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991.
A facile approach to carbapenams via Kinugasa reaction between terminal copper acetylides and nonracemic cyclic nitrones derived from malic and tartaric acid is reported. The stereochemical preferences observed in these reactions are explained. The reaction provides an entry to the carbapenams basic skeleton. 相似文献
992.
Radka Křikavová Ján Vančo Tomáš Šilha Jaromír Marek 《Journal of Coordination Chemistry》2016,69(16):2422-2436
Platinum(II) complexes, [Pt(Lx)X2] (1–6), where X = Br or I and Lx = 2,2′-bipyridine or 1,10-phenanthroline derivatives (5,5′-dimethyl-2,2′-bipyridine (5-Mebpy), 4,4′-dimethyl-2,2′-bipyridine (4-Mebpy), and 5-amino-1,10-phenanthroline (5-NH2phen)) were prepared. The complexes were characterized by the elemental analysis, mass spectrometry, infrared, and multinuclear (1H, 13C and 195Pt) 1-D and 2-D NMR spectroscopies, and by single-crystal X-ray analysis of [Pt(4-Mebpy)I2] (4). All the platinum(II) complexes (1–6) were evaluated for in vitro cytotoxicity against human cancer cell lines A2780 and A2780R, and against non-malignant MRC5 cell line. All the complexes were nontoxic up to the 50 μM concentration, although they were found to readily bind to calf-thymus DNA (CT-DNA), as determined by spectrophotometric titration (Kb ≈ 107 M?1) and ethidium bromide displacement assay. 相似文献
993.
994.
Marek Gołębiowski Aleksandra Ostachowska Monika Paszkiewicz Mieczysława I. Boguś Emilia Włóka Marta Ligęza-Żuber Piotr Stepnowski 《Chemical Papers》2016,70(10):1360-1369
Entomopathogenic fungi are referred to as potential candidates as insect pest control agents. The objective of the study was to identify fatty acids and amino acids from Conidiobolus coronatus cultured on two different media. Each medium was extracted with ethyl acetate and its mixtures with isopropanol, acetonitrile and methanol. Analyses of fatty acids and amino acids of entomopathogenic fungus C. coronatus were performed by means of gas chromatography coupled with mass spectrometry. The analysis showed that the fungus C. coronatus produces the following groups of compounds: fatty acids and amino acids; α- and β-glucopyranose were also identified. The identified fatty acids included 12–20, 22 and 24 carbon atoms per chain. The highest content of fatty acids was detected in a mycelium sample cultured in a liquid minimal medium extracted with ethyl acetate. The lowest content of these organic compounds was identified in mycelium cultured in a liquid nutrient-rich medium extracted with ethyl acetate–methanol mixture. Fatty acids were found to account for 62.0 mass % to 94.4 mass % of all organic compounds in the analyzed mycelia. C18:1 acids were detected in the highest amounts when ethyl acetate was used as the extracting agent. The identified amino acids accounted for 4 mass % to 21 mass % of all organic compounds. Upon extraction of C. coronatus mycelium samples with the ethyl acetate—methanol mixture, two anomeric forms of glucose were also identified. An analysis of the studied material confirmed, that the entomopathogenic fungus C. coronatus is a very rich source of organic compounds, which might encourage its further research so as to identify an even larger number of compounds being produced by this species. 相似文献
995.
Inside Cover: A Rotational BODIPY Nucleotide: An Environment‐Sensitive Fluorescence‐Lifetime Probe for DNA Interactions and Applications in Live‐Cell Microscopy (Angew. Chem. Int. Ed. 1/2016) 下载免费PDF全文
996.
Magorzata Szczesio Andrzej Olczak Katarzyna Gobis Ida Mazerant Sylwia Kauyska Henryk Foks Marek L. Gwka 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(1):75-79
The emergence of drug‐resistant strains of Mycobacterium tuberculosis has intensified efforts to identify new lead tuberculostatics. Our earlier studies concluded that the planarity of a molecule correlates well with its tuberculostatic activity. According to our hypothesis, only derivatives whose molecules are capable of adopting a planar conformation may show tuberculostatic activity. The structures of three new potentially tuberculostatic compounds, namely N′‐[bis(methylsulfanyl)methylidene]‐N‐methyl‐4‐nitrobenzohydrazide (denoted G1), C11H13N3O3S2, N′‐[bis(benzylsulfanyl)methylidene]‐N‐methyl‐4‐nitrobenzohydrazide (denoted G2), C23H21N3O3S2, and N′‐[(benzylsulfanyl)(methylsulfanyl)methylidene]‐4‐nitrobenzohydrazide (denoted G3), C16H15N3O3S2, were determined by X‐ray diffraction. The significant distortion from planarity caused by the methyl substituent at the N atom of the hydrazide group or the NO2 substituent in the aromatic ring leads to the loss of tuberculostatic activity for G1, G2 and G4 {systematic name: N′‐[bis(methylsulfanyl)methylidene]‐2‐nitrobenzohydrazide}. A similar effect is observed when there are large substituents at the S atoms (G2 and G3). 相似文献
997.
