Chemical Papers最新文献

In this research, the thermodynamic properties and molecular interactions of 1-hexyl-3-methylimidazolium bromide + methylparaben + water system were reported using conductometric method and molecular dynamics simulations. The conductometric data were collected for 1-hexyl-3-methylimidazolium bromide ionic liquid from 0.0012 to 0.1983 mol kg⁻¹ on various molality of methylparaben in aqueous solution (m_MP = 0.0000, 0.0005 and 0.0010 mol kg⁻¹) at T = (300.2, 310.2 and 320.2) K and P = 0.1 MPa. Fuoss–Onsager equation was applied to get the ion association constants and limiting molar conductivities of ionic liquid and to determine the thermodynamic of ion association. Moreover, molecular dynamics simulations were made to understand the interactions between ionic liquid and methylparaben at the molecular and microscopic level. Radial distribution functions, root-mean-square deviations, hydrogen bonding and van der Waals and electrostatic interactions were obtained. Furthermore, the diffusion coefficients of ionic liquid in methylparaben and water mixtures were obtained from molecular dynamics simulation to calculate the molar conductivity of 1-hexyl-3-methylimidazolium bromide using Einstein’s Nernst equation at T = 310.2 K and were in agreement with experimental molar conductivity.

Owing to global warming and the shortage of fossil fuel reserves, there has been a search for sustainable and cleaner energy sources. Thermoelectric (TE) generators, which are environmentally friendly alternatives using the Seebeck effect, can generate electricity with some of the waste heat and contribute to slowing the rate of global warming. It can be said that thermoelectric polymer materials have become more attractive than inorganic thermoelectric materials due to their high mechanical elasticity, non-toxicity, low cost, easy processability, and poor thermal conductivity. However, since the thermoelectric properties alone are not sufficient, the thermoelectric properties can be increased by adding conductive polymers, organic, inorganic, or polymeric nanoparticles. In this study, free-standing and flexible nanofiber composites were obtained with poly(ε-caprolactone) (PCL), poly(m-anthranilic acid) (PANA), Fe₂O₃, and Fe₃O₄ by the electrospinning method. The TE properties of the obtained nanofiber were investigated. The highest Seebeck coefficient and thermoelectric power factor were obtained from PCL/PANA/Fe₃O₄ nanofiber composite as 49 µV/K and 0.13 µW/mK², respectively. Nanofibers were characterized by XRD and FTIR, and their surface morphology was examined by SEM.

A new p-tert-butylcalix[4]crown-6 ether derivative was synthesized as a potential extractant for cesium and other alkali metal ions from water. The synthesized p-tert-butylcalix[4]crown-6 ether derivative was characterized via spectroscopic methods. The p-tert-butylcalix[4]crown-6 ether derivative was employed for the extraction of alkali metal ions as picrate and witnessed selective cesium ion extraction from the aqueous to organic phase with high efficiency. Both UV–Vis and atomic absorption spectrometry were used to assess the extraction efficiency. This material can be used in water purification systems for removing nuclear radioisotope cesium. The p-tert-butylcalix[4]crown-6 ether derivative was also analyzed using M06-2X/6-31G(d)/LANL2DZ methods. The computational method suggested the role of O–H⋯O and O–H⋯π interactions in the stability of different conformers of p-tert-butylcalix[4]crown-6 ether derivative. Moreover, it was witnessed through calculations that three conformers of p-tert-butylcalix[4]crown-6 ether derivative (cone, partial cone, and 1,3-alternate) can form a complex with cesium ion.

