1,720,972 research outputs found
Addition of aliphatic, secondary amines to coordinated isonitriles. N-acyclic carbene (NAC) platinum(II) complexes from trans-[Pt(mu-Cl)Cl(PPh3)](2)
No full textIsocyanide ligands RNC (R = 4-(MeO)C6H4-, PhCH2) react smoothly with trans-[Pt(mu-Cl)Cl(PPh3)](2) to afford trans-[PtCl2(PPh3)(CNR)] complexes, which are promptly converted, in solution, to the corresponding cis isomers. The obtained derivatives react with N,N-dialkylamines to afford the corresponding N-acyclic carbene (NAC) addition products. When alicyclic N,N-dialkylamine (R2NH, R=ethyl, benzyl) were used, only the expected neutral dichlorocarbene product cis-[PtCl2(PPh3)(R2NCN(H)R)] were obtained in high yields, while when cyclic amines (R'2N) over capH were used (morpholine, piperidine, pyrrolidine), variable amounts of ionic [PtCl(PPh3) ((R' 2N) over capH)((R' 2N) over cap CN(H)R)]Cl were observed, arising from the substitution of a residual chlorido ligand by the used amine. The amount of the ionic derivative observed depends on the amine nucleophilicity
Platinum(II) triphenylphosphane and triphenylarsane complexes help overcome resistance against cisplatinum resistant cancer cell lines
No full textIn the field of anticancer metal complexes many efforts are continuously devoted to overcome resistance phenomena. Within thousands of new complexes proposed each year as potential metallodrugs, compounds showing modes of action other than that of cisplatin appear promising. This minireview reports about the class of triphenylphosphane complexes of platinum(II), describing their synthesis, antiproliferative properties and modes of action, with a special focus on the possibility of overcoming resistance phenomena
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
1d-zigzag eu3+/tb3+ coordination chains as luminescent ratiometric thermometers endowed with multicolor emission
Full text linkTwo homometallic Coordination Polymers (CPs) with composition [Ln(hfac)3bipy]n (Ln3+ = Eu3+, 1, and Tb3+, 2; hfac = hexafluoroacetylacetonato, bipy = 4,4′-bipyridine) were used to develop a family of ratiometric luminescent thermometers containing Eu3+ and Tb3+ as red and green emitters, respectively. The thermometric properties of pure CPs and of their mixtures having an Eu3+/Tb3+ molar ratio of 1:1, 1:3, 1:5, and 1:10 (samples: Eu1Tb1, Eu1Tb3, Eu1Tb5, and Eu1Tb10) were studied in the 83–383 K temperature range. Irrespective of the chemical composition, we observed similar thermometric responses characterized by broad applicative temperature ranges (from 100 to 165 K wide), and high relative thermal sensitivity values (Sr ), up to 2.40% K−1, in the physiological temperature range (298–318 K). All samples showed emissions endowed with peculiar and continuous color variation from green (83 K) to red (383 K) that can be exploited to develop a colorimetric temperature indicator. At fixed temperature, the color of the emitted light can be tuned by varying composition and excitation wavelength
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Sandwich d/f Heterometallic Complexes [(Ln(hfac)3)2M(acac)3] (Ln = La, Pr, Sm, Dy and M = Co; Ln = La and M = Ru)
Full text linkSandwich d/f heterometallic complexes [(Ln(hfac)3)2M(acac)3] (Ln = La, Pr, Sm, Dy and M = Co; Ln = La and M = Ru) were prepared in strictly anhydrous conditions reacting the formally unsaturated fragment [Ln(hfac)3] and [M(acac)3] in a 2-to-1 molar ratio. These heterometallic complexes are highly sensitive to moisture. Spectroscopic observation revealed that on hydrolysis, these compounds yield dinuclear heterometallic compounds [Ln(hfac)3M(acac)3], prepared here for comparison purposes only. Quantum mechanical calculations supported, on the one hand, the hypothesis on the geometrical arrangement obtained from ATR-IR and NMR spectra and, on the other hand, helped to rationalize the spontaneous hydrolysis reaction
Heterometallic [Ln(hfac)3Cu(acac)2] complexes with late 4f ions
Full text linkHeterometallic [Ln(hfac)3Cu(acac)2] complexes (Ln = Eu 1, Dy 2, Er 3) can be prepared along the f-transition
series. X-rays diffraction studies on well-shaped single crystals revealed for 1 – 3 a dinuclear structure. No ligand
scrambling occurred, a Lewis acid-base interaction has been observed with the two metals bridged through two
oxygen atoms of the acetylacetonato ligands and an oxygen atom of a hexafluoroacetylacetonato ligand. Compounds
2 and 3 can be obtained only in anhydrous conditions. (1) can be sublimed under reduced pressure, and
crystals of the sublimed product, 1a, showed a polymorph structure with the same molecular identity. Magnetic
studies have been carried out on 2, displaying an antiferromagnetic interaction and a field-induced slow relaxing
magnetic moment with a significant phonon bottleneck effect. Compound 3, on the other hand, did not present
any magnetization dynamics, with or without applied field. Quantum mechanical calculations rationalize the
variation of the bond strengths from the reagents to the heterometallic complexes and quantify the Ln and Cu
direct interaction, which is relevant, especially for 2
Dibromo–Isonitrile and N-acyclic Carbene Complexes of Platinum(II): Synthesis and Reactivity
Full text linkA series of dibromo-N-acyclic (NAC) carbene complexes of platinum(II) were synthesized, starting from trans-[Pt(μ-Br)Br(PPh3)]2 and according to a protocol previously optimized for the preparation of analogous chlorinated compounds. In the first step of the synthesis, the ring opening of the dinuclear precursor was carried out using suitable isonitrile ligands, while the following step consisted of the addition of N,N-diethylamine to the products obtained in the first step. The two reactions were separately investigated, and attention was given to the differences between brominated and chlorinated systems
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