Robert Pepin Kenneth J. Laszlo Aleš Marek Bo Peng Matthew F. Bush Helène Lavanant Carlos Afonso František Tureček 《Journal of the American Society for Mass Spectrometry》2016,27(10):1647-1660
Heptapeptide ions containing combinations of polar Lys, Arg, and Asp residues with non-polar Leu, Pro, Ala, and Gly residues were designed to study polar effects on gas-phase ion conformations. Doubly and triply charged ions were studied by ion mobility mass spectrometry and electron structure theory using correlated ab initio and density functional theory methods and found to exhibit tightly folded 3D structures in the gas phase. Manipulation of the basic residue positions in LKGPADR, LRGPADK, KLGPADR, and RLGPADK resulted in only minor changes in the ion collision cross sections in helium. Replacement of the Pro residue with Leu resulted in only marginally larger collision cross sections for the doubly and triply charged ions. Disruption of zwitterionic interactions in doubly charged ions was performed by converting the C-terminal and Asp carboxyl groups to methyl esters. This resulted in very minor changes in the collision cross sections of doubly charged ions and even slightly diminished collision cross sections in most triply charged ions. The experimental collision cross sections were related to those calculated for structures of lowest free energy ion conformers that were obtained by extensive search of the conformational space and fully optimized by density functional theory calculations. The predominant factors that affected ion structures and collision cross sections were due to attractive hydrogen bonding interactions and internal solvation of the charged groups that overcompensated their Coulomb repulsion. Structure features typically assigned to the Pro residue and zwitterionic COO-charged group interactions were only secondary in affecting the structures and collision cross sections of these gas-phase peptide ions. 相似文献
998.
999.
Lenka Dastychová Marie Sotolářová Dalibor Dastych Jan Taraba Marek Nečas Jiří Příhoda 《Polyhedron》2007
The reaction of P4S10 (1) with N,N′-diphenylurea (PhNH)2CO (2) results in new heterocyclic compounds: the pyridinium salt of 1,3-diphenyl-2-sulfido-2-thioxo-1,3-diaza-2λ5-phosphetidine (3) (with a P–N–C–N cycle) and the pyridinium salt of 1,4-diphenyl-2,5-disulfido-2,5-dithioxo-1,4-dithiadiaza-2λ5,5λ5-diphosphinane (4), containing the (P–S–N)2 cycle and the cyclic thiophosphates [pyH]2[P2S8] (5), [pyH]2[P2S7] (6) and [pyH]3[P3S9] (7). A similar reaction, but carried out with N,N′-diphenylthiourea (PhNH)2CS (8), leads to the formation of 4 and 6. pyPS2Cl (9), used as an alternative starting material, also yields compounds 3, 4, 5, and further [pyH][PS2Cl2] (10) and S8 after reaction with 2. Compound 3 reacts with Pd(CH3COO)2, with the formation of the complex [Pd(Ph2N2COPS2)2] (11). The crystal structures of 3 and 7 were determined by single-crystal X-ray diffraction. 相似文献
1000.
Bae WS Convertine AJ McCormick CL Urban MW 《Langmuir : the ACS journal of surfaces and colloids》2007,23(2):667-672
Surface-initiated grafting of N,N-dimethylacrylamide, styrenesulfonate (SS), and (ar-vinylbenzyl)trimethylammonium chloride (VBTAC) from microwave plasma carboxylated, initiator-functionalized poly(dimethylsiloxane) (PDMS) surfaces was accomplished utilizing reversible addition-fragmentation chain transfer (RAFT) polymerization. Surface spectroscopic attenuated total reflectance (ATR) FT-IR analysis and atomic force microscopy (AFM) measurements were utilized to determine surface grafting and morphological surface features. The VBTAC-grafted PDMS provided a smooth, hydrophilic cationic surface for creating layer-by-layer (LBL) surfaces via alternating deposition of well-defined poly(SS) and poly(VBTAC), also prepared via aqueous RAFT. Comparisons of the ATR FT-IR spectra of the LBL assemblies and those of respective anionic poly(SS) and cationic poly(VBTAC) components confirmed strong electrostatic complexation of a fraction of the sulfonate and quarternary ammonium species in the layers as well as the existence of noncomplexed species. AFM images of surface topology indicated the presence of domains, likely phase-separated segments of the respective homopolymers, as well as interlayer mixing. The employed LBL methodology results in formation of stable, highly hydrophilic surfaces on a PDMS substrate. To our knowledge, this is the first study that illustrates surface functionalization of PDMS using microwave plasma and RAFT polymerization, followed by LBL deposition of polyelectrolytes. 相似文献