Dispiro[indene‐2,5′‐indeno[2,1‐a]fluorene‐6′,2′′‐indene]‐1,1′′,3,3′′,11′,12′‐hexaone: a three‐dimensional hydrogen‐bonded framework

The title compound, C₃₆H₁₆O₆, (I), was obtained as a new and unexpected oxidation product of 1,2′‐biindene‐1′,3,3′(2H)‐trione. The molecules of (I) exhibit approximate, but noncrystallographic, twofold rotation symmetry and the central ring of the fused pentacyclic portion is distinctly puckered, with a conformation intermediate between half‐chair and screw‐boat. Six independent C—H...O hydrogen bonds link the molecules into a three‐dimensional framework structure of considerable complexity. Comparisons are drawn between the crystal structure of (I) and those of several simpler analogues, which show wide variation in their patterns of supramolecular aggregation.     

Free glycerol determination in biodiesel samples using palladium nanoparticles modified glassy carbon electrode associated with solid phase extraction

Journal of Solid State Electrochemistry - In this work, we developed a method for the quantification of free glycerol in biodiesel using electrochemical detection and solid phase extraction (SPE)....     

Nonlinear viscoelasticity of fat crystal networks

The rheology of fat crystal networks under linear shear deformations has been extensively studied due to its role in material functionality and sensory perceptions. In contrast, there has been limited focus on their viscoelastic response under large shear deformations imposed during processing and product use. We probed the nonlinear viscoelastic behavior of fats displaying mechanics akin to ductile and brittle solids using large amplitude oscillatory shear (LAOS). Using the FT-Chebyshev stress decomposition method, and local measures of nonlinear viscoelasticity, we obtained rheological properties relevant to bulk behavior. We found that ductile fats dissipate more viscous energy than brittle fats and show increased plastic deformation. Structural characterization revealed the presence of three hierarchy levels and layered microstructures in ductile fats in contrast to only two hierarchies and random microstructures in brittle fats. We suggest that these structural features account for increased hypothesize dissipation, which contributes to their ductile-like macroscopic behavior.     

Recent Advances in the Core-Annulation of Naphthalene Diimides

This review focuses on describing all known synthetic strategies leading to core-annulation of naphthalene diimides (NDIs). Strategies presented involve the formation of four-, five- and six-membered ring annulations bearing different heteroatomic and carbocyclic derivatives, including annulenes. The core-annulation method opens the possibility for obtaining designer molecules with tuneable electronic characteristics such as a reduced energy band gap, and enhanced intermolecular overlap of π-systems that improve electronic coupling between molecules—which is highly desirable for charge transport properties summarised in the final pages for applications in electronic devices such as organic field-effect transistors (OFETs) and organic photovoltaic (OPV) cells. Molecular recognition in pH and fluoride sensing, or as a DNA probe, are some of additional applications of core-annulated NDIs presented here. Additionally, recent advances in core modification of NDIs are presented, opening an entire new chemical avenue to be explored. Finally, the outlook on the future prospect of annulated NDIs in various applications is summarised.     

Reevaluating the synthesis of 2,5-disubstituted-1H-benzimidazole derivatives by different green activation techniques and their biological activity as antifungal and antimicrobial inhibitor

A comparative study concerned with the preparation of diversely substituted-1H-benzimidazole under different green activation techniques and conventional methods is reported. Data are collected for infrared, ultrasound, microwave, and simultaneous irradiation with US and IR sources, as this last strategy shows an important improvement. Further, the small library of potentially bioactive benzimidazole 17-76 synthesized was screened as an antifungal and antimicrobial agent. Strong activity against Candida albicans and Staphylococcus aureus was observed. Remarkably, 2-(4-aminophenyl)-5-phenylamino-1H-benzimidazole 63 resulted better than that of reference drugs miconazole with a zone of inhibition up to 42 mm. Likewise, 2-(2-aminophenyl)-1H-benzimidazole 21 showed substantial antimicrobial activity against MRSA strain. When assayed by the microdilution method, this azaheterocyclic compound presented a minimum inhibitory concentration (MIC) ≥ 16.4 μg/100 mL and a bacterial percentage reduction of 96%.     

Hydrogen‐bonding patterns in two aroylthiocarbamates and two aroylimidothiocarbonates

In O‐ethyl N‐benzoylthiocarbamate, C₁₀H₁₁NO₂S, the molecules are linked into sheets by a combination of two‐centre N—H...O and C—H...S hydrogen bonds and a three‐centre C—H...(O,S) hydrogen bond. A combination of two‐centre N—H...O and C—H...O hydrogen bonds links the molecules of O‐ethyl N‐(4‐methylbenzoyl)thiocarbamate, C₁₁H₁₃NO₂S, into chains of rings, which are linked into sheets by an aromatic π–π stacking interaction. In O,S‐diethyl N‐(4‐methylbenzoyl)imidothiocarbonate, C₁₃H₁₇NO₂S, pairs of molecules are linked into centrosymmetric dimers by pairs of symmetry‐related C—H...π(arene) hydrogen bonds, while the molecules of O,S‐diethyl N‐(4‐chlorobenzoyl)imidothiocarbonate, C₁₂H₁₄ClNO₂S, are linked by a single C—H...O hydrogen bond into simple chains, pairs of which are linked by an aromatic π–π stacking interaction to form a ladder‐type structure.     

Synthesis of Novel Pyrimido[4,5‐b]quinolin‐4‐ones with Potential Antitumor Activity

The 5,6,7,8,9,10‐hexahydro‐2‐methylthiopyrimido[4,5‐b]quinolines 4a , 4b , 4c , 4d , 5a , 5b , 5c , 5d and their oxidized forms 6a , 6b , 6c , 6d , 7a , 7b , 7c , 7d were obtained from the reaction of 6‐amino‐2‐(methylthio)pyrimidin‐4(3H)‐one 2 or 6‐amino‐3‐methyl‐2‐(methylthio)pyrimidin‐4(3H)‐one 3 and α,β‐unsaturated ketones 1a , 1b , 1c , 1d using BF₃.OEt₂ as catalyst and p‐chloranil as oxidizing agent. Some of the new compounds were evaluated in the US National Cancer Institute (NCI), where compound 5a presented remarkable activity against 46 cancer cell lines, with the most important GI₅₀ values ranging from 0.72 to 18.4 μM from in vitro assays.     

Application of a catalyst-free Domino Mannich/Friedel-Crafts alkylation reaction for the synthesis of novel tetrahydroquinolines of potential antitumor activity

A useful and efficient method to construct diversely substituted 1,2,3,4-tetrahydroquinolines in good to excellent yields has been developed through a catalyst-free Domino Mannich and intramolecular Friedel-Crafts alkylation reactions of N-arylamines with paraformaldehyde and electron-rich olefins via the formation of N-aryl-N-alkylmethyleneiminium ions as the key intermediates to afford the target products. Nine of the new compounds were evaluated in the US National Cancer Institute (NCI), where compound 5f (R1?=?6-MeO, R2?=?p-ClC6H4 and X?=?pyrrolidin-2-onyl) presented a remarkable activity against 57 cancer cell lines, with the most important GI50 values ranging from 1.46 to 8.28?μM from in vitro assays. Further studies performed over the active compound 5f on HCT116 colon cancer cells indicated that its effect on cell death is exerted through a cell cycle arrest (S phase) in a dose dependent manner, as well as suppression on the cell proliferation process.