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Dominik Göbel, Nils Clamor, Boris J Nachtsheim
A highly regioselective functionalization of 7-bromofluorene-2-carbaldehydes, potent organic chromophores, in position C3 using a mild ortho-metallation strategy (DoM) with TMPMgCl·LiCl has been developed. This approach allows the preparation of highly functionalized fluorene derivatives by conversion of the in situ generated metalated species with various electrophiles giving a fast access to novel organic phosphorescent dyes.
May 22, 2018: Organic & Biomolecular Chemistry
Patrizia Monti, Gaia Rocchitta, Salvatore Marceddu, Maria A Dettori, Davide Fabbri, Samir Jaoua, Quirico Migheli, Giovanna Delogu, Pier A Serra
Interference rejection in amperometric biosensors can be more effective introducing some modifiers during electro-deposition of permselective film. Addition of β-cyclodextrin (βCD), a cyclic oligosaccharide composed of seven glucose units, to the ortho-phenylendiamine (oPD) monomer were already demonstrated to provide an enhancement in ascorbic acid (AA) rejection. Here we evaluated the improvement in permselectivity of poly-eugenol and poly-magnolol films electro-polymerized in presence of different amounts of βCD or eugenol-βCD inclusion complex for amperometric biosensor application...
August 15, 2018: Talanta
Arnaud Thevenon, Anish Cyriac, Dominic Myers, Andrew J P White, Christopher B Durr, Charlotte K Williams
The alternating copolymerization of CO2 /epoxides is a useful means to incorporate high levels of carbon dioxide into polymers. The reaction is generally proposed to occur by bimetallic or bicomponent pathways. Here, the first indium catalysts are presented, which are proposed to operate by a distinct mononuclear pathway. The most active and selective catalysts are phosphasalen complexes, which feature ligands comprising two iminophosphoranes linked to sterically hindered ortho-phenolates. The catalysts are active at 1 bar pressure of carbon dioxide and are most effective without any cocatalyst...
May 21, 2018: Journal of the American Chemical Society
Daniel Obando, Yasuko Koda, Namfon Pantarat, Sophie Lev, Xiaoming Zuo, Johanes Bijosono Oei, Fred Widmer, Julianne Djordjevic, Tania Sorrell, Katrina Jolliffe
A series of bis(4-pentylpyridinium) compounds with a variety of spacers between the pyridinium headgroups was synthesised and their antifungal activity has been investigated. Lengthening the alkyl spacer between the pentylpyridinium headgroups from twelve to sixteen methylene units resulted in increased antifungal activity against C. neoformans and C. albicans, but also resulted in increased hemolytic activity and cytotoxicity against mammalian cells. However, inclusion of an ortho-substituted benzene ring in the centre of the alkyl spacer resulted in reduced cytotoxicity and hemolytic activity, while maintaining antifungal potency...
May 20, 2018: ChemMedChem
Vargini Thangavadivale, Pedro M Aguiar, Naseralla A Jasim, Sarah J Pike, Dan A Smith, Adrian C Whitwood, Lee Brammer, Robin N Perutz
The syntheses of three series of complexes designed with self-complementary motifs for formation of halogen bonds between an iodotetrafluorophenyl ligand and a halide ligand at square-planar nickel are reported, allowing structural comparisons of halogen bonding between all four halides C6 F4 I···X-Ni (X = F, Cl, Br, I). In the series trans -[NiX(2,3,5,6-C6 F4 I)(PEt3 )2 ] 1pX and trans -[NiX(2,3,4,5-C6 F4 I)(PEt3 )2 ] (X = F, Cl, Br, I) 1oX , the iodine substituent on the benzene ring was positioned para and ortho to the metal, respectively...
April 21, 2018: Chemical Science
Katharina Plasch, Gerhard Hofer, Walter Keller, Sam Hay, Derren J Heyes, Alexander Dennig, Silvia M Glueck, Kurt Faber
The utilization of gaseous carbon dioxide instead of bicarbonate would greatly facilitate process development for enzyme catalyzed carboxylations on a large scale. As a proof-of-concept, 1,3-dihydroxybenzene (resorcinol) was carboxylated in the ortho -position using pressurized CO2 (∼30-40 bar) catalyzed by ortho -benzoic acid decarboxylases with up to 68% conversion. Optimization studies revealed tight pH-control and enzyme stability as the most important determinants.
April 21, 2018: Green Chemistry: An International Journal and Green Chemistry Resource: GC
Konstantin L Ivanov, Geoffrey Bodenhausen
A novel conceptual approach is described that is based on the transfer of hyperpolarization from para-hydrogen in view of generating a population imbalance between the two spin isomers of H2 O. The approach is analogous to SABRE (Signal Amplification By Reversible Exchange) and makes use of the transfer of spin order from para-hydrogen to H2 O in a hypothetical organometallic complex. The spin order transfer is expected to be most efficient at avoided level crossings. The highest achievable enrichment levels of para- and ortho-water are discussed...
