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171.
The crystal structure of a new complex of a diaza-crown ether having two side arms has been determined from X-ray diffraction data. The compound crystallizes in space group P1 with cell dimensions a = 9.982(1), b = 10.685(1), c = 20.376(2)Å, = 81.09(1), = 80.92(1), = 88.43(1)0, Z = 2. The structure has been solved by direct methods and refined to the final R value of 0.053 for 3458 observed reflections and 424 parameters. The diaza-18-crown-6 ligand adopts an approximate D3d conformation. The Na+ ion is held inside the molecular cavity of this macroring ligand and a ClO-4 oxygen coordinates with Na+. The average Na–-O (18-crown-6) and Na–-N bond lengths are 2.426(4) and 2.786(5)Å, respectively; the Na–-O (ClO-4) bond length is 2.472(4)Å. The mean cavity radius is 1.10 Å and the NN nonbonding distance is 4.605(6)Å.  相似文献   
172.
Aryl-substituted boratriazaindacenes (Aza-Bodipy's) are a new class of dyes with long wavelength absorption and emissions. We now report the first application of these dyes in metal ion sensing. 2-Pyridyl substituents at positions 1 and 7 create a well-defined pocket for metal ion binding. The chemosensor described here is selective for Hg(II) ions, and both absorption and emission spectra display large changes that would allow ratiometric sensing. [reaction: see text].  相似文献   
173.
The production cross-sections, intensity ratios, and radiative Auger intensity ratios of Co, Ni, Cu, and Zn elements in different complexes were measured. The chemical effects on the K shell fluorescence parameters and the radiative Auger intensity ratios of these elements were investigated and the changes in these parameters were interpreted according to the charge transfer process. The samples were excited by 59.5 keV γ-rays from a 241Am annular radioactive source. K X-rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV.  相似文献   
174.
Three new phenylethyl glycosides, 3′′′′‐O‐methylmaxoside (=2‐(3,4‐dihydroxyphenyl)ethyl Oβ‐D ‐glucopyranosyl‐(1→3)‐O‐[β‐D ‐glucopyranosyl‐(1→6)]‐4‐O‐(E)‐feruloyl‐β‐D ‐glucopyranoside; 1 ), digilanatosides A (=2‐(3,4‐dihydroxyphenyl)ethyl O‐6‐O‐(E)‐sinapoyl‐β‐D ‐glucopyranosyl‐(1→3)‐4‐O‐(E)‐caffeoyl‐β‐D ‐glucopyranoside; 2 ), and digilanatoside B (=2‐(3,4‐dihydroxyphenyl)ethyl O‐6‐O‐(E)‐p‐coumaroyl‐β‐D ‐glucopyranosyl‐(1→3)‐4‐O‐(E)‐caffeoyl‐β‐D ‐glucopyranoside; 3 ) were isolated from the aerial parts of Digitalis lanata, along with two known phenylethyl glycosides, purpureaside A and maxoside, a phenylpropanoid glucose ester, 1‐O‐(E)‐feruloyl‐β‐glucopyranose, a benzoquinolethanoid glucoside, cornoside, a cardenolide, lanatoside C, a furostane‐type steroidal saponin, purpureagitoside, and a disaccharide, sucrose. Their structures were elucidated on the basis of spectroscopic evidence (1D‐ and 2D‐NMR, and HR‐MALDI‐MS).  相似文献   
175.
The use of electron spin resonance (ESR) spectroscopy to accurately distinguish irradiated from unirradiated sage tea was examined. Before irradiation, sage tea samples exhibit one asymmetric singlet ESR signal centered at g=2.0037. Besides this central signal, two weak satellite signals situated about 3 mT left and right to it in radiation-induced spectra. Irradiation with increasing doses caused a significant increase in radiation-induced ESR signal intensity at g=2.0265 (the left satellite signal) and this increase was found to be explained by a polynomial varying function. The stability of that radiation-induced ESR signal at room temperature was studied over a storage period of 9 months. Also, the kinetic of signal at g=2.0265 was studied in detail over a temperature range 313–353 K by annealing samples at different temperatures for various times.  相似文献   
176.
Heat-induced paramagnetic centers in modern and archaeological lentils (Lens culinaris, Medik.) were studied by X-band (9.3 GHz) electron spin resonance (ESR) technique. The modern red lentil samples were heated in an electrical furnace at increasing temperatures in the range 70–500 °C. The ESR spectral parameters (the intensity, g-value and peak-to-peak line width) of the heat-induced organic radicals were investigated for modern red lentil (Lens culinaris, Medik.) samples. The obtained ESR spectra indicate that the relative number of heat-induced paramagnetic species and peak-to-peak line widths depends on the temperature and heating time of the modern lentil. The g-values also depend on the heating temperature but not heating time. Heated modern red lentils produced a range of organic radicals with g-values from g = 2.0062 to 2.0035. ESR signals of carbonised archaeological lentil samples from two archaeological deposits of the Van province in Turkey were studied and g-values, peak-to-peak line widths, intensities and elemental compositions were compared with those obtained for modern samples in order to assess at which temperature these archaeological lentils were heated in prehistoric sites. The maximum temperatures of the previous heating of carbonised UA5 and Y11 lentil seeds are as follows about 500 °C and above 500 °C, respectively.  相似文献   
177.
178.
A variety of analytical techniques, such as scanning electron microscopy and 19F dynamic nuclear polarization (DNP) methods, are applied to characterize asphaltene extracted from MC-800 liquid asphalt in fluorobenzene derivatives at 1.53 mT and at room temperature. Different solvents show variable affinities for the asphaltene surface. The low field EPR spectrum of the asphaltene/hexafluorobenzene sample was recorded. The DNP parameters were determined. Additionally, the interactions between the nuclei of the solvent and the electrons delocalized on the asphaltene are interpreted. Not only dipolar but also scalar interactions between the nuclear spin and the electron spin were found.  相似文献   
179.
We introduce a novel class of water soluble, extended conjugation boradiazaindacene dyes which are efficient singlet oxygen generators and have spectacular photoinduced cytotoxicity when excited in the "therapeutic window" of the electromagnetic spectrum.  相似文献   
180.
New palladium(II) and platinum(II) complexes containing bis(2-pyridylmethyl)amine (bpma) and saccharinate (sac), [Pd(bpma)(sac)](sac)·2H2O (1), [Pt(bpma)(sac)](sac)·2H2O (2), [Pd(bpma)Cl](sac)·2H2O (3) and [Pt(bpma)(sac)]Cl·1.5H2O (4), were synthesized and characterized by elemental analysis, IR, NMR and TG-DTA. A single-crystal X-ray analysis of 3 and 4 proved a distorted square-planar geometry around the metal ions with one tridentate bpma ligand and one Cl or sac monoanion. The [Pd(bpma)Cl]+ ions in 3 form dimers by intermolecular N-H?Cl and Pd?Pd interactions. The cations reside in the centers of a hydrogen-bonded honeycomb network formed by the uncoordinated sac ions and the lattice water molecules, while the cations of 4 are connected by N-H?Cl and OW-H?O hydrogen bonds into one-dimensional chains. Cyclic planar tetrameric and trimeric water clusters were observed in 3 and 4, respectively. Cytotoxicity of 1-4 was tested against A549, C6 and CHO cells. Although 2 and 4 have no cytotoxicity, the best results were achieved for 1 and 3. In particular, the cyctotoxic activity of 3 is comparable to cisplatin.  相似文献   
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