Chemistry - An Asian Journal最新文献

Although bimetallic heterogeneous catalysts are widely used in several industries, understanding the active components at the atomic and molecular levels and their intricate structure is quite challenging. Through the analysis of various bimetallic systems, their differing structural properties, along with catalytic efficiencies, an understanding of the structure-reactivity relationships for heterogeneous bimetallic catalysts can be developed which can be utilized to enhance catalyst technology. This review will focus on the geometric and electronic structures of the three representative types of bimetallic catalysts (bimetallic binuclear sites, bimetallic nanoclusters, and nanoparticles) while providing details of their synthesis routes and characterization methods that have been achieved over the last decade. The roles of catalysis for supported bimetallic binuclear sites, bimetallic nanoclusters, and nanoparticles in a number of significant reactions will be presented. Finally, the gaps in research with an emphasis on supported bimetallic catalysts will be discussed along with broader expectations on the next advances in heterogeneous catalysis from a fundamental and applicative point of view. Bimetallic nanoparticles (NPs) are changing catalysis by combining two metals to create effects that are better than those of systems with only one metal.

Estimating substance use in Japan traditionally depends on police seizure records and national self-reporting surveys, which face substantial challenges due to social stigma. This study applies wastewater-based epidemiology to overcome these challenges of monitoring illicit drug and legal stimulant use in a Japanese metropolitan area serving ∼1.8 million residents. Influent wastewater samples collected over 4 weeks in 2021 were analyzed for 29 substances. Methamphetamine was the only illicit drug consistently detected (consumption at 17.0 ± 5.1 mg/day/1000 people), reflecting its prevalence in Japan's drug scene and aligning with patterns in other East Asian countries. Ephedrine and pseudoephedrine, known precursors of methamphetamine were detected at high levels, suggesting their common use in legal medicines. Nicotine and methamphetamine consumption remained stable across weekdays and weekends. Higher ephedrine consumption during the lockdown period likely resulted from increased use of Kampo medicines to manage COVID-19 symptoms. This study provides the first objective evidence of population-level methamphetamine use in a large urban catchment of Japan, which is relatively low compared to other countries. The findings demonstrate the feasibility of wastewater analysis as a complementary surveillance approach to the existing system, enabling more responsive and evidence-based drug policy.

The present work documents organophotocatalytic transformation of N-phosphorylated arylhydrazones into indazoles. The strategy relies on the visible light-mediated generation of N-centered radical intermediate. The reaction employs organic dye as a photocatalyst and air as a terminal oxidant. The mild conditions, operational simplicity and fairly general scope are the notable attributes of the methodology.

The ongoing quest for developing new chromophores or fluorophores capable of detecting heavy metal ions and explosive nitroaromatic compounds remains a critical challenge. Higher rylene dyes, particularly terrylene and its structural derivatives are renowned for their exceptional photophysical properties, characterized by remarkably high molar extinction coefficient and fluorescence emission. Inspired by the distinct photophysical characteristics of terrylene, herein, for the first time, we synthesized a novel pyridine-substituted terrylene small molecule (TERPy), which emerged as a highly selective probe for colorimetric and fluorometric sensing of mercuric ion (Hg^{2 +}) and nitroaromatic explosives like 2,4,6-trinitrophenol (TNP). TERPy exhibited an impressive limit of detection (LOD) at 140 nM with an exceptionally high binding constant (logK = 11.4), indicating remarkable sensitivity and strong molecular interaction with Hg²⁺. Morphological evolution upon addition of Hg²⁺ indicated a successful complex formation between TERPy and Hg²⁺. Moreover, a reversible unbinding of Hg²⁺ from the complex by EDTA in both solution and solid-state enables their future optoelectronic device applications. Additionally, TERPy displayed remarkable selectivity for TNP, achieving a detection limit of 360 nM and demonstrated strong molecular affinity with a high binding constant (logK) of 0.92, reflecting excellent analytical performance.

Thermally activated delayed fluorescence (TADF) materials hold the key to next-generation optoelectronics by converting both singlet and triplet excitons into light via rapid reverse intersystem crossing (RISC). However, designing chromophores that simultaneously feature a small singlet-triplet gap (ΔE_ST), strong charge-transfer (CT) character, and high photoluminescence efficiency remains elusive, as conventional donor-acceptor scaffolds suffer from nonradiative losses. Here, we harness through-space charge transfer (TSCT) architectures, which spatially separate donor and acceptor units to suppress vibrational quenching and boost RISC, to overcome this trade-off. We pair an N-(4-methylphenyl)-1,8-naphthalimide acceptor with a suite of heteroatom-modified 9,9-dimethyl-9,10-dihydroacridine donors (D-A), including a dual-donor (D-A-D) analogue, and systematically tune electronic coupling and molecular rigidity. To evaluate the photophysical implications of these structural modifications, we performed quantum-chemical analyses of ground and excited-state parameters (S₁, T₁, ΔE_ST, ΔE_HL), along with natural transition orbital and energy decomposition studies to probe the nature of electronic transitions. Spin-orbit coupling constants and ISC/RISC rate estimates were calculated to assess the excited-state mechanism, while electron-hole correlation metrics quantified the extent of charge separation. Together, these descriptors offer a comprehensive understanding of how donor identity, spatial arrangement, and conjugation control TADF behavior.

We report the synthesis and catalytic evaluation of new Ru(II)-protic-NHC complexes featuring β-NH groups with either γ-NH (Ru8) or γ-NMe (Ru9) substituents. These compounds, along with previously reported Ru(II)-protic-NHC and their classical NHC analogues (Ru1-Ru7), provide a platform for systematically probing the influence of β- and γ-substituents on formic acid dehydrogenation (FADH). All complexes exhibited notable catalytic activity under both base-assisted, solvent-free conditions and in the ionic liquid 1-butyl-3-methylimidazolium acetate (BMIMOAc) without an external base. Among them, Ru1 excelled in the ionic liquid medium, achieving a remarkable turnover number (TON) of 65,000 and turnover frequency (TOF) of 4300 h^-1 over 15 consecutive formic acid addition cycles. Mechanistic investigations, supported by NMR and control experiments, reveal that under base-assisted conditions, catalysis proceeds via a protic-NHC pathway, whereas in ionic-liquid mediated FADH, anionic-NHC intermediates dominate. Furthermore, the evolved H₂/CO₂ mixture was successfully applied for the hydrogenation of alkenes, and CO₂ capture experiments confirmed the selective utilization of the generated gases. The presence of a β-NH moiety enhances the catalytic activity relative to its N-methylated analogue, suggesting a favorable role in facilitating the reaction pathway, whereas the γ-NH functionality exerts a detrimental effect compared to its corresponding γ-N-alkyl and γ-N-aryl substituted derivatives.