1,720,973 research outputs found
Crystal structure of chlorotris(2,2,6,6-tetramethyl-3,5-heptanedionato)-zirconium(IV), [ZrCl{(CH3)(3)CCOCHCOC(CH3)(3)}(3)]
No full textSYNTHESIS AND CHARACTERIZATION OF URANYL(VI) AND THORIUM(IV) COMPLEXES WITH PHOSPHINE OXIDES - THE CRYSTAL-STRUCTURE OF UO2(NO3)2(NO2-C6H4PH2PO)2
No full textPalladium and platinum complexes with N,N-dimethylselenourea
No full textPalladium and platinum dihalides reacted with N,N-dimethylselenourea (dmsu) yielding complexes of the general formulae [M(dmsu)(4)]X(2), [M(dmsu)(3)X]X, [Pd(dmsu)(2)X(2)] and Pt(dmsu)(1.5)X(2), (M = Pd or Pt; X = Q or Br); which were characterized by IR and proton NMR spectroscopy and thermogravimetric analysis (TD, DTG and DTA). The 1:4 adducts can be obtained in two crystalline forms, depending on the crystallization medium. In particular, [Pd(dmsu)(4)]Cl-2 crystals have been obtained in deuterated chloroform, which differ from those of [Pd(dmsu)(4)]Cl-2 . 0.5EtOH samples obtained in ethanol/n-pentane. In the latter case a solvent molecule is interspersed in the crystal packing. The crystal structures of both modifications have been determined by X-ray crystallography and refined to R = 0.042 and R = 0.062, respectively. In both structures the Pd(dmsu)(4)(2+) complex cation is approximately square planar with Pd-Se bonds ranging from 2.43 to 2.46 Angstrom. An extensive net of NH ... Cl bonds is present in the crystal packing of the compounds
Gold(III) dithiocarbamate derivatives as potential antitumor agents: synthesis, characterization, solution chemistry and cytotoxic properties
No full textINTERACTION OF 2,4,6-HEPTANETRIONE WITH 1,5-DIAMINO-3-AZAPENTANE AND SIMILAR POLYAMINES - THE CRYSTAL AND MOLECULAR-STRUCTURE OF A NEW HETEROCYCLIC COMPOUND
No full textLANTHANIDE COMPLEXES WITH MALTOL - THE CRYSTAL-STRUCTURE OF DIAQUATRIS(MALTOLATO)PRASEODYMIUM(III) TRIHYDRATE
No full textThe reaction of lanthanide trichlorides with excess of maltol (HMa, 3-hydroxy-2-methyl-4H-pyran-4-one) in benzene or acetone yields the [Ln(HMa)3Cl3].nH2O (Ln = Pr, Nd or Eu; n = 0,1) adducts, whereas in water species as [Pr(Ma)3(H2O)2] or [Sm(Ma)2(OH)(H2O)2] have been isolated. The compounds have been characterized by IR and proton NMR spectroscopy and by thermogravimetric (TG and DTA) analysis. The crystal structure of diaquatris(maltolato)praseodynium(III) trihydrate is also reported. Crystals are triclinic, P1BAR, with a = 9.608(3), b = 11.318(3), c = 12.537(4) angstrom, alpha = 115.39(3)-degrees, beta = 103.08(8)-degrees, gamma = 94.11(4)-degrees, V = 1177 angstrom3, Z = 2. The structure was refined to R = 0.034 based on 3329 observed reflexions. The compound consists of [Pr(Ma)3(H2O)2] molecules in which the Pr atom is eight-coordinated. Three H2O molecules of crystallization are also present
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Gold dithiocarbamate derivatives as potential antineoplastic agents: design, spectroscopic properties and in vitro antitumor activity
No full textAt present, cisplatin (cis-diamminodichloroplatinum(II)) is one of the most largely employed anticancer drugs as it is effective in the treatment of 70-90% of testicular and, in combination with other drugs, of ovarian, small cell lung, bladder, brain, and breast tumors. Anyway, despite its high effectiveness, it exhibits some clinical problems related to its use in the curative therapy, such as a severe normal tissue toxicity (in particular, nephrotoxicity) and the frequent occurrence of initial and acquired resistance to the treatment. To obtain compounds with superior chemotherapeutic index in terms of increased bioavailability, higher cytotoxicity, and lower side effects than cisplatin, we report here on some gold(I) and gold(III) complexes with dithiocarbamate ligands (DMDT = N,N-dimethyldithiocarbamate; DMDTM = S-methyl-N,N- dimethyldithiocarbamate; ESDT = ethylsarcosinedithiocarbamate), which have been synthesized, purified, and characterized by means of elemental analyses, conductivity measurements, mono- and bidimensional NMR, FT-IR, and UV-vis spectroscopy, and thermal analyses. Moreover, the electrochemical properties of the designed compounds have been studied through cyclic voltammetry. All the synthesized gold complexes have been tested for their in vitro cytotoxic activity. Remarkably, most of them, in particular gold(III) derivatives of N,N-dimethyldithiocarbamate and ethylsarcosinedithiocarbamate, have been proved to be much more cytotoxic in vitro than cisplatin, with IC50 values about 1- to 4-fold lower than that of the reference drug, even toward human tumor cell lines intrinsically resistant to cisplatin itself. Moreover, they appeared to be much more cytotoxic also on the cisplatin-resistant cell lines, with activity levels comparable to those on the corresponding cisplatin-sensitive cell lines, ruling out the occurrence of cross-resistance phenomena and supporting the hypothesis of a different antitumor activity mechanism of action
Synthesis, characterization and in vitro cytotoxicity of new organotin(IV) derivatives of N-methylglycine
No full textThe synthesis and characterization of new coordination compounds of some diorganotins(IV) with N-methylglycine (sarcosine) are reported; all these derivatives mainly tend to assume a chelate structure. As single crystals were not obtained, a large number of experimental techniques were used to accomplish a definitive characterization and determination of their structure. Results obtained by 1H/119Sn NMR, FT-IR and 119mSn-Mössbauer spectroscopy and thermogravimetric analysis allow us to deduce the pentacoordination for 1:1 (Sn/sarcosine) derivatives [R2SnCl2(Sar)]+Cl- (R=Me, n-Bu) in a trigonal-bipyramidal structure, and the hexacoordination for 1:2 complexes [R′2Sn(Sar)2]2+2Cl- (R′=Me, n-Bu, Ph) in an octahedral structure; however, the probability of partially or totally non-chelate structures for some adducts increases with the steric hindrance of the R/R′ groups and the number of the sarcosine molecules bound to the tin atom, so that they give rise to fluxional equilibria in solution. Finally, the synthesized compounds have been tested for in vitro cytotoxic activity against human adenocarcinoma HeLa cells showing, in some cases, strong activity even at low concentration
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