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Covalent organic frameworks (COFs) are organic porous materials with many potential applications, which very often depend on the presence of chemical functionality at the organic building blocks. Functionality that cannot be introduced into COFs directly via de novo syntheses can be accessed through post-synthetic modification (PSM) strategies. Current strategies for the post-synthetic modification of COFs involve (i) incorporation of a variety of active metal species by using metal complexation through coordination chemistry, (ii) covalent bond formation between existing pendant groups and incoming constituents and (iii) chemical conversion of linkages. (iv) The post-synthetic modification is sometimes assisted by a monomer truncation strategy for the internal functionalization of COFs. (v) Even more intriguing methods that go beyond PSM are herein termed building block exchange (BBE) which encompasses framework-to-framework transformations taking advantage of the fact that reversible bond formation is a characteristic feature of COFs. This strategy allows the use of protoCOF structures (i.e., the utilization of a parent COF as a template) for the evolution of new COF structures with completely new components. [ABSTRACT FROM AUTHOR]

Covalent organic-frameworks (COFs) are an emerging class of porous and ordered materials formed by condensation reactions of organic molecules. Recently, the Schiff-base chemistry or dynamic imine-chemistry has been widely explored for the synthesis of COFs. The main reason for this new tendency is based on their high chemical stability, porosity and crystallinity in comparison to previously reported COFs. This critical review article summarizes the current state-of-the-art on the design principles and synthetic strategies toward COFs based on Schiff-base chemistry, collects and rationalizes their physicochemical properties, as well as aims to provide perspectives of potential applications which are at the forefront of research in materials science. [ABSTRACT FROM AUTHOR]

Dipyrazino[2,3-f:2′,3′-h]quinoxaline also known as 1,4,5,8,9,12-hexaazatriphenylene (HAT) is an electron deficient, rigid, planar, aromatic discotic system with an excellent π–π stacking ability. Because it is one of the smallest two-dimensional N-containing polyheterocyclic aromatic systems, it has been used as the basic scaffold for larger 2D N-substituted polyheterocyclic aromatics. Furthermore, it is the building block of choice in a plethora of molecular, macromolecular and supramolecular systems for a variety of applications. This review is aimed to critically review the research performed during the almost three decades of research based on HAT from the synthetic, theoretical and application points of view. The design principles and synthetic strategies towards HAT derivatives will be established and their use in n-type semiconductors, sensors, nonlinear optical chromophores, liquid crystals, microporous polymers for energy storage and nano and microstructures will reveal the relevance of HAT as a basic scaffold in the areas of organic materials and nanoscience. [ABSTRACT FROM AUTHOR]

Definition: Interest in covalent organic frameworks as high-value materials has grown steadily since their development in the 2000s. However, the great advantage that allows us to obtain these crystalline materials—the reversibility of the bonds that form the network—supposes a drawback in terms of thermal and chemical stability. Among the different strategies employed for the stabilization of imine-based Covalent Organic Frameworks (COFs), cycloaddition and other related cyclization reactions are especially significant to obtain highly stable networks with extended π-delocalization and new functionalities, expanding even further the potential application of these materials. Therefore, this entry gathered the most recent research strategies for obtaining stable COFs by means of cyclization reactions, including the Povarov reaction and intramolecular oxidative cyclization reactions as well as some other recent innovative approaches. [ABSTRACT FROM AUTHOR]

Abstract: In this article we describe the synthesis of an electron donor–acceptor dyad containing a [6,6]diphenylmethanofullerene moiety as the electron acceptor and a dialkylamino-substituted oligo-p-phenylenevinylene as the electron donor. The synthesis of this material has been successfully accomplished by an esterification reaction between a [6,6]diphenylmethanofullerene functionalized with a carboxylic acid and the corresponding oligomer substituted with a benzyl alcohol. Cyclic voltammetry and absorption spectroscopy show that both electroactive units preserve their nature in the ground state, whereas preliminary photophysical investigations show a strong fluorescence quenching. [Copyright &y& Elsevier]

The article suggests some examples of plastic solar-cell technology that can be used to demonstrate core concepts in chemistry. The principles of operation of a plastic solar cell can be utilized to introduce primary concepts such as the photovoltaic effect or the photoinduced electron transfer, which are essential in comprehending photosynthesis and the key processes that govern most novel optoelectronic devices. Also, from a spectroscopic point of view, the optical bandgap of the light-absorbing parts can be correlated with their electronic and physical structure. From the materials science perspective, the primary concept of molecular design can be introduced.

