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131.
Synthesis and Biological Evaluation of a Class of Mitochondrially‐Targeted Gadolinium(III) Agents 下载免费PDF全文
Dr. Daniel E. Morrison Dr. Jade B. Aitken Dr. Martin D. de Jonge Dr. Fatiah Issa Prof. Hugh H. Harris Prof. Louis M. Rendina 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(50):16602-16612
A structure–activity relationship study of a library of novel bifunctional GdIII complexes covalently linked to arylphosphonium cations is reported. Such complexes have been designed for potential application in binary cancer therapies such as neutron capture therapy and photon activation therapy. A positive correlation was found between lipophilicity and cytotoxicity of the complexes. Mitochondria uptake was determined by means of inductively coupled plasma mass spectrometry (ICP‐MS), and Gd uptake was determined by means of quantification using synchrotron X‐ray fluorescence (XRF) imaging. A negative correlation between lipophilicity and tumour selectivity of the GdIII complexes was demonstrated. This study highlights the delicate balance required to minimise in vitro cytotoxicity and optimise in vitro tumour selectivity and mitochondrial localisation for this new class of mitochondrially‐targeted binary therapy agents. We also report the highest in vitro tumour selectivity for any Gd agent reported to date, with a T/N (tumour/normal cell) ratio of up to 23.5±6.6. 相似文献
132.
On the Synthesis,Characterization and Reactivity of N‐Heteroaryl–Boryl Radicals,a New Radical Class Based on Five‐Membered Ring Ligands 下载免费PDF全文
Dr. Mohamad‐Ali Tehfe Dr. Stéphane Schweizer Dr. Anne‐Caroline Chany Dr. Cédric Ysacco Dr. Jean‐Louis Clément Dr. Didier Gigmes Dr. Fabrice Morlet‐Savary Prof. Jean‐Pierre Fouassier Dr. Markus Neuburger Dr. Théophile Tschamber Dr. Nicolas Blanchard Prof. Jacques Lalevée 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(17):5054-5063
The synthesis and physical characterization of a new class of N‐heterocycle–boryl radicals is presented, based on five membered ring ligands with a N(sp2) complexation site. These pyrazole–boranes and pyrazaboles exhibit a low bond dissociation energy (BDE; B?H) and accordingly excellent hydrogen transfer properties. Most importantly, a high modulation of the BDE(B?H) by the fine tuning of the N‐heterocyclic ligand was obtained in this series and could be correlated with the spin density on the boron atom of the corresponding radical. The reactivity of the latter for small molecule chemistry has been studied through the determination of several reaction rate constants corresponding to addition to alkenes and alkynes, addition to O2, oxidation by iodonium salts and halogen abstraction from alkyl halides. Two selected applications of N‐heterocycle–boryl radicals are also proposed herein, for radical polymerization and for radical dehalogenation reactions. 相似文献
133.
Tandem CH Activation/Arylation Catalyzed by Low‐Valent Iron Complexes with Bisiminopyridine Ligands 下载免费PDF全文
Elise Salanouve Ghania Bouzemame Dr. Sébastien Blanchard Dr. Etienne Derat Dr. Marine Desage‐El Murr Prof. Louis Fensterbank 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(16):4754-4761
Tandem C?H activation/arylation between unactivated arenes and aryl halides catalyzed by iron complexes that bear redox‐active non‐innocent bisiminopyridine ligands is reported. Similar reactions catalyzed by first‐row transition metals have been shown to involve substrate‐based aryl radicals, whereas our catalytic system likely involves ligand‐centered radicals. Preliminary mechanistic investigations based on spectroscopic and reactivity studies, in conjunction with DFT calculations, led us to propose that the reaction could proceed through an inner‐sphere C?H activation pathway, which is rarely observed in the case of iron complexes. This bielectronic noble‐metal‐like behavior could be sustained by the redox‐active non‐innocent bisiminopyridine ligands. 相似文献
134.
