Journal of Chemical Sciences最新文献

In this paper, we report the synthesis and the structure–activity relationship study of three hydrazone analogs; the Schiff base hydrazone SBH and 2, 4-dinitrophenylhydrazones H1 & H2 derived from (E)-chalcones, to identify the active fragment of each structure. This identification has been carried out following in vitro biological evaluation, which revealed that the analogs H1 and H2 showed significant antibacterial activity due to their (E)-chalcone fragments characterized by proton NMR data and demonstrated by the docked view with emphasis on the involvement of these moieties in the interaction with the DNA gyrase, and thus contributes to the pharmacophore modeling. At the same time, SBH exhibited the highest free radical DPPH scavenging power associated with hydrogen bonding and conjugated push−pull chromophores, which were elucidated by reported vibrational assignments and absorption spectra. The DFT optimizations gave rise to non-planar and distorted structures around the hydrazone group with comparable geometrical parameters. The chemical descriptors predict comparable biological activities, while the BDE necessary for the H-abstraction indicated the best antioxidant activity for the Schiff base hydrazone SBH compound.

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2, 4-Dinitrophenylhydrazone analogs with (E)-chalcone and/or push-pull moieties were synthesized and characterized. The in-vitro and in-silico studies were carried out both to find the structure-activity relationship and to model the pharmacophore.

We have investigated the photophysical properties of chalcone derivatives by UV-visible absorption spectra. The HOMO–LUMO energies were calculated. Electrochemical properties of the compounds (5a–5d) via cyclic voltammetry showed that compounds have oxidation peaks. In addition, chalcone derivatives were analyzed for DNA binding study. It revealed that chalcone derivatives had a promising affinity towards DNA double helix. DNA binding constants of the complexes indicate the intercalative binding mode involving a strong aromatic chromophore and DNA base pairs.

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Synopsis: We have calculated the photophysical and electrochemical properties of chalcone derivatives by UV-visible absorption spectra. Along with this DNA binding studies were also performed.

A novel strategy for the chemoselective conversion of sulfoxides to sulfide utilizing D-camphorsulfonic acid (D-CSA) as a reducing reagent has been developed under metal and additive-free conditions. A variety of sulfoxides such as alkyl–aryl, allyl–aryl, benzyl–aryl, aryl–ethyl sulfoxides have been effectively utilized to achieve the corresponding reduced products in good to excellent yields under mild conditions without any additive. The proposed method offers a practical solution for the deoxygenation of sulfoxides, which has potential applications in various fields such as pharmaceuticals, materials science, and organic synthesis.

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A novel strategy for the chemoselective deoxygenation of diverse sulfoxides without metal and additive has been disclosed using D-camphorsulfonic acid (D-CSA) as the reducing agent. The reaction proceeds under mild conditions to afford the sulphides in moderate to good yields with great tolerance of diverse functional groups.

Dihydrogen bond (DHB) interaction that exists in ammoniated metal borohydride systems is recognized as an effective intermediate step involved in the evolution of H₂ molecules. Mechanism of DHB formation and its electronic properties upon halogenations were explored for Mg(BH₄)₂·2NH₃⋯M(BH₃X) (where M = Li, Na, K, and X = H, F, Cl, and Br) systems using ab initio (MP2) and DFT (ωB97XD) calculations. The influence of halogens in varying the nature of the DHB that forms in Mg(BH₄)₂·2NH₃⋯M(BH₃X) complexes was explored with the Quantum Theory of Atoms In Molecule (QTAIM) analysis. Further, Energy decomposition analysis (EDA) was made to understand the strength of DHB interaction through the calculation of the E_disp term in interaction energy. The results obtained from EDA and QTAIM were found to correlate well with the structural parameter and the interaction energy values. This study reveals the influence of halogenations on tuning the electronic properties of DHB interaction in all the complexes. Our results suggest that the effective substitution of halogens in BH₄ molecule enhances DHB interaction, and the impact of halogenations on DHB has been revealed through QTAIM, EDA, Natural Bond Order (NBO), Non-covalent Interaction (NCI), and Bader charge analyses.

