Journal of Chemical Sciences最新文献

To facilitate and understand interatomic diffusion between pure Pd and Ag nanoparticles, which were prepared using solvated metal atom dispersion (SMAD) technique, herein we employed different capping agents and their combination. After subjecting to the digestive-ripening process, monodispersed spherical nanoparticles were obtained in the case of Ag, while ripening of Pd nanoparticles resulted in the formation of nanoflowers-like morphology. The judicious/tailored combination of tri-n-octylphosphine and tri-n-octylphosphine oxide, not merely allowed controlling of the nucleation and growth of the alloy nanoparticles, but also played a key role in attaining high phase purity and homogeneity of the resulting Pd–Ag alloy nanoparticles. Finally, we investigated hydrogen sorption properties of phase-pure Pd–Ag nanoalloys by measuring their pressure–composition isotherms at 25°C and 1 atm H₂ pressure. The hydrogen storage capacities of Pd and Pd–Ag alloy nanoparticles were found to be 0.4 and 0.25 wt%, respectively. This study revealed a reduction in the hydrogen sorption behaviour of Pd upon dilution of Pd content by alloying with Ag and a rationale for the observed behaviour has been discussed in detail.

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In this study, 2.5 wt% of Au and Cu were uniformly immobilized within the pores of hierarchically porous zeotype materials to investigate the plasmonic catalysis under visible-light irradiation. Both monometallic and bimetallic catalysts of Au and Cu were prepared to investigate the catalytic performance due to the synergistic interaction between the two metal nanoparticles (NPs). All the prepared catalysts were characterized using PXRD, HAADF-STEM, DRS-UV and XAS to unveil the proximity and interaction between bimetallic NPs. The HAADF-STEM images revealed the proximity between Au and Cu NPs, and a significant difference in the NPs size was observed. Owing to the very small size of Cu NPs, exceptional behaviour of Cu-containing catalysts was observed. Plasmonic activity of the photocatalysts was investigated using p-nitrophenol (4-NP) reduction as a model reaction in the presence of ammonia borane as an in situ source of hydrogen. Interestingly, a 3.7-times enhancement in the rate of 4-NP reduction was achieved in the presence of bimetallic Cu/Au/HP-AlPO-5 (LSPR) under visible light irradiation compared to the dark conditions. We believe our findings will pave the way for advanced research to understand the unique plasmonic behaviour of AuCu NPs under light conditions.

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In this report, the CuAu bimetallic nanostructures immobilized within the hierarchically porous zeotype material have been prepared via the LSPR-assisted synthesis method. The nanostructures displayed synergistic catalytic performance in reducing nitroaromatics. A 3.7 times enhancement in the reduction rate was achieved under visible light irradiation compared to the dark conditions.

A zinc-containing, one-dimensional coordination polymer, [Zn(NH₂trz)₃](NO₃)₂ (1D-CP, NH₂-trz (=) 4-amino-4H-1,2,4-triazole) has been employed to synthesize two water-insoluble proton conductors, ZnL-PW₁₂ and ZnL-SiW₁₂ (L (=) 4-amino-4H-1,2,4-triazole), that are formulated as {[Zn(NH₂trz)₃](NO₃)}₂{HPW₁₂O₄₀}·4H₂O and [Zn(NH₂trz)₃][NH₃trz]₂[SiW₁₂O₄₀]·10H₂O, respectively. These proton conductors were prepared through simple room-temperature aqueous reactions involving [Zn(NH₂trz)₃](NO₃)₂ and phosphotungstic or silicotungstic acids, which proceed via aqueous disassembly of the CP, followed by recrystallization into a new phase driven by the addition of heteropolyanions. Here, the Keggin POMs, specifically H₃PW₁₂O₄₀ and H₄SiW₁₂O₄₀, impart enhanced stability to the overall structures of the resulting Zn-complex-POM adducts, ZnL-PW₁₂ and ZnL-SiW₁₂. Upon mixing the aqueous solutions of 1D-CP and POMs, immediate precipitations of the water-insoluble inorganic–organic hybrid products are obtained, the aqueous suspensions of which exhibit acidic pH. This observation prompted us to investigate proton conductivity behaviour of the resulting materials. As anticipated, the isolated products, ZnL-PW₁₂ and ZnL-SiW₁₂ exhibit significant proton conductivity values of 5.1 × 10⁻³ and 5.6 × 10⁻³ S cm⁻¹, respectively, at 80°C and 98% relative humidity, demonstrating excellent stability for about 30 h with decent cycling stability over four heating–cooling cycles.

