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131.
Barbieri A Ventura B Flamigni L Barigelletti F Fuhrmann G Bäuerle P Goeb S Ziessel R 《Inorganic chemistry》2005,44(22):8033-8043
The syntheses, structural characteristics, electrochemical behavior, ground-state spectra, photophysical properties, and transient absorption (TA) spectra in CH(3)CN solvent are reported for binuclear [(bpy)(2)Ru(bpy-E(T)(n)()E-bpy)Ru(bpy)(2)](4+) complexes, Ru(bpyT(n)bpy)Ru, where the Ru-based units are connected by alternating 3,4-dibutylthiophene (DBT')/thiophene (T') fragments linked via ethynyl groups (E) to bpy ligands at the 5-position (bpy is 2,2'-bipyridine). The ligand bpyT(3)bpy represents a module containing DBT'/T'/DBT' subunits, and bpyT(5)bpy accounts for a DBT'/T'/DBT'/T'/DBT' pattern. The syntheses and electrochemical and spectroscopic (emission and TA) properties in CH(2)Cl(2) solvent of the bpyT(n)()bpy ligands are likewise reported. The behavior of the Ru(bpyT(n)bpy)Ru dimers has been compared to that of the bpyT(n)bpy ligands and to that of a related mononuclear complex, [(bpy)(2)Ru(bpy-E-DBT')](2+), Ru(bpyDBT'). For the dimeric complexes, the electrochemical results show that the first reduction step takes place at the bpy ligand(s) bearing an ethynylene group, the first oxidation step is thiophene-centered, and further oxidation involves the metal centers, which are only weakly interacting. The photophysical and TA results for the Ru(bpyT(n)bpy)Ru dimers account for the presence of low-lying oligothiophene-centered (3)pi,pi levels, while higher-lying metal-ligand charge transfer ((3)MLCT) levels are thermally accessible only for the case of Ru(bpyT(3)bpy)Ru; the possible role of charge separation (CS) levels (from oxidation at the thiophene bridge and reduction at one of the coordinated bpy's) is also discussed. 相似文献
132.
Francesco A. Devillanova Gaetano Verani D. N. Sathyanarayana 《Journal of heterocyclic chemistry》1978,15(6):945-947
An infrared investigation cm N-methyl-1,3-thiazolidine-2-thione and -2-selone in the range 4000-200 cm?1 is reported. The v CS and v CSe vibrations give contributions to the absorptions around 1000 cm?1 and below 600 cm?1. The assignments are supported by comparison of their ir spectra with those of S- and Se-methiodides. The π-bond orders of the thio- and seleno-ketonic links in these compounds are higher than those found for 1,3-imidazolidine-2-thione and -2-selone. 相似文献
133.
The determination by neutron activation of trace quantities of calcium, strontium and barium in single crystals of alkali halides has been studied. The matrix is eliminated before the irradiation by an ion-exchange procedure. Gamma spectroscopy after radiochemical separation is used to determine strontium and barium. Calcium is determined by measuring the β-activity of 49Sc formed by the decay of 49Ca. Long-lived radioactive tracers are used to determine the chemical yields. 相似文献
134.
Francesco Demartin Fabrizia Fabrizi de Biani Cristina Femoni Maria Carmela Iapalucci Giuliano Longoni Piero Macchi Piero Zanello 《Journal of Cluster Science》2001,12(1):61-74
The [Ni36Pt4(CO)45]6- and [Ni37Pt4(CO)46]6- clusters have been obtained in mixture upon reaction in acetonitrile of [Ni6(CO)12]2- salts with K2PtCl4 in a 2.5:1 molar ratio. The two hexaanions were indistinguishable by spectroscopic techniques. Crystallization of their trimethylbenzylammonium salts led to crystals of composition 0.5[NMe3CH2Ph]6[Ni36Pt4(CO)45]-0.5[NMe3CH2Ph]6[Ni37Pt4(CO)46]·C3H8O, hexagonal,space group P63 (No. 173), a=17.853(9), c=27.127(13) Å, Z=2; final R=0.057. The metal core of the [Ni36Pt4(CO)45]6- anion consists of a Pt4 tetrahedron fully encapsulated in a shell of 36 Ni atoms belonging to a very distorted and incomplete 5 tetrahedron. The [Ni37Pt4(CO)46]6- hexaanion derives from the former by capping the unique triangular face of the metal polyhedron with an additional Ni(CO) fragment. The [Ni36Pt4(CO)45]6--[Ni37Pt4(CO)46]6- mixture is rapidly degraded to the known [Ni9Pt3(CO)21]4- cluster by exposure to carbon monoxide. Its reaction with protic acids initially affords the corresponding [H6-nNi36Pt4(CO)45]n--[H6-nNi37Pt4(CO)46]n- (n=5, 4) derivatives, and eventually leads to rearrangement to the known [H6-n Ni38Pt6(CO)48]n- species. Both [Ni36Pt4(CO)45]6--[Ni37Pt4(CO)46]6- and [HNi36Pt4(CO)45]5--[HNi37Pt4(CO)46]5- mixtures have been chemically and electrochemically reduced to their corresponding [Ni36Pt4(CO)45]n--[Ni37Pt4(CO)46]n- (n=7–9) and [HNi36Pt4(CO)45]n--[HNi37Pt4(CO)46]n- (n=6–8) mixtures. 相似文献
135.