May 17, 2018: Journal of Magnetic Resonance
Rui Wang, Ting Tang, Guining Lu, Kaibo Huang, Hua Yin, Zhang Lin, Fengchang Wu, Zhi Dang
Polybrominated diphenyl ethers (PBDEs) undergo debromination when they were exposed in zerovalent metal or bimetallic systems. Yet their debromination pathways and mechanisms in these systems were not well understood. Here we reported the debromination pathways of three BDE congeners (BDE-21, 25 and 29) by nano-zerovalent iron (n-ZVI). All these BDE congeners have three bromine substituents that were located in ortho-, meta- and para-positions. Results demonstrated that BDE-21, 25 and 29 preferentially debrominate meta-, ortho- and para-bromines, respectively, suggesting that bromine substituent at each position (i...
May 17, 2018: Environmental Pollution
Kleopatra Kedikoglou, Danae Costopoulou, Irene Vassiliadou, Evangelos Bakeas, Leondios Leondiadis
Sample preparation is of critical importance in dioxin analysis of food and feed samples. It is a complex procedure that includes lipid extraction followed by the application of chromatographic separation techniques, aiming in removing undesirable interferences from the matrix. The separation of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) from polychlorinated biphenyls (PCBs) is achieved by carbon-based materials which should have high fat capacity in order to be suitable for lipid-containing matrices...
May 7, 2018: Chemosphere
Sergey Artyukhin, Dmitry Fishman, Clément Faugeras, Marek Potemski, Alexandre Revcolevschi, Maxim Mostovoy, Paul H M van Loosdrecht
We study the absorption spectra of the yellow excitons in Cu2 O in high magnetic fields using polarization-resolved optical absorption measurements with a high frequency resolution. We show that the symmetry of the yellow exciton results in unusual selection rules for the optical absorption of polarized light and that the mixing of ortho- and para- excitons in magnetic field is important. The calculation of the energies of the yellow exciton series in strong and weak magnetic field limits suggests that a broad n = 2 line is comprized by two closely overlapping lines, gives a good fit to experimental data and allows to interpret the complex structure of excitonic levels...
May 18, 2018: Scientific Reports
Subhash Chander, Cheng-Run Tang, Ashok Penta, Ping Wang, Deepak P Bhagwat, Nicolas Vanthuyne, Muriel Albalat, Payal Patel, Sanskruti Sankpal, Yong-Tang Zheng, Murugesan Sankaranarayanan
In the current study, twenty-two compounds based upon 3-hydroxy-3-(2-oxo-2-phenylethyl)indolin-2-one nucleus were designed, synthesized and in vitro evaluated for HIV-1 RT inhibition and anti-HIV-1 activity. Compounds 3d, 5c and 5e demonstrated encouraging potency against RT enzyme as well as HIV-1 in low micromolar to nanomolar concentration with good to excellent safety index. Structure activity relationship studies revealed that halogens such as bromo or chloro at 5th the position of oxindole ring remarkably enhanced the potency against RT...
May 9, 2018: Bioorganic Chemistry
Thomas Franz, Frank Scheufler, Klaus Stein, Michael Uhl, Torsten Dame, Gerlinde Schwarz, Hans Sachs, Gisela Skopp, Frank Musshoff
Drugs which are commonly smoked or sniffed (e.g. cocaine), can contaminate hair through smoke or dust; therefore testing for metabolites, especially hydroxy metabolites, is highly recommended. The presence of hydroxy metabolites in street-cocaine (COC) has been discussed. To check if detection of hydroxy metabolites definitely proves ingestion, the presence of these metabolites in street COC samples has to be checked. It is expected that the more hydrophilic hydroxy metabolites of COC are incorporated into the hair-matrix to a lesser extent...
April 12, 2018: Forensic Science International
Abhinanda Kundu, Mariko Inoue, Haruki Nagae, Hayato Tsurugi, Kazushi Mashima
A mixed ligated amidoyttrium complex, Y(NBn2 )(L1)(THF)2 (8, L1 = N,N'-bis(2,6-diisopropylphenyl)ethylenediamine), served as a catalyst for addition of the ortho-pyridyl C(sp2 )-H bond of 2-substituted pyridines to non-activated imines; complex 8 showed superior catalytic performance compared with Y[N(SiMe3 )2 ]3 (1) and Y[N(SiMe3 )2 ]2 (NBn2 )(THF) (2). Concerning the reaction mechanism, we conducted a stoichiometric reaction of an alkylyttrium complex, Y(CH2 SiMe3 )(L1)(THF)2 (7), with 2-ethylpyridine (4e), giving a mixture of (η3 -pyridylmethyl)yttrium complex 9 and (η2 -pyridyl)yttrium complex 10 along with elimination of SiMe4 ...
