Journal of Chemical Sciences最新文献

We have reported an effective, seed-assisted organic structure directing agent (OSDA) free synthesis of ferrierite (FER) zeolites. In the current study, we have observed effects of physicochemical properties of two different seeds over synthesis of FER zeolites. The physicochemical properties of seeds, such as particle size and phase purity impart significantly over crystallization time and overall synthesis duration, costs of process and crystalline nature of FER zeolites. It is noteworthy that particle size of seed mainly affects the kinetics of crystallization for concerned FER zeolites. The synthesized zeolites were well characterized by XRD, FESEM, TEM, Raman spectroscopy, ²⁷Al and ²⁹Si MAS NMR, EDAX and BET surface area analyser to get more insights. We also evaluated, the catalytic activity of synthesized FER zeolites in oleic acid isomerization study to derive branched-chain fatty acids formation and attempted their structure and catalytic activity relationship with respect to purity of phases in seed.

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Two novel phenyl or biphenyl-based organogelators G1 and G2 were designed and synthesized. Owing to the non-coplanar geometry of the two benzene rings in biphenyl group, gelling performance of G1 was dramatically better than that of G2. Hydrogen bonding, π–π stacking and van der Waals interactions were emerged as the dominant intermolecular forces governing the self-assembly-driven gelation of G1. G1-DMSO gel could act as a multi-stimuli-responsive sensor for detecting Cu²⁺ and present selective gel–sol transformation and colorimetric changes. Furthermore, the selective ion-recognition properties of G1-DMSO gel for Cu²⁺ were investigated by UV–Vis spectra and ESI-MS. It was found that the detection limit for Cu²⁺ was 9.1445 × 10⁻⁶ M and the binding stoichiometric ratio of G1 to Cu²⁺ was 1:1.

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A microwave-assisted and solvent-free protocol for secondary and benzyl alcohols oxidation to the corresponding ketones and aldehydes, using the inexpensive and widely available Cu(NO₃)₂·2.5H₂O salt as catalyst and aqueous tert-butyl hydroperoxide (TBHP) as oxidant, has been developed. The present strategy allows the isolation of the oxidation products with yields up to 80% for the majority of the tested substrates. Extremely short reaction times and the usage of low-power microwave irradiation are factors that contribute to the smoothness of the process and are shown as an asset of the described experiment. Remarkably, the approach features a one-pot procedure, an earth-abundant copper catalyst, a wide substrate scope (22 alcohols) and a high compatibility with several functional groups.

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As an ecological, widely available and economical material, the copper salt Cu(NO3)2∙2.5H2O show a high performance as catalyst in the oxidation of a series of secondary and benzyl alcohols. The developed protocol, using TBHP as oxidant and assisted by microwave radiation, proceeds without the use of an organic solvent and is very chemoselective tolerating the presence of several functional groups.

This study uses computational methods to explore the triple hydrogen bonding between cytosine and guanine. It specifically focuses on two tautomers: the GC tautomer, which forms during DNA replication, and the tautomer resulting from double proton transfer, denoted as G*C*. The latter tautomer is linked to genetic mutations. The geometric, vibrational, and electronic structures of both tautomers have been calculated using DFT-B3LYP and MP2 levels of theory. The results are then compared to those of the non-interacting bases. The findings indicate that hydrogen bonding is moderately strong for both tautomers, with electrostatic interaction being the primary component. While the variations in the HOMO energy contribute to the stabilization of the triple hydrogen bond in G*C*, the kinetics of the reaction from GC to G*C* is hindered by a relatively high potential barrier. This barrier is mainly caused by a significant increase in nuclear repulsion within G*C*, which is not adequately counterbalanced by the favourable changes in HOMO energies.

