1,721,037 research outputs found
Molecular and Supramolecular Architectures of Organic Semiconductors for Field Effect Transistor Devices and Sensors: a Synthetic Chemical Perspective
No full textOrganic field-effect transistors (OFETs) are key devices in organic electronics, and their performances largely depend on molecular structure and solid-state organization of the π-conjugated compounds used as semiconductors. This microreview reports several examples of materials for OFET devices and sensors, which have been selected to highlight the basic criteria of molecular design together with the synthetic logic driving the development of organic semiconductors. Versatile synthetic methodologies enable to optimize properties by tailoring molecular structures and functionalization, thus playing a key role in the progress of OFET technology, and more in general of organic electronics, which is emphasized in the discussion
Direct Arylations via C–H Bond Functionalization of 1,2,3-Triazoles by a Reusable Pd/C Catalyst Under Solvent-Free Conditions
Full text linkFully substituted triazoles are synthesized by a sustainable direct arylation reaction performed under solvent-free conditions and in the presence of a recyclable Pd/C heterogeneous catalyst. Exclusion of air as well as anhydrous conditions are not required, enabling a convenient synthesis of 1,4,5-trisubstituted 1,2,3-triazoles and 1,2,3-triazole-fused isoindolines starting from 1,4-disubstituted 1,2,3-triazoles, easily prepared via click chemistry, and functionalized aryl iodides
Structural investigation of iridium phenylpyridine complexes functionalized with fluorine and sulfonyl substituents
No full textRecent studies on the synthesis, properties and structural characterization of some Ir complexes
with arylpyridine ligands have attracted considerable interest in both academic and industrial
fields due to their use as phosphorescent materials in light emitting diodes (PHOLEDs)[1]. One of
the main advantages offered by this class of Ir complexes is the possibility to careful control their
light emission colour by suitably choosing the kind and position of substituent groups[2]. Latest
literature also shows that the stereochemistry of these complexes has a significant influence on
their photophysical properties and performance in devices[3]. Therefore, structural studies of these
materials are very important in order to identify univocally the atomic arrangement of the
compounds under investigation. In a recent publication, we have synthesized and
spectroscopically characterized a series of heteroleptic iridium complexes functionalized with
benzylsulfonyl groups and fluorine atoms in different positions of 2-phenylpyridine ligands.
Investigation of the stereochemistry of these complexes has been firstly carried out by 1H and 13C
and NMR spectroscopy of their iridium dichloro-bridged dimer precursors.
Here, we report the crystallographic characterization of the iridium dimers (PhSO2-F2ArPy)4Ir2Cl2
and (PhSO2-FArPy)4Ir2Cl2 which sheds light on their stereochemistry, as well as on the
stereochemistry of the corresponding heteroleptic iridium complexes. The crystal structures were
determined by SCXRD. Both complexes crystalize in P space group and have a trans
configuration of the arylpyridine ligands. The geometry parameters and the atomic coordination
around central Ir3+ ion are similar in both complexes, each one showing a regular octahedral
arrangement of the donor atoms
Ciclodimerizzazione chemo-diastereoselettiva di 1-aril-1-feniletileni indotta da sali di amminio: effetto solvente
No full textSynthesis of organic semiconductors functionalized with biological molecules
No full textOrganic polymeric and molecular semiconductors functionalized with biological molecules represent a very interesting class of materials for highly selective electrical and optical sensors. Molecular design and synthetic approaches to several bio-substituted conjugated oligomers and polymers are discussed, highlighting the impact of synthetic pathways on the properties of the materials
Synthetic Routes to Extended Polyconjugated Structures
No full textThis review covers our recent contribution on the synthesis of extended polyconjugated compounds, such as conjugated polymers and small molecules. The synthetic strategies developed in our research group are mainly based on palladium-catalyzed cross-coupling reactions involving a variety of organometallic intermediates as well as on direct arylation reactions via C–H functionalization. This report is organized according to the synthetic methods used (coupling of unsaturated organosilanes, Suzuki–Miyaura cross-coupling, Stille cross-coupling, direct arylation) and the typologies of the structures synthesized (polymers, small molecules)
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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