New Journal of Chemistry最新文献

The Hubbard-corrected density functional theory (DFT) has been shown to effectively mitigate self-interaction errors in studying the properties of various materials. However, its effectiveness in evaluating the thermoelectric properties of non-magnetic semiconducting quaternary Heusler alloys remains largely unexplored. In this study, we apply GGA, GGA+U, and its extensions GGA+U+V, along with spin–orbit coupling (SOC), to examine the structural, electronic, elastic, thermodynamic, and thermoelectric properties of the non-magnetic NaHfXSn (X = Co, Rh, Ir) quaternary Heusler alloys. The Hubbard parameters (on-site U and inter-site V) are determined self-consistently using density-functional perturbation theory, eliminating the need for empirical inputs. For more precise optical property analysis, we use the Sternheimer method within the framework of time-dependent density functional theory (TDDFT). Our results show maximum thermoelectric efficiency (figure of merit) at 1200 K, with ZT values of approximately 1.02, 0.86, and 0.71 for X = Co, Rh, and Ir, respectively, indicating the potential of these materials for high-temperature thermoelectric device applications.

This work documented the synthesis of diverse bioactive polysubstituted 2-amino-4H-chromenes using a DABCO dicationic ionic solid (DDIS) supported on Merrifield resin (DDIS@PS) as a catalyst. The catalyst is characterized by FT-IR, SEM-EDX, and TGA analysis. The resulting PS contains supported DABCO units with free tertiary nitrogen functionality on their external surface. The catalyst effectively catalyzed cascade Knoevenagel–Michael addition reactions of various aldehydes and active methylene compounds (malononitrile and phenyl sulfonyl acetonitrile) with dimedone, yielding good to excellent results in water or ethanol at room temperature or 78 °C. The time required for the reaction of phenyl sulfonyl malononitrile is comparatively very high compared to malononitrile. The synthesis of bis-dimedone derivatives and 1,8-dioxo-octahydro-xanthenes was also achieved in both solvents at RT and 78 °C, with high yields. The catalyst demonstrated greater efficiency and maintained its activity over at least five cycles.

MXenes are emerging as highly promising materials for pseudocapacitive applications, offering exceptionally high specific capacitance. To date, over 30 distinct MXene compositions and nearly 20 solid solutions have been synthesized in the lab. However, research predominantly centers on Ti₃C₂T_x and a handful of other single-metal MXenes, with scant attention paid to solid-solution MXenes. Herein, a series of solid solution MAX phases (Nb_1−yTi_y)₄AlC₃ and corresponding (Nb_1−yTi_y)₄C₃T_x MXenes have been synthesized. The maximum proportion of Ti that can be incorporated into the M site has been examined. We found that the rate performance of MXenes improves with increasing Ti content. Especially, (Nb_0.7Ti_0.3)₄C₃T_x and (Nb_0.6Ti_0.4)₄C₃T_x retain 62.92% and 68.38% of their capacitances, when the scan rate is increased from 5 mV s⁻¹ to 1000 mV s⁻¹, respectively, compared to Nb₄C₃T_x's 13.88% retention. (Nb_0.7Ti_0.3)₄C₃T_x shows a specific capacitance of 311.06 F g⁻¹ under a current density of 1 A g⁻¹ and good cycling stability. This research demonstrates that the electrochemical characteristics of (Nb_1−yTi_y)₄C₃T_x solid solution MXenes can be manipulated by adjusting the ratio of transition metals.

The indiscriminate use of organic dyes without adequate wastewater treatment can result in severe water pollution and pose significant threats to biological health. This underscores the urgent need for the development of advanced materials capable of selectively removing contaminant organic dyes from water systems. In this study, highly crystalline covalent organic framework (COF) materials with pyridine structures were synthesized via a molten polymerization method, employing a Knoevenagel condensation reaction between 2,4,6-trimethylpyridine and 1,4-phthalaldehyde. Following modification with hydrochloric acid, cationic COF materials (S-iCOF) were obtained. These positively charged COF exhibited excellent crystallinity and a high specific surface area of up to 354.1 m² g⁻¹. They demonstrated exceptional efficiency in adsorbing anionic dyes, with maximum adsorption capacities of 481.7 mg g⁻¹ for methyl orange (MO) and 460.4 mg g⁻¹ for orange II (O II). The adsorption behavior adhered to a pseudo-second-order kinetic model. Furthermore, due to the difference in charge, S-iCOF exhibited significantly lower adsorption capacities for cationic dyes such as methylene blue (MB) and crystal violet (CV), enabling its use as a selective adsorbent for separating dyes with different ionic properties. By changing the 1,4-phthalaldehyde to 4,4′-biphenyldicarbaldehyde, the pore size of the COFs could be precisely expanded. It was demonstrated that large-pore cationic COFs (L-iCOF) are more advantageous for the removal of medium- to large-sized dyes. The molten polymerization method used for the synthesis of iCOF is both cost-effective and efficient. This study highlights the immense potential of cationic COFs for removing and separating organic dye pollutants from wastewater, offering promising applications in the remediation of organic contamination.

