Journal of Chemical Sciences最新文献

A novel approach using a soft ionic atmosphere model for the diffusion of ions in concentrated aqueous electrolytes is developed to quantify molar conductivity ((Lambda)), diffusion coefficient (D), and relative viscosity ((eta _{text {r}}^*)). The entropy-driven expansion of the ionic atmosphere in the concentrated electrolyte is characterized through average ion size (({overline{r}}_{text {H}})), ionic screening length for point particle ions ((l_{text {D}})) and a hardness exponent ((gamma)). The radius ((l_{text {s}})) of expanded ionic sphere for finite size ions: (l_{text {s}}= l_{text {D}}(1+ ({overline{r}}_{text {H}} /l_{text {D}})^3)). (l_{text {s}}) circumvents the limitations of the classical Debye screening length ((kappa ^{-1})) in concentrated electrolytes. This model leads to a power law dependence of (Lambda), D and (eta _{text {r}}^*) on (l_{text {s}}). The extent of the hardness of the ionic atmosphere is characterized by an exponent (gamma), which is characteristic of an electrolyte solution and lies between 0.2–0.8. The expansion of the ionic sphere increases with concentration causing enhancement of the effective size of ions, resulting in the reduction in diffusion coefficient and molar conductivity. The model captures the experimental molar conductivity data for the fifteen salts in the aqueous medium.

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1,2,3-Triazole, 1,3-imidazole, and 1,3-thiazole are a class of organic heterocyclic compounds with notable applications in a diverse range of biological and pharmacological activities. Herein, we report the synthesis of molecules having these three moieties together. Each of the fused molecule was characterized with elemental analysis, melting point determination, FTIR, NMR, and mass spectrometry. The final fused molecules were screened for in vitro biological activities against a wide spectrum of microorganisms, such as gram-positive bacteria (E. coli, P. aeruginosa, S. aureus, S. phogenes), gram-negative bacteria (S. typhi, V. cholerae, B. subtilis, C. tetani), as well as fungus (C. albicans, A. niger, and A. Clavatus). Each of the compounds showed moderate to good activity which is comparable to commercially available drugs. Further, the molecular docking study on the crystal structure of the 43K ATPase domain of Thermus thermophilus gyrase B (PDB:1KIJ) and on crystal structure of penicillin-binding protein 4 from Staphylococcus aureus COL (PDB:3HUN) revealed strong binding affinities by the synthesized compounds. The ADME study also showed the drug likeliness of the compounds.

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Annulation reactions involving acetoxy allenoates and enolizable carbonyl substrates under DBU (DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene) catalysis is described in this paper. Thus DBU catalyzed (3 + 3) annulation reactions of acetoxy allenoates with the bifunctional nucleophiles benzo-oxathiin-dioxide and phenylthiazolone afford fused 4H-pyrans. Both β′-acetoxy allenoates and δ-acetoxy allenoates undergo this annulation to give pyrano-oxathiines or pyrano-thiazoles.

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Acetoxy allenoates undergo facile (3 + 3) annulation with benzo-oxathiin-dioxide and phenylthiazolone under DBU catalysis to afford pyrano-oxathiines and pyrano-thiazoles.

A regioselective novel one-pot synthesis of heterocyclic purine derivative antiviral agent Ganciclovir in which initially guanine is treated with acetic anhydride in the presence of iodine (5%) to get diacetyl guanine intermediate, which undergoes in situ N-alkylation with AMDP in presence of catalytic acidic Amberlite IR-120 to get N-alkylated intermediate and finally deacetylation to get pure regioselective Ganciclovir, which is commercially viable and eco-friendly.

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We developed one-pot synthesis of antiviral drug Ganciclovir. Initially, Guanine is treated with acetic anhydride and iodine to yield diacetyl guanine 3. This intermediate then reacted with AMDP in the presence of acidic Amberlite IR-120 to obtain compound 5. Finally, deacetylation yields Ganciclovir 1, a commercially viable and eco-friendly process.

