86,515 research outputs found
Cavitand-Based Coordination Cages: Achievements and Current Challenges
No full textThe research results obtained in the self-assembly of cavitand-based coordination cages are presented. Cavitands are ideal multidentate ligands for the creation of coordination cages due to their structural rigidity, concave structure, and great versatility in terms of synthetic modularity. The introduction of the ligand moieties on the resorcinarene building block proceeds at the upper rim of the cavity, to take full advantage of the structural rigidity of the cavitand scaffold. Two different synthetic strategies are employed for the formation of multidentate cavitand ligands: (a) functionalization at the apical positions and (b) introduction of the ligands as bridging units. The key features to control the cage self-assembly process emerging from this overview are the preorganization, for the cavitands, and kinetic versus thermodynamic stability of the resulting complexes, for the connecting metal. The versatility of this class of coordination cages is demonstrated by the formation of their heterotopic and heteronuclear versions, as well as their self-assembly on gold and silicon surfaces. Desymmetrization of the cages is appealing because of the resulting differentiation of the inner cavities in terms of shape and interactivity, while surface self-assembly represents an important opportunity to expand the application range of these objects
Self-assembly of a cavitand-based heteronuclear coordination cage
No full textA new self-assembly protocol leading to the formation of heteronuclear coordination cage 10 is reported. Reaction of tetradentate cavitand ligand 1, bearing one ethynylpyridine and three benzonitriles at the apical positions, with Pt(dppp)OTf2 and Pd(dppp)OTf2 in a 1:3 ratio yields 10 as the thermodynamic product. Under the same conditions, the self-assembly of 1 with either Pt or Pd metal precursors gives a mixture of isomeric homonuclear cages 8a-c or 9a-c, respectively
Molecular Recognition with Ditopic Cavitand Re-Complexes
No full textThe synthesis of a series of cavitand receptors bearing increasing numbers of phosphonate groups at their upper rims and of the corresponding Re-based ditopic complexes is reported. The molecular recognition properties of these phosphonate cavitands towards both monotopic and ditopic N-methylpyridinium salts were investigated. The numbers and spatial dispositions of P=O units are pivotal for the complexation of guest ions. The removal of a single P=O bridge from the parent tetraphosphonate cavitand was sufficient to reduce the association constant by almost three orders of magnitude. Elimination of a second P=O unit completely abolished complexation in the AC distal isomer, both in monotopic and in ditopic hosts. The preorganised structure obtained by interconnection of two triphosphonate cavitands through a Re system showed moderate positive self-assembly cooperativity in the inclusion of ditopic N-methylpyridinium salts in both polar and nonpolar solvents. The speciation profile in ethanol indicates that the clamshell 1: 1 complex is dominant at low concentrations (< 10(-4) M) whereas the 1: 2 complex is preferred at higher concentrations of ditopic guest
Author Correction: Using mortuary and burial data to place COVID-19 in Lusaka, Zambia within a global context
No full textCorrection to: Nature Communicationshttps://doi.org/10.1038/s41467-023-39288-6, published online 29 June 2023 In this Article, the affiliation details for Emanuele Del Fava & Alessia Melegaro were incorrectly given as ‘Carlo F. Dondena Centre for Research on Social Dynamics and Public Policy, Boccini University, Milan, Italy’ but should have been ‘Carlo F. Dondena Centre for Research on Social Dynamics and Public Policy, Bocconi University, Milan, Italy’. This has now been corrected in the PDF and HTML versions of the Article
Variations on the Author
No full text“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
Synthesis of Partially-Bridged Phosphonate and Thiophosphonate Resorcinarenes
No full textThe synthesis of partially bridged thiophosphonate and phosphonate resorcinarenes is reported in this paper. Resorcinarenes functionalised at the upper rim with two or three P=X (X=S,O) bridges oriented towards the molecular cavity are obtained from the treatment of the corresponding (iiii) tetrasubstituted cavitand with 1,2-dihydroxybenzene and base in DMF. This synthetic route selectively promoted the formation of one of the two disubstituted resorcinarenes, the AC isomer. The crystal structure of the AC-dithiophosphonated resorcinarene 4 has been determined
Statistical analyses of grain-size, geochemical and mineralogical data in core CM92-43, Central Adriatic basin
No full text[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
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