Journal of The Chinese Chemical Society最新文献

We investigate the dynamics of an asymmetric two-level system (TLS) subject to stochastic energy fluctuations described by a dichotomic Markov process, which is a powerful model applicable to excitonic transport in molecular aggregates, decoherence in qubits, and spectral fluctuations in single-molecule spectroscopy. While the standard dichotomic noise model offers exact solutions that capture non-Markovian dynamics, it violates detailed balance and fails to ensure thermal equilibrium. To overcome this, we introduce a temperature-corrected version by adding a counterterm to the exact equations of motion, thereby restoring the correct equilibrium behavior. Furthermore, we explore the TLS dynamics under varying initial conditions and parameter regimes. The results demonstrate that the model reproduces both short-time coherent evolution and long-time thermal populations and captures single-system behavior relevant to experiments on isolated quantum systems. This work provides a powerful framework for studying non-Markovian dynamics in open quantum systems.

Electrochemical carbon dioxide reduction reaction (eCO₂RR) offers a promising pathway for the sustainable production of hydrocarbons, with potential for industrial-scale implementation. While electrolyte cations are known to influence product selectivity, their effects in flow cell systems still remain elusive. In this study, we systematically investigate the role of alkali metal cations under alkaline conditions on copper-based eCO₂RR in a flow cell configuration, with a particular focus on their interfacial interactions between the cations and the catalyst surface, and their impact on product distribution and electrochemical performance. Our results show that electrolytes containing lithium ions exhibit negligible eCO₂RR activity, attributed to the strong interaction between Li⁺ and CO₂, which hinders the reaction. Sodium-containing electrolytes favor the formation of C1 product (CH₄), while potassium and cesium ions promote the generation of C2 products (C₂H₄ and C₂H₅OH). The variation in selectivity is found to be closely related to the hydration radius of the cations, which influences the structure of the electric double layer and modulates the interfacial electric field strength. These findings offer valuable insights into the rational design of electrolyte compositions for steering product selectivity in future eCO₂RR applications.

Polycyclic aromatic hydrocarbons (PAHs) are known to exhibit fluorescence in solution, but generally do not emit in the solid state, with the notable exception of anthracene. We previously reported that PAHs containing multiple chromophores show solid-state emission, and we have investigated the relationship between their crystal structures and photoluminescence properties. In particular, PAHs with herringbone-type crystal packing, such as 2,6-diphenylnaphthalene (DPhNp), which has a slender and elongated molecular structure, exhibits red-shifted solid-state fluorescence spectra relative to their solution-phase counterparts. In this study, we synthesized 2,6-naphthalene derivatives bearing phenyl and/or pyridyl substituents (PhPyNp and DPyNp) and observed distinct, red-shifted emission in the solid state compared with that in solution. Crystallographic analysis revealed that both PhPyNp and DPyNp adopt herringbone packing motifs. These findings support our hypothesis that the spectral characteristics of PAH emission are closely linked to crystal packing arrangements, providing a useful strategy for screening PAH candidates for applications in organic semiconducting materials.

Three anthracene derivatives—9-(2′-mesitylethynyl)-10-phenylanthracene (MEPA), 4,4′-bis(9-(2′-mesitylethynyl)-10-phenylanthracene) (BMEPA), and 1,4-bis(2-((10′-phenylanthracen-9′-yl)ethynyl)mesityl)butane (DMEPA)—were used as fluorophores to study photon energy upconversion. Rose Bengal (RB) served as an organic photosensitizer and was mixed with each fluorophore in a tetrahydrofuran/methanol solution. Upon excitation at 568 nm, upconverted fluorescence was observed at 450 nm, with an anti-Stokes shift of 0.57 eV, corresponding to green-to-blue upconversion. Residual fluorescence emission from RB contributed to a combined emission spectrum, resulting in white light generation. The key mechanism driving this process is triplet-triplet annihilation (TTA), where two triplet-excited chromophores interact to form a singlet-excited fluorophore. Since TTA is diffusion-controlled, its efficiency is significantly reduced in solid-state films. To address this, a carbon chain was used to link two chromophore units in the structures of BMEPA and DMEPA, enabling intramolecular TTA after simultaneous photoexcitation. This approach is aimed at enhancing energy upconversion efficiency, particularly in solid or low-concentration environments. Experimental results showed the highest upconversion fluorescence quantum yields: 0.52% for MEPA, 0.43% for BMEPA, and 0.21% for DMEPA. Analysis of fluorescence intensity versus fluorophore concentration revealed a likely intramolecular TTA in the BMEPA system. However, a higher rate of quenching due to more flexible structures limited the overall performance of BMEPA and DMEPA.

