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51.
Dr. Albert Ferrer‐Ugalde Dr. Arántzazu González‐Campo Prof. Dr. Clara Viñas Dr. Jesús Rodríguez‐Romero Dr. Rosa Santillan Dr. Norberto Farfán Prof. Dr. Reijo Sillanpää Dr. Antonio Sousa‐Pedrares Dr. Rosario Núñez Prof. Dr. Francesc Teixidor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(32):9940-9951
Two sets of o‐carborane derivatives incorporating fluorene and anthracene fragments as fluorophore groups have been successfully synthesized and characterized, and their photophysical properties studied. The first set, comprising fluorene‐containing carboranes 6 – 9 , was prepared by catalyzed hydrosilylation reactions of ethynylfluorene with appropriate carboranylsilanes. The compound 1‐[(9,9‐dioctyl‐fluorene‐2‐yl)ethynyl]carborane ( 11 ) was synthesized by the reaction of 9,9‐dioctyl‐2‐ethynylfluorene and decaborane (B10H14). Furthermore, reactions of the lithium salt of 11 with 1 equivalent of 4‐(chloromethyl)styrene or 9‐(chloromethyl)anthracene yielded compounds 12 and 13 . Members of the second set of derivatives, comprising anthracene‐containing carboranes, were synthesized by reactions of monolithium or dilithium salts of 1‐Me‐1,2‐C2B10H11, 1‐Ph‐1,2‐C2B10H11, and 1,2‐C2B10H12 with 1 or 2 equivalents of 9‐(chloromethyl)anthracene, respectively, to produce compounds 14 – 16 . In addition, 2 equivalents of the monolithium salts of 1‐Me‐1,2‐C2B10H11 (Me‐o‐carborane) and 1‐Ph‐1,2‐C2B10H11 (Ph‐o‐carborane) were reacted with 9,10‐bis(chloromethyl)anthracene to produce compounds 17 and 18 , respectively. Fluorene derivatives 6 – 9 exhibit moderate fluorescence quantum yields (32–44 %), whereas 11 – 13 , in which the fluorophore is bonded to the Ccluster (Cc), show very low emission intensity (6 %) or complete fluorescence quenching. The anthracenyl derivatives containing the Me‐o‐carborane moiety exhibit notably high fluorescence emissions, with ?F=82 and 94 %, whereas their Ph‐o‐carborane analogues are not fluorescent at all. For these compounds, we have observed a correlation between the Cc?Cc bond length and the fluorescence intensity in CH2Cl2 solution, comparable to that observed for previously reported styrene‐containing carboranes. Thus, our hypothesis is that for systems of this type the fluorescence may be tuned and even predicted by changing the substituent on the adjacent Cc. 相似文献
52.
Dr. Wawrzyniec Kaszub Andrea Marino Dr. Maciej Lorenc Prof. Eric Collet Prof. Elena G. Bagryanskaya Prof. Evgeny V. Tretyakov Prof. Victor I. Ovcharenko Prof. Matvey V. Fedin 《Angewandte Chemie (International ed. in English)》2014,53(40):10636-10640
Molecular compounds with photoswitchable magnetic properties have been intensively investigated over the last decades due to their prospective applications in nanoelectronics, sensing and magnetic data storage. The family of copper‐nitroxide‐based molecular magnets represents a new promising type of photoswitchable compounds. We report the first study of these appealing systems using femtosecond optical spectroscopy. We unveil the mechanism of ultrafast (<50 fs) spin state photoswitching and establish its principal differences compared to other photoswitchable magnets. On this basis, we propose potential advantages of copper‐nitroxide‐based molecular magnets for the future design of ultrafast magnetic materials. 相似文献
53.
Inga Kwiecie Natalizia Miceli Manuela DArrigo Andreana Marino Halina Ekiert 《Molecules (Basel, Switzerland)》2022,27(3)
Studies carried out using three different in vitro assays and a biological setting (Escherichia coil) demonstrated the antioxidant activity of Scutellaria lateriflora microshoot extract. Moreover, the extract exhibited no toxicity in a brine shrimp lethality bioassay. These results indicated that microshoots are a rich, safe source of antioxidants, which encouraged us to enhance their production in vitro. In agar and agitated cultures, two biotechnological strategies were applied: feeding the cultures with the biogenetic precursors of the phenolics—phenylalanine and tyrosine, and eliciting them with methyl jasmonate. Specific Scutellaria flavonoids and verbascoside were analysed by HPLC. Feeding with precursors (1 g/L) in agar cultures decreased the production of the metabolites. In agitated cultures, different concentrations of precursors (1.0–2.5 g/L) and the elicitor (10; 50; 100 µM) were tested. Additionally, parallel feeding with the precursor and elicitor in a concentration of 50 µM were applied. The best strategy for total flavonoid and verbascoside production was phenylalanine feeding (1.5 g/L), max. 3765 and 475 mg/100 g DW, respectively, after 7 days. This is the first report documenting the high antioxidant production in S. lateriflora microshoots after feeding with phenylalanine. Moreover, for the first time, bioreactor cultures were successfully maintained, obtaining attractive results (max. total flavonoid content 2348 and verbascoside 485 mg/100 g DW). 相似文献
54.
