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Bottlebrush polymers with optoelectronic function show promise for applications in photonic crystals, nanomedicine, and encoding of information. In particular, bottlebrush polymers formed from organic semiconductors give wire-like nanoparticles where band gaps, fluorescence, and energy transfer can be tuned. To date, such bottlebrush polymers have largely been prepared by grafting-through polymerization of organic semiconductor macromonomers, where pre-synthesized side chains are polymerized along a bottlebrush backbone. While this approach provides high side-chain grafting densities, the length of bottlebrush polymers that is possible to obtain is limited by steric crowding at the propagating chain end. Here, we describe methods for preparing ultralong bottlebrush nanofibers from organic semiconductors, with backbone lengths approaching 800 repeating units and molecular weights in excess of 4 MDa. By combining reversible addition fragmentation chain transfer and Cu(0) reversible deactivation radical polymerization, a 'grafting-from' protocol is described where monomers can be grown from a pre-synthesized backbone. Bottlebrush polymers were prepared from organic semiconductors used as n-type, p-type, and host materials in multilayer organic devices. Finally, a two-component bottlebrush polymer exhibiting deep blue emission, two-photon fluorescence, and a quantum yield of unity is also prepared by this method. Key words: bottlebrush polymers, Cu(0)-RDRP, organic semiconductors, RAFT, optoelectronics Les polymères en brosse de type << écouvillons moléculaires >> dotés de propriétés optoélectroniques sont des matériaux prometteurs qui pourraient trouver des applications dans les domaines des cristaux photoniques, de la nanomédecine et du codage de données. Plus particulièrement, les écouvillons moléculaires produits à partir de semi-conducteurs organiques forment des nanoparticules filiformes dont les bandes interdites, la fluorescence et le transfert d'énergie sont réglables. Jusqu'à maintenant, de tels écouvillons moléculaires ont été en grande majorité préparés par des méthodes de polymérisation par greffage de macromonomères semi-conducteurs organiques, où les chaînes latérales sont préalablement synthétisées et polymérisées autour d'une tige centrale. Bien que cette approche offre des densités élevées de greffage des chaînes latérales, la longueur des polymères en brosse que l'on peut ainsi obtenir est limitée par l'encombrement stérique à l'extrémité de la chaîne de polymérisation. Dans le présent article, nous décrivons des méthodes, à partir de semi-conducteurs organiques, pour la synthèse de nanofibres en brosse très longues, dont la longueur du squelette approche les 800 unités répétitives et le poids moléculaire dépasse les 4 MDa. En combinant la polymérisation radicalaire contrôlée par transfert de chaîne réversible par addition-fragmentation (RAFT) et la polymérisation radicalaire par désactivation réversible (PRDR) catalysée par le Cu(0), nous avons décrit une méthode dite de << grafting from >> (greffage à partir de) dans laquelle les monomères peuvent croître à partir d'un squelette présynthétisé. Nous avons ainsi préparé des écouvillons moléculaires à partir de semi-conducteurs organiques utilisés comme matériaux de type n, de type p et de type << hôte >> dans des dispositifs organiques multicouches. Enfin, nous avons également préparé par cette méthode un écouvillon moléculaire à deux composants, présentant une émission dans le bleu profond, une fluorescence à deux photons et un rendement quantique de 1. [Traduit par la Redaction.] Mots-clés : écouvillons moléculaires, PRDR catalysée par le Cu(0), semi-conducteurs organiques, RAFT, optoélectronique, Introduction Molecular polymer brushes, also known as bottlebrush polymers, have recently emerged as a versatile polymer architecture enabling new applications of nanotechnology. (1-5) Characterized by pendant polymer chains attached to [...]

With respect, sadness, and the fondest of memories, we are pleased to introduce this special issue of the Canadian journal of Chemistry celebrating the life of Suning Wang. Suning was [...]

