Journal of Chemical Sciences最新文献

Indirect reductive amination of aromatic aldehydes was studied in this work; aqueous ammonia was used as a nitrogen source. The results showed that aromatic aldehydes’ reaction with aqueous ammonia produced compounds known as hydrobenzamides (N,N´-(phenylmethylene)bis(1-phenylmethanimines), having good yield. The reaction of hydrobenzamides with sodium borohydride reduced both imine and aminal carbons and produced a primary and secondary benzylamine mixture. This article analyses such behaviour and proposes a possible mechanism for explaining such transformation.

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The reaction of aromatic aldehydes with aqueous ammonia produced compounds known as hydrobenzamides (N,N´-(phenylmethylene)bis(1-phenylmethanimines). The reaction of hydrobenzamides with sodium borohydride reduced both imine and aminal carbons and produced a primary and secondary benzylamine mixture.

The quantitative structure-property relationship (QSPR) technique is used to gauge the n-octanol/water partition coefficient (log K_OW) and enthalpy of vaporization (∆_vapH_m) of 133 Polychlorinated Biphenyls (PCBs) using conceptual density functional theory (CDFT)-based global reactivity and information-theory (IT) based parameters. Regression models are established using linear and multi-linear relationships to correlate the observed physicochemical properties of PCBs with the predicted ones. The study explored the significance of CDFT and IT descriptors, and based on the calculation of Pearson correlation coefficient values, the selection of suitable descriptors is made for successful QSPR models of selected PCBs. It is found that some of the CDFT parameters are highly correlated with the IT parameters, as suggested by their high Pearson correlation coefficient values for PCB systems. The regression model generated using the descriptors I_G, g₁, g₂, EA, η for predicting log K_OW and I_F, g₃, η, S_S, S_GBP for predicting ∆_vapH_m gives R² value of 0.9342 and 0.8662, respectively, for the selected 133 PCB congeners. Furthermore, to verify the descriptor selection, a machine learning approach is also used to develop QSPR models in this study.

Graphical Abstract

QSPR modelling using CDFT and information theory-based descriptors for predicting n-octanol/water partition coefficient and enthalpy of vaporization for the selected PCBs

Synthesis of 5-substituted-1H-tetrazole derivatives from aryl aldehydes under the influence of Palladium nanoparticles entrapped in aluminum hydroxide matrix (Pd/AlO(OH) NPs) was carried out in ethanol for 3-6 h. The use of the catalyst in this synthesis is the first. Sodium azide and malononitrile used in the reaction are chemical compounds required in the synthesis of tetrazoles. The reactions were concluded with good yields under thermal conditions. In the reactions, twelve derivatives were synthesized. The synthesized compounds were characterized by IR, ¹H, and ¹³C NMR. The olefinic proton's signal, which is around 8.5 ppm, reveals the formation of the tetrazole ring. The tyrosinase enzyme activity for each synthesized derivative was examined, and the results were recorded. According to the results obtained, all tetrazole derivatives were found to be effective compounds for tyrosinase enzyme inhibition. 3-(3,4-dichlorophenyl)-2-(1H-tetrazol-5-yl)acrylonitrile (2k) with two chloride groups at the meta and para position of the phenyl ring seems to be the most potent tyrosinase inhibitor with an IC₅₀ value of 45 µM.

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SYNOPSIS: 5-substituted-1H-tetrazole derivatives were synthesized under the influence of PdAlO(OH) NPs and under mild conditions. Tyrosinase enzyme activity was investigated for each of the twelve synthesized derivatives. As a result, synthesized tetrazole derivatives were identified as potential tyrosinase inhibitors.

A new ternary coordination polymer (CP), {[Cd(L)(nip)(H₂O)]·H₂O}_n (1) (L = 1,6-bis(benzimidazol-2-yl)hexane, H₂nip = 5-nitroisophthalic acid), was hydrothermally synthesized and characterized. 1 is a two-dimensional sheet and extends into three-dimensional supramolecular networks through O-H···O hydrogen bonding interactions, which displays high thermal and pH stabilities. 1 demonstrated notable selectivity, sensitivity, and reusability for the luminescent sensing of chlortetracycline (CTC) and Fe³⁺ ions. Density functional theory calculations and UV−Vis absorption spectroscopy were employed to investigate the possible sensing mechanisms.

