Antimosquito Activity of a Titanium–Organic Framework Supported on Fabrics

Waste swamps, stagnant water, and poor hygiene practices result in the proliferation of mosquitoes that may cause transmissible and infectious diseases such as malaria, typhoid, cholera, and Zika virus sickness. It has been shown that composites of the traditional natural fibers cotton, viscose, and linen and a Ti-bearing metal–organic framework, NH₂-MIL-125, are very effective against mosquitoes in the absence of any conventional insecticides. In our study, prior to coating with NH₂-MIL-125 crystals, the fabrics were modified with 3-glycidyloxypropyltrimethoxysilane. The composite materials were characterized by powder X-ray diffraction, UV–vis spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy with energy-dispersive X-ray spectroscopy analysis. The latter, in particular, has shown the uniform coating of the fabrics with NH₂-MIL-125 crystals. The modified fabrics have excellent antimosquito properties, attracting and killing them

Ohmic Heating-Assisted Synthesis of 3‑Arylquinolin-4(1<i>H</i>)‑ones by a Reusable and Ligand-Free Suzuki–Miyaura Reaction in Water

Potential bioactive 3-arylquinolin-4­(1<i>H</i>)-ones were synthesized under ohmic heating using an efficient, reusable, and ligand-free protocol developed for the Suzuki–Miyaura coupling of 1-substituted-3-iodoquinolin-4­(1<i>H</i>)-ones with several boronic acids in water using Pd­(OAc)₂ as a catalyst and tetrabutylammonium bromide (TBAB) as the phase transfer catalyst. Good substrate generality, ease of execution, short reaction time, and practicability make this method exploitable for the generation of libraries of B ring-substituted 3-arylquinolin-4­(1<i>H</i>)-ones. After a simple workup, the Pd/catalyst-H₂O-TBAB system could be reused for at least seven cycles without significant loss of activity

Synthesis of Enantiopure 2‑<i>C</i>‑Glycosyl-3-nitrochromenes

A novel methodology has been developed to obtain enantiopure 2-<i>C</i>-glycosyl-3-nitrochromenes. First, (<i>Z</i>)-1-bromo-1-nitroalkenes were prepared from the corresponding sugar aldehydes through a sodium iodide-catalyzed Henry reaction with bromonitromethane followed by elimination of the resulting 1-bromo-1-nitroalkan-2-ols. In the next step, reaction of the sugar-derived (<i>Z</i>)-1-bromo-1-nitroalkenes with <i>o</i>-hydroxybenzaldehydes afforded enantiopure (2<i>S</i>,3<i>S</i>,4<i>S</i>)-3-bromo-3,4-dihydro-4-hydroxy-3-nitro-2<i>H</i>-1-benzopyrans, which, upon SmI₂-promoted β-elimination, yielded chiral enantiopure 2-<i>C</i>-glycosyl-3-nitrochromenes

Structural Effects of the β‑Vinyl Linker in Pyridinium Porphyrins: Spectroscopic Studies in Organic Solvents and AOT Reverse Micelles

Two isomeric β-vinylpyridinium porphyrins, 2-[2-(2-methylpyridinium)­vinyl]-5,10,15,20-tetraphenylporphyrin (<b>1</b>, <i>ortho</i> isomer) and 2-[2-(4-methylpyridinium)­vinyl]-5,10,15,20-tetraphenylporphyrin (<b>2</b>, <i>para</i> isomer), which have shown different photodynamic behavior were investigated in organic solvents and sodium 1,4-bis­(2-ethylhexyl)­sulfosuccinate (AOT) reverse micelles. In organic systems, the absorption spectra present a red-shifted band that is more intense in the <i>para</i> isomer, in addition to the usual Soret band. This new band presents interesting solvatochromic effects which obey the multiparametric Kamlet–Taft equation. In AOT reverse micelles, the <i>ortho</i> isomer exhibits a strong dependence with the parameter ω₀ = [H₂O]/[AOT] which indicates that the molecule resides at the interface toward the organic phase. By contrast, no evidence was detected for the encapsulation of <i>para</i> isomer <b>2</b> in AOT reverse micelles. The hypothesis of two ground state isomers with different contributions of <i>trans</i> and <i>quinoid</i> structures is advanced on the basis of the overall data collected from electronic absorption, steady-state, and transient-state fluorescence emission. A charge transfer state in which an electron is fully transferred from the porphyrin to the pyridinium moiety is associated to a <i>quinoid</i> structure in isomer <b>2</b>. The <i>trans/quinoid</i> relative proportions may be accounted for by the orientation of the <i>ortho-</i>/<i>para-</i>pyridinium isomers relatively to the porphyrin core