The thermal degradation behaviour, in the absence of oxygen, of poly(p-methylstyrene) has been investigated. Monomer is the main product formed in the degradation process, together with different oligomers which have been identified and whose amounts have been determined. A reaction mechanism accounting for the formation of the degradation products, and similar to the mechanism established for polystyrene, is proposed. The main differences of the process comparing with polystyrene are the higher amount of monomer which is produced and the crosslinking structures which are formed at T < 400° C. 相似文献
55.
Dr. Steve Y. Rhieu Dr. Aaron A. Urbas Dr. Daniel W. Bearden Dr. John P. Marino Dr. Katrice A. Lippa Dr. Vytas Reipa 《Angewandte Chemie (International ed. in English)》2014,53(2):447-450
Non‐invasive and real‐time analysis of cellular redox processes has been greatly hampered by lack of suitable measurement techniques. Here we describe an in‐cell nuclear magnetic resonance (NMR) based method for measuring the intracellular glutathione redox potential by direct and quantitative measurement of isotopically labeled glutathione introduced exogenously into living yeast. By using this approach, perturbations in the cellular glutathione redox homeostasis were also monitored as yeast cells were subjected to oxidative stress. 相似文献
56.
Summary A multiresidue method has been developed for identification and quantitation of the herbicides most commonly used in cultivation
of maize and grain, and of their transformation products, in soil samples. The analytes were isolated by soil column extraction
(SCE) and the extracts were purified by use of a Carbograph-1 cartridge. Analysis was performed by liquid chromatography coupled
with tandem mass spectrometric detection (LC-TISP-MS-MS) in negative-ion mode. To optimize the extraction conditions affecting
the performance of SCE, e.g. the extracting solvent used, temperature, extracting volume, and solvent flow rate, were studied.
To evaluate the matrix effect in SCE, recovery experiments were performed on soil samples, with different physical and chemical
characteristics, fortified with the 100 ng g−1 of the target compounds. Recovery data were satisfactory and the method detection limits were between 3 and 100 ng g−1, depending on the compound. 相似文献
57.
Carmen FestaSimona De Marino Valentina SepeMaria Valeria D’Auria Giuseppe BifulcoRosa Andrés Maria Carmen TerencioMiguel Payá Cécile DebitusAngela Zampella 《Tetrahedron》2011,67(40):7780-7786
Two new cyclopeptides, perthamides E and F were isolated from the polar extracts of the sponge Theonella swinhoei. The new structures, featuring an unprecedented β-amino acid unit (AHMOA), were determined by interpretation of NMR and MS data. The absolute configuration of the AHMOA residue was proposed on the basis of quantum chemical calculation of NMR chemical shifts. Perthamides were proved to inhibit TNF-α and IL-8 release in primary human keratinocytes cells and therefore could represent potentially leads for the treatment of psoriasis. 相似文献
58.
DellErba C Gasparrini F Grilli S Lunazzi L Mazzanti A Novi M Pierini M Tavani C Villani C 《The Journal of organic chemistry》2002,67(5):1663-1668
Static and dynamic stereochemistry of the hydrocarbon comprising a phenyl ring bearing two alpha-naphthyl substituents in the ortho positions, i.e., 1,2-di-(4-methyl-naphth-1-yl)-benzene 1, has been studied by a combination of variable temperature NMR, cryogenic HPLC, and MM calculations. Whereas in solution both syn (meso) and anti (chiral) forms were observed and the corresponding interconversion barrier was determined (Delta G(++) = 19.5 kcal mol(-1)), only the diastereoisomer anti was found to be present in the crystalline state (X-ray diffraction). When the molecule is rendered asymmetric by introduction of a nitro group in the phenyl ring as in 1,2-di-(4-methyl-naphth-1-yl)-4-nitrobenzene 2, the chiral syn and anti diastereoisomers are simultaneously present both in solution and in the solid state, albeit in different proportions. Cryogenic chromatography on a HPLC chiral stationary phase at 20 degrees C allowed the stereolabile diastereoisomers and the corresponding enantiomers to be separated. 相似文献
59.
N-[1-(Phenylsulfonyl)alkyl]oxazolidin-2-ones are successfully prepared by condensation of the corresponding optically active oxazolidin-2-ones with aldehydes and benzenesulfinic acid. At low temperature, in the presence of titanium tetrachloride, these sulfones are converted into N-acyliminium ions, which react with allyltrimethylsilane with a variable degree of stereoselectivity. The best results are obtained with (R)-5,5-dimethyl-4-phenyloxazolidin-2-one as a chiral auxiliary. Cleavage of the oxazolidin-2-one ring with lithium/ammonia affords the corresponding homoallylamines, which reveal an absolute configuration opposite that expected on the basis of the usual steric effects. A complexation of the Lewis acid with the N-acyliminium ion may be responsible of this rather unusual stereochemical outcome. 相似文献
60.
Bulky trialkylsilyl-protected alkynes such as triethylsilyl (TES), tert-butyldimethylsilyl (TBS), and triisopropylsilyl (TIPS) acetylenes underwent the Cadiot-Chodkiewicz cross-coupling reaction with different bromoalkynes to form a variety of synthetically useful unsymmetrical diynes in good yields. The diyne alcohol 10 was transformed regio- and stereoselectively into enynes by hydrotelluration, carbometalation, and reduction reactions. 相似文献