Abstract: The first main-chain copolymer containing TCAQ and enantiomerically pure binaphthyl moieties connected at 2,6 positions of the TCAQ ring was successfully synthesized by means of a polycondensation reaction. Cyclic voltammetry investigations show that TCAQ preserves its acceptor ability in the polymer system and preliminary photophysical investigations show fluorescence quenching in mixtures containing the acceptor polymer and fluorescent conjugated polymers. [Copyright &y& Elsevier]

Abstract: The possibility to use new organic semiconductor materials, in place of silicon wafers, in the fabrication of photovoltaic devices on substrates offer the prospect of lower manufacturing costs, particularly for large area applications. Thus, one of the most promising areas in fullerene research involves its potential application, mixed with conjugated polymers, in mimicking photosynthesis and in the related solar energy conversion. The tendency to phase segregation in blends of C60 derivatives and conjugated polymers has to be optimized to improve both charge photogeneration and transport in photovoltaic devices. In order to optimize device performances, a great deal of work has been devoted to the development of new device architectures and to elucidating the photophysical processes underlying the photovoltaic response. However, optimization of cells has been carried out with just a few materials and recent findings show that new developments can be very successful if a broader scope of materials in the composite layers becomes accessible. Thus, in this communication we present new approaches toward the synthesis of [60]fullerene derivatives specifically designed to be used in the fabrication of photovoltaic devices. (i) the first approach involves the synthesis of functionalized C60 and C70 derivatives with enhanced solubility; (ii) the second approach is directed to the synthesis of systems containing a conjugated moiety antenna covalently linked to the C60 unit. Together with the synthesis of these new materials, electrochemical and photophysical investigations have been also carried out. Photovoltaic devices have been fabricated with selected materials. [Copyright &y& Elsevier]

Examines the synthesis of 1,1'-binaphthyl-based enantiopure C[sub 60] dimers. Cycloaddition of compounds in situ generated diazo compounds; Exhibition of optical and electrochemical activity; Preparation of intrinsic chiral polymers to control conjugation length.

Studies the tetrathiafulvalene (TTF) derivatives as nonlinear optical (NLO)-phores. Synthesis of TTF; Electrochemical properties of the TTF-based NLO chromophores; Energy absorption bands in electronic spectra observed for compounds.

Covalent organic frameworks (COFs) are defined as crystalline organic polymers with programmable topological architectures using properly predesigned building blocks precursors. Since the development of the first COF in 2005, many works are emerging using this kind of material for different applications, such as the development of electrochemical sensors and biosensors. COF shows superb characteristics, such as tuneable pore size and structure, permanent porosity, high surface area, thermal stability, and low density. Apart from these special properties, COF's electrochemical behaviour can be modulated using electroactive building blocks. Furthermore, the great variety of functional groups that can be inserted in their structures makes them interesting materials to be conjugated with biological recognition elements, such as antibodies, enzymes, DNA probe, aptamer, etc. Moreover, the possibility of linking them with other special nanomaterials opens a wide range of possibilities to develop new electrochemical sensors and biosensors. [ABSTRACT FROM AUTHOR]

A new quinoline‐based COF (covalent organic framework), obtained by Povarov reaction, containing 2,6‐diisopropylphenyl moieties as substituents over the heterocyclic ring is described for detecting Zn2+ in aqueous solution. The introduction of the mentioned bulky phenyl rings into the network favors an increase of the distance between the reticular sheets and their arrangement, obtaining a new material with an alternating AB type stacking. The new material exhibits good selectivity to detect Zn2+ by fluorescence emission in aqueous solutions up to a concentration of 1.2 × 10−4 m of the metal ion. In order to have a deeper insight into the interaction between the COF and the zinc cation, a thorough spectroscopical, microscopical, and theoretical study is also presented and discussed in this communication. [ABSTRACT FROM AUTHOR]

This article presents a study on the exceptionally small attenuation factors in molecular wires. The potential of molecular-sized materials for electronic and photonic applications has led to an ever increasing interest in developing and probing molecular-scale wires) &b.pie;-Conjugated oligomers, such as oligo p-phenylenevinylenes, oligo-PPVs, are among those molecules which act as efficient molecular wires. Only a few reports on electron transfer through the &b.pie;-conjugated chains of oligo-PPVs are known. In this light, the importance of energy matching between the donor and bridge components, for achieving molecular-wire behavior, has been highlighted.

