1,721,071 research outputs found
ChemInform Abstract: Is Water a Friend or Foe in Organometallic Chemistry? The Case of Group 13 Organometallic Compounds
No full textChemInform Abstract: Organosilanetriols: Model Compounds and Potential Precursors for Metal-Containing Silicate Assemblies
No full textChemInform Abstract: Molecular Phosphonate Cages: Model Compounds and Starting Materials for Phosphate Materials
No full textUnravelling the Role of Sterically Encumbered Ligands in Tuning the Magnetic Properties of Lanthanide‐Based D 5h Single‐Ion Magnets
No full textAbstract Isostructural Dy(III) and Er(III) complexes [L 1 2 Ln(H 2 O) 5 ][I] 3 ⋅ L 1 2 ⋅ (CH 2 Cl 2 ) (Ln=Dy ( 1 ), Er ( 3 )) and [L 2 2 Ln(H 2 O) 5 ][I] 3 ⋅ L 2 2 ⋅ (CH 2 Cl 2 ) 2 (Ln=Dy ( 2 ), Er ( 4 )), with distorted pentagonal bipyramidal geometry ( D 5h ) around the central metal were synthesized by utilizing two bulky phosphonamide ligands, adamantyl phosphonamide, (Ad)P(O)(NH i Pr) 2 ( L 1 ) and carbazolyl phosphoramide (Cz)P(O)(NH i Pr) 2 ( L 2 ). The resultant complexes were investigated for their magnetic properties in order to elucidate the impact of modification of the coordinating P−O bond environment either by increasing steric bulk and/or introduction of a third P−N bond at the central phosphorus atom. Magnetic studies revealed substantial energy barriers ( U eff ) of 640 K and 491 K for Dy compounds 1 and 2 , respectively, rendering them as some of the best‐performing air‐stable SIMs amongst the class of SIMs with D 5h symmetry. Compounds 1 and 2 exhibit magnetization blocking ( T B ) at 6.5 K and 6 K, respectively, at a sweep rate of 20 Oe/s. Compound 1 benefits from increased lattice intermetallic distances due to bulky adamantyl substituent, but exhibits a significant deviation from linear axial (P)O−Dy−O(P) geometry (173.7(1)°). In addition to the deviation from linearity, the incorporation of a bulky adamantane (or carbazole) ligand in complex 1 (or 2 ) was found to result in relatively strong Dy…H−C agostic interactions, with distances of 3.698 Å (3.376 Å). These interactions are expected to induce transverse anisotropy. Ab initio CASSCF/RASSI‐SO/SINGLE_ANISO calculations offer valuable insights into the dynamics of magnetic relaxation and the impact of axial bulkiness on the anisotropy of D 5h systems. Beyond highlighting the crucial role of crystal field and symmetry in achieving high‐temperature SIMs, this study also explores how the secondary coordination sphere can be engineered to create novel SIMs.Indian Institute of Technology Delhi https://doi.org/10.13039/501100007488Deutsche Forschungsgemeinschaft https://doi.org/10.13039/501100001659Science and Engineering Research Board https://doi.org/10.13039/50110000184
Tuning Magnetic Anisotropy in Co(II) Tetrahedral Carbazole-Modified Phosphine Oxide Single-Ion Magnets: Importance of Structural Distortion versus Heavy-Ion Effect
No full textHourglass-Shaped Homo- and Heteronuclear Nonanuclear Lanthanide Clusters: Structures, Magnetism, Photoluminescence, and Theoretical Analysis
No full textStabilization of p-block organoelement terminal hydroxides, thiols, and selenols requires newer synthetic strategies
No full textMetal hydroxides represent a very interesting and highly useful class of compounds that have been known to chemists for a very long time. While alkali and alkaline earth metal hydroxides (s-block) are commonplace chemicals in terms of their abundance and their use in a chemical laboratory as bases, the interest in Bronsted acidic molecular terminal hydroxides of p-block elements, such as aluminum and silicon, has been of recent origin, with respect to the variety of applications these compounds can offer both in materials science and catalysis. Moreover, these systems are environmentally friendly, relative to the metal halides, owing to their -OH functionality (resembling that of water). Design and conceptualization of the corresponding terminal thiols, selenols, and tellurols (M-SH, M-SeH, and M-TeH) offer even more challenging problems to synthetic inorganic chemists. This concept summarizes some of the recent strategies developed to stabilize these otherwise very unstable species. The successful preparation of a number of silicon trihydroxides a few years back resulted in the generation of several model compounds for meta I-silicates. The recent synthesis of unusual aluminum compounds such as RAl(OH)(2), RAl(SH)(2), and RAl(SeH)(2) with terminal EH (E=O, Se, or Se) groups is likely to change the ways in which some of the well-known catalytic conversions are being carried out. The need for very flexible and innovative synthetic strategies to achieve these unusual compounds is emphasized in this concept
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
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