New Journal of Chemistry最新文献

A multi-active site 1,1′,1′′-(2-hydroxybenzene-1,3,5-triyl)tris(N-benzyl-N,N-dimethylmethanammonium)bromide (3) and hierarchical ionic polymers 9, 11, 13, and 16 have been synthesized. Compound 3 showed the best catalytic activity under co-catalyst free and mild reaction conditions, namely, 1 mL of substrate (epoxide), 2 mol% catalyst loading at 90 °C for 24 h under atmospheric pressure, as compared to its polymeric equivalents (9, 11, 13, and 16). Interestingly, an increase in the number of active sites within the backbone of 3 showed an inverse relationship with the halide nucleophilicity associated with it, viz., Cl⁻ > Br⁻. This phenomenon arises from the large size of the bromide anion, leading to a ‘congested active site’ effect, as demonstrated by both experimental and theoretical studies. This was evident as the benzylic ammonium catalyst with bromide ions achieved higher epoxide conversion than its chloride counterpart, whereas the opposite was observed for catalyst 3, likely due to a less congested catalyst structure with chlorides. Unexpectedly, during a five-run recyclability experiment, a modified and less active form of the organocatalyst 3′ was isolated. The overall reaction mechanism was elucidated and further supported by DFT calculations.

Acrylonitrile hyperbranched polymer/chitosan composite (AC–Hyp/CS) material was synthesized for the removal of diclofenac. In this method, a hyperbranched polymer was prepared by crosslinking an acrylonitrile monomer to obtain a host with a large surface area (AC/Hyp). To improve the functional sites of AC/Hyp, it was functionalized with chitosan (AC–Hyp/CS), which led to excellent removal efficiency. The physiochemical characterization of AC–Hyp/CS was carried out using FTIR, XPS, PXRD, DLS, TGA-DTA and SEM coupled with EDS. The uptake of diclofenac by AC–Hyp/CS was optimized through RSM in combination with BBD. Four factors, namely, AC–Hyp/CS dose (0.002–0.0180 g), concentration of diclofenac (10–30 mg L⁻¹), solution pH (2–6) and contact time (20–100 min), were considered to examine influencing parameters that resulted in the excellent removal efficiency. A high value of R² (0.9969) confirmed the excellent agreement of equilibrium data to the quadratic model. The obtained results suggested that 0.01 g AC–Hyp/CS was sufficient to eliminate 99.6% diclofenac from 20.0 mL (20.0 mg L⁻¹) solution at pH 4. Isothermal investigation suggested that the Langmuir isotherm model was administrated well with equilibrated data as it showed appropriate R² values (0.9814–0.9908) and low values of error functions (SSE: 0.002–11.742, χ²: 1 × 10⁻⁵–0.048 and RMSD: 0.0447–3.426). The adsorption capacity (maximum) obtained from the Langmuir model was 200 mg g⁻¹. The high values of R² (0.9878–0.9982) and low values of error functions (SSE: 0.160–1.343, χ²: 0.004–0.0534, RMSD: 0.40–1.158) of the pseudo-second-order kinetic model confirmed that the absorption was chemisorption. Diffusion-based kinetic studies revealed that both diffusion processes (film and intraparticle) participated in this sorption. Adsorption/desorption cycling test suggested that the composite exhibited excellent reusability characteristics up to 7 cycles, which confirmed that AC–Hyp/CS could be an effective sorbent for elimination of diclofenac from aqueous environments.

Interfacial intermolecular interactions between phosphorescent, square-planar, cyclometallated platinum(II) complexes may lead to the formation of bimolecular excited states that emit at lower energy than the isolated complexes in dilute solution. We study compounds in which two Pt(NCN)Cl units are appended onto a rigid xanthene scaffold to favour the intramolecular formation of such states and thus promote low-energy emission even at high dilution {where NCN represents a cyclometallated tridentate ligand based on 2,6-di(2-pyridyl)benzene}. Here, we show how the metathesis of the monodentate Cl⁻ ligand to thiocyanate SCN⁻ has a profound effect on the emissive properties of such compounds in solution and in polymer-doped and neat films. Intramolecular Pt⋯Pt interactions are promoted by the change to SCN⁻ (as evident by a short Pt⋯Pt distance of 3.253(4) Å in the crystal, determined by X-ray diffraction). This increased propensity for the Pt(NCN) units to interact, induced by the thiocyanate, is also manifest in the emission spectra: the spectra show only the low-energy, excimer-like bands in solution, even at very low concentrations. That contrasts with the appearance of emission bands typical both of isolated Pt(NCN) units and of excimers for the chloro parent compound. Nevertheless, data at low temperature and in dilute polymer-doped films suggest that some degree of conformational change is still required to form the low-energy emitting states. Meanwhile, the change of the monodentate ligand from chloride to iodide suppresses the formation of the low-energy-emitting states and lowers the emission efficiency. Taken together, the results offer new insight into strategies for obtaining efficient NIR-emitting phosphors based on dinuclear Pt^II₂ excited states.