In this study, we present a novel approach for the synthesis of covalent organic frameworks (COFs) that overcomes the common limitations of non‐scalable solvothermal procedures. Our method allows for the room‐temperature and scalable synthesis of a highly fluorinated DFTAPB‐TFTA‐COF, which exhibits intrinsic hydrophobicity. We used DFT‐based calculations to elucidate the role of the fluorine atoms in enhancing the crystallinity of the material through corrugation effects, resulting in maximized interlayer interactions, as disclosed both from PXRD structural resolution and theoretical simulations. We further investigated the electrocatalytic properties of this material towards the oxygen reduction reaction (ORR). Our results show that the fluorinated COF produces hydrogen peroxide selectively with low overpotential (0.062 V) and high turnover frequency (0.0757 s−1) without the addition of any conductive additives. These values are among the best reported for non‐pyrolyzed and metal‐free electrocatalysts. Finally, we employed DFT‐based calculations to analyse the reaction mechanism, highlighting the crucial role of the fluorine atom in the active site assembly. Our findings shed light on the potential of fluorinated COFs as promising electrocatalysts for the ORR, as well as their potential applications in other fields. [ABSTRACT FROM AUTHOR]

In this study, we present a novel approach for the synthesis of covalent organic frameworks (COFs) that overcomes the common limitations of non‐scalable solvothermal procedures. Our method allows for the room‐temperature and scalable synthesis of a highly fluorinated DFTAPB‐TFTA‐COF, which exhibits intrinsic hydrophobicity. We used DFT‐based calculations to elucidate the role of the fluorine atoms in enhancing the crystallinity of the material through corrugation effects, resulting in maximized interlayer interactions, as disclosed both from PXRD structural resolution and theoretical simulations. We further investigated the electrocatalytic properties of this material towards the oxygen reduction reaction (ORR). Our results show that the fluorinated COF produces hydrogen peroxide selectively with low overpotential (0.062 V) and high turnover frequency (0.0757 s−1) without the addition of any conductive additives. These values are among the best reported for non‐pyrolyzed and metal‐free electrocatalysts. Finally, we employed DFT‐based calculations to analyse the reaction mechanism, highlighting the crucial role of the fluorine atom in the active site assembly. Our findings shed light on the potential of fluorinated COFs as promising electrocatalysts for the ORR, as well as their potential applications in other fields. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Chemical Speciation Analysis of Sport Drinks by Acid-Base Titrimetry and Ion Chromatography: A Challenging Beverage Formulation Project," by H. Drossman.

In this article we describe novel synthetic strategies toward well-defmed disubstituted conjugated hexaaza-triphenylene (HAT) derivatives. The systems are designed as novel V-shaped chromophores displaying C2 symmetry suitable for nonlinear optical investigations. Different donor moieties and linkers have been used in order to tune the electrochemical properties as well as the absorption spectra of the novel HAT derivatives. β values as high as 1010 x 10-48 esu have been obtained for a derivative containing the electron-rich dibutyl- amino moiety. Theoretical calculations have been performed showing a reasonable agreement with the experimental results and supporting the two-dimensional NLO character of these chromophores. [ABSTRACT FROM AUTHOR]

In this article we present the synthesis, characterization, electrochemical, optical, and preliminary photophysical investigation of two novel poly(fluorene-alt-thiophenc) conjugated polymers endowed with pendant perylenediimide electron acceptor units. We show a route to the synthesis of easily functionalizable monomers paving the way to the preparation of a variety of functionalized polymers with different properties and applications and reflecting the versatility of this synthetic methodology. [ABSTRACT FROM AUTHOR]

Abstract: A donor–acceptor dyad containing perylenediimide as the electron acceptor and π-extended tetrathiafulvalene as electron donor has been successfully synthesized by means of a Wittig reaction. Cyclic voltammetry and absorption spectroscopy show that both electroactive units preserve their nature, whereas preliminar photophysical investigations show a strong fluorescence quenching. [Copyright &y& Elsevier]

Abstract: A convenient and straightforward procedure has been developed for the preparation of functionalized 3,4-ethylenedithiathiophene (EDTT) derivatives by using a new bromomethyl–EDTT derivative as a versatile synthon. Based on this procedure a novel EDTT derivative endowed with 9,10-anthraquinone moieties has been synthesized and electrochemically polymerized to yield a donor–acceptor PEDTT derivative. [Copyright &y& Elsevier]

Abstract: A general synthetic strategy toward unsymmetrical hexaazatriphenylene (HAT) derivatives has been developed. The versatility of the strategy is used to synthesize a family of ambipolar donor–acceptor–donor (D–A–D) chromophores, which exhibit broad intramolecular charge transfer (ICT) bands in their solution UV–vis spectra. [Copyright &y& Elsevier]

Abstract: The synthesis of the first donor–acceptor phenylazomethine dendrimers ( 4 and 5 ) is described. A convergent method is used via the condensation of aromatic ketones with an appropriately functionalized tri(aminophenyl)-s-triazine promoted by titanium (IV) chloride. Cyclic voltammetry investigations show a donor–acceptor behaviour due to the presence of the electron acceptor s-triazine core and the donor ability of the conjugated peripheral butoxybenzene units. [Copyright &y& Elsevier]