This study elucidates a fast, uncomplicated, convenient, and environmentally friendly technique for removing hazardous dyes such as acid red (AR1) and methylene blue (MB) from aquatic solutions. The process of adsorption was employed to eliminate AR1 and MB dyes by utilizing nanocomposite (NCs) consisting of cross-linked polyaniline (ClPani) combined with variety carbon nanomaterials (CNMs). ClPani was synthesized using aniline (ANI) and p-phenylenediamine (PPDA) were chemically oxidatively copolymerized with triphenylamine (TPA) at the existence of carbon nanomaterials (CNMs), namely, Graphene (Gr), multi-walled carbon nanotube (MW), and graphene-multi-walled carbon nanotube (Gr-MW). The characteristics of the NCs, including their shape, structure, and thermal properties, were analyzed using various techniques. When compared to other nanocomposites, the adsorption analysis demonstrated that ClPani/Gr-Mw exhibited the highest removal effectiveness for AR1 and MB dyes. Different factors that impact adsorption efficacy, including pH solution, adsorbent mass, temperature, the duration of shaking, and KNO₃ concentration. The efficiency of AR1 and MB dyes' adsorption on ClPani/Gr-Mw was studied kinetically, and the obtained data showed the processes followed a pseudo-second-order system. The Langmuir model was determined to be appropriate for telling the isotherm behavior of dye removal by ClPani/Gr-Mw, under optimal conditions. The maximal adsorption capacity was found to be 153.8 mg g⁻¹ for AR1 and 46.1 mg g⁻¹ for MB. Furthermore, the thermodynamic study suggests that the elimination of AR1 and MB dyes is a process that absorbs heat, while the attachment of dyes is a procedure that involves chemical bonding and occurs naturally. Ultimately, the removal effectiveness of AR1 and MB dyes was tested on three distinct actual samples using ClPani/Gr-Mw, resulting in a (E%) exceeding 94%. In summary, ClPani/Gr-Mw was found to be a cost-effective and environmentally acceptable chemical for effectively eliminating the hazardous dyes AR1 and MB.

Organic crystals, composed of small organic molecules held together by noncovalent intermolecular interactions, exhibit a diverse range of properties. Careful consideration of these interactions enables scientists to tailor crystal properties for specific applications. This study investigated the structural and electronic features of a 1,5-benzodiazepine-based heterocycle, 1-((3-(2-chlorophenyl)isoxazol-5-yl)methyl)-4-(2-hydroxyphenyl)-1H-benzodiazepin-2-one. Employing a multifaceted approach combining structural and quantum chemical methods, we elucidated the molecular geometry, crystal packing, and chemical reactivity in both mono- and dimeric forms. We revealed a network of noncovalent interactions governing the solid-state structure, including C–H⋯O and C–H⋯N hydrogen bonds, alongside π-interactions (C–H⋯π and π–π stacking). Multi-approach quantum mechanics analysis using dispersion-corrected DFT (ωB97X-D/aug-cc-pVTZ) unveiled the nature and energetics of these interactions, incorporating natural bond orbital analysis, quantum theory of atoms in molecules, and Hirshfeld surfaces. Conceptual DFT identified the studied heterocycle as a moderate electrophile and strong nucleophile in polar organic reactions, while Parr functions pinpoint favourable sites for electrophilic and nucleophilic attacks.

In this study, a series of imidazo[1,2-a]pyridine-mannich bases were designed and synthesized for the inhibition of cholinesterases, one of the important pathways in the treatment of Alzheimer's dementia. The imidazopyridine scaffold, which is found in the structure of many active compounds in pharmaceutical use, is derived from Mannich-bases containing morpholine and various aromatic groups. In vitro AChE and BChE enzyme activities and enzyme kinetics studies of new potential drug candidates (9a-j) that can target the critical binding regions of cholinesterases were conducted. In vitro evaluation with donepezil, tacrine (control compounds), and 9a-j, it was found that naphthalene-substituted compound 9j exhibited the most potential anti-cholinesterase activity (IC₅₀s: 57.75 nM for AChE; 99.0 nM for BChE). Molecular docking studies performed with hAChE and hBChE enzyme crystal structures revealed that compound 9j has a higher binding affinity by targeting the CAS and PAS binding sites. Additionally, drug-likeness and pre-ADMET evaluation of the compounds showed that compound 9j had the most favorable drug properties. These results might be a new milestone in terms of the promising importance of the imidazopyridine scaffold in future drug design for the treatment of AD.

