1,721,112 research outputs found
Mechanistic investigation of light-driven catalysis for solar fuel formation
No full textSolar energy conversion into chemical fuels currently represents a viable solution to the
global energy issue. In this regard, water splitting with formation of dihydrogen as an energy
carrier has been usually considered as a target reaction. Due to the mechanistic complexity
associated with both the oxidation (oxygen evolving reaction, OER) and reduction (hydrogen
evolving reaction, HER) half-reactions, the design of active catalysts and their efficient
coupling with photoactive components appears as a major target. Optical spectroscopies
turn out to be key tools to monitor the photoreaction dynamics and extract detailed kinetic
data which can be profitably employed towards performance optimization of both catalytic
routines. This chapter will describe the application of steady-state and time-resolved
absorption and emission spectroscopy to the investigation of the mechanistic aspects as-
sociated with both the OER and HER performed using molecular components both as light-
harvesting and catalytic units. Through the case studies examined, we will give an overview
of how these spectroscopic tools allow proper identification of the photoreaction mech-
anism, the rate and efficiency of each (photo)chemical step, the possible involvement of
proton-coupled electron-transfer (PCET) processes and the occurrence of detrimental side-
reactions, thus defining precise guidelines towards improvement of solar fuel formation
Photochemistry of transition metal complexes (2019-2020)
No full textThis Chapter aims to summarise the major advances achieved over 2019 and 2020 in the field of photochemistry and photocatalysis by transition metal compounds. In the last years, one of the central research themes has been the development of efficient photocatalytic complexes based on earth-abundant metals as a potential eco-friendly, resource-efficient, and sustainable photochemical approach. Nevertheless, second- and third-row metal complexes still represent key building blocks in the design of new photocatalysts in organic transformations, biomedical applications, as well as in green chemistry fields
Photochemistry of transition metal complexes (2017–2018)
No full textThis chapter reviews the major advances in the field of photochemistry and photocatalysis by transition metal compounds published in 2017–2018. Particular attention has been given to (i) photocatalysis in synthesis (ii) photoreactivity; (iii) biomedical applications of photoactive transition metal complexes, e.g. as photo-CORMs and PDT (photodynamic therapy) agents
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
Photocatalyst-free, Visible Light Driven, Gold PromotedSuzuki Synthesis of (Hetero)biaryls
Full text linkAvisible-light driven Suzuki cross-coupling reactionwas per-formed with colored and bench-stable arylazosulfones in thepresenceofPh3PAuCl (5 mol %) as the catalyst.The absence ofaphotocatalyst ,along with the use of commercially availableand easy-to-handle arylboronic acids underline the novelty andsynthetic usefulness of the protocol. Areaction mechanism in-volvingthe generation of an aryl radicalasthe key intermedi-ate has been proposed on the basis of experimental investigations
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
Visible-Light-Driven Synthesis of 1,3,4-Trisubstituted Pyrroles from Aryl Azides
No full textThe synthesis of 1,3,4-trisubstituted pyrroles via visible-light mediated photoredox catalyzed condensation of arylazides and aldehydes has been reported herein. The methodology avoids the use of stoichiometric oxidants and provides the corresponding N-containing arenes in good yields (up to 78%) and mild conditions. Mechanistic rationale is provided via a dedicated and combined spectroscopic/experimental investigations
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
- …