Abstract: Within the context of exploring photophysical properties of [60]fullerene-based donor–acceptor ensembles, we highlight in this contribution an approach towards the synthesis of a novel series of donor-bridge-acceptor, C60–wire–exTTF, ensembles that incorporate p-phenylenevinylene oligomers, in which the conjugation length has been systematically increased, as bridges that connect π-extended tetrathiafulvalenes (exTTF) (electron donor) with [60]fullerene (electron acceptor). This molecular design allows probing the effects of distance and rate, at which electron transfer processes occur, as well as the molecular-wire behavior of the oligo-PPV fragments. [Copyright &y& Elsevier]

A 1,1,2,2-tetrakis(4-aminophenyl)ethene with three paths of π-conjugation, linear-cis, linear-trans and a cross-conjugation, has been prepared. The molecule is able to bind to gold electrodes forming molecular junctions for single-molecule conductance measurements. Only two regimes of conduction are found experimentally. The modelling of the conductance allows to assign them to through-bond transmission in the linear case, while the cross-conjugated channel is further assisted by through-space transmission, partially alleviating the destructive quantum interference. [ABSTRACT FROM AUTHOR]

The copper‐catalyzed azide–alkyne cycloaddition (CuAAC) click reaction is among the most extensively used strategies for the post‐polymerization modification of COFs. This work shows a new procedure for the postsynthetic functionalization of imine‐based COFs by using a heterogeneous solid–gas reaction between alkyne‐functionalized COFs and azides in the absence of a copper catalyst. This new alternative represents a step forward towards a greener postsynthetic modification of COFs opening a high potential for the development of new applications. [ABSTRACT FROM AUTHOR]

A novel naphthalene diimide-based covalent organic framework (NDI-COF) has been synthesized and successfully exfoliated into COF nanosheets (CONs). Electrochemical measurements reveal that the naphthalene diimide units incorporated into NDI-CONs act as efficient electrocatalyst for oxygen reduction in alkaline media, showing its potential for the development of metal-free fuel cells. [ABSTRACT FROM AUTHOR]

Amplified spontaneous emission (ASE) in optically pumped polystyrene (PS) films doped with two different oligo-(p-phenylenevinylene) derivatives (OPVs), with three (3-OPV) and five (5-OPV) monomer units is reported. It is observed that there is a maximum content of oligomer (25 wt. % for 3-OPV and 20 wt. % for 5-OPV) that can be introduced in the films, due to degradation (in 3-OPV) and ASE quenching (in 5-OPV). Optimal concentrations (with minimum pump-intensity thresholds for the observation of ASE) of 15 wt. % and 9 wt. % are measured for the trimer and the pentamer, respectively. The concentration dependence of the ASE threshold is discussed in terms of the optical absorption spectra. Gain coefficients are obtained by analyzing the dependence of the ASE with the length of the pump stripe. The results show that films based on 5-OPV appear to be more efficient and stable than those based on 3-OPV. [ABSTRACT FROM AUTHOR]

Lithium‐sulfur batteries stands out as a promising technology for energy storage owing to a combination of favorable characteristics including a high theoretical gravimetric capacity, energy density, inexpensive character, and environmental benignity. Covalent organic frameworks (COFs) are a rapidly developing family of functional nanostructures which combine porosity and crystallinity, and which have been already used in these kinds of batteries to build sulfur electrodes, by embedding sulfur into porous COFs in order to enhance cycle lifetimes. In this contribution, this is taken one step forward and a COF endowed with vinyl groups is used, in order to graft sulfur to the COF skeleton through inverse vulcanization. The main aim of the article is to show the synergistic effect of covalent bonding and physical encapsulation of sulfur in the pores of the COF in order to alleviate the fatal redox shuttling process, to improve the cycling performance, and to provide faster ion diffusion pathways. In addition, it is shown how the material with covalently‐bound S provides better electrochemical performance under demanding and/or changeable charge conditions than a parent analogue material with sulfur physically confined, but without covalent linkage. [ABSTRACT FROM AUTHOR]

