Recently, contemporaneous strategies to achieve the vicinal difluorination of alkenes via an I(I)/I(III) catalysis manifold were independently reported by this laboratory and by Jacobsen and co-workers. Both strategies proceed through a transient ArI(III)F2 species generated by oxidation of the ArI catalyst. Herein, an efficient synthesis of p-TolIF2 from p-TolI and Selectfluor is presented, together with a crystallographic and spectroscopic study. To mitigate safety concerns and simplify reaction execution, an HF-free protocol was devised employing CsF as a substitute fluoride source. The study provides insight into the initial I(I)→I(III) oxidation stage of the catalytic protocol using Selectfluor.

Deconstructing the Catalytic, Vicinal Difluorination of Alkenes: HF-Free Synthesis and Structural Study of p-TolIF2.

Anion exchange membranes (AEMs) fabricated using polyethylene (PE) and ethylene tetrafluoroethylene films are subjected to degradation tests in deionised water for electrolyser/fuel cell operation. After the degradation test, the decrease in ion-exchange capacity (IEC) of the AEM, hence decrease in ionic conductivity, is found to be influenced by the applied gamma radiation dose rate. The use of high radiation dose rate produces membranes with improved stability in terms of % IEC loss due to shorter, more uniformly distributed vinylbenzyl chloride (VBC) grafts. For LDPE-based AEMs, increasing the applied radiation dose rate during grafting from 30 to 2000 Gy h−1 significantly reduces AEM % IEC loss from 38 to 11%, respectively. Analyses of both the aged functionalised membranes and their resulting degradation products confirm the loss of not only the functional group, but also the VBC group, which have not been reported previously in the literature. Oxidation reactions taking place in solutions close to neutral can be the main contributor to the IEC loss in contrast to the widely reported E2 or SN2 attack on the head group in high alkalinity solutions. We therefore propose parallel degradation mechanisms to head group loss of AEM that involves peroxide radicals which is more dominant at low alkalinity solutions.

/pdf/degradation-of-radiation-grafted-hydroxide-anion-exchange-1dyx6osxpc.pdf

Degradation of radiation grafted hydroxide anion exchange membrane immersed in neutral pH: removal of vinylbenzyl trimethylammonium hydroxide due to oxidation

A series of fused ring-based nitrate esters/azides and a coupled-ring-based nitrate ester were prepared using a simple and efficient nitrogen-functionalization approach. All new energetic compounds were fully characterized. Structures of four (1–4) were further confirmed by single crystal X-ray diffraction. These nitrate esters have good thermal stabilities and high densities. Energetic performance was evaluated by using EXPLO5 v6.01 based on measured densities and calculated heats of formation (Gaussian 03 (Revision D. 01)). The results show that some of the representative fused ring-based nitrate esters exhibit good detonation properties, for example, 1 (vD, 8674 m s−1; P, 33.1 Gpa) and 2 (vD, 8669 m s−1; P, 33.4 Gpa), that approach those of current high explosive benchmarks, such as 1,3,5-trinitroperhydro-1,3,5-triazine (RDX). Sensitivity data based on impact and friction tests show these compounds have better stabilities than the traditional nitrate ester explosive, pentaerythritol tetranitrate (PETN).

N-functionalized nitroxy/azido fused-ring azoles as high-performance energetic materials

A novel class of antimalarial compounds, based on an indol-3-yl linked to the 2-position of a 4-aminoquinoline moiety, shows promising activity against the malaria parasite, Plasmodium falciparum . Compounds with a quaternary nitrogen on the quinoline show improved activity against the chloroquine-resistant K1 strain. Nonquaternerized 4-aminoquinolines retain significant potency but are relatively less active against the K1 strain. Alkylation of the 4-amino group preferentially improves the activity against the chloroquine-sensitive 3D7 strain. The quinoline-indoles show only weak activity as inhibitors of β-hematin formation, and their activities are only weakly antagonized by a hemoglobinase inhibitor. The compounds appear to dissipate mitochondrial potential as an early event in their antimalarial action and therefore may exert their activity by compromising Plasmodium mitochondrial function. Interestingly, we observed a structural relationship between our compounds and the anticancer and anthelminthic compound, pyrvinium pamoate, which has also been proposed to exert its action via compromising mitochondrial function.

