Recent advances on carbazole-based photoinitiators of polymerization

International audiencePhotoinitiators of polymerization that can be activated under visible light and low intensity are actively researched as these compounds constitute the next generation of photoinitiators that will replace the controverted UV-photoinitiators. Over the years, a family of compounds has been identified as being highly promising in light of its remarkable photoinitiating ability, photochemical stability, low cost and easiness to functionalize, namely carbazoles. In this review, an overview of the different carbazole-based photoinitiators reported to date is presented. Interestingly, carbazoles have mostly been used as electron donors in push-pull structures, as photosen-sitizers for iodonium salts, as ligands for ferrocenium salts or as chromophores for phenacyl onium salts. These different applications clearly demonstrate the versatility of this structure used as the elemental building block for the design of UV, near-UV or visible light photoinitiators

Recent advances in organic light-emitting devices comprising copper complexes: a realistic approach for low-cost and highly emissive devices

International audienceThe past decades have driven a great deal of interest for developing low-cost electroluminescent devices. In this aim, highly emissive phosphors based on Earth-abundant metals and presenting the advantage of environment-benignancy are actively researched. Based on these requirements, copper(I) complexes have been identified as favorable candidates that could advantageously replace the well-established iridium(III) complexe

Carbazole-based polymers as hosts for solution-processed organic light-emitting diodes: simplicity, efficacy

International audiencePolymer light emitting diodes (PLEDs) have attracted a great deal of interest within academia and industry because of their potential applications in flat panel displays and solid-state lighting technologies. The solution processability of polymers offers the advantages of simple and mild fabrication conditions enabling to cut cost and produce large area displays. Among all polymeric hosts under investigation, carbazole-based materials benefit from the wide bandgap of carbazole as well as its remarkable thermal, photochemical and chemical stability. Especially, the relatively high triplet energy level of carbazole makes it an appealing candidate to design hosts for wide bandgap triplet emitters such as blue dopants. In this review, an overview of all carbazole-based polymeric hosts reported to date is presented. Noticeably, easiness of synthesis has been an aspect largely developed to access to these polymeric structure

Recent advances on pyrene-based photoinitiators of polymerization

International audiencePhotoinitiators of polymerization activable under low light intensity and in the visible range are actively researched by both the academic and industrial communities. To efficiently harvest light and initiate a polymerization process, polyaromatic structures are ideal candidates. In this field, pyrene can be cited as a relevant example. Over the years, a wide range of Type I and Type II photoinitiators have been developed, ranging from push-pull dyes to polyaromatic structures, ferrocenium, ketones, chromones or acridinediones. In this review, an overview of the different pyrene-based photoinitiators reported to date is presented. Especially, a structure-performance relationship will be established with benchmark photoinitiators, evidencing all the interests of this polyaromatic structure

Recent Advances on Visible Light Metal-Based Photocatalysts for Polymerization under Low Light Intensity

WOS:000489178000038International audienceIn recent years, polymerization processes activated by light have attracted a great deal of interest due to the wide range of applications in which this polymerization technique is involved. Parallel to the traditional industrial applications ranging from inks, adhesives, and coatings, the development of high-tech applications such as nanotechnology and 3D-printing have given a revival of interest to this polymerization technique known for decades. To initiate a photochemical polymerization, the key element is the molecule capable to interact with light, i.e., the photoinitiator and more generally the photoinitiating system, as a combination of several components is often required to create the reactive species responsible for the polymerization process. With the aim of reducing the photoinitiator content while optimizing the polymerization yield and/or the polymerization speed, photocatalytic systems have been developed, enabling the photosensitizer to be regenerated during the polymerization process. In this review, an overview of the photocatalytic systems developed for polymerizations carried out under a low light intensity and visible light is provided. Over the years, a wide range of organometallic photocatalysts has been proposed, addressing both the polymerization efficiency and/or the toxicity, as well as environmental issues

Récent avancées sur les push-pull organiques et les molécules fluorophores contenant un 1,2,3-triazole