Covalent organic Frameworks (COFs) are a class of crystalline macromolecular materials build-up by monomers with specific symmetries or functionalities. There are important limitations in the synthesis of highly ordered COFs, such as the shape and packing of the building blocks. Thus, the presence of fluorine atoms that lie perpendicular to the bisecting plane of BODIPY derivatives together with the presence of four bulky methyl groups could hinder the crystallization process in COF synthesis. For that reason, BODIPY-based COFs are rarely incorporated to COF networks. In this work, following the mixed linker strategy, a pre-synthetic method to dope COF structures with BODIPY units was developed. The materials have been processed into fluorescent Covalent Organic Nanosheets (CONs) with defined particle-size distributions around 100 nm, suitable for cellular biomedical applications. The viability of the CONs was evaluated using Sk-Mel-103 cells, demonstrating the internalization showing 100% cell viability. We envisage that this work could accelerate the discovery of new COF-based materials for biomedical sciences. • BODIPY doped COFs were prepared via a one-pot procedure by solvothermal Schiff's base condensation reaction. • The bulk COFs were delaminated into Covalent Organic Nanosheets (CONs) via liquid phase exfoliation. • The CONs were characterized by UV-VIS and Fluorescence spectroscopies, corroborating the introduction of BDP chromophores. • The developed material did not exhibit any sign of toxicity in cells after the cell internalization. [ABSTRACT FROM AUTHOR]

An imine-based covalent organic framework (COF) decorated in its cavities with uracil groups has shown selective recognition towards adenine in water. These results show how the confinement of the base-pair inside the COF's pores allows a remarkable selective recognition in aqueous media. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are emerging materials with structural modularity that allows their application in many fields. The aim of this work is to determine the environmental impact of using an imine based covalent organic framework (RT-COF-1) for both surface printing (Case A) and 3D inkjet printing (Case B) by applying Life Cycle Assessment (LCA) methodology. Experimental data on RT-COF-1 synthesis as well as results obtained by simulation of their precursors production, 1,3,5-tris-(4-aminophenyl) benzene (TAPB) and 1,3,5-benzenetricarbaldehyde (BTCA), are used. LCA results show that monomer synthesis is the most important contributor to environmental impacts in both case studies. On the other hand, the contribution of solvents used in Case A is also remarkable. The comparison between both case studies indicates that the environmental impacts of Case B is lower than that of Case A (reduction within 5%–65%). Finally, LCA results of Case B are compared to other materials used for 3D-printing, such as polymerizable ionic liquids (PILs). The results show that RT–COF–1 compares favourably with PILs in five of nine impact categories, being especially relevant the reductions achieved in the abiotic depletion and acidification potential (>90%), in the primary energy consumption (⁓35%) and carbon footprint (⁓50%), suggesting the potential of RT–COF–1 as 3D-printing material from an environmental perspective. This work is a first step for further research to highlight the main environmental burdens of using COF-based materials in this application. [Display omitted] • LCA methodology applied to imine-based COF for inkjet printing. • 3D-printing is superior to surface printing from an environmental point of view. • Solvents and synthesis of precursors are the main contributors to overall impact. • Environmental footprint of RT–COF–1 is comparable to polymerizable ionic liquids. [ABSTRACT FROM AUTHOR]

There is a great interest in peryleneimide (PI)-containing compounds given their unique combination of good electron accepting ability, high abosorption in the visible region, and outstanding chemical, thermal, and photochemical stabilities. Thus, herein we report the synthesis of perylene imide derivatives endowed with a 1,2-diketone functionality (PIDs) as efficient intermediates to easily access peryleneimide (PI)-containing organic semiconductors with enhanced absorption cross-section for the design of tunable semiconductor organic materials. Three processable organic molecular semiconductors containing thiophene and terthiophene moieties, PITa, PITb, and PITT, have been prepared from the novel PIDs. The tendency of these semiconductors for molecular aggregation have been investigated by NMR spectroscopy and supported by quantum chemical calculations. 2D NMR experiments and theoretical calculations point to an antiparallel π-stacking interaction as the most stable conformation in the aggregates. Investigation of the optical and electrochemical properties of the materials is also reported and analyzed in combination with DFT calculations. Although the derivatives presented here show modest electron mobilities of ∼10-4 cm²V-1s-1, these preliminary studies of their performance in organic field effect transistors (OFETs) indicate the potential of these new building blocks as n-type semiconductors. [ABSTRACT FROM AUTHOR]

Inversion of the connections of amidine linkers combined with controlled oligothiophene chain catenation in oligothiophene-naphthalimide assemblies provides an efficient method to tune the HOMO and LUMO values in this type of assemblies. This modification also suppresses the intramolecular charge transfer (ICT) band normally found in this type of derivatives, also delocalizing the frontier molecular orbitals over the whole conjugated skeleton. The resultant assemblies were used in the fabrication of field-effect transistors, which showed well-balanced ambipolar transport. [ABSTRACT FROM AUTHOR]