Stephen D. Williams Warren Harper Gleb Mamantov Louis J. Tortorelli George Shankle 《Journal of computational chemistry》1996,17(15):1696-1711
Molecular geometries were fully optimized for AlCl3, AlCl4-, Al2Cl6, Al2Cl7-, AlF3, AlF4-, Al2F6, Al2F7-, BCl3, BCl4-, B2Cl6, B2Cl7-, BF3, BF4-, B2F6, and B2F7-, as well as a few mixed halogen species, at the Hartree-Fock (HF) level, using basis sets from STO-3G to 6–311 + G(d). In some cases geometries were also optimized at the MP2 level. Where possible, the computed geometries were compared to known structures from electron or X-ray diffraction. The agreement between these was quite good for the neutral species, and somewhat poorer for the anions. Vibrational frequencies were calculated for all species at the HF level with the largest basis set. The geometries were characterized as minima or transition structures. Various formation reaction enthalpies were calculated; these compare well with known values. More extensive calculations on the BF3/BF4- system indicate the structures and enthalpies are nearly converged with respect to basis set size and level of correlation treatment. The previously unknown species B2Cl7- is predicted to be energetically stable on the basis of the calculations. Some features of the 11B NMR spectra of room temperature melts consisting of mixtures of boron trichloride with 1-methyl-3-ethylimidazolium chloride are presented. These features suggest that these melts may contain small amounts of B2Cl7- as an intermediate in an exchange reaction. © 1996 by John Wiley & Sons, Inc. 相似文献
135.
Isaac O. Donkor Rajesh Devraj Sherry F. Queener Louis R. Barrows Aleem Gangjee 《Journal of heterocyclic chemistry》1996,33(6):1653-1661
A series of diaminobenzo[f]- and diaminobenzo[h]pyrimido[4,5-b]quinolines 1–11 were designed as 5-deaza tetracyclic nonclassical, lipophilic antifolates. The compounds were designed as conformationally semi-rigid and rigid analogs of 2,4-diamino-6-phenyl- 12 and 2,4-diamino-7-phenylpyrido[2,3-d]pyrimidines 13 and 14 . The target compounds were synthesized by cyclocondensation of chlorovinyl aldehydes obtained from appropriately substituted 1- or 2-tetralone, with 2,4,6-friaminopyrimidine. Compounds 1–11 were evaluated as inhibitors of P. carinii and T. gondii dihydrofolate reductases. These pathogens cause fatal opportunistic infections in AIDS patients. In addition, the selectivity of these agents was evaluated using rat liver dihydrofolate reductase as the mammalian source. In general the benzo[f]pyrimido[4,5-b]quinolines 1–5 were more potent than the corresponding benzo[h]pyrimido[4,5-b]quinoline analogues 6–11 against P. carinii and rat liver dihydrofolate reductase and were equipotent against T. gondii dihydrofolate reductase. Compounds 6–11 were moderately selective towards T. gondii dihydrofolate reductase with IC50S in the 10−7 M range. In contrast analogues 1–5 lacked selectivity against P. carinii or T. gondii dihydrofolate reductase and were, in general, potent inhibitors of rat liver dihydrofolate reductase with IC50S in the 10−8 M range. Analogues 1 and 4 were evaluated against a series of tumor cell lines in vitro and were found to have moderate antitumor activity (IC50 10−6 M). The structure activity/selectivity relationships suggest that benzo[f]pyrimido analogues 1–5 with the phenyl ring substitution in the “upper” portion of the tetracyclic ring are better accommodated within the rat liver (mammalian) dihydrofolate reductase and P. carinii dihydrofolate reductase active sites compared to the benzo[h]pyrimido analogues 6–11 which have the phenyl ring substitution in the “lower” portion of the tetracyclic ring. In contrast T. gondii dihydrofolate reductase does not discriminate between the isomers and binds to both series of compounds with similar affinities. 相似文献
136.
Peter Louis Weegels 《Macromolecular theory and simulations》1996,5(2):299-303
The directionality (Dn) of a polymerization mechanism can be defined as the average orientation of the reaction or the degree of randomness of head-to-tail, head-to-head, tail-to-tail or tail-to-head reactions within the polymer at the n-th monomer or reaction (n ≫ 2). Directionality of a polymer type can be defined as the average orientation inside a polymer. If the directionality is random, Dn = 0.5. For full directionality, Dn = 1. It is demonstrated that these situations correspond to step and chain polymerization, respectively. Directionality can be as important for the functional properties of polymers as length and composition distributions and the functionality of the original monomers. 相似文献
137.