The sponges Raspailia pumila and ramosa (Demospongiae, Tetractinomorpha, Axinellida) from the North-East Atlantic are shown to contain a series of novel long-chain enol ethers of glycerol where the enol ether C?C bond is conjugated, in sequence, to both an acetylenic and an olefinic bond. Polar extracts give raspailynes hydroxylated at their (1Z5Z)-1,5-alkadien-3-ynyl chain, like raspailyne Al ( = (+)-(S)-3-[((1Z,5Z)-16-hydroxy-hexadeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; (+ 2 ) and isoraspailyne A ( = (+)-3-[((1Z,5Z)-17-hydroxyocta-deca-1,5-dien-3-ynyl)oxy]-1,2-[propanediol; (+)- 3 ). Less polar extracts give 3 different types of raspailynes not hydroxylated at the chain. Raspailynes of the first type have either the (1Z,5Z)-configuration in a linear chain such as raspailyne B2 (( = (?)-(s)-3-[((1Z,5Z)-trideca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; (?)-4), raspailyne Bl ( = (?)-3-[((1Z,5Z)-tetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol;(?)- 5 ), and raspailyne B ( = 3-[((1Z,5Z)-pentadeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 6 ) or the (1Z,5Z)-pentadeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 6 )or the (1Z,5Z)-configuration in a chain ending with an isopropyl group, like isoraspailyne Bl ( = 3-[((1Z,5Z)-12-methyltrideca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 7 ) and isoraspailyne B ( = 3-[((1Z,5Z)-13-methyltetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 8 ). Raspailynes of the second type have the (1Z,5E)-configuration, like isoraspailyne Bla ( =3-[((1Z,5E)-tetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 9 ) and isoraspailyne Ba ( = 3-[((1Z,5E)-13-methyltetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 10 ). Raspailynes of the third type have the (1E,5Z)-configuration, like isoraspailyne Blb ( = 3-[((1E,5Z)-tetradeca-1,5-dien-3-ynyl)oxy]-1,2,-propanediol; 11 ). The (S)-configuration for (+)- 1 ,((+)- 2 , and (?)- 4 is derived from chemical correlations. 相似文献
136.
A new high-performance liquid chromatographic/electrospray ionization tandem mass spectrometric (HPLC/ESI-MS/MS) method was developed for the simultaneous quantification of 5-fluorouracil (5FU), methotrexate (MTX) and cyclophosphamide (CP) in environmental samples. These compounds, commonly used in the treatment of cancer, are recognized as genotoxic. In order to estimate the occupational exposure of hospital personnel handling these drugs, wipe samples were taken from the working surfaces and directly analyzed (with trophosphamide as internal standard) using a reversed-phase capillary column and MS/MS detection. This is the first HPLC/MS/MS method for the simultaneous determination of 5FU, MTX and CP. The present method offers high sensitivity, with detection limits of 1.1 microg l(-1) for MTX and CP and 33.3 microg l(-1) for 5FU, avoiding any sample preconcentration procedure. Rapidity, specificity, high accuracy (mean values between 92.4 and 99.9%) and precision (mean RSD values between 3.4 and 12.1%) make the method suitable for the routine determination of these three antineoplastic drugs. 相似文献
137.
Giuseppe Werber Francesco Buccheri Manlio Gentile 《Journal of heterocyclic chemistry》1977,14(7):1263-1265
The ambident nucleophilic behaviour of some 2-amino-5-H-1,3,4-thiadiazoles in alkylation, acylation and nitrosation reaction has been verified. The structures assigned to the 2-amino-1,3,4-thiadiazoles ( 1a-i ) and to the Δ2-1,3,4-thiadiazolines ( 2a-e ) agree with the spectral data. 相似文献
138.
[reaction: see text] Ytterbium triflate was shown to be an effective catalyst in promoting the synthesis of either isopropyl esters or free alpha-hydroxy-arylacetic acids from substituted aromatic glyoxals and aryl methyl ketones, respectively. The reaction to provide acids starting from differently substituted ketones was carried out by an environmentally friendly method using an aqueous medium as a solvent and giving the adducts in 78-99% yield without any further purification after the usual workup. 相似文献
139.
Attilio Citterio Anna Gentile Francesco Minisci Marco Serravalle Susanna Ventura 《Tetrahedron》1985,41(3):617-620
The homolytic decomposition of hydroxylamine-O-sulphonic acid in alcoholic solvents was investigated in the presence or absence of protonated heteroaromatic bases and Fe(II) salt. The addition of the α-hydroxyalkyl radicals to the base and their oxidation by Fe(III) salt to the corresponding alkyl cyanide were competitive processes. A redox chain process involving the amino radical cation, NH3t., is suggested and the factors affecting the yields of the homolytic substitution are discussed. 相似文献
140.
Belpassi L Tarantelli F Sgamellotti A Quiney HM 《The Journal of chemical physics》2005,122(18):184109
An implementation of the generalized gradient approximation within the four-component formulation of relativistic density-functional theory using G-spinor basis sets is presented. This approach is based on the direct evaluation of the relativistic density and its gradient from the G-spinor amplitudes and gradients without explicit reference to the total density matrix. This proves to be a particularly efficient scheme, with an intrinsic computational cost that scales linearly with the number of G-spinor basis functions. In order to validate this new implementation, incorporated in the parallel version of the program BERTHA, a detailed study of the diatomic system CsAu is also reported. The spectroscopic constants D(e),r(e),omega(e), and x(e)omega(e) and the dipole moment mu have been calculated and compared with the best available theoretical and experimental data. The sensitivity of our results to the details of the numerical schemes used to evaluate the matrix elements is analyzed in detail. Also presented is a comparative study of molecular properties in the alkali auride series which have been obtained using several standard non-relativistic density functionals. 相似文献