This study examines the intricate thermal decomposition of sweet sorghum bagasse, an agricultural residue with significant potential as a renewable energy and biofuel feedstock. Both slow and flash pyrolysis has been conducted over a temperature range of 300–450°C and flash pyrolysis experiments were performed through analytical pyrolysis via Py-GC/MS to comprehensively assess the pyrolysis behaviour and elucidate the biomass degradation pathways. In the slow pyrolysis experiments, sweet sorghum bagasse underwent controlled thermal decomposition at different temperatures (300–450°C), allowing for the investigation of the influence of temperature on product yields and compositions. The evolved volatile compounds and biochar products were analyzed to determine the impact of temperature on biomass degradation. The results revealed that 400°C is the optimum pyrolysis temperature for maximizing valuable bio-oil production with approximately 42 wt.% yields with an overall conversion of 73%. Various characterization techniques were employed to analyze the slow pyrolysis products, including GC-MS, TGA, FTIR, SEM, and XRD. Flash pyrolysis was employed to provide a detailed understanding of the rapid biomass breakdown under extreme heating conditions with a heating rate of 20°C/ms to complement the slow pyrolysis findings. This technique elucidated the primary mechanisms responsible for the degradation of sweet sorghum bagasse, shedding light on the fragmentation patterns and the formation of vital intermediate compounds during flash pyrolysis. These insights into the transient phenomena occurring during pyrolysis provide valuable information for developing efficient and sustainable biomass conversion processes.

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The pyrolysis behaviour of sweet sorghum bagasse (SSB) is comprehensively assessed using TGA, slow pyrolysis via lab scale glass tubular reactor and flash pyrolysis via analytical tool Py-GC/MS from 300–450°C. The study reveals the potential use of SSB as a renewable energy and biofuel feedstock.

A novel organic fluorescent material, namely 2,6-di([1,1'-biphenyl]-4-yl)-4-(perfluorophenyl)hepta-1,6-diene-1,1,7,7-tetracarbonitrile (DBPDT), has been synthesized and characterized in this study. Due to the special molecular packing mode in the solid state, J-aggregation, DBPDT displayed red-shifted emission compared with that in dilute solution. In this study, it was found that DBPDT showed aggregation-induced enhanced emission (AIEE) and solvatochromic properties. Assisted by quantum chemistry calculations, optical response properties to external electric field (EEF) were investigated, where it was found that external electric field (EEF) would affect the structures and optical properties of DBPDT distinctly. The optical response characteristics of DBPDT can provide an alternative structure for constructing advanced photoelectric functional materials.

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A novel organic fluorescent material, namely 2,6-di([1,1'-biphenyl]-4-yl)-4-(perfluorophenyl)hepta-1,6-diene-1,1,7,7-tetracarbonitrile (DBPDT), has been synthesized and characterized in this study. Assisted by quantum chemistry calculations, optical response properties to external electric field (EEF) were investigated, where it was found that external electric field (EEF) would affect the structures and optical properties of DBPDT distinctly.

In this study, the simultaneous synthesis of poly(methyl methacrylate-b-ε-caprolactone) block copolymer was fulfilled by atom transfer radical polymerization of methyl methacrylate and ring-opening polymerization of ε-caprolactone. The synthesis of poly(methyl methacrylate-b-ε-caprolactone) block copolymer was carried out by varying the amount of ε-caprolactone monomer, the amount of methyl methacrylate monomer, the amount of 2-(2-chloroethoxy) ethanol initiator, the amount of toluene solvent, and the polymerization time. The effects of these parameters on the reaction conditions were investigated. Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and static light scattering methods were used for the characterization of the synthesized block copolymer. The surface images of the block copolymer were photographed with a scanning electron microscope instrument. In addition, thermal analysis of the synthesized block copolymer was performed using a thermogravimetric analyzer. These analyses prove the formation of the block copolymer structure.

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The simultaneous synthesis of poly(methyl methacrylate-b-ε-caprolactone) block copolymer was fulfilled by the atom transfer radical polymerization of methyl methacrylate and ring-opening polymerization of ε-caprolactone. The effects of the parameters on the polymerization reaction conditions were investigated. Thermal and spectroscopic measurements prove the formation of the block copolymer structure.