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A zinc-based one-dimensional coordination polymer, [Zn(NH₂-trz)₃](NO₃)₂ (1D-CP), was modified into two water-insoluble proton conductors by a process involving the disassembly and subsequent restructuring of the coordination polymer into more stable inorganic–organic hybrids by the addition of phosphotungstic and silicotungstic heteropolyanions. The resulting hybrid materials, ZnL-PW₁₂ and ZnL-SiW₁₂ (L = 4-amino-4H-1,2,4-triazole), exhibit significant proton conductivities of 5.1 × 10⁻³ and 5.6 × 10⁻³ S cm⁻¹, respectively, and demonstrate excellent stability for >30 h under the operational conditions.

Oxidative synthesis of pyrazoles from aromatic alcohols and phenyl hydrazine has been achieved by using trans-5-hydroperoxy-3,5-dimethyl-1,2-dioxolan-3-yl ethaneperoxate and KOH. The reaction proceeds via oxidative coupling of primary and secondary alcohols with phenylhydrazines by singlet molecular oxygen produced from trans-5-hydroperoxy-3,5-dimethyl-1,2-dioxolane-3-yl ethaneperoxate at room temperature, and broad range of derivatives were obtained in good to excellent yields. Advantageous features of the present methodology include mild reaction conditions, transition metal-free, good functional-group tolerance, use of readily available primary and secondary alcohols and so on.

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Oxidative synthesis of pyrazoles from aromatic alcohols and phenyl hydrazine has been achieved by using trans-5-hydroperoxy-3,5-dimethyl-1,2-dioxolan-3-yl ethaneperoxate/KOH. The reaction proceeds via oxidative coupling of primary and secondary alcohols with phenylhydrazines by singlet oxygen produced from trans-5-hydroperoxy-3,5-dimethyl-1,2-dioxolane-3-yl ethaneperoxate and a range of derivatives were obtained in good to excellent yields

Weakly bound complexes of inert gas atoms with aromatic rings have received the attention because these are important for understanding the several solution- and condensed-phase properties. Extrapolated complete basis set (CBS) limit interaction energies for van der Waal complexes of benzene with He, Ne and Ar were calculated by using MP2 level and B2PLYPD3 and M06-2X functionals, employing aug-cc-pVTZ basis set. It was observed that as the size of inert gas increases, the interaction energy becomes more negative suggesting more stabilizing interaction. In sandwich complexes, the magnitude of CBS interaction energies was found to be double when compared to benzene complexes. The calculated vibrational stretching frequencies of cationic benzene complexes show red-shift, whereas almost same frequencies are found in sandwich complexes, with respect to benzene–X (X = He, Ne and Ar) complexes. However, in deuterated benzene–X complexes, the C–D stretching frequencies show a decrease in frequency value compared to benzene–X complexes and this may due to the presence of deuterated atom. Apart from that, the complexes, (benzene)⁺⁺–X dication and X–(benzene)⁺–X sandwich cation were also studied using MP2/aug-cc-PVTZ level. It is observed that the charge is increased when moving from (benzene)⁺–X to (benzene)⁺⁺–X complexes, the strength of interaction is increasing. Further, the nature of interaction present in benzene–X complexes was investigated by energy decomposition analysis using SAPT analysis. The SAPT analysis revealed that the contribution from dispersion terms is increasing when moving from He to Ar complexes.

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A series of thiazolo[4,5-e]indole derivatives have been obtained by a three-component domino reaction of 2-methylbenzo[d]thiazol-5-amine, arylglyoxal monohydrates and cyclohexane-1,3-dione in ethanol medium at 80°C catalyzed by acetic acid. Notable features of this synthesis are mild reaction, high synthesis efficiency, simple post-treatment operation and only water is generated as a byproduct.