The synthesis, characterization, and optical properties of a novel star-shaped oligothiophene with a central rigid trithienobenzene (BTT) core and diketopyrrolopyrrole (DPP) units are reported and compared with homologous linear systems based on the benzodithiophene (BDT) and the naphthodithiophene (NDT) units end capped with DPPs. This comparison is aimed at elucidating the effect of the star-shaped configuration versus linear conformation on the optical and electrical properties. Electronic and vibrational spectroscopies, together with transient absorption spectroscopy, scanning electronic microscopy, and DFT calculations are used to understand not only the molecular properties of these semiconductors, but also to analyze the supramolecular aggregation in these derivatives. We conclude that although the subject star-shaped derivative is not optimal in terms of π-conjugation, its extended BTT unit significantly favors intermolecular π-stacking interactions, which is interesting for their applications in devices. Field-effect transistors and solar cells were fabricated with these new molecular semiconductors and the performance difference discussed. [ABSTRACT FROM AUTHOR]

• The Covid-19 pandemic made it necessary for academic and teaching activities to be held in virtual mode. • An international consortium with a focus on Epilepsy Surgery was established. • The consortium included different centers in Latin America and Canada. An international consortium with a focus on Epilepsy Surgery Education was established with members from different centers in Latin America and Canada. All members of the consortium and attendees from different centers in Latin America and Canada have been meeting to discuss epilepsy surgery cases in a virtual manner. We surveyed all to assess the value of the meetings. The results and description of these meetings are being presented. [ABSTRACT FROM AUTHOR]

Two 2D π-extended hexaazatriphenylene (HAT) derivatives with different alkyl chain peripheries are synthesized and electrochemically characterized showing their good electron acceptor ability. We highlight the influence of the peripheral alkyl chains in the liquid crystal properties of both HAT derivatives. [ABSTRACT FROM AUTHOR]

A new family of naphthalimide-fused thienopyrazine derivatives for ambipolar charge transport in organic field-effect transistors is presented. Their electronic and molecular structures were elucidated through optical and vibrational spectroscopy aided by DFT calculations. The results indicate that these compounds have completely planar molecular skeletons which promote good film crystallinity and low reorganization energies for both electron and hole transport. Their performance in organic field-effect transistors is compared with twisted and planar naphthaleneamidine monoimide-fused terthiophenes in order to understand the origin of ambipolarity in this new series of molecular semiconductors. [ABSTRACT FROM AUTHOR]

Abstract: The possibility to functionalize polymers after a successful polymerization process is often an important challenge in macromolecular science. Herein, modified electrodes based on azide-containing potentiodynamically electropolymerized PEDOT derivatives are reported. This reactive coatings are subsequently modified under mild heterogeneous conditions by copper-catalyzed Huisgen 1,3-dipolar cycloaddition with terminal alkynes, the so-called ‘click’-reaction. A series of terminal alkynes have been successfully used for the facile immobilization of neutral, electron-accepting and electron-donating units to the conducting PEDOT with high conversion efficiencies showing the broad scope of the strategy. The route is devoid of the limitations generated by the various steric and electronic impacts of the substituents when attached to the monomer before polymerization. [ABSTRACT FROM AUTHOR]

Abstract: New luminescent polymers containing two individual emission species-poly(fluorene-alt-phenylene) as a blue host and variable amounts of 1,8-naphthalimide as red dopant have been designed and synthesized. Optical studies (optical absorption (OA) and steady-state photoluminescence emission (PL)) in diluted solutions and thin solid films reveal that the emission spectrum can be tuned by varying the content of 1,8-naphthalimide moieties. Although no significant interaction can be observed between both moieties in the ground state, after photoexcitation an efficient energy transfer takes place from the PFP backbone to the red chromophore, indeed, by adjusting the polymer/naphthalimide ratio it is possible to obtain single polymers which emit white light to the human eye in solid state. Energy transfer is more effective in the co-polymers than in physical mixtures of the two chromophores. We prepared single-layer electroluminescent simple devices with structure: ITO/poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT:PSS)/active layer/Ba/Al. With this single layer–single component device structure, white light with Commission Internationale de l’Eclairage (CIE) color coordinates (0.3, 0.42) is obtained for the electroluminescence (EL) emission with an efficiency of 22.62Cd/A. [Copyright &y& Elsevier]

Abstract: In this Letter we report the synthesis, characterization, and electrochemical investigation of a 3,4-ethylenedioxythiophene (EDOT) derivative covalently linked to the nucleobase uracil. The successful electrochemical polymerization of this derivative has provided modified electrodes with a novel functional poly(3,4-ethylenedioxythiophene) derivative. Recognition experiments in aqueous media have shown the specific recognition of the complementary base adenine. The electrochemical detection of the selective binding of nucleobases to this PEDOT derivative in aqueous media can be of particular interest for electrochemical sensor applications in physiological media. [Copyright &y& Elsevier]

