An operationally facile O−H insertion followed by intramolecular rearrangement was illustrated with Rh-azavinyl carbenes to access biologically relevant 2-aminoquinolines and 1-aminoisoquinolines.

Abstract

Herein, we developed an efficient approach to access biologically relevant 2-aminoquinolines and 1-aminoisoquinolines from readily available N-sulfonyl-1,2,3-triazoles and 2-quinolones or 1-isoquinolones. This transformation involves the selective O−H insertion of these derivatives onto the in situ generated Rh-azavinyl carbenes (Rh-AVC) followed by rearrangement. The reaction proceeds smoothly under operationally simple conditions and the protocol was found to be scalable.

By employing an acceptorless BH/NH dehydrocoupling strategy, regioselective B(3)-amination of o-carboranes with amines has been achieved via iridium catalysis, offering an array of B(3)-aminated-o-carboranes in one-pot process.

Abstract

An efficient and convenient strategy for Ir-catalyzed selective B(3)-amination of o-carboranes with amines via acceptorless BH/NH dehydrocoupling was developed, affording a series of B(3)-aminated-o-carboranes in moderate to high isolated yields with H₂ gas as a sole by-product. Such an oxidant-free system endues the protocol sustainability, atom-economy and environmental friendliness. A reaction mechanism via an Ir(I)-Ir(III)-Ir(I) catalytic cycle involving oxidative addition, dehydrogenation and reductive elimination was proposed.

Naphthalene- and phenanthrene-fused [22]smaragdyrins BF₂ complexes and their [20]smaragdyrin free bases are synthesized by Suzuki-Miyaura coupling, Witting-type methoxymethylenation, methanesulfonic acid-catalyzed cyclization reaction, and demetalation. These fused [22]smaragdyrin BF₂ complexes and [20]smaragdyrin free bases show decreased aromatic characters and antiaromatic characters, respectively. These fused compounds exhibit red-shifted and enhanced absorption bands in NIR region.

Abstract

Naphthalene- and phenanthrene-fused [22]smaragdyrin BF₂-complexes were synthesized by 1) Suzuki-Miyaura coupling of β-brominated [22]smaragdyrin BF₂ complexes with 2-formylarylboronates, 2) Witting-type methoxymethylenation of the formyl group, and 3) methanesulfonic acid-catalyzed cyclization reaction. Subsequently these BF₂ complexes were deboronized and oxidized to the corresponding antiaromatic [20]smaragdyrin free bases. The installed fused structures led to decrease of the aromatic characters of the [22]smaragdyrin BF₂ complexes and the antiaromatic characters of the [20]smaragdyrin free bases.

We have successfully achieved dynamic manipulation of fluorescence color (540 nm to 607 nm) and intensity by altering the counterions of zinc complexes and switching the isomer from Z to E.

Abstract

Achieving effective manipulation of emission color in photoresponsive materials is crucial for various advanced photonic applications. In this study, we designed and synthesized a hydrazone compound 1, ethyl (Z)-2-(2-([2,2′:6′,2′′-terpyridin]-4′-yl)hydrazineylidene)-2-(4-(diphenylamino)phenyl)acetate, which possesses a push-pull structure incorporating triphenylamine and terpyridine. The emission intensity of compound 1 can be repeatedly switched “off” and “on” by irradiation with visible light and UV light, which induces the isomerization transition between the Z and E forms. In addition, compound 1 is capable of changing its emission wavelength from 540 nm to 607 nm through coordination with different zinc salts in toluene/CH₂Cl₂ mixture (v : v=1 : 1). Importantly, we have successfully achieved dynamic manipulation of fluorescence color and intensity by altering the counterions of zinc complexes and switching the isomer from Z to E. Moreover, both compound 1 and its zinc complexes demonstrate remarkable photoswitchable properties with different fluorescence colors in the thin films. Finally, these films with various fluorescence colors were used for the production of luminescent tags.

This review focuses on graphene-functionalized metal oxide nanostructures designed for gaseous molecules detection, mainly hydrogen gas sensing applications. Perfect structured pristine graphene (left-top), electron-hole transport mechanism in metal-graphene system (center) and a typical metal/metal oxide-graphene-based gas sensor (right-top) along with functional metal/metal oxide-graphene for hydrogen sensing material (background) is shown.

Abstract

Chemiresistive sensing lies in its ability to provide fast, accurate, and reliable detection of various gases in a cost-effective and non-invasive manner. In this context, graphene-functionalized metal oxides play crucial role in hydrogen gas sensing. However, a cost-effective, defect-free, and large production schemes of graphene-based sensors are required for industrial applications. This review focuses on graphene-functionalized metal oxide nanostructures designed for gaseous molecules detection, mainly hydrogen gas sensing applications. For the convenience of the reader and to understand the role of graphene-metal oxide hybrids (GMOH) in gas sensing activities, a brief overview of the properties and synthesis routes of graphene and GMOH have been reported in this paper. Metal oxides play an essential role in the GMOH construct for hydrogen gas sensing. Therefore, various metal oxides-decorated GMOH constructs are detailed in this review as gas sensing platforms, particularly for hydrogen detection. Finally, specific directions for future research works and challenges ahead in designing highly selective and sensitive hydrogen gas sensors have been highlighted. As illustrated in this review, understanding of the metal oxides-decorated GMOH constructs is expected to guide ones in developing emerging hybrid nanomaterials that are suitable for hydrogen gas sensing applications.