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A new Cd(II) metal coordination polymer, namely {[Cd(L)(nip)(H₂O)]·H₂O}_n can act as a sensitive luminescent probe for chlortetracycline (CTC) and Fe³⁺ ions in water with excellent selectivity and recyclability.

We report six new 2,6-disubstituted fluorene-based conjugated molecules carrying orthogonal triphenylamine and pyridine moiety as donor-acceptor units at the C-9 position. The geminal donor-acceptor is connected to the fluorene core by σ-conjugation. Optical/solvatochromic studies, investigated by UV-VIS absorption and fluorescence spectroscopy, show blue emission with good quantum yield (40–70%) in solution and in thin film state for the synthesized compounds. In microsecond order, the derivatives give a shorter delayed lifetime (both in solution and thin films), facilitating reverse intersystem crossing (RISC). TD-DFT studies for all the derivatives show minimal singlet-triplet splitting in the gas phase (close to 0.2 eV), and the high thermal stability confirmed by the compound's TGA method (320–398 °C) makes them very useful in the optoelectronic market.

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D-σ-π-σ-A based blue emitters carrying orthogonal triphenylamine and pyridine moiety as donor-acceptor unit at C-9 position were synthesized. Optical/solvatochromic studies, investigated by UV-VIS absorption and fluorescence spectroscopy, show blue emission with good quantum yield (40–70%) in solution and in thin film state for the synthesized compounds.

The search for better energy storage systems that are less expensive, resource-abundant, and safer has sparked intense research into zinc ion batteries (ZIBs). Organic materials, especially quinones-based ZIBs, improved the rate performances by providing structural flexibility for the movement of zinc ions. In this work, a highly conjugated quinone molecule, tetrakis-lawsone (TLS), with multiple active sites, was used to enhance the capacity of the ZIBs. The non-planar geometry of TLS due to the different orientations of all four lawsone units of TLS provided a sufficient void for the Zn²⁺ movement, making it a suitable host cathode material for the ZIBs.

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TLS molecule consists of four LS units, which are aligned differently, thus, creating many empty void spaces in its matrix. Hence, it facilitates the Zn²⁺ ion movement within its lattice and thereby maximizes the utilization of TLS for energy storage.

Silicon is one of the most important components of electronic devices. Surface passivation of a silicon wafer is an active area of research. The Si(OH)₂ sites of partially oxidized silicon surface could exist as hydroxylated [Si(OH)₂] or hydrated silanone [SiO∙(OH₂)]. The previously reported disiladicarbene (cAAC)₂Si₂ has been reacted here with water to obtain elusive, hydrated silanone (3) co-crystallized with its silanol analog (2) in a 1:3 molar ratio. The mass spectrometric characterization of acyclic silanone, followed by the isolation and characterization of the zwitterionic hydrated silanone, has been achieved. The detailed energy decomposition analysis coupled with natural orbital for chemical valence (EDA-NOCV) calculations revealed that the central Si(O)OH unit of the hydrated silanone possesses a covalent electron sharing σ- and a dative σ-bonds (C_L−Si, Si←C_L) with hydrogen-containing cyclic alkyl(amino) carbene ligands. These two bonds are stabilized by 49% coulombic interaction and 47.8% orbital interaction. The presence of N-atoms at the hydrogenated and/or protonated carbene part (cAACH/cAACH₂) has reduced the stability of these species. The electron pair on the N-atom of the cAACH unit displays a sort of anomeric effect relevant to the cyclic form of the sugar molecule.

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A disiladicarbene containing two Si(0) centres reacts with water to produce a mixture of co-crystallized products in a 3:1 molar ratio. EDA-NOCV analyses further analysed the bonding and stability of zwitterionic-hydrate-silanone to probe the nature of chemical bonds in it. This species has further been characterized by ES-MS spectrometry.