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• Dihydrogen bonds in ammine metal borohydride systems are responsible for its large hydrogen storage capacity.

• This study reveals the DHB interaction found in the chosen Mg(BH₄)2.2NH₃⋯M(BH₃X) systems and their property enhancement upon introducing halogens through QTAIM parameters.

Two new zinc azole complexes incorporated Strandberg-type cluster-based solids, namely (Hpz)₆{Zn(pz)₄(H₂O)₂}[{Zn(pz)₂P₂Mo₅O₂₃}₂]·8H₂O (1) and (Himi)₄{Zn(imi)₃P₂Mo₅O₂₃}·7H₂O (2) were crystallized using isomeric azole ligands, i.e., pyrazole (pz) and imidazole (imi), respectively. While solid 1 crystallized in triclinic system with space group P-1 with cell parameters a = 9.5647(15), b = 12.558(2), c = 20.340(3) Å, α = 75.907(7), β = 84.727(6), γ = 87.525(7)°, Z = 1; 2 crystallized in orthorhombic system with space group P2₁2₁2₁ having cell parameters a = 12.048(3), b = 19.561(5), c = 20.732(5) Å, Z = 4. Both pyrazole and imidazole can form a complex with zinc centres to form an extended solid in 1 and a derivatized Strandberg-type cluster in 2. Interestingly, 1 is a new supramolecular isomer of previously reported solid viz., (pz)[{Zn(pz)₃}₃{P₂Mo₅O₂₃}]·2H₂O and 2 is the only example wherein a zinc imidazole complex has derivatized a Strandberg-type cluster. Detailed structure analysis of 1 and 2 was carried out, and the role of tectons in dictating the self-assembly of these solids was evaluated. In addition, a solid-state photoluminescence study was carried out for 1 and 2 at room temperature.

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Two zinc azole complexes incorporated Strandberg-type cluster-based solids and have been crystallized. While 1 is a new supramolecular isomer of (pz)[{Zn(pz)₃}₃{P₂Mo₅O₂₃}]·2H₂O; 2 is the only example wherein a zinc imidazole complex has derivatized a Strandberg-type cluster. Apart from detailed structural analysis, solid-state photoluminescence of solids has also been investigated.

Density Functional Theory (DFT) suffers from a strong dichotomy between accuracy and consistency. There exists a paucity of a generic linear route to the systematic improvement of computed results. Benchmark studies are often unidimensional and based on molecular/atomic properties that contour on a single Potential Energy Surface. Thus, the DFT functionals so developed and optimized to similar chemical accuracy lack a universal adherence to the unique density distribution for a fixed nuclear arrangement. We have identified this as a major source of inconsistency within the DFT framework and have explored through the cross-correlations between Structure, Energy, and Dipolar Strength. Since Range Separated Hybrid (RSH) functionals are well-known in literature to produce one of the finest molecular structures in both ground and excited states, in this communication, we have utilized CAM-B3LYP, LC-(omega)HPBE, and (omega)-B97XD to explore the above cross-correlations on well-studied test subjects comprising of Anthracene, Tetracene, Phenanthrene and Pyrene in all possible combination of these functionals. The combined responses from the functionals have revealed that major inconsistency operating between structure and energy dictates the variations in the dipolar strength and that lower RMSD and higher charge reorganization are the keys to higher dipolar strength. While LC-(omega)HPBE stands out, CAM-B3LYP and (omega)B97XD remain comparatively more like each other except in the Adiabatic Energy Difference (AED) trend.

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In this work, we prepared CuO NPs@UiO-66, a zirconium-based metal-organic framework with a nanoporous structure and high surface area, through a solvothermal method involving the in situ incorporation of pre-synthesized CuO nanoparticles. The synthesized material was characterized using various techniques, including Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption-desorption isotherms (BET-BJH). The catalytic activity of the synthesized catalyst, CuO NPs@UiO-66, was examined in both the Henry reaction and one-pot allylic C-H bond oxidation of olefins. Remarkably, the catalyst exhibited excellent recyclability, maintaining high yields and activity for up to three cycles.

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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.

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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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