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General methods for the highly site-selective monocoupling of alkyl 2,4- and 2,5-dihalobenzoates have been discovered. By switching from PdCl₂(PCy₃)₂/P(p-MeOPh)₃ to Pd(OAc)₂/L9, the preferred coupling site can be shifted from the C2-position to the C4 or C5-position. The formation of the substituted alkyl monohalobenzoate derivatives is highly site-selective and tolerant to both electron-withdrawing and electron-donating groups on aryl and heteroaryl titanium reagents and the reaction gives twenty-four substituted alkyl monohalobenzoate derivatives (except for 4ea, the other were novel compounds) were prepared and their structure was confirmed by FTIR, spectroscopy, ¹H and ¹³C NMR, and mass spectrometry. This simple synthetic route is designed to improve the rapid construction of mutiple aryl cross-coupling products.

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The same substrate alkyl 2,4- and 2,5-dihalobenzoates can selectively generate C2-position and C4- or C5-position products by switching catalytic system from PdCl₂(PCy₃)₂/P(p-MeOPh)₃ to Pd(OAc)₂/L9. The reaction gives twentyfour substituted alkyl monohalobenzoate derivatives, and the simple synthetic route is designed to improve the rapid construction of mutiplearyl cross-coupling products.

Optimizing metal nanoparticles (NPs) efficiency through uniform dispersion and downsizing to smaller clusters/atoms holds substantial potential to enhance catalytic activity, thereby improving the sensitivity and selectivity of the sensor. Herein, we report an ultra-high dispersion of Pd (downsized to <1 nm), achieved by synthesizing Pd/NC-ZnO via a reverse sintering route derived from Pd@ZIF-8. As a proof-of concept, uniform dispersion of Pd in Pd/NC-ZnO demonstrated a chemiresistive hydrogen (H₂) sensor with response of 4.6 ± 0.2% and response/recovery times of 6.1 ± 0.3/5.8 ± 0.3 s, respectively towards 1% H₂ at 120 °C, while Pd@ZIF-8, the precursor material remained innocent for sensing H₂. The sensor exhibited selective detection towards H₂ among typically interfering gases and was active for sensing at room temperature despite low loading of Pd (0.09 wt.%). This work highlights judicious usage of Pd by means of high dispersion and small-sized clusters/atoms stabilized by ideal supports to achieve low-cost, rapid H₂ sensors.

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Despite low Pd loading (0.09 wt.%), ultra-high dispersion of Pd through reverse sintering from Pd@ZIF-8 enabled low-cost and rapid H₂ detection. The sensor Pd/NC-ZnO showed selective detection towards H₂ among typically interfering gases and was active for sensing at room temperature.

A series of di-phenyl ether derivatives were designed and synthesized through structure-based virtual screening followed by chemical optimization. 17 new compounds were submitted to activity evaluation against BRD4 BD2 utilizing the time-resolved fluorescence resonance energy transfer (TR-FRET) assay. Compound 10 exhibited good inhibitory activity to BRD4 BD2 with an IC₅₀ value of 0.95 μM. The molecular docking studies revealed the binding mechanism of the inhibitors to BRD4 BD2. Drug-likeness predictions demonstrated acceptable drug-like profiles of representative compounds. The resulting compound 10 represents a new lead compound for further optimization to generate more potent inhibitors of BRD4 BD2.

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A hit compound with weak binding activity was identified through virtual screening of an in-house library comprising 1,000 compounds, followed by TR-FRET assay validation of representative candidates. Structural optimization of this hit led to the discovery of a potent BRD4 BD2 inhibitor featuring a novel di-phenyl ether-coupled benzisoxazole scaffold.

