Fdd2\to C2 $$ at 90 GPa and 1000 K. SrC2$$ {}_2 $$O5$$ {}_5 $$-Fdd2$$ Fdd2 $$ and SrC2$$ {}_2 $$O5$$ {}_5 $$-C2$$ C2 $$ are characterized by the framework and layered structures of [CO4$$ {}_4 $$]4−$$ {}^{4-} $$ tetrahedra, respectively. For BaC2$$ {}_2 $$O5$$ {}_5 $$, with increasing pressure, decomposition of BaC2$$ {}_2 $$O5$$ {}_5 $$-P21/c$$ P{2}_1/c $$ into BaCO3$$ {}_3 $$ and CO2$$ {}_2 $$ is observed at 34 GPa without any polymorphic transitions.

Photoexcited Carrier Transfer in CuInS2 Nanocrystal Assembly by Suppressing Resonant‐Energy Transfer

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Photoexcited Carrier Transfer in CuInS2 Nanocrystal Assembly by Suppressing Resonant-Energy Transfer

Photoexcited carrier transfer in high-density assemblies of Cd- and Pb-free semiconductor nanocrystals of chalcopyrite CuInS2 is investigated. By suppressing the competing process via excitation-energy transfer between nanocrystals, thermally activated scheme of excited carrier transfer is observed, and their characteristic parameters are determined.


Abstract

High-density assemblies or superlattice structures composed of colloidal semiconductor nanocrystals have attracted attention as key materials for next-generation photoelectric conversion devices such as quantum-dot solar cells. In these nanocrystal solids, unique transport and optical phenomena occur due to quantum coupling of localized energy states, charge-carrier hopping, and electromagnetic interactions among closely arranged nanocrystals. In particular, the photoexcited carrier dynamics in nanocrystal solids is important because it significantly affects various device parameters. In this study, we report the photoexcited carrier dynamics in a solid film of CuInS2 nanocrystals, which is one of the potential nontoxic substitutes with Cd- and Pb-free compositions. Meanwhile, these subjects have been extensively studied in nanocrystal solids formed by CdSe and PbS systems. A carrier-hopping mechanism was confirmed using temperature-dependent photoluminescence spectroscopy, which yielded a typical value of the photoexcited carrier-transfer rate of (2.2±0.6)×107 s−1 by suppressing the influence of the excitation-energy transfer.

Ferrocene as a Redox Catalyst for Organic Electrosynthesis

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Ferrocene as a Redox Catalyst for Organic Electrosynthesis


Abstract

Despite substantial advancements in thermal and photochemical catalysis, the evolution of similar processes within the realm of organic electrochemistry has seen a slower pace. However, recent years have heralded a remarkable surge in molecular electrocatalysis. This innovative technique harnesses the power of molecular catalysts to expedite electrochemical transformations. This article underscores the application of ferrocene (Fc) as a redox catalyst in organic electrosynthesis. It delves into the extensive utilization of Fc in organic electrosynthesis, particularly emphasizing its role in the electrocatalytic generation and reactions of heteroatom- and carbon-centered radicals, among various other reactions.