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An investigation into the molecular recognition, structural and extraction properties of hydrogen bonding anion receptors
No full textEThOS - Electronic Theses Online ServiceGBUnited Kingdo
An introduction to anion receptors based on organic frameworks
No full textThis review article provides a broad overview to the area of anion coordination by synthetic organic receptors and includes examples of different functional groups used to bind anions. The first section examines neutral anion receptors containing amide-, sulfonamide-, urea- and thiourea-based receptors. Then aromatics such as pyrrole, carbazole and indole are discussed before concluding the discussion of neutral systems with examples of hydroxy OH donors. A brief overview of charged systems is also provided
Interactions of organic halide and nitrate salts with meso-octamethylcalix[4]pyrrole
No full textProton NMR titrations have been performed with meso-octamethylcalix[4]pyrrole and a variety of organic chloride and bromide salts in dichloromethane-d2. The results show apparently increasing chloride stability constants within each set of anion salts (tetrabutylammonium < imidazolium < pyridinium). Addition of 1-ethyl-3-methylimidaolium (EMIM) nitrate to dichloromethane-d2 solutions of calix[4]pyrrole caused significantly larger downfield shifts of the pyrrole NH protons of calix[4]pyrrole than addition of equimolar quantities of tetrabutylammonium nitrate. The first crystal structure of a nitrate complex of a calix[4]pyrrole is also presented
Anion-induced conformational changes in 2,7-disubstituted indole-based receptors
No full textThe conformational preorganization and anion-induced conformational changes of indole-based receptors functionalized with an amide group at the 2-position and a variety of amide, urea and thiourea moieties at the 7-position have been studied by the means of NMR spectroscopy. NOE experiments showed that anti–anti orientation across C2–C2 and C7–N7 bonds is preferred for receptors 1–4 in acetone solution in the absence of anions. Anion–receptor interactions have been evaluated through 1H and 15N chemical shift changes. In 2,7-bis-carboxamido functionalized indoles the interaction with chloride and bromide anions primarily occurs at the indole H1 proton. The introduction of urea and thiourea moieties increases the number of hydrogen bond donor sites which manifests itself in a distribution of halide–receptor interactions among the H1, H7 and H7 protons. Acetate anions also interact strongly with indole and urea NH donor groups, whereas nitrate anions interact solely with H7 and H7 urea/thiourea protons. NOE enhancements in the presence of anions revealed that anion–receptor complexes favour the syn–syn conformation of the C2 and C7 substituents
Organic salt inclusion: the first crystal structures of anion complexes of N-confused calix[4] pyrrole
No full textThe first crystal structures of anion complexes of N-confused calix[4]pyrrole are presented showing chloride binding to the three unconfused pyrrole NH groups and imidazolium inclusion in the calixpyrrole cup
2,7-functionalized indoles as receptors for anions
No full textA series of 2,7-functionalized indoles have been synthesized with appended amide and/or urea or thiourea groups. Anion complexation studies show a marked difference in the mode of interaction of carboxylates with indole-ureas vs indole-amides
Ionic liquid-calix[4]pyrrole complexes: pyridinium inclusion in the calixpyrrole cup
No full textPyridinium based ionic liquids form complexes with meso-octamethylcalix[4] pyrrole with both the anion and cation binding to the tetrapyrrole macrocycle
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
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