New chiral, soluble binaphthyl derivatives that incorporate stilbenoid dendrons at the 6,6'-positions have been prepared. The synthesis of the new enantiopure dendrimers was performed in a convergent manner by Horner-Wadsworth-Emmons (HWE) reaction of the appropriately functionalized 1,1'-binaphthyl derivative (R)-1 and the appropriate dendrons (R)[sub 2n]G[sub n]-CHO. Different electroactive units were incorporated in the peripheral positions of the dendrons in order to tune both the optical and electrochemical behavior of these systems. Fluorescence measurements on the chiral dendrimers reveal a strong emission with maxima between 409 and 508 nm depending upon the substitution pattern. Finally, the redox properties of the dendrimers were determined by cyclic voltammetry, showing the influence of the functional groups at the peripheral positions of the dendrimer on the redox behavior of these systems. [ABSTRACT FROM AUTHOR]

Several generations of phenylenevinylene dendrons, covalently attached to a C[sub 60] core, have been developed as synthetic model systems with hierarchical, fine-tuned amhitectures. End-capping of these dendritic spacers with dibutylaniline or dodecyloxynaphthalene, as antennas/electron donors, yielded new donor-bridge-acceptor ensembles in which one, two, or four donors are allocated at the peripheral positions of the well-defined dendrons, while the electron accepting fullerene is placed at the focal point of the dendren. On the basis of our cyclic voltammetry experiments, which disclose a single anodic oxidation and several cathodic reduction processes, we rule out significant, long-range couplings between the fullerene core and the end-standing donors in their ground-state configuration. Photophysical investigations, on the other hand, show that upon photoexcitation an efficient and rapid transfer of singlet excited-state energy (6 × 10[sup 10] to 2.5 × 10[sup 12] s[sup -1]) controls the reactivity of the initially excited antenna portion. Spectroscopic and kinetic evidence suggests that yet a second contribution, that is, an intramolecular electron-transfer, exists, affording C[sub 60]·-dendron·+ with quantum yields (φ) as high as 0.76 and lifetimes (τ) that are on the order of hundreds of nanoseconds (220-725 ns). Variation of the energy gap modulates the interplay of these two pathways (i.e., competition or sequence between energy and electron transfer). [ABSTRACT FROM AUTHOR]

Examines the synthesis of conjugated oligomer ensembles. Modulation of competition between photoinduced energy and electron transfer; Details on the systematic change in the nature of oligometric component; Absorption of the chromophore by shifting the ground-state absorption from the ultraviolet.

Friedreich ataxia (FRDA) is a progressive neurodegenerative disease caused by a severe autosomal recessive genetic disorder of the central nervous (CNS) and peripheral nervous system (PNS), affecting children and young adults. Its onset is before 25 years of age, with mean ages of onset and death between 11 and 38 years, respectively. The incidence is 1 in 30,000–50,000 persons. It is caused, in 97% of cases, by a homozygous guanine-adenine-adenine (GAA) trinucleotide mutation in the first intron of the frataxin (FXN) gene on chromosome 9 (9q13–q1.1). The mutation of this gene causes a deficiency of frataxin, which induces an altered inflow of iron into the mitochondria, increasing the nervous system's vulnerability to oxidative stress. The main clinical signs include spinocerebellar ataxia with sensory loss and disappearance of deep tendon reflexes, cerebellar dysarthria, cardiomyopathy, and scoliosis. Diabetes, hearing loss, and pes cavus may also occur, and although most patients with FRDA do not present with symptomatic visual impairment, 73% present with clinical neuro-ophthalmological alterations such as optic atrophy and altered eye movement, among others. This review provides a brief overview of the main aspects of FRDA and then focuses on the ocular involvement of this pathology and the possible use of retinal biomarkers. [ABSTRACT FROM AUTHOR]

The neurodegenerative disease amyotrophic lateral sclerosis (ALS) affects the spinal cord, brain stem, and cerebral cortex. In this pathology, both neurons and glial cells are affected. However, few studies have analyzed retinal microglia in ALS models. In this study, we quantified the signs of microglial activation and the number of retinal ganglion cells (RGCs) in an SOD1G93A transgenic mouse model at 120 days (advanced stage of the disease) in retinal whole-mounts. For SOD1G93A animals (compared to the wild-type), we found, in microglial cells, (i) a significant increase in the area occupied by each microglial cell in the total area of the retina; (ii) a significant increase in the arbor area in the outer plexiform layer (OPL) inferior sector; (iii) the presence of cells with retracted processes; (iv) areas of cell groupings in some sectors; (v) no significant increase in the number of microglial cells; (vi) the expression of IFN-γ and IL-1β; and (vii) the non-expression of IL-10 and arginase-I. For the RGCs, we found a decrease in their number. In conclusion, in the SOD1G93A model (at 120 days), retinal microglial activation occurred, taking a pro-inflammatory phenotype M1, which affected the OPL and inner retinal layers and could be related to RGC loss. [ABSTRACT FROM AUTHOR]