Wide-bandgap 2D materials for UV photodetectors have many advantages, such as flexibility and efficiency. For this reason, the quest for novel 2D semiconductor materials is the primary focus of ongoing research endeavors. In this study, the electronic and optical characteristics of Janus Al₂M₂ClBr (M = O, S) monolayers have been meticulously examined by density functional theory (DFT). It was confirmed that these monolayers exhibit structural robustness for indirect bandgap Al₂O₂ClBr or direct bandgap Al₂S₂ClBr. Moreover, they demonstrate a low effective mass for the photogenerated electrons and holes. The bandgap is notably modulated by strain engineering, whereas the impact of the electric field is minimal. Notably, strong light absorption within the 8 to 12 eV range has been confirmed, with absorption coefficients surpassing 10⁵ cm⁻¹ for Janus Al₂M₂ClBr (M = O, S) monolayers. The optical properties can be finely tuned by strain engineering, although the influence of an electric field on these properties is insignificant. Considering the combination of optical and electrical characteristics, Janus Al₂M₂ClBr (M = O, S) monolayers are promising for UV photodetector applications. As a result, this study provides invaluable theoretical insights into the development of UV photodetectors utilizing Janus monolayers and is poised to significantly enrich the expansion of Janus monolayer materials in the foreseeable future.

Vertically aligned WO₃ nanoplate films were synthesized on stainless steel (SS) via a simple hydrothermal method. The prepared WO₃ films were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Results of these analyses reveal that the SS surface was well-covered with compact and vertical WO₃ nanoplates with a monoclinic single-crystalline structure. The film obtained through a 2.5 h hydrothermal reaction exhibited excellent photoelectrochemical performance under visible-light illumination and generated an anodic photocurrent of 0.754 mA cm⁻² at 0.8 V (vs. Ag/AgCl). WO₃ photoelectrodes could degrade 98.9% of methylene blue (MB) within 120 min through a photoelectrocatalytic (PEC) process. The stability of the as-prepared photoelectrode was also studied, and no significant reduction in PEC activity was observed after recycling for 5 times. The supreme PEC activity of the aligned WO₃ nanoplate films can be attributed to the direct charge transport pathway in the 2D structure and the bias potential applied to reduce the recombination of photogenerated electron–hole pairs.

Considering the increasing demand for gold and the scarcity of mineral resources, this study presents a promising avenue for its recovery from secondary resources. In this paper, N1,N1′-(1,4-phenylene)bis(N1-(4-aminophenyl)benzene-1,4-diamine) and 2,3,5,6-tetrafluoro-p-dibenzaldehyde were successfully prepared by the solvothermal method to synthesize a highly fluorinated covalent organic polymer with imine bonds (N-TFACOP), which can be used to recover gold ions from secondary sources. Covalent organic polymer (COP) materials have controllable structures that can be significantly improved by introducing appropriate functional groups into the structural units. The introduction of fluorine atoms with strong electron-absorbing ability into COP materials not only significantly increases the specific surface area of the materials and provides more surface active sites but also improves the chemical and thermal stability of the materials, even in strong acids and bases. The adsorption capacity for gold was further improved. At pH = 4, adsorption time of 720 min, and adsorption temperature of 45 °C, the maximum adsorption capacity of N-TFACOP for gold was as high as 2975.08 mg g⁻¹. There was no significant decrease in the adsorption rate after six cycles, which proved that the adsorption performance for gold was significantly improved by N-TFACOP. Au(III) was reduced to monomeric gold by complexation and redox reaction between the functional atom (N) and Au(III). In summary, we verified the adsorption potential of a novel covalent organic polymer for Au(III), which provides a strong reference for the recycling of the precious gold metal from secondary resources and the protection of environmental resources.

Transition metal sulfides are promising non-noble metal catalysts for hydrogen production through electrochemical water splitting due to their rich redox behaviors, good conductivity and stability. Herein, mesoporous Cu₂MoS₄ nanocubes were rapidly synthesized at room temperature via a novel electron beam irradiation-assisted method. During the electron beam irradiation process, a large number of free radicals were produced. These radicals are highly active and effectively accelerate the rapid formation of Cu₂MoS₄ nanocubes with I-phase. The as-obtained Cu₂MoS₄ nanocubes presented a mesoporous structure, which not only provides abundant electrocatalytic active sites but also facilitates the diffusion of electrolyte and the overflow of H₂ bubbles. As a result, the titled catalyst exhibits good electrocatalytic activity toward the hydrogen evolution reaction (HER) in acidic, neutral and alkaline electrolytes. Specifically, the catalyst with an irradiation dose of 300 kGy exhibited the best HER performance with low overpotentials of 160.2 mV, 256.2 mV and 225 mV to achieve a current density of 10 mA cm⁻² in 0.5 M H₂SO₄, 1 M PBS and 1 M KOH, respectively. This work demonstrates the effectiveness of electron beam-assisted synthesis in producing well-defined nanostructured catalysts for water splitting.