Louis M. Leung W. H. Chan Sew Koo Leung 《Journal of polymer science. Part A, Polymer chemistry》1993,31(7):1799-1806
A series of aliphatic and aromatic polytrithiocarbonates was prepared using a novel “one-pot” synthesis procedure employing a phase-transfer catalyst. The starting reagents were either an aliphatic or an aromatic dihalide and an excessive amount of carbon disulfide. The effects of the phase-transfer catalyst and reaction conditions on yield were studied. The structure and composition of the polymers and reaction side-products were determined from infrared, ultraviolet, 1H-NMR spectra, and elemental analyses. The polymers were further characterized by viscosity measurement and thermal analysis. © 1993 John Wiley & Sons, Inc. 相似文献
138.
Mustafa M. Musameh Mark Hickey Ilias Louis Kyratzis 《Research on Chemical Intermediates》2011,37(7):705-717
Carbon nanotubes (CNT)/Nafion-modified glassy carbon (GC) electrodes were used to immobilize the enzyme acetylcholinesterase (AChE) by crosslinking with glutaraldehyde. The CNT-modified electrodes exhibited a sensitive and stable electrocatalytic behavior towards thiocholine (TCh). Compared to ordinary GC electrodes modified with Nafion, a substantial (500-mV) decrease in the overvoltage of the TCh oxidation reaction is observed, along with a tenfold enhancement in the amperometric response. The CNT/Nafion/AChE electrode has very good stability of at least a month compared to surfaces made without crosslinking in the absence and presence of Nafion. Under optimal loadings of CNT, Nafion, AChE, and glutaraldehyde, a solution of CNT/Nafion in N,N-dimethylformamide (DMF) containing 4 mg/mL CNT and 0.01% Nafion was used to construct the electrodes in order to maximize the sensitivity of the biosensor for inhibition studies. An optimal enzyme loading of 0.137 U and crosslinking in 0.01% glutaraldehyde for 1 h was also needed to achieve this goal. The prepared electrodes had very good reproducibility to 1.0 mM acetylthiocholine (ATCh) (relative standard deviation [RSD] <5% for eight electrodes). Using paraoxon as a model pesticide, the biosensor was able to detect as low as 1.0 nM after 30 min of incubation at 30 °C. Using a log scale, the biosensor had good linearity in the concentration range 50?C800 nM, with a correlation coefficient of 0.99. The prepared biosensor was used to test real water samples spiked with paraoxon and showed good correlation with a calibration curve using phosphate buffer. 相似文献
139.
β‐Hydroxy nitroethanol ethers are prepared by selective alcoholysis of oxiranes. The best results are obtained using a clay (monmorillonite K10) or a π‐acid (TCNE) as the catalyst. 相似文献
140.
Dr. Renata Avena Maia Felipe Lopes Oliveira Prof. Vincent Ritleng Prof. Qiang Wang Dr. Benoît Louis Prof. Pierre Mothé Esteves 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(30):8048-8055
Covalent organic frameworks (COFs) RIO-13, RIO-12, RIO-11, and RIO-11m were investigated towards their CO2 capture properties by thermogravimetric analysis at 1 atm and 40 °C. These microporous COFs bear in common the azine backbone composed of hydroxy-benzene moieties but differ in the relative number of hydroxyl groups present in each material. Thus, their sorption capacities were studied as a function of their textural and chemical properties. Their maximum CO2 uptake values showed a strong correlation with an increasing specific surface area, but that property alone could not fully explain the CO2 uptake data. Hence, the specific CO2 uptake, combined with DFT calculations, indicated that the relative number of hydroxyl groups in the COF backbone acts as an adsorption threshold, as the hydroxyl groups were indeed identified as relevant adsorption sites in all the studied COFs. Additionally, the best performing COF was thoroughly investigated, experimentally and theoretically, for its CO2 capture properties in a variety of CO2 concentrations and temperatures, and showed excellent isothermal recyclability up to 3 cycles. 相似文献