1,720,965 research outputs found
An amphiphilic C-60 derivative with a tris(2,2 '-bipyridine)ruthenium(II) polar head group: synthesis and incorporation in Langmuir films
No full textAn amphiphilic C60 derivative with a tris(2,2′-bipyridine)ruthenium(II) polar head group has been prepared. The Langmuir film of this compound has been characterized by its surface pressure versus molecular area (Π/A) isotherm and Brewster angle microscopy (BAM) observations
Carbon Nanostructures: Covalent and Macromolecular Chemistry
No full textThe aim of this introductory chapter is to bring to the attention of the readers the
achievements made in the chemistry of carbon nanostructures and, mostly, in the
chemistry of fullerenes, carbon nanotubes (CNTs), and the most recent graphenes.
Since the discovery of fullerenes in 1985 and their further preparation in multigram
amounts, the chemistry and reactivity of these molecular carbon allotropes have been
well established. Actually, this chemical reactivity has been used as a benchmark for
further studies carried out in the coming carbon nanotubes (single and multiple wall)
and graphenes. Assuming that the fundamental chemistry of fullerenes is known
and basically corresponds to that of typical electron-deficient alkenes, we have mainly
focused on the chemistry of fullerene-containing polymers. In this regard, the
combination of the unique fullerenes with the highly versatile polymer chemistry
has afforded a new and interdisciplinary field in which the resulting architectures are
able to exhibit unprecedented properties. The basic knowledge of this important topic
of macromolecular chemistry of fullerenes nicely complements the following
chapters devoted to their supramolecular chemistry
Fullerene-containing Polymers
Full text linkIn the present chapter, the different C60-based polymers have been classified according to structural parameters and the different synthetic strategies to prepare them have been highlighted. Two new families have been added, namely fullerene–nanotubes hybrid and DNA–fullerene hybrid, due to the nondiscrete nature of the corresponding members. Finally, fullerene-containing polymers’ most promising applications have been discussed, mainly focusing on nonlinear optics, DNA-cleaving and photovoltaic properties
Hydrogen Bonding Donor–Acceptor Carbon Nanostructure
Full text linkThe natural process of photosynthesis is paradigmatic in converting sunlight into energy. This complicated process requires a cascade of energy- and electron-transfer events in a highly organised matrix of electron–donor, electron–acceptor and antennae units and has prompted researchers to emulate it. In fact, energy- and electron-transfer processes play a pivotal role in molecular-scale optoelectronics. In this chapter we compile a number of remarkable examples of noncovalent aggregates formed by the combination of carbon-based electroactive species (fullerenes and carbon nanotubes) hydrogen bonded with a variety of moieties. We will show that: (a) the connection of complementary electroactive species by means of H bonds in C60-based donor–acceptor ensembles is at least as efficient as that found in covalently connected systems; (b) hydrogen-bonding fullerene chemistry is a versatile concept to construct supramolecular polymers, and (c) H-bonding interactions is contributing to create very appealing carbon-nanotube-based donor–acceptor supramolecular architectures
A luminescent multicomponent species made of fullerene and Ir(III) cyclometallated subunits
No full textThe first system containing a luminescent Ir(III) cyclometallated species and a functionalized C60 unit has been prepared; triplet–triplet energy transfer from the Ir-based MLCT state to the C60 triplet state occurs, leading to phosphorescence (lifetime, 4.8 ms) of the derivatized-C60 at 77 K
Synthesis and excited state properties of a [60] fullerene derivative bearing a star-shaped multi-photon absorption chromophore
No full textThe synthesis and excited state properties of a compound assembling C60 with a new multi-photon absorption chromophore are reported
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
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
- …