Synthesis of Enantiopure 2‑<i>C</i>‑Glycosyl-3-nitrochromenes

A novel methodology has been developed to obtain enantiopure 2-<i>C</i>-glycosyl-3-nitrochromenes. First, (<i>Z</i>)-1-bromo-1-nitroalkenes were prepared from the corresponding sugar aldehydes through a sodium iodide-catalyzed Henry reaction with bromonitromethane followed by elimination of the resulting 1-bromo-1-nitroalkan-2-ols. In the next step, reaction of the sugar-derived (<i>Z</i>)-1-bromo-1-nitroalkenes with <i>o</i>-hydroxybenzaldehydes afforded enantiopure (2<i>S</i>,3<i>S</i>,4<i>S</i>)-3-bromo-3,4-dihydro-4-hydroxy-3-nitro-2<i>H</i>-1-benzopyrans, which, upon SmI₂-promoted β-elimination, yielded chiral enantiopure 2-<i>C</i>-glycosyl-3-nitrochromenes

Elucidating the Role of Aromatic Interactions in Rotational Barriers Involving Aromatic Systems

The measurement of aryl-naphthyl rotational barriers, Δ<i>G</i>^⧧, in various solvents for two substituted 1,8-diarylnaphthalenes by dynamic ¹H NMR showed that Δ<i>G</i>^⧧ trends in aromatic systems can be fully rationalized only when considering the different types of aromatic interactions that can be established in the ground and transition states, namely, intramolecular interactions involving the aromatic rings and specific solvation interactions

Effect of Self-Association on the Phase Stability of Triphenylamine Derivatives

The self-association equilibrium, i.e. formation of noncovalent dimers, in two triphenylamine derivatives, TPD (<i>N,N</i>′-bis­(3-methylphenyl)-<i>N,N</i>′-diphenylbenzidine) and mMTDAB (1,3,5-tris­[(3-methylphenyl)­phenylamino]­benzene), in solution was evaluated by ¹H NMR spectroscopy. The gas-phase energetics of the respective dimerization processes was explored by computational quantum chemistry. The results indicate that self-association is significantly more extensive in TPB than in TDAB. It is proposed that this fact helps to explain why TPB presents a stability higher than expected in the liquid phase, which is reflected in a lower melting temperature, a less volatile liquid, and possibly a higher tendency to form a glass. These results highlight the influence of self-association on the phase equilibria and thermodynamic properties of pure organic substances

Lipophilic Extracts of Cynara cardunculus L. var. altilis (DC): A Source of Valuable Bioactive Terpenic Compounds

Lipophilic extracts of Cynara cardunculus L. var. altilis (DC) from the south of Portugal (Baixo Alentejo) were studied by gas chromatography–mass spectrometry. One sesquiterpene lactone, four pentacyclic triterpenes, and four sterols were reported for the first time as cultivated cardoon components, namely, deacylcynaropicrin, β- and α-amyrin, lupenyl and ψ-taraxasteryl acetates, stigmasterol, 24-methylenecholesterol, campesterol, and Δ⁵-avenasterol. In addition, other new compounds were identified: ten fatty acids, eight long-chain aliphatic alcohols, and six aromatic compounds. Four triterpenyl fatty acid esters were also detected. Sesquiterpene lactones and pentacyclic triterpenes were the major lipophilic families, representing respectively 2–46% and 10–89% of the detected compounds. Cynaropicrin was the most abundant sesquiterpene lactone, while taraxasteryl acetate was the main pentacyclic triterpene. Fatty acids and sterols, mainly hexadecanoic acid and β-sitosterol, were present at lower amounts (1–20% and 1–11% of the detected compounds). Long-chain aliphatic alcohols and aromatic compounds were detected at reduced abundances (1–6% of the detected compounds)

Porphyrin-Oligopyridine Triads: Synthesis and Optical Properties

The synthesis of two triads with two porphyrinyl units linked by oligopyridine derivatives and a new β-functionalized porphyrin-dihydroazepine is described. One of the porphyrin-oligopyridine triads has a quinquepyridine unit connecting the porphyrins β-pyrrolic positions, while the other one has an asymmetric quaterpyridine with one of the pyridines fused to the porphyrin. All compounds have fluorescence emission quantum yields in the range of <i>meso</i>-tetraphenylporphyrin (16–22%)

α-Glucosidase inhibition by flavonoids: an <i>in vitro</i> and <i>in silico</i> structure–activity relationship study

<p>α-Glucosidase inhibitors are described as the most effective in reducing post-prandial hyperglycaemia (PPHG) from all available anti-diabetic drugs used in the management of type 2 diabetes <i>mellitus</i>. As flavonoids are promising modulators of this enzyme’s activity, a panel of 44 flavonoids, organised in five groups, was screened for their inhibitory activity of α-glucosidase, based on <i>in vitro</i> structure–activity relationship studies. Inhibitory kinetic analysis and molecular docking calculations were also applied for selected compounds. A flavonoid with two catechol groups in A- and B-rings, together with a 3-OH group at C-ring, was the most active, presenting an IC₅₀ much lower than the one found for the most widely prescribed α-glucosidase inhibitor, <b>acarbose</b>. The present work suggests that several of the studied flavonoids have the potential to be used as alternatives for the regulation of PPHG.</p