Herein, a series of BaAl₄Sb₂O₁₂:Bi³⁺ phosphors (BASO:Bi³⁺) with desired orange-red emission were synthesized through a high-temperature solid-state reaction method. Under 365 nm excitation, an orange-red emission with the main peak at 598 nm and a full width at half maximum (FWHM) of 60 nm appeared, attributed to the transition from the ³P₁ → ¹S₀ energy level of Bi³⁺ ions. The emission intensity of BASO:xBi³⁺ (0.01 ≤ x ≤ 0.03) phosphors first increased along with Bi³⁺ doping and reached the maximum at x = 0.02 under excitation at 365 nm. Interestingly, the emission coefficient of the prepared phosphors is linearly related to temperature, and the intensity decreases sharply with increasing temperature. Bi³⁺-doped BASO host phosphors exhibit strong temperature-dependence within the range of 298 K to 473 K, and their activation energy is 0.30 eV for the thermal quenching mechanism. The temperature-dependent characteristics of luminescent materials doped with Bi³⁺ suggest that the maximum relative sensitivity of BASO:Bi³⁺ at 473 K is 2.59% K⁻¹, indicating that the sample is suitable for measurement in a wider temperature range. Under the co-doping of Bi³⁺/Eu³⁺, single-phase white light emission was achieved, and the CIE coordinates (0.3320, 0.3812) were extremely close to the standard white light coordinates. Thus, BaAl₄Sb₂O₁₂:Bi³⁺ phosphors show potential applications in optical temperature sensing fields.

The reactions of a series of divalent 3d metal ions (Co, Ni, Cu, Zn) with two tris-amide functionalised tacn ligands, {PhNHC(O)CH₂}₃-tacn (1) and {ⁱPrNHC(O)CH₂CH₂}₃-tacn (2), in alcohol solution are described. The resulting complexes, [M(1)](NO₃)₂ and [M(2)](NO₃)₂ are characterised by elemental analysis, mass spectrometry, IR, UV-vis, ¹H and ¹³C{¹H} NMR spectroscopy, as appropriate, and by single crystal X-ray analysis for four representative examples. In all cases the ligands behave as hexadentate chelators to the divalent metal ion, with N₃O₃ donor sets through the tacn N-donor atoms and the O-bound carboxamide pendant arms. However, the reaction of 1 with Co(NO₃)₂·6H₂O produces the Co(III) complex, [Co(1-H)](NO₃)₂, via air oxidation. The X-ray crystal structure of this complex confirms a distorted octahedral N₄O₂ coordination environment at cobalt(III) through the three facial tacn amine groups, the anionic N atom from one deprotonated amide group, and two O-bound carboxamides. In comparison, the coordination of 1 towards the trivalent group 13 nitrates, M(NO₃)·9H₂O (M = Ga and In) at room temperature in MeOH yields the distorted octahedral [M(1)](NO₃)₃ salts initially (from NMR and IR spectroscopy and elemental analysis data) as colourless solids. However, they are less stable than the divalent complexes, undergoing slow amide hydrolysis in MeOH at room temperature over several hours, or more rapidly with heating. This process occurs more readily with Ga(III) than with the less Lewis acidic In(III) analogue. The crystal structure of one hydrolysis product, [Ga(3)](NO₃), is also reported (3 = {PhNHC(O)CH₂-tacn-(CH₂CO₂)₂}²⁻), in which two amide arms from 1 are converted to carboxylates.

An unprecedented Ru(II)-catalyzed carbonylative annulation reaction of phenyl-phthalazinediones and phenyl-indazolones is developed. In this reaction, sulfoxonium ylide is used as the carbonyl source in the presence of air for the synthesis of indazolo-phthalazinetriones and indazolo-indazolediones.

In this work, a robust “turn-on” NIR fluorescent probe Cx-Cys was constructed for cysteine detection and imaging in Arabidopsis thaliana. Specifically, a 1,8-naphthalimide-based NIR fluorophore was used as the signaling group, while the acrylate group served as the recognition moiety for cysteine as well as the fluorescence quenching group. The probe shows a remarkable NIR response toward cysteine in the infrared region (718 nm), and a large Stokes shift (103 nm). Cx-Cys displayed high sensitivity and selectivity to cysteine with low detection limits of 73 nM over other amino acids and bio-thiols. Impressively, it was applied to obtain images of Arabidopsis thaliana and enabled visualization of cysteine content changes under external stimulations in root tips in vivo. Cx-Cys was also used to monitor the dynamic changes of the cysteine pool after incubation in cysteine solutions.

Photothermal catalytic degradation of volatile organic compounds (VOCs) has been deemed as a promising strategy for air purification. In this work, LaMnO₃/N-doped biochar (NBC) composites with rich oxygen defects and nitrogen-containing functional groups were successfully synthesized by co-pyrolysis of soybean dregs and Mn/La salts, and they were employed for photo-thermal catalytic decomposition of p-xylene. N atoms from soybean dregs were successfully embedded into the biochar framework by the La³⁺ and Mn²⁺ modification. The abundant nitrogen-containing functional groups promoted the adsorption and enrichment of p-xylene on the catalyst surface. The carbon doping from soybean dregs increased oxygen defects of LaMnO₃, which acted as the active center for p-xylene degradation. The p-xylene degradation rate reached as high as 99.6% for the LaMnO₃/NBC-1.5 composite, which was significantly higher than that of pristine LaMnO₃ (65.2%). The biochar introduction enhanced the visible light absorption of LaMnO₃/NBC composites, which then converted light energy into thermal energy, serving as the extra heat source for p-xylene degradation. Moreover, the photogenerated electron–hole pairs of LaMnO₃/NBC composites further generated active radicals such as ˙OH and ˙O₂⁻ with strong oxidative properties on the catalyst surface, which participated in and enhanced the oxidative degradation of p-xylene.