In this communication, a novel two-dimensional polymer network (DAPT-TFP) has been synthesized based on pyrenetetraone moieties connected through robust enamine functional groups. Results show that DAPT-TFP exhibit high thermal and chemical stability, even after subjecting the material to a basic or acidic media for certain time (1 M H 2 SO 4 or 1 M NaOH, respectively). An application to conductive additive-free electrode is detailed, as a proof of the ideal interaction between the ions of the neutral aqueous electrolyte and the molecular polymer nanostructure activated by simple acidic treatment. Thus, the study indicates that the redox properties of new organic electrode materials exhibiting limited electroactive properties can be boosted by a straightforward acidic treatment. Image 1 • A novel 2D polymer network was synthesized based on pyrenetetraone moieties linked by enamine groups. • The polymer shows reversible redox activity in neutral aqueous media after acidic activation without any conductive additives. • This strategy envies novel possibilities of developing materials by applying low-cost methods. [ABSTRACT FROM AUTHOR]

A novel naphthalimide derivative endowed with a diketone functionality has been synthesized and used to develop a family of highly symmetric, flat, n-type semiconducting naphthalimide-based pyrazinacenes. By changing the symmetry of these compounds and the number of naphthalimide constituents, fine tuning of their electrochemical, photophysical, and morphological properties is achieved. [ABSTRACT FROM AUTHOR]

A 2D Covalent Organic Framework (named [HC≡C] 0.5 -TPB-DMTP-COF) was synthesized and post synthetically functionalized with dopamine via Copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction (COF DOPA) to obtain 2D nanoparticles with antioxidant activity. COF DOPA nanoparticles were exfoliated into nanosheets (COF DOPA -e) and incorporated into plasticized poly(lactic acid) (PLA) matrix with 15 wt% of acetyl trybutyl citrate (ATBC) to develop non-migratory sustainable packaging. The effect of COF DOPA and exfoliated COF DOPA -e (in 0.5, 1 and 3 wt%) on the structural, thermal and mechanical properties of PLA-ATBC was studied. The bionanocomposites loaded with low amounts of COF DOPA -e (0.5 wt% and 1 wt%) resulted optically transparent and showed good interfacial adhesion, increased crystallinity, thermal and mechanical performance. Moreover, the overall migration level assayed in a fatty food simulant was below the migration limits required for food packaging materials and showed effective antioxidant activity. Thus, these bionanocomposites show great potential as non-migration antioxidant materials with interest in the sustainable food packaging field. Image 1 • An imine-based covalent organic framework was synthesized and functionalized with dopamine as antioxidant agent (COF DOPA) via click chemistry. • Antioxidant COF DOPA was exfoliated into COF DOPA -e nanosheets and incorporated into plasticized PLA to obtain non-migrating bionanocomposites. • Low amounts of exfoliated COF DOPA -e (0.5 wt% and 1 wt%) improved the mechanical and thermal performance of plasticized PLA. • Bionanocomposites loaded with low amounts of COF DOPA -e (0.5 wt% and 1 wt%) showed their effectiveness as non-migrating antioxidant materials. [ABSTRACT FROM AUTHOR]

Background: This study compared functional and structural visual changes in Friedreich ataxia (FRDA) patients with healthy controls (HC) and correlated these changes with neurological disability. Methods: Eight FRDA Spanish patients and eight HC were selected from 2014 to 2018. Best corrected visual acuity (BCVA), visual field (VF), optic coherence tomography (OCT), and neurological disability measured by "scale for the assessment and rating of ataxia" (SARA) were taken in a basal exploration and repeated after 6 months. A linear mixed analysis and Bonferroni p-value correction were performed. Results: FRDA baseline and follow-up patients showed statistically significant decreases in BCVA, VF, and OCT parameters compared with the HC. Some of the VF measurements and most of the OCT parameters had an inverse mild-to-strong correlation with SARA. Moreover, the analysis of the ROC curve demonstrated that the peripapillary retinal nerve fiber layer (pRNFL) average thickness was the best parameter to discriminate between FRDA patients and HC. Conclusions: The follow-up study showed a progression in OCT parameters. Findings showed a sequential effect in pRNFL, ganglion cell complex (GCC), and macula. The VF and the OCT could be useful biomarkers in FRDA, both for their correlation with neurological disease as well as for their ability to evaluate disease progression. [ABSTRACT FROM AUTHOR]