1,720,978 research outputs found
Solarylations via 4-Aminophenyl Cations
No full textThe application of the photo-SN1 reaction on some 4-chloroanilines was explored under solar irradiation in view of obtaining a convenient metal-free arylation method. Several reactions
previously carried out by UV irradiation, as well as some new ones, where either a new trap (alpha-methylstyrene) or a new halide (N,N-dimethyl-4-fluoroaniline) were adopted, were studied under these conditions and found to occur conveniently. Furthermore, at least in some cases the halide starting concentration could be raised up to 0.2 M, the excess trapping agent reduced from 20:1 to 2.5:1, and the solvent replaced by more environmentally friendly (co)solvents including water. Under
these improved conditions, the photoarylation was carried out in a gram scale by merely exposing the solution to solar irradiation. This process has a low impact on the environment and can be considered a serious competitor of metal-catalyzed arylations
Photoluminescent nanocluster-based probes for bioimaging applications
Full text linkIn the continuous search for versatile and better performing probes for optical bioimaging and biosensing applications, many research efforts have focused on the design and optimization of photoluminescent metal nanoclusters. They consist of a metal core composed by a small number of atoms (diameter < 2–3 nm), usually coated by a shell of stabilizing ligands of different nature, and are characterized by molecule-like quantization of electronic states, resulting in discrete and tunable optical transitions in the UV–Vis and NIR spectral regions. Recent advances in their size-selective synthesis and tailored surface functionalization have allowed the effective combination of nanoclusters and biologically relevant molecules into hybrid platforms, that hold a large potential for bioimaging purposes, as well as for the detection and tracking of specific markers of biological processes or diseases. Here, we will present an overview of the latest combined imaging or sensing nanocluster-based systems reported in the literature, classified according to the different families of coating ligands (namely, peptides, proteins, nucleic acids, and biocompatible polymers), highlighting for each of them the possible applications in the biomedical field. Graphical abstract: [Figure not available: see fulltext.
Eco-friendly hydrodehalogenation of electron-rich aryl chlorides and fluorides by photochemical reaction
No full textPhotochemistry 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
Confined space design by nanoparticle self-assembly
Full text linkNanoparticle (NP) self-assembly has led to the fabrication of an array of functional nanoscale systems, having diverse architectures and functionalities. In this perspective, we discuss the design and application of NP suprastructures (SPs) characterized by nanoconfined compartments in their self-assembled framework, providing an overview about SP synthetic strategies reported to date and the role of their confined nanocavities in applications in several high-end fields. We also set to give our contribution towards the formation of more advanced nanocompartmentalized SPs able to work in dynamic manners, discussing the opportunities of further advances in NP self-assembly and SP research
Singlet/triplet phenyl cations and benzyne from the photodehalogenation of some silylated and stannylated phenyl halides
No full textMultibranched superfluorinated molecular probes for 19F MRI
No full text19F MRI has been emerging as promising whole-body imaging technique complementary to 1H MRI. In fact, 19F has 100% natural abundance, a gyromagnetic ratio very close to that of the proton and 83% sensitivity of 1H. Moreover, in the human body there are only low amounts of inorganic fluorine in bones and teeth, which are not detectable by 19F MRI due to their low T2. Thus, the only in vivo detectable fluorine comes from exogenous tracers that can be clearly imaged and quantified by 19F MRI. However, the intrinsically low sensitivity of MRI has prompted efforts to develop effective 19F MRI tracers. An ideal 19F MRI tracer should have a high number of equivalent 19F atoms to yield a single sharp resonance signal [1]. In this sense, the first molecules used as 19F MRI tracers were perfluorocarbons (PFC) containing a high number of nonequivalent 19F atoms, such as perfluoro-octyl-bromide (PFOB), perfluorodecaline (PFD) and perfluorotributylamine (PFTBA). Later, PFC bearing many equivalent 19F atoms, such as perfluoro-15-crown ether (PFCE), and blends of perfluoropolyethers (PFPE) containing a huge number of 19F atoms (pseudoequivalent), were also proposed as more sensitive 19F MRI tracers [2, 3] (see Fig. 3.1). Despite PFC being widely used as 19F MRI agents, they were not specifically designed for this function, and thus, it should be possible to produce tailored polyfluorinated molecules for sensitive19F MRI
Green chemistry: State of the art through an analysis of the literature
No full textThe literature of green chemistry has undergone a dramatic increase in the new millennium. Besides that, in ad
hoc journals, papers of this type are published in journals of general, organic, and catalytic chemistry. The high
proportion of communications within this area indicates that this is a hot topic. These reports mainly concern
more environment-friendly synthetic methods, based on better catalytic systems, less harmful solvents and, more
rarely, ‘‘alternative’’ physical techniques. Although the compliance with the green chemistry postulates is still
partial, a trend in this direction is recognizable. For example, the number of preparative papers that introduce an
environmental assessment is rapidly increasing
Halogen bonding as a key interaction in the self-assembly of iodinated diphenylalanine peptides
Full text linkThe diphenylalanine peptide FF (H2N-Phe-Phe-COOH) is a simple building-block that has been extensively studied for multiple purposes. Among the many possible mutations finalized to tailor specific functions and properties of FF-based materials, halogenation was marginally considered despite the huge changes it confers to molecular self-assembly. Here, we report a detailed study on the role of halogenation, specifically iodination, in the aggregation behavior of iodine-modified FF dipeptides. Single-crystal X-ray structures of mono-iodinated—F(I)F—and bis-iodinated—F(I)F(I)—diphenylalanine reveal that halogen atoms exert a key role in the packing features of these compounds. Specifically, halogen bonding provides additional stability to the dry interfaces formed by the aromatic rings, providing a contribution in the solid-state packing of these dipeptides. The structural evidence of halogen bonding as crucial noncovalent interaction confirms the great potential of halogenation as supramolecular tool for peptide-based systems
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