Introduction of a tropine-based dication ionic liquid catalyst for the synthesis of polyhydroquinoline and 1,8-dioxodecahydroacridine derivatives

Research on Chemical Intermediates - In this work, 1,1-(butane-1,4-diyl)bis(tropinium)chloride is prepared, identified and used for the promotion of the synthesis of polyhydroquinoline and...     

Jacob Bernoulli's analyses of the Funicularia problem

Jacob Bernoulli's entries about mechanics in his scientific notebook, the ‘Meditationes’, reveal new facts about the history of the catenary curve. Bernoulli's analyses show that the catenaria, velaria, lintearia and elastica curves together form a family of curves, which I will refer to as the funicularia family. Attending to the history of the whole family of these curves provides remarkable insights into the origin of the catenary problem and the process of its discovery. Studying the ‘Meditationes’ together with Bernoulli's correspondence and publications shows how analysis of one curve led him to the discovery of the others. As a result, this study shows that – although Leonhard Euler is known to be the one who unified the catenary problem and the elastica problem in 1728 – Jacob Bernoulli had in fact proven the same more than thirty years earlier, providing in his notebook a general differential equation for this family of curves. Furthermore, I demonstrate Jacob Bernoulli's priority over his brother Johann in finding the velaria curve.     

Irreversible replacement of sodium with thallium in sodium coordination polymer nanostructures by solid-state mechanochemical cation exchange process

Solid-state conversion of Na^I coordination polymer nanostructure, synthesized by sonochemical procedure, to Tl^I coordination polymer has been observed upon liquid-assisted mechanochemical reaction of [Na₂TP] _n (1) (H₂TP = terephthalic acid), with TlNO₃. During this conversion, ion exchange process of Na(I) with Tl(I) was occurred and [Tl₂TP] _n (2) was synthesized. The X-ray diffraction (XRD) pattern of 2 after mechanochemical reaction of it with NaNO₃ indicated that this transformation is irreversible. Compounds 1 and 2 were characterized by IR spectroscopy, X-ray powder diffraction (XRD), elemental analysis, thermogravimetric and differential thermal analyses and scanning electron microscopy.     

Magnetite nanoparticles surface-modified with a zinc(II)-carboxylate Schiff base ligand as a sorbent for solid-phase extraction of organochlorine pesticides from seawater

Magnetite nanoparticles were surface-modified with mercaptoacetic acid (MAA), complexed with Zn(II), and then treated with the dual Schiff base (referred to as imine-based ligand; IBL; obtained by reaction of p-aminobenzoic acid and 2,3-butanedione) to give particles with an architecture of type Fe₃O₄@MAA@IBL. These are shown to be viable sorbents for magnetic solid phase extraction of organochlorine pesticides (OCPs) from seawater samples. Efficient extraction of the OCPs probably is due to lone pair-π, π-complexation and π-interactions. The sorbent was characterized by transmission electron microscopy, scanning electron microscopy, FT-IR and energy-dispersive X-ray spectroscopy. The effects of the volumes of sample, sorbent dosage and eluent, adsorption and desorption times, and the salinity of the sample on the extraction efficiencies were optimized. The OCPs (heptachlor, aldrin, dieldrin, p,p’-DDE and p,p’-DDT) were quantified by gas chromatography with microelectron capture detection. Under optimal conditions, the limit of detections range was between 1.0 and 1.9 ng L^?1. The enrichment factors are between 84.1 and 99.9 %. The sorbent was applied to the rapid extraction of trace quantities of OCPs from seawater samples and gave good relative recoveries (78 to 108 %) and relative standard deviations (<8.3 %).

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Graphical Abstract Fe₃O₄ nanoparticles were functionalized with mercaptoacetic acid. The carboxylate was coordinated with Zn(II) and the ligands were immobilized via coordination with Zn(II). The lone pair-π, π-complexation and π-interaction of modified magnetite nanoparticles made this sorbent effective for extraction of organochlorine pesticides.