JMC 2013,56, 2200-15 supp info Novel conjugated quinoline-indoles compromise Plasmodium falciparum mitochondrial function and show promising antimalarial activity

https://eprints.ncl.ac.uk/file_store/production/240360/82C59C4F-0E5C-40B3-93BD-67C6D44887A6.pdf

Degradation of radiation grafted anion exchange membranes tethered with different amine functional groups via removal of vinylbenzyl trimethylammonium hydroxide

Photoelectrochemical biosensing platforms for tumor marker detection

A series of 1-aryl/alkyl-1H-1,2,3,4-tetrazoles, 5-substituted 1H-tetrazoles, and 1,5- and 2,5-disubstituted 1H-tetrazoles were studied by a combination of experimental NMR (natural abundance 15N, 15N/1H HMBC, and 13C) and computational GIAO-NMR techniques to explore substituent effects on 15N (and 13C) NMR chemical shifts in the tetrazole (TA) moiety Computed 15N chemical shifts via GIAO-B3LYP/6-311+G(2d,p) calculations gave satisfactory results in comparison with experimental data Whereas N-alkylation leads to large 15N chemical shift changes, changes in the N1-aryl derivatives bearing diverse substituent(s) are generally small except for polar ortho-substituents (COOH, NO2) Large Δδ15N values were computed in N1-aryl derivatives for p-COH2+ and p-OMeH+ as extreme examples of electron-withdrawing substituents on a TA moiety

Experimental and GIAO 15N NMR Study of Substituent Effects in 1H-Tetrazoles

A series of giant tris(heteroaryl)methanes are easily assembled by one-pot three-component synthesis by simple reflux in ethanol without catalyst or additives. Diversely substituted indoles (Ar1) react with quinoline aldehydes, quinolone aldehydes, chromone aldehydes, and fluorene aldehydes (Ar2CHO) and coumarins (Ar3) in 1:1:1 ratio to form the corresponding tris(heteroaryl)methanes (Ar1Ar2Ar3)CH along with (Ar1Ar1Ar2)CH triads. A series of new 2:1 triads were also synthesized by coupling substituted indoles with Ar2CHO. The coupling reactions could also be carried out in water (at circa 80 °C) but with chemoselectivity favoring (Ar1Ar1Ar2)CH over (Ar1Ar2Ar3)CH. The molecular structure of a representative (Ar1Ar2Ar3)CH triad was confirmed by X-ray analysis. Model tris(heteroaryl/aryl)methylium salts were generated by reaction with DDQ/HPF6 and studied by NMR and by DFT and GIAO-DFT.

https://www.beilstein-journals.org/bjoc/content/pdf/1860-5397-15-60.pdf

Catalyst-free assembly of giant tris(heteroaryl)methanes: synthesis of novel pharmacophoric triads and model sterically crowded tris(heteroaryl/aryl)methyl cation salts.

Reaction of Selectfluor (F-TEDA-BF4) with chloromethylated-DABCO monocation salts (X = BF4, NTf2) and other nitrogen bases (Et3N; piperidine; basic ionic liquid); unexpected formation of symmetrical [N−H−N]+ trication salts

Ionotropic γ-aminobutyric acid (GABA) receptors (iGABARs) are validated targets of drugs and insecticides. Our previous studies showed that the competitive antagonists of insect iGABARs exhibit insecticidal activities and that the 3-isothiazolol scaffold is used as a lead for developing novel iGABAR antagonists. Here, we designed a novel series of 4-aryl-5-(4-pyridinyl)-3-isothiazolol (4-API) analogs that have various aromatic substituents at the 4-position. Two-electrode voltage clamp experiments showed that all synthesized 4-APIs exhibited antagonistic activity against Musca domestica and Spodoptera litura iGABARs (RDL) expressed in oocytes of Xenopus laevis at 100 μM. Of the 4-APIs, the 4-(1,1'-biphenylyl) analog was the most potent antagonist with IC50s of 7.1 and 9.9 μM against M. domestica and S. litura RDL receptors, respectively. This analog also showed a certain insecticidal activity against S. litura larvae, with >75% mortality at 100 μg/g diet. Molecular docking studies with a M. domestica iGABAR model indicated that the π-π stacking interactions formed between the pyridinyl ring and Y252 and between the 4-substituted aromatic group and Y107 might be important for antagonism by the 4-(1,1'-biphenylyl) analog. Our studies provide important information for designing novel iGABAR antagonists and suggest that the 4-APIs acting on iGABARs are promising insecticide leads for further studies.

5-(4-Pyridinyl)-3-isothiazolols as Competitive Antagonists of Insect GABA Receptors: Design, Synthesis, and a New Mechanism Leading to Insecticidal Effects.

Chunqing Zhao

Papers

Photoelectrochemical biosensing platforms for tumor marker detection

Experimental and GIAO 15N NMR Study of Substituent Effects in 1H-Tetrazoles

Catalyst-free assembly of giant tris(heteroaryl)methanes: synthesis of novel pharmacophoric triads and model sterically crowded tris(heteroaryl/aryl)methyl cation salts.

Reaction of Selectfluor (F-TEDA-BF4) with chloromethylated-DABCO monocation salts (X = BF4, NTf2) and other nitrogen bases (Et3N; piperidine; basic ionic liquid); unexpected formation of symmetrical [N−H−N]+ trication salts

5-(4-Pyridinyl)-3-isothiazolols as Competitive Antagonists of Insect GABA Receptors: Design, Synthesis, and a New Mechanism Leading to Insecticidal Effects.