A new series of β-functionalized meso-tetraphenylporphyrins bearing 4-methoxyphenyl, 3,5-dimethoxyphenyl and 3,4,5-trimethoxyphenyl groups appended selectively to the single pyrrole unit of the porphyrin macrocycle, H₂TPPR₂ (where R = p-CH₃O-Ph, m-CH₃O-Ph and m,p-CH₃O-Ph), and their Co(II), Ni(II), Cu(II) and Zn(II) metal complexes were synthesized, characterized and meticulously examined for their adjustable electronic spectral, electrochemical and structural attributes. A gradual bathochromic shift of absorption bands (Δλ_max = 5–8 nm) was observed in these porphyrins relative to the unsubstituted parent porphyrin, H₂TPP. A progressive cathodic shift in the first ring oxidation potential was observed in the series. Among all free base porphyrins, H₂TPP(p-CH₃O-Ph)₂ showed the maximum red shifted absorption and the largest cathodic shift in the first ring oxidation, unveiling the effective electron donation via the +R effect of methoxy groups placed at the para position of β-phenyl rings. Within this framework, fine-tuning of the HOMO–LUMO gap accompanied by a gradual reduction in energy was observed which followed the trend H₂TPP(m,p-CH₃O-Ph)₂ (2.22 V) > H₂TPP(m-CH₃O-Ph)₂ (2.13 V) > H₂TPP(p-CH₃O-Ph)₂ (2.08 V). Single crystal X-ray analyses of H₂TPP(p-CH₃O-Ph)₂, ZnTPP(m-CH₃O-Ph)₂ and CuTPP(m-CH₃O-Ph)₂ unfolded planar, quasi-planar and saddle conformations respectively. Hirshfeld surface and 2D fingerprint plot analysis were also performed to see the significant intermolecular interactions. Further, DFT and TDDFT calculations were performed to gain a deeper understanding of the observed experimental results.

Atrazine, a human-made herbicide, is infamous for its endocrine-disrupting properties, with adverse consequences on the immune, reproductive, and nervous systems. Consequently, effective recognition of atrazine in various environments, such as water, is critically important. This work presents a precise and efficient method for detecting atrazine across various environments, utilizing a well-established electrochemical technique. A metal organic framework (MOF) ZIF-67 has been synthesized and employed as a catalyst for the electrochemical detection of the triazine herbicide atrazine. Structural, morphological, and chemical analyses were conducted to evaluate the sensing material and to elucidate the interactions between the sensor and the analyte. The ZIF-67 was then integrated on the surface of the working electrode (carbon paste electrode (CPE)) to form a ZIF-67 modified-CPE (ZIF-67/MCPE). The ZIF-67/MCPE was utilized to detect atrazine by electrochemical techniques including differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The sensor demonstrated excellent sensitivity and was effective in detecting atrazine. The modified sensor demonstrated a lower limit of detection (LLOD) of 3.7 μM within a linear concentration range of 4–44 μM and exhibited a strong linear correlation efficiency of 0.97. Computational results corroborated the experimental findings, revealing that the combination of ZIF-67 with atrazine forms minor triangular structures and exhibits enhanced dynamics compared to the pristine MOF. This improvement in the crystallinity of the ZIF-67 MOF with atrazine is attributed to the negative binding energy and reduced energy gap at the interface between the MOF and atrazine. Additionally, the sensor's practical application was evaluated by testing it on sewage water and fresh liquid milk. The sensor demonstrated an exceptional ability to detect atrazine, with a recovery rate ranging from 96% to 99%. This approach holds promise for developing electrochemical or solid-state devices for real-time atrazine monitoring.

This study investigates the modification of graphene oxide (GO) with ethylenediamine (EDA) to enhance its interlayer spacing to 1.04 nm and increase water flux to 879.2 L m⁻² h⁻¹. Subsequently, gallic acid (GA) was employed for secondary modification of the ethylenediamine-modified graphene oxide (EGO). Cellulose acetate (CA) served as the substrate for membrane fabrication, with the GA–EGO membrane prepared via a vacuum filtration method. The fundamental properties of the GA–EGO membrane were characterized using various analytical techniques, including water contact angle measurements and Fourier transform infrared spectroscopy (FTIR). The results indicated that the optimal concentration of GA in the GA–EGO membrane was 1 mg. Under these conditions, significant alterations to the membrane surface were observed, achieving a water contact angle of 0°, which corresponds to a superhydrophilic state. The GA–EGO membrane demonstrated an increased water flux of 1058.2 L m⁻² h⁻¹ and exhibited excellent emulsion separation capabilities, achieving a separation efficiency of 95.3% for coal–oil emulsions. Notably, after ten cycles of use, the GA–EGO membrane retained its operational efficiency. Furthermore, it maintained a separation efficiency exceeding 90% for emulsions derived from various oils, underscoring its promising potential for practical applications.