The effect of n-type (CeO₂, SnO₂ and TiO₂) and p-type (SnO and TiO) semiconductors on the photoconversion of colchicine (COL) was investigated. All investigated semiconductors induced quenching of the fluorescence emission of COL with Stern–Volmer quenching constants ({k}_{sv}), ranging from (1.8 ± 0.1) × 10⁴ mol⁻¹ · L for CeO₂ to (3.5 ± 0.1) × 10³ mol⁻¹ · L for TiO₂. n-type semiconductors (SnO₂ and TiO₂) exhibited the most reduction in photo conversion rate constant and yields, achieving ≈50% inhibition in the presence of 8×10⁻⁵ mol · L⁻¹ of TiO₂ and SnO₂. While p-types showed minimal effects. Density functional theory (DFT) calculations were used to provide a clear insight into the effects of semiconductors on Frontier Molecular Orbitals (FMO) structure and HOMO-LUMO energy gaps of COL. DFT calculations showed the presence of n-type semiconductors reduces the HOMO-LUMO energy gap. Moreover, in the presence of n-type semiconductors, changes in the electronic topologies and dihedral angles of phenyl, 7-membered ring and tropolone ring in COL indicate a noticeable involvement of the tropolone and phenyl π-systems of COL with the conduction band of the semiconductors. These results support the observed fluorescence quenching and reduction of the photoconversion rate of COL in the presence of n-type semiconductors. The combined experimental and computational results elucidate the mechanism underlying fluorescence quenching and photoconversion inhibition, highlighting the crucial role of semiconductor type in modulating COL’s photochemical behavior.

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We investigate the role of n and p-type semiconductors on the photoconversion of colchicine. Both the semiconductors were found to quench the colchicine fluorescence, and n-type semiconductors exhibited a more pronounced effect. Moreover, it reduced colchicine, and the HOMO-LUMO energy gap influenced its electronic structure, leading to decreased photoconversion rates.

One of the basic organic transformations is the oxidative cleavage of 1,2-diol, which is currently primarily carried out by stoichiometric oxidants like Pb(OAc)₄ or KMnO_4, producing stoichiometric hazardous waste. The current method uses 1,2-diols as key reagents instead of benzaldehydes because it has been shown that periodic acid is an effective and mild reagent for the one-pot synthesis of pyran analogues from a variety of 1,2-diols. In this process, 1,2-diols are oxidized in situ to aldehydes, which then undergo a three-component reaction with malononitrile and phenols/4-hydroxycoumarin/dimedone to yield pyran analogues. The process is accelerated by the iodic acid produced in situ from periodic acid. The process has several appealing characteristics, including mild reaction conditions, short reaction times, broad functional group tolerance, easy product isolation, and excellent yields, use of an ecofriendly oxidant, potentially making it environmentally friendly.

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This research introduces the development of 5‐(4‐chlorophenyl)‐1‐(4‐sulphamoylphenyl)‐1H‐1,2,3‐triazole‐4‐carbothioamide (2) focusing on its selective metal ion affinity and biological activities. Compound 2 exhibited remarkable selectivity for Cu²⁺ ions, demonstrating a distinctive colour change (naked-eye detection), significant alterations in absorbance and emission spectra upon exposure to copper ions, and no such responses to other metal ions. Density functional theory (DFT) studies elucidated the binding mechanism, emphasizing electron transfer as crucial in facilitating coordinate bond formation between 2 and Cu²⁺ ions. Comparative studies with another derivative, 4‐[5‐(4‐chlorophenyl)‐4‐cyano‐1H‐1,2,3‐triazol‐1‐yl]benzenesulphonamide (1), underscore the importance of functional group having nitrogen and sulphur atoms in compound 2’s skeleton as pivotal binding sites for Cu²⁺ ions. Compound 2 also displayed excellent antimicrobial activity (against Gram-positive and Gram-negative bacterial strains, and a fungal strain) and notable antioxidant activity. Calculated values of ADME parameters confirmed the favourable drug-likeness behaviour of 2. Non-toxic nature of 2 proves it applicable for Cu²⁺ detection in systems, where both biocompatibility and sensing ability are required.

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This research presents novel photophysical and biological applications of 5‐(4‐Chlorophenyl)‐1‐(4‐sulfamoylphenyl)‐1H‐1,2,3‐triazole‐4‐carbothioamide (2) as a chemosensor and antimicrobial as well as anti-oxidant agent, respectively. Compound 2 exhibited a distinct color change from colorless to yellow with Cu2+ ions, selectively. Further, compound 2 exhibited excellent inhibition potential against the growth of pathogenic microbes as well as free radicals.