International audienceSince the discovery of the copper catalyzed azide alkyne cycloaddition in the early 2000s, tremendous efforts have been devoted to enlarging the scope of applications of this relatively simple to handle reaction. The chemistry of dyes has not been excluded from this enthusiasm so that a wide range of compounds have been synthesized over the years. Several key elements have sustained such research activity, such as the possibility to fine tune the photophysical properties, the easiness of structure screening in order to optimize the optical properties or the thermal stability of the triazole moiety. In this review, an overview of different dyes as well as their applications is reported.Desde el descubrimiento de cicloadición de azidas y alquinos de Huisgen en el principio de los años 2000, freneticos effuerzos fueron hechos para agrandir los dominios de applicacion de esta reaccion. La quimica de los colorantes no ha sido excluido de esta frenesia, porque una grande variedad de compuestos fueron sintetisados durante los ultimos años. Muchas razones han motivado estas investigaciones, como la possibilidad de modificar la propriedades fotophysica, la realisacion simple de catalogo de compuestos por cribado por optimisar la propriedades opticas o la estabilidad termica de los triazole. En esta revista, un vista general de los differentes colorantes, como sus applicaciones son reportadosDepuis la découverte de la cyclocaddition d'un azoture et d'un alcyne catalysée au cuivre au début des années 2000, des efforts frénétiques ont été fait afin d'élargir les domaines d'applications de cette réaction. La chimie des colorants n'a pas été exclue de cette frénésie, puisque une grande variété de composées ont été synthétisées au fil des années. De nombreux raisons ont motivé de telles recherches, comme la possibilité de finement modifié les propriétés photophysiques, la réalisation simple de librairies de composés dans le but d'optimiser les propriétés optiques ou la stabilité thermique des motif triazole. Dans cette revue, un aperçu des différents colorants, tout comme leur applications sont reportés

Molecular engineering in 2D surface covalent organic frameworks: Towards next generation of molecular tectons - A mini review

International audienceMolecular engineering on surface has been revolutionized by the possibility to create covalent connections between molecular tectons. Following the pioneering works on supramolecular structures and their triumphal developments during a decade, covalent organic frameworks on surface open up new routes towards robust and regular porous macromolecular structures usable in practical applications such as molecular electronics, energy conversion or catalysis. Metal surfaces can be also be decorated with semiconducting organic structures, widening the scope of applicability of these polymer-modified surfaces. If the first generation of molecular building blocks was designed so that the functional groups were introduced for a specific reactivity, recently, a breakthrough has been achieved in 2016 and 2017 with the almost simultaneous reports of ENA and INDO4 capable to initiate different reaction pathways depending of the surface topography or the surface coverage. Prior to these two works, in 2015, another exciting candidate (i.e. TAPB) exhibiting however a more limited range of reactivity than ENA or INDO4 was reported, its reactivity being based on the presence of acetyl end-groups. In this minire-view, the intriguing properties of these unique building blocks are presented

Recent Advances on Copper Complexes as Visible Light Photoinitiators and (Photo) Redox Initiators of Polymerization

International audienceMetal complexes are used in numerous chemical and photochemical processes in organic chemistry. Metal complexes have not been excluded from the interest of polymerists to convert liquid resins into solid materials. If iridium complexes have demonstrated their remarkable photochemical reactivity in polymerization, their high costs and their attested toxicities have rapidly discarded these complexes for further developments. Conversely, copper complexes are a blooming field of research in (photo) polymerization due to their low cost, easy syntheses, long-living excited state lifetimes, and their remarkable chemical and photochemical stabilities. Copper complexes can also be synthesized in solution and by mechanochemistry, paving the way towards the synthesis of photoinitiators by Green synthetic approaches. In this review, an overview of the different copper complexes reported to date is presented. Copper complexes are versatile candidates for polymerization, as these complexes are now widely used not only in photopolymerization, but also in redox and photoassisted redox polymerization processes

Recent advances on naphthalic anhydrides and 1,8-naphthalimide-based photoinitiators of polymerization

International audienceThe design of photoinitiators of polymerization is an active research field and the development of initiators activable in the visible range and under low light intensity have been the focus of numerous research efforts from both the academic and industrial communities. Recently, two families of polyaromatic compounds, i.e. 1,8-naphthalic anhydride and naphthalimides, have been extensively studied by different research groups due to their easiness of synthesis and the possibility to easily tune the photophysical properties. Especially, panchromatic, crosslinkable or water-soluble photoinitiators could be easily developed starting from the benchmark and cheap 1,8-naphthalic anhydride. In this review, an overview of the different photoinitiators based on naphthalic anhydride or the naphthalimide scaffold is presented. Based on the diversity of structures reported in the literature, a structure-performance relationship could be established in this review

Recent syntheses of steroidal derivatives containing heterocycles

International audienc