May 18, 2018: Journal of the American Chemical Society
Zhuan Zhang, Pierre H Dixneuf, Jean-François Soulé
Phosphorus containing molecules have seen widespread applications in the development of innovative metal-ligand catalysts and materials. In recent years, the implementation of late-stage modifications of phosphorus derivatives via ortho-regioselective C-H bond functionalisation has led to faster and better ways for the synthesis of complex ligands by creating new reactions with low impact on the environment. This Feature article highlights transition-metal catalysed regioselective C-H bond functionalisation of phosphorus-containing molecules, in which the phosphorus containing unit plays the role of a directing group for C-H bond activation and the synthesis of new functional phosphorus derivatives...
May 18, 2018: Chemical Communications: Chem Comm
Lin-Su Wei, Guo-Xue He, Xiang-Fei Kong, Cheng-Xue Pan, Dong-Liang Mo, Gui-Fa Su
A series of 1,2- and 2,3-fused quinazolinones have been synthesized in good to excellent yields through gold-catalyzed selective hydroarylations of alkynyl quinazolinone-tethered pyrroles. The studies revealed that 1,2-fused quinazolinones were obtained through a 1,3-rearrangement and sequential 6-exo-trig cyclization of N1-alkynyl quinazolinone-tethered pyrroles while N3-alkynyl quinazolinone-tethered pyrroles went through 6-exo-dig or 7-endo-dig cyclizations directly to afford 2,3-fused quinazolinones. The fused quinazolinones could be prepared at gram scale in three steps from commercial ortho-aminobenzamide...
May 17, 2018: Journal of Organic Chemistry
Xiong Ding, Pengfei Wang
We have demonstrated that the 3-diethylaminobenzyl (DEABn) photolabile protecting group (PPG) is an effective and structurally simple PPG for releasing molecules in aqueous environment. In general, the photoreaction is clean, and the released substrate and the PPG product, i.e., 3-diethylaminobenzyl alcohol, are obtained in high yield. The clean photoreaction can also be achieved under mild ambient conditions with sunlight while the reactant is stable under indoor lighting. Release of two substrates from one PPG chromophore in aqueous solution has been demonstrated to be feasible...
May 17, 2018: Journal of Organic Chemistry
Dongmin Lee, Hyeri Bu, Dohwan Kim, Jooeun Hyoung, Seung-Tae Hong
The crystal structure of calcium perchlorate anhydrate was determined from laboratory X-ray powder diffraction data. The title compound was obtained by heating hydrated calcium perchlorate [Ca(ClO4 )2 · x H2 O] at 623 K in air for 12 h. It crystallizes in the ortho-rhom-bic space group Pbca and is isotypic with Ca(AlD4 )2 . The asymmetric unit contains one Ca, two Cl and eight O sites, all on general sites (Wyckoff position 8 c ). The crystal structure consists of isolated ClO4 - tetra-hedra and Ca2+ cations...
April 1, 2018: Acta Crystallographica. Section E, Crystallographic Communications
Laura N F Cardoso, Thais C M Noguiera, James L Wardell, Marcus V N de Souza, William T A Harrison
The crystal structures of three isomeric ( E )- N '-(chloro-phenyl-methyl-idene)- N -methyl-2-(thio-phen-2-yl)acetohydrazides (C14 H13 ClN2 OS) are described, with the Cl atom in ortho (I), meta (III) and para (IV) positions in the benzene ring. The ortho -bromo derivative (II) (C14 H13 BrN2 OS), which is isostructural with its chloro congener (I), is also reported. Mol-ecules (I)-(III) have similar conformations, which approximate to l-shapes, as indicated by their N-C-C-Ct (t = thio-phene) torsion angles of -90...
March 1, 2018: Acta Crystallographica. Section E, Crystallographic Communications
Yue Liu, Nan Sun, Jianshe Hu, Song Li, Gaowu Qin
The phthalate ester compounds in industrial wastewater, as kinds of environmental toxic organic pollutants, may interfere with the body's endocrine system, resulting in great harm to humans. In this work, the photocatalytic degradation properties of dibutyl phthalate (DBP) were investigated using α-Fe2 O3 nanoparticles and H2 O2 in aqueous solution system. The optimal parameters and mechanism of degradation were discussed by changing the morphology and usage amount of catalysts, the dosage of H2 O2 , pH value and the initial concentration of DBP...
April 2018: Royal Society Open Science
Dongzheng Yang, Jing Huang, Junxiang Zuo, Xixi Hu, Daiqian Xie
A full-dimensional ab initio potential energy surface for the H2 -HF van der Waals complex was constructed by employing the coupled-cluster singles and doubles with noniterative inclusion of connected triples with augmented correlation-consistent polarised valence quadruple-zeta basis set plus bond functions. Using the improved coupled-states approximation including the nearest neighbor Coriolis couplings, we calculated the state-to-state scattering dynamics for pure rotational and ro-vibrational energy transfer processes...
May 14, 2018: Journal of Chemical Physics
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