Recent research underscores the significance of metal-organic frameworks as catalysts, owing to their structural adaptability, substantial surface areas, adjustable pore dimensions, and customizable catalytic sites. Using Friedländer synthesis, we evaluated the catalytic potential of three synthesized metal-organic framework materials, MIL-53(Al), MIL-101(Cr), and MOF-5(Zn), in quinoline derivative synthesis. MIL-53(Al) outperformed MIL-101(Cr) and MOF-5(Zn), highlighting the vital role of Lewis acidic sites (Al³⁺) in quinoline production. Potentiometric titration analyses revealed MIL-53(Al)'s superior Lewis acid strength. Reaction optimization involved varying temperatures, catalyst loading, reaction duration, and solvents. MIL-53(Al) exhibited four-cycle recyclability. Mechanistic insights underscored Lewis acid strength and the significance of sites. The Al-based catalyst proficiently facilitated Friedlander synthesis, yielding enhanced conversion and considerable physiologically active quinoline yields. The findings offer insights into diverse catalytic strategies and demonstrate the adaptability of metal-organic framework materials in varied chemical reactions.

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The Al-based Lewis acid MOF catalyst MIL-53(Al) efficiently facilitated the Friedlander synthesis, resulting in improved conversion and significant yields of physiologically active quinolines. These findings provide insights into versatile catalytic strategies and showcase the adaptability of MOFs in diverse chemical reactions.

A series of K₂Ca_1-xP₂O₇:xEu³⁺ phosphors were prepared by a high-temperature solid-state reaction method. The crystal structure was analyzed by X-ray diffraction (XRD). Fluorescence spectra, decay curves, and color coordinates were investigated. Under excitation at 393 nm, the strongest emission peak was located at 590 nm, corresponding to the ⁵D₀→⁷F₁ transition of Eu³⁺, and the sub-strongest one was located at 612 nm which belongs to the ⁵D₀→⁷F₂ transition of Eu³⁺. XRD results show that the patterns doped with a small amount of Eu³⁺ were fitted well with the standard card of K₂CaP₂O₇, while the pattern with the doping of high concentration Eu³⁺ (heavy-doping) indicated the co-existence of K₂CaP₂O₇ and EuPO₄ phase which leads to luminescent intensity of phosphors enhance remarkablely. The concentration quenching mechanism was explained through dipole-dipole interaction. Different doping amounts of Eu³⁺ and charge compensators will affect the symmetry of the host lattice, thereby affecting the emission intensity ratio of orange and red light. The color coordinates of K₂Ca_0.49P₂O₇:0.51Eu³⁺ and K₂Ca_0.33P₂O₇:0.67Eu³⁺, 0.1Na⁺ phosphor were near the red region, which was close to commercial red-emitting phosphors Y₂O₃:Eu³⁺ and standard red light, respectively.

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A series of K₂CaP₂O₇ phosphors emitting orange-red light with different concentrations of Eu³⁺ doping and alkali metal ions co-doping were synthesized via a high-temperature solid-state method, and their structure and luminescent properties were characterized. A new strategy for adjusting the light color parameters of K₂CaP₂O₇ phosphors has been constructed.

A facile green accessibility for the synthesis of novel, distinctly substituted 2H-pyran analogues employing montmorillonite K10 clay as a sustainable catalyst via a one-pot multi-component reaction involving various aldehydes, thiophenol and cyanoacetic acid with acetophenone has been developed. The noteworthy features of the current methodology are short reaction time (1.5-2 h), good yields (70-82%), convenient technique, operational simplicity, ease of work-up, and reusability of the catalyst up to two runs, adhering to green chemistry principles. A spectroscopic assessment validated the structure of all the synthesized products. This multi-component one-pot transformation conveniently forms two new C-C bonds, one C-O bond, one C-S bond, and two new rings with all reactants consumed efficiently. Additionally, all synthesized compounds have been evaluated for anti-cancer activity, and two of them were found to be efficacious against human breast cancer cell line, namely, MDA-MB 231.

Graphical Abstract

A green and efficient method has been developed for synthesizing novel 2H-pyran analogues using montmorillonite K10 clay as a catalyst. The method involves a one-pot multi-component reaction and yields high products (70–82%) while adhering to green chemistry principles. The synthesized compounds have shown efficacy against human breast cancer cell line MDA-MB 231.