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Heavy crude oil viscosity reduction is essential for the petroleum industry because of its high density and viscosity, elevated concentration of asphaltene, and limited mobility. The primary aim of this investigation is to decrease the viscosity of Sharqy Baghdad heavy crude oil with 20.32 API by ultrasonic irradiation using Fe₂O₃-functionalized silica nanoparticles (SiFe). SiFe of an average size of 67.11 nm and 426.12 m²/g surface area were created by the incipient wetness technique with Fe₂O₃ over SiO₂ nanoparticles, prepared by the sol–gel method using local sand. The X-ray diffraction analysis (XRD) indicates the presence of an amorphous silica with α-Fe₂O₃. Scanning electron microscopy analysis (SEM) showed that SiFe nanoparticles tend to agglomerate. Energy dispersive X-ray analysis (EDX) reveals the presence of Si, O, Al, and Fe elements. Fourier transform infrared spectra (FTIR) exhibit the presence of siloxane, silanol groups, and the Fe–O stretching mode of Fe₂O₃. A low total weight loss of 8.23% is revealed by thermogravimetric analysis (TGA), which validates the thermal stability of SiFe nanoparticles. The optimal outcomes were observed when the ultrasound exposure time was set at 2 min, 30% power intensity, 0.8 duty cycle, 35 °C, with 1000 mg/L SiFe nanoparticles, resulting in a reduction in viscosity of 33.74%, asphaltene concentration reduced from 6.379 to 4.119 wt%, and sulfur content decreased from 4.68 to 3.85 wt%. These findings demonstrated the effectiveness of employing nanoparticles and ultrasonic waves to increase the light components in crude oil compared to ultrasonication alone, and this plays a significant role in facilitating oil transportation through pipelines and enhancing the production of lighter fractions of high economic and industrial value during oil refining.

Boron oxide (B₂O₃) is investigated as a second oxide with regard to magnesium oxide (MgO) to inhibit the vanadic corrosion caused by the ash resulting from burning heavy fuel oil (HFO). The inhibitory effect is achieved by changing the composition of the resultant ash by forming higher melting points components as magnesium pyroborate (Mg₂B₂O₅) (PB) and magnesium orthoborate (Mg₃B₂O₆) (OB) that in turn reacts with corrosive, low melting point vanadium oxide (V₂O₅) to yield refractory higher melting point magnesium orthovanadate (Mg₃V₂O₈) (OV). MgO nanoparticles were successfully synthesized by co-precipitation technique at room temperature using magnesium nitrate and sodium hydroxide as a precursor, and B₂O₃ was successfully synthesized by thermal decomposition of boric acid. Both oxides were sonicated with oleic acid (OA). The morphological investigation of both nanoparticles oxides was done by Scanning Electron Microscope (SEM–EDX), X-ray Diffraction (XRD) for indicating the crystallinity and crystal size of nanoparticle, Fourier Transform Infrared spectroscopy for analyzing the functional groups of the samples. Nanoparticle oxides suspended in OA was added to HFO which is burned to obtain ash according to ASTM D482. The morphological investigation and composition of the ash were done by (SEM) and (XRD) to identify and compare the resulting compounds before and after the addition of the oxides.

Lactic acid holds significant application potential across multiple domains, encompassing medicine, food science, and biotechnology, among others. Consequently, the accurate detection of lactic acid has emerged as a primary research focus. Presently, numerous lactic acid detection techniques exist, leveraging chromatography, colorimetry, and electrochemical principles to measure lactic acid concentrations both externally and internally within the human body. Furthermore, the exploration of wearable biosensors capable of directly monitoring lactic acid levels in bodily fluids is gaining momentum. Hence, this paper aims to comprehensively review the chemical structures, physiological roles, and detection techniques of lactic acid biosensors, while also exploring their future research prospects.