Thiols are ubiquitous compounds found in almost all spheres of life, viz: from simple matter to complex human body. It has widespread applications in diverse domains such as pharmaceuticals, materials, agricultural science, fire science, laser science, catalytic systems, reagent systems, and industry. Although all sulphur compounds encompass one or the other significant properties. However, thiols containing –SH bond are vital as they act as starting substrates for many chemical reactions, are directly present in the biological systems, are abundantly found in natural products, and exhibit profound chemical and biotechnological properties. For example, the –SH group can be easily manipulated to a range of other potent functionalities such as –S–S, –SO₂Cl₂, –SOCH₃, –SOCl₂, –SONH₂, –Cl, –NH₂, –OH, etc. In this view, this review focuses on reporting detailed synthetic methodologies giving access to thiols (–SH). For interesting reading, it has been categorised as follows: (i) via isothiouronium salts; (ii) catalytic preparation of thiols using H₂S; (iii) using silanethiol/disilathiane; (iv) using thiolacetic acid/thioacetates; (v) from xanthates; (vi) reaction of sodium thiocyanate; (vii) using sodium trithiocarbonates; (viii) using Lawesson’s reagent; (ix) using phosphorus decasulfide; (x) enzymatic method; and the rest of a methods are classified under miscellaneous section.

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Synthetic methodologies to form terminal –SH bonds using various reagent systems, viz; (i) isothiouronium salts; (ii) catalytic preparation using H₂S; (iii) silanethiol/disilathiane; (iv) thiolacetic acid/thioacetates; (v) xanthates; (vi) reaction of sodium thiocyanate; (vii) sodium trithiocarbonates; (viii) Lawesson’s reagent; (ix) phosphorus decasulfide and (x) few enzymatic methods.

Among the various Schiff bases, those containing 2,4-diaminotoluene as a primary amine and 2-hydroxy-4-methoxybenzaldehyde as a carbonyl compound are new and deserve special attention because their logical spectral properties find application in analytical chemistry as a smart probe. The new Schiff base has been synthesized to its pure crystalline form. It is characterized by single-crystal XRD, FT-IR, NMR, TGA, and mass spectrometry. We have studied the spectral properties of the Schiff base and its aluminium adduct by UV-vis and fluorescence spectroscopy and rationalized them by computational analysis. The Job's plot and mass spectrometry indicate the 1:1 binding ratio between the ligand and the Al³⁺ ion. The suitable binding constant value (8.329×10³ M^–1) leads to the development of Al³⁺ sensation by the Schiff base. The sensor has an appreciably low limit of detection value of 7.638×10^–9(M), i.e., 0.00163 ppm for Al³⁺. The logical behaviour of the probe (NAND-type molecular logic gate with two inputs, Al³⁺ and EDTA) leads to the development of a renewable aluminium testing kit.

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The synthesis of poly(4-vinylbenzyl-g-β-butyrolactone) (poly(VB-g-BL)) graft copolymer was carried out by “click” chemistry of terminal azido poly(4-vinylbenzyl chloride) (PVB-N₃) and terminal propargyl poly(β-butyrolactone) (β-BL-propargyl). For this purpose, poly(4-vinylbenzyl chloride) (poly-4-VBC) was obtained using 4-vinylbenzyl chloride and 2,2′-azobis(2-methylpropionitrile) by free-radical polymerization. PVB-N₃ was synthesized using sodium azide and poly-4-VBC. β-BL-propargyl was obtained by the reaction of β-butyrolactone monomer with propargyl alcohol via ring-opening polymerization. The graft copolymer was also synthesized via “click” chemistry, employing PVB-N₃ and β-BL-propargyl. The products were thoroughly characterized by GPC, FT-IR, SEM, and ¹H-NMR. DSC and TGA were used to track the graft copolymer’s thermal characteristics. Thermal and spectroscopic measurements verified that the reactions were effectively completed.

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Poly(4-vinylbenzyl chloride) was obtained by free-radical polymerization. Terminal azido poly(4-vinylbenzyl chloride) was synthesized using sodium azide and poly(4-vinylbenzyl chloride). Terminal propargyl poly(β-butyrolactone) was obtained by β-butyrolactone and propargyl alcohol via ring-opening polymerization. Poly(4-vinylbenzyl-g-β-butyrolactone) graft copolymer was synthesized by “click” chemistry. Thermal and spectroscopic measurements verified that the reactions were completed.