Color Control in π-Conjugated Organic Polymers for Use in Electrochromic Devices

Fundamentals, processes and applications of high-permittivity polymer–matrix composites

Fluorescence imaging techniques have been widely used to visualize biological molecules and phenomena. In particular, several studies on the development of small-molecule fluorescent probes have been carried out, because their fluorescence properties can be easily tuned by synthetic chemical modification. For this reason, various fluorescent probes have been developed for targeting biological components, such as proteins, peptides, amino acids, and ions, to the interior and exterior of cells. In this review, we cover advances in the development of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-based fluorescent probes for biological studies over the past decade.

BODIPY-based probes for the fluorescence imaging of biomolecules in living cells

3.10 - Nitroxide-Mediated Polymerization

Higher efficiency in the end-use of energy requires substantial progress in lighting concepts. All the technologies under development are based on solid-state electroluminescent materials and belong to the general area of solid-state lighting (SSL). The two main technologies being developed in SSL are light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs), but in recent years, light-emitting electrochemical cells (LECs) have emerged as an alternative option. The luminescent materials in LECs are either luminescent polymers together with ionic salts or ionic species, such as ionic transition-metal complexes (iTMCs). Cyclometalated complexes of IrIII are by far the most utilized class of iTMCs in LECs. Herein, we show how these complexes can be prepared and discuss their unique electronic, photophysical, and photochemical properties. Finally, the progress in the performance of iTMCs based LECs, in terms of turn-on time, stability, efficiency, and color is presented.

Luminescent ionic transition-metal complexes for light-emitting electrochemical cells.

Electrofluorochromism deals with electrochemical monitoring of luminescence features There are several reasons to be interested in that field The first one is the design of displays working in a similar way to electrochromic devices, substituting colors due to absorption with colors due to emission, thus producing much higher brilliance This requires designing smart molecules and materials, which are likely to exhibit reversible switch of emission by controlling their redox state There are also a lot of analytical applications, especially in biochemical issues, where in situ dual detection of electrochemical and fluorescence signals can lead to very sensitive and selective biosensors To achieve this goal, instrumental developments are necessary, involving, among others, beyond diffraction limit and single molecule detection optical techniques This paper reviews the most recent developments in the above mentioned fields of fluorescence spectroelectrochemistry, coupled detection of fluorescence and electrochemical signals and design of molecules and materials exhibiting electrofluorochromic properties The first part describes the required features for molecular systems to exhibit a reversible switch in their luminescence properties according to a change in their redox state Examples among organic and organometallic dyes and redox labelled fluorophores are listed The second part focuses on the instrumental development in fluorescence spectroelectrochemistry and recent coupling of electrochemical techniques with fluorescence microscopy Finally, some applications and devices are presented in the last part of this review This should give an overview of this emerging research field at the interface between physics, chemistry and biology

Electrofluorochromism: from molecular systems to set-up and display

Synthesis and Physical Chemistry of s-Tetrazines: Which Ones are Fluorescent and Why?

New tetrazines substituted by heteroatoms have been synthesized and their electrochemical and photochemical properties investigated. All compounds are reversibly electroactive with standard potentials shifting cathodically according to the donor character of the substituent. The tetrazine derivatives are also fluorescent with maximum emission wavelengths in the range 550-575 nm. Some of them show very long fluorescence lifetimes (several tens of ns) and remain fluorescent in the solid state without major changes in the spectral features. The fluorescence of one of the derivatives can be efficiently quenched by the presence of electron-rich compounds such as triphenylamines, phenol or anisole, which make them very promising compounds for sensor applications.

Synthesis and properties of new tetrazines substituted by heteroatoms: towards the world's smallest organic fluorophores.

Broad-frequency dielectric behaviors of multiwalled carbon nanotubes (MWCNTs) embedded in room temperature vulcanization silicone rubber (RT-SR) matrix were studied by analyzing alternating current (ac) impedance spectra, which would make a remarkable contribution for understanding some fundamental electrical properties in the MWCNT/RT-SR nanocomposites. Equivalent circuits of the MWCNT/RT-SR nanocomposites were built, and the law of polarization and mechanism of electric conductance under the ac field were acquired. Two parallel RC circuits in series are the equivalent circuits of the MWCNT/RT-SR composites. At different frequency ranges, dielectric parameters including conductivity, dielectric permittivity, dielectric loss, impedance phase, and magnitude present different behaviors.

/pdf/broad-frequency-dielectric-behaviors-in-multiwalled-carbon-4ycapa4ehq.pdf

Broad-frequency dielectric behaviors in multiwalled carbon nanotube/rubber nanocomposites

Original tetrazines substituted by heterocyclic rings have been prepared. Their syntheses, as well as their electrochemical and spectroscopic features, are described. Calculations have also been made on the cation radicals, anion radicals and neutral compounds and are in correct agreement with the experimental results. All compounds are electroactive, both in oxidation and reduction, and display two absorption bands in the UV and visible regions of the spectrum. Reduction potentials and maximum wavelengths are correlated with the electron-rich character of the heterocyclic substituent on the tetrazine ring. None of these compounds gives good quality polymers upon electro-oxidation, which was unexpected, especially for the bis(2-pyrrolyl) tetrazine. This latter result can be explained by the occurrence of a self-deprotonation equilibrium in the cation radical.

Fabien Miomandre

Papers

Electrofluorochromism: from molecular systems to set-up and display

Synthesis and Physical Chemistry of s-Tetrazines: Which Ones are Fluorescent and Why?

Synthesis and properties of new tetrazines substituted by heteroatoms: towards the world's smallest organic fluorophores.

Broad-frequency dielectric behaviors in multiwalled carbon nanotube/rubber nanocomposites

Synthesis of new substituted tetrazines: electrochemical and spectroscopic properties