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A new procedure for the synthesis of thiazolo[4,5-e]indole derivatives.

Proton conductors play a significant role in various fields, and recent research has focused on exploring crystalline porous materials for their favourable proton-transport properties. However, synthesizing these materials often poses challenges, especially in achieving crystallinity. In this study, we have successfully developed an innovative approach by constructing an amorphous microporous polymer (AMP) structure. Unlike traditional methods that require crystallization, our AMP maintains a certain pore space, while avoiding the need for strict crystallinity. Remarkably, this newly developed AMP displays high-density sulphonic acid sites on its skeleton, enabling it to function as an efficient proton conductor across a wide range of relative humidity (RH) levels. At 70°C and 100% RH, it achieves an impressive maximum conductivity value of 3.34 × 10⁻³ S cm⁻¹. Such an excellent performance can be attributed to the low activation energy for proton conduction, measuring a mere 0.266 eV. This signifies a Grotthuss mechanism, indicating that protons readily jump along hydrogen bonds within the material.

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Electric field experienced by a protic group depends primarily on solvent configuration and those configurations in which the electric field along the protic group exceeds a critical value, results in spontaneous proton transfer. Electronic structure calculations using density functional theory (DFT) result in artifacts in estimating critical electric fields for the spontaneous proton transfer process, often leading to bistable behaviour, in contrast to MP2 level calculations. Discrepancies in assessing critical electric fields using the DFT method can be attributed to the under-representation of Hartree–Fock exchange in many commonly used functionals, such as B3LYP and M06-2X, whose effect is precipitative in the proton transferred structures. Using the (critical) electric field values obtained by the MP2 level of theory as a benchmark, it is shown that the B3LYP functional altered to include 40% Hartree–Fock exchange, which omits the bistable behaviour and calculates reasonably accurate critical electric fields.

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Accurate electrostatic description of proton transfer reactions can be accomplished by incorporating 40% Hartree–Fock exchange to the standard B3LYP functional.

Combination of organic donor–linker–acceptor dyes for panchromatic enhancement in photoelectrodes of dye-sensitized solar cells enables their environmentally friendly and cost-effective design. A promising combination in terms of spectral broadening and miscibility are the dyenamo red and blue dyes, which differ only in their molecular structure via linkers. In this work, we investigate the sequential co-sensitization of both dyes together with the co-adsorption of aggregation inhibitor, chenodeoxycholic acid to increase the optical absorption and energy conversion efficiency. Finally, with a J_SC of 10.2 mA cm⁻² and a V_OC of 584 mV, a small increase was achieved.

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Combining Dyenamo Red and Blue dyes with chenodeoxycholic acid in dye-sensitized solar cells enhances optical absorption and energy efficiency. These combination enable cost-effective, environmentally friendly designs by broadening the spectral range and improving miscibility through sequential co-sensitization and co-adsorption techniques.

Use of magnesium oxide-coated magnetite nanoparticles (Fe₃O₄@MgO) as a heterogeneous base-catalyst in organic functional group transformations has been demonstrated. Catalytic efficiency of the Fe₃O₄@MgO platform as an inorganic base-catalyst was firstly explored in the oxidative hydroxylation of arylboronic acids in the presence of aq. H₂O₂, affording the corresponding phenols with outstanding effectiveness. In addition, the direct O-benzylation of phenols catalyszed by the Fe₃O₄@MgO platform, was efficiently conducted in an aqueous environment, resulting in the formation of benzyl phenyl ethers. Lastly, the hydration of benzonitriles was also achieved when the Fe₃O₄@MgO platform was employed under aqueous conditions, yielding the corresponding benzamides.

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Magnesium oxide-coated magnetite nanoparticles (Fe O @MgO) were used as a base catalyst in organic transformations. It efficiently catalyzed the oxidative hydroxylation of arylboronic acids, O-benzylation of phenols, and hydration of benzonitriles in aqueous conditions, producing phenols, benzyl phenyl ethers, and benzamides, respectively.