This article presents a comparative computational study on the optical and charge transport properties of fused acenes and their chalcogen-based analogues. Two series of molecules were investigated, with the benzene rings in the acenes replaced by five-membered heterocyclic rings. The heterocycles studied include furan, thiophene, and selenophene. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) methodologies were employed to analyze the absorption properties of all the molecules. Additionally, the hole and electron reorganization energies, along with ionization potentials and electron affinities, are reported for each designed molecule. The aim of this study is to elucidate the impact of replacing benzene rings with five-membered rings on the optical and charge transport properties.

Organic sunscreen chemicals (OSSC) are a two-edged sword, filtering UV irradiation from the human body (preventing it from penetrating the skin and causing damage) while infiltrating the environment as pollutants, especially aquatic bodies. Interestingly, photocatalytic degradation employing nanoarchitecture materials has emerged as a cutting-edge technique for cleaning up these aquatic contaminants. The goal of this work is to review the remediation of OSSC through photocatalytic degradation-oriented technology and holistically evaluate the performance of various nanoarchitecture materials. As part of the novelty to demonstrate the pilot/industrial-scale potential and eco-economic benefits of this strategy, this work reviews recyclability and real-life application studies, which are sometimes overlooked. Also, this work reviews the effect of radical scavengers and electron trapping studies to clarify the process of OSSC photocatalytic degradation. Remarkably, it was discovered that various nanomaterials can deliver over 70%–100% degradation efficiency in 4–540 min. Additionally, the electron trapping studies revealed that the primary radicals in charge of photocatalytic degradation activities are ˙O₂⁻ and ˙OH. The findings also showed that different nanomaterials may be reused 2–10 times while maintaining >70% of the initial efficiency. This review demonstrated that nanoarchitecture materials are game changers for the sustainable and effective remediation of organic sunscreen chemicals.

Two new diphenylbenzoimidazole-based bis-cyclometalated Ir(III) complexes containing different ancillary ligands, namely [(fppbiz)₂Ir(piz)][PF₆] (Ir1) and [(fppbiz)₂Ir(pbiz)][PF₆] (Ir2) (where fppbiz = 2-(4-fluorophenyl)-1-phenyl-1H-benzo[d]imidazole, piz = 2-(pyridin-2-yl)-1H-imidazole and pbiz = 2-(pyridin-2-yl)-1H-benzo[d]imidazole), were synthesized and characterized. The crystal structure of Ir2 was determined by X-ray analysis, revealing intermolecular π-π and C-H···π interactions within the crystal packings. These Ir(III) complexes exhibited green and yellow emission with high photoluminescence quantum yields of 40.9% and 36.3% and short lifetimes of 0.20 and 0.27 μs, respectively. Their photophysical and electrochemical properties were systematically studied to establish the structure–property relationship upon the change of ancillary ligands, and theoretical calculations were used to further support the deduction.

The pharmacological, biological, and biochemical properties of quercetin hold significant implications in the realms of medicinal chemistry, biochemistry, and clinical medicine. In this study, metal–organic framework (Cu-MOF), nickel nitrate, and cobalt nitrate were used as raw materials, and metal-oxide (CuO-C/NiCo₂O₄) composites containing carbonaceous and floral structures were prepared by annealing and co-precipitation techniques. The CuO-C/NiCo₂O₄/GCE composite electrode was acquired by embellishing CuO-C/NiCo₂O₄ on polished glassy carbon electrodes (GCE) using dropwise coating. The synthesized CuO-C/NiCo₂O₄ was investigated through: (i) scanning electron microscopy (SEM) imaging for morphological evaluation, (ii) X-ray diffraction (XRD) for phase identification, and (iii) X-ray photoelectron spectroscopy (XPS) for elemental state determination. The results revealed that the CuO-C/NiCo₂O₄ composites have a loose and porous surface, an elevated active surface area, high electrical conductivity, and electrocatalytic properties. Based on this result, an electrochemically novel sensor for the detection of quercetin using CuO-C/NiCo₂O₄ composites was developed. The sensor displayed high reproducibility, redox stability, and anti-interference capability in the detection of quercetin. In addition, the peak current measured by this sensor was linearly correlated with the density of quercetin, exhibiting a wide linearity response from 0.1 to 20 μM with an ultralow detection limit of 0.092 μM. These advantages originate in the synergy between CuO-C and NiCo₂O₄. Currently, the constructed electrochemical sensor has been successfully employed for the determination of quercetin content in ginkgo biloba leaf.

Focus of the figure: Piezoresponse force microscopy results demonstrate that ZnFe₂O₄-BaTiO₃ magnetoelectric core-shell nanoparticles exhibit a stable core-shell configuration up to 1V, beyond which structural disintegration occurs. The instability of ZFO-BTO ME CSNPs is attributed to non-uniform interfacial strain, low ZnFe₂O₄ core magnetostriction, and a suboptimal core-to-shell thickness ratio. These findings provide valuable insights into the design of novel core-shell nanocomposites with enhanced magnetoelectric coupling and structural stability. More details about this figure will be discussed by Dr. A. Rajesh and his co-workers on pages 775–786 in this issue.