An operationally simple and efficient protocol for the transformation of carbonyl compounds to tertiary amines with various secondary amine-boranes is reported. The reaction proceeds at room temperature and requires a short reaction time under mild conditions. The reaction encompasses a broad substrate scope and furnishes good-to-excellent yields of the amines in a chemoselective fashion.

Abstract

Tertiary amines are ubiquitous and play an essential role in organocatalysis, pharmaceuticals, and fine chemicals. Amongst various synthetic procedures known for their synthesis, the reductive amination of carbonyl compounds has been found to be a proficient method. Over the past few decades, different synthetic strategies for reductive amination have been developed. Most of them suffer from the use of transition metals and/or harsh reaction conditions. Herein, we present an efficient, operationally simple protocol for the chemoselective transformation of carbonyl compounds to tertiary amines under benign conditions. The strategy encompasses a broad substrate scope under the metal-free condition at room temperature and does not require any solvent. A detailed mechanistic investigation was performed with the aid of control experiments and computational study to shed light on the reaction pathway.

The introduction of 3, 4-ethylenedioxythiophene (EDOT) into indolocarbazole-based hole-transporting materials (HTMs) as π-spacers significantly promoted the PCEs of up to 17.5 % of their corresponding perovskite solar cells (PSCs).

Abstract

In this work, we have successfully synthesized 15 new examples (LLA01-06; LinLi01-10) of small-molecule hole-transporting materials (HTM) using the less explored indolocarbazole (ICbz) as core moiety. Different from previously reported ICbz HTMs, LinLi01-10 exhibit new molecular designs in which 3,4-ethylenedioxythiophene (EDOT) units are inserted as crucial π-spacers and fluorine atoms are introdcued into end-group molecules. These substantially improve the materials solubility and device power conversion efficiencies (PCEs) while fabricated in perovskite solar cells (PSC). More importantly, LinLi01-10 are generated by a sustainable synthetic approach involving the use of straightforward C−H/C−Br couplings as key transformations, thus avoiding additional synthetic transformations including halogenation and borylation reactions called substrate prefunctionalizations usually required in Suzuki reactions. Most HTM molecules can be purified simply by reprecipitations instead of conducting column chromatography. In contrast to LLA01-06 without additional EDOT moieties, PSC devices using LinLi01-10 as hole-transport layers display promising PCEs of up to 17.5 %. Interestingly, PSC devices employing seven of the LinLi01-10 as hole-transport molecules, respectively, are all able to show an immediate >10 % PCE (t=0) without any device oxidation/aging process that is necessary for the commercial spiro-OMeTAD based PSCs.

A core-shell structured catalyst with dual active sites (Pd and acidic sites) was designed to investigate the synergistic effect of Pd and acid sites in TS-1 during the hydrogenation of nitrobenzene.

Abstract

A core-shell structured Pd@TS-1@meso-SiO₂ catalyst with confined Pd nanometals has been fabricated by one-pot synthesis, impregnation method and sol-gel method. With the promotion of acid sites and protection of mesoporous silica shell, Pd@TS-1@meso-SiO₂ shows higher activity than commercial comparison and higher stability than sample without mesoporous silica shell in the hydrogenation of nitrobenzene. The schematic illustration of the synergy effect is also proposed.

Schematic showing the probable charge transfer mechanism in a p-n junction consisting of p-type CoO and n-type Fe₂V₄O₁₃. The depletion region is formed at the interface due to the diffusion of charge

Abstract

Herein, the synthesis of a novel composite photocatalyst, Co/CoO@Fe₂V₄O₁₃, is reported by the deposition of CoO metal oxide nanoparticles on the surface of Fe₂V₄O₁₃ bimetallic oxide. The synthesised photocatalyst exhibited a band gap of roughly 1.8 eV, rendering it responsive to the complete visible light spectrum of the sun, thereby enabling optimal absorption of solar radiation. The Co/CoO@Fe₂V₄O₁₃ composites demonstrated an enhanced photoelectrochemical water oxidation capacity compared to pristine Fe₂V₄O₁₃ when exposed to visible light. The enhanced performance is attributed primarily to the creation of a p-n junction at the interface of Fe₂V₄O₁₃ and Co/CoO, as well as the Z-scheme charge transfer mechanism, which aids in the separation and transfer of photogenerated charge carriers. Light absorption by Co nanoparticles via plasmonic excitation and intra- and inter-band transitions in the composite structure is also likely, resulting in increased composite efficiency. Our findings indicate that Co/CoO@Fe₂V₄O₁₃ composites show promising performance for solar water splitting applications and offer new perspectives for designing effective photocatalysts.

Red fluorescent proteins (RFPs) have powered bioimaging advances in life sciences due to their long-wavelength emissions and reduced phototoxicity. Recent advances in engineering, characterizing, and optimizing several major categories of RFPs have included photoconvertible, photoswitchable, large Stokes shift, and noncanonical FPs that achieve red emissions. A critical correlation of the available crystallographic and spectroscopic results can provide ultrafast and functional structural dynamics insights into the redding mechanisms of RFPs, which range from characteristic ring twists, conjugation extension to excited state proton transfer. More information can be found in the Review by Taylor Krueger, Cheng Chen, and Chong Fang.