     

Carbon‐iodide bond activation by cyclometalated Pt (II) complexes bearing tricyclohexylphosphine ligand: A comparative kinetic study and theoretical elucidation

Cyclometalated Pt (II) complexes [PtMe(C^N)(L)], in which C^N = deprotonated 2,2′‐bipyridine N‐oxide (Obpy), 1 , deprotonated 2‐phenylpyridine (ppy), 2 , deprotonated benzo [h] quinolone (bzq), 3 , and L = tricyclohexylphosphine (PCy₃) were prepared and fully characterized. By treatment of 1–3 with excess MeI, the thermodynamically favored Pt (IV) complexes cis‐[PtMe₂I(C^N)(PCy₃)] (C^N = Obpy, 1a ; ppy, 2a ; and bzq, 3a ) were obtained as the major products in which the incoming methyl and iodine groups adopted cis positions relative to each other. All the complexes were characterized by means of NMR spectroscopy while the absolute configuration of 1a was further determined by X‐ray crystal structure analysis. The reaction of methyl iodide with 1–3 were kinetically explored using UV–vis spectroscopy. On the basis of the kinetic data together with the time‐resolved NMR investigation, it was established that the oxidative addition reaction occurred through the classical S_N2 attack of Pt (II) center on the MeI reagent. Moreover, comparative kinetic studies demonstrated that the electronic and steric nature of either the cyclometalating ligands or the phosphine ligand influence the rate of reaction. Surprisingly, by extending the oxidative addition reaction time, very stable iodine‐bridged Pt (IV)‐Pt (IV) complexes [Pt₂Me₄(C^N)₂(μ‐I)₂] (C^N = Obpy, 1b ; ppy, 2b ; and bzq, 3b ) were obtained and isolated. In order to find a reasonable explanation for the observation, a DFT (density functional theory) computational analysis was undertaken and it was found that the results were consistent with the experimental findings.     

Copper(I)–creatine complex on magnetic nanoparticles as a green catalyst for N- and O-arylation in deep eutectic solvent

Immobilization of copper(I) ions on magnetic nanoparticles was performed using surface modification of Fe₃O₄ with creatine. Fe₃O₄@creatine-Cu(I) magnetic catalyst was synthesized and applied in C&bond;X cross-coupling reactions with aryl halides in a deep eutectic as a green solvent. The results indicate the Fe₃O₄@creatine-Cu(I) magnetic nanoparticles showed excellent activity and high stability. In addition, it was revealed that this catalyst can be recycled five times without significant loss in catalytic activity.     

Synthesis of 4-alkylaminoimidazo[1,2-a]pyridines linked to carbamate moiety as potent α-glucosidase inhibitors

Molecular Diversity - In this work, various imidazo[1,2-a]pyridines linked to carbamate moiety were designed, synthesized, and evaluated for their α-glucosidase inhibitory activity. Among...     

Synthesis, characterization and fluorimetric studies of novel photoactive poly(amide-imide) from anthracene 9-carboxaldehyde and 4,4′-diaminodiphenyl ether by microwave irradiation

Trimellitic anhydride acid chloride (2) was obtained by the reaction of trimellitic anhydride (1) and excess amount of thionyl chloride. The acid chloride was reacted with 4,4′-diaminodiphenyl ether (3), and produced the monomer 4. Anthracene-9-carboxaldehyde (5) was reacted with sulfuryl chloride to produce anthracene-9-carboxylic acid chloride (6) in a quantitative yield. Through the reaction of 6 and 2,4,6-triamino-1,3,5-triazine (7), the monomer 8 was produced in high yield. Two monomers were characterized by ¹H NMR and FT-IR spectroscopy, and then were used in the polymerization reaction. A new facile and rapid polycondensation reaction of the two monomers was performed by using a domestic microwave oven. The polymerization reaction proceeded rapidly, compared with the conventional solution polycondensation and was completed within 10 min, producing a photoactive poly(amide-imide) in a quantitative yield. The resulting polymer was characterized by IR, ¹H NMR and TGA techniques. Thermogravimetric analysis indicated that polymer 9 was thermally stable in nitrogen atmosphere. In addition the initial decomposition temperature, 5% and 10% weight loss (T5, T10) were 284, 356 and 408 °C. The residual weight percent at 700 °C was 51.5%, which shows it is moderately thermally stable. Fluorescence properties of polymer 9 were investigated in several solvents. The ideal concentration of each case was determined by fluorescence self quenching phenomena. Also the self quenching mechanism was studied according to the specific behavior of the polymer in different solvents.     

The energy level shift of one-electron atom in Anti-(de Sitter) space time

In the present study we consider the Hamiltonian of the Dirac equation in curved space in fermi normal coordinates to first order in the Riemann tensor, including the corrections to the electromagnetic field. Then the energy level shifts by the local curvature for both relativistic and nonrelativistic levels in (Anti-)de Sitter space-time are calculated.