Despite the number of methods available for dehalogenation and carbon-carbon bond formation using aryl halides, strategies that provide chemoselectivity for systems bearing multiple carbon-halogen bonds are still needed. Herein, we report the ability to tune the reduction potential of metal-free phenothiazine-based photoredox catalysts and demonstrate the application of these catalysts for chemoselective carbon-halogen bond activation to achieve C-C cross-coupling reactions as well as reductive dehalogenations. This procedure works both for conjugated polyhalides as well as unconjugated substrates. We further illustrate the usefulness of this protocol by intramolecular cyclization of a pyrrole substrate, an advanced building block for a family of natural products known to exhibit biological activity.

Here we report the use of 10-phenylphenothiazine (PTH) as an inexpensive, highly reducing metal-free photocatalyst for the reduction of carbon-halogen bonds via the trapping of carbon-centered radical intermediates with a mild hydrogen atom donor. Dehalogenations were carried out on various substrates with excellent yields at room temperature in the presence of air.

This document provides a comprehensive discussion on the topic of organic neuromorphics and bioelectronics. It covers various aspects such as the mechanism of large-scale transistors detecting single molecules, the effects of nonspecific adsorption on the transistor, the sampling process for pancreatic cancer patients, and the use of poly-D-lysine as a surface coating. The text also explores the selection of aptamers, their selectivity when adsorbed on a surface, and the use of conjugated polymers for separating metallic and semiconducting carbon nanotubes. It delves into the relationship between ionic strength, buffer strength, and Debye length, as well as the selectivity of a sensor towards histamine. The document also discusses the mechanism for the decrease in threshold voltage, the selectivity of the sensor towards H2O2, and the choice of polymer semiconductor for the study. It addresses the stability of the functionalized gate electrode, the effects of different linker lengths, and the potential applications of the device. The influence of temperature on the oxidation process is examined, and the text also includes questions and responses related to transistor characteristics and polymer synthesis. The synthesis of certain polymers using the discussed methodology may be challenging, and the detection limits and binding kinetics in ultrasensitive detection are topics of discussion. [Extracted from the article]

Heptazine-based materials have recently emerged as a promising motif for thermally activated delayed fluorescence, as their near-zero or negative singlet–triplet energy gaps enable extremely fast reverse intersystem crossing (rISC) rates. Another method for achieving a high rate of rISC is through the use of highly symmetric emitters, which benefit from energy-level degeneracies and a high density of states. Here, we investigate the effect of combining these two design strategies on the excited-state dynamics of C3-symmetric emitters containing heptazine cores. We find that in two of the four emitters studied, the S1 state has a high degree of locally excited (LE) character with density on the heptazine moiety, preventing excited-state localization and a loss of symmetry in the energy-minimized S1 geometry. Surprisingly, these symmetric molecules still suffer from a loss of density of triplet states below the S1 state. Overall, we find that maintaining C3 symmetry will not necessarily maintain density of states, but that heptazine-based materials with LE S1 states still benefit from maximized rISC rates via increased spin–orbit coupling with low-lying charge-transfer triplet states and exhibit advantageous photophysical properties, such as near-unity photoluminescence quantum yields and high colour purity. [ABSTRACT FROM AUTHOR]

Organic small molecules with high photothermal conversion efficiencies that absorb near‐infrared light are desirable for photothermal therapy due to their improved biocompatibility compared to inorganic materials and their ability to absorb light in the biological transparency window (650–1350 nm). Here we report three donor‐acceptor organic materials DM‐ANDI, O‐ANDI, and S‐ANDI that show high photothermal conversion efficiencies of 46–68 % with near‐infrared absorption. The design of these molecules is based on the rational modification of a thermally activated delayed fluorescence material to favour a low photoluminescence quantum yield by reducing HOMO‐LUMO overlap. Encapsulating these materials into either neat nanoparticles or aggregated organic dots modulates their photothermal conversion efficiencies, and also facilitates dispersion in water. [ABSTRACT FROM AUTHOR]

Planarized donor and acceptor groups are promising building blocks for high-performance thermally activated delayed fluorescence emitters, as their rigidity minimizes non-radiative decay pathways. In this work, the planarized azatriangulene donors HMAT, OMAT, and SMAT are synthesized and incorporated into donor–acceptor (D–A) TADF materials with naphthalimide (NAI) acceptors. The relative strength of each donor is compared by photophysical and electrochemical measurements, finding that HMAT is the weakest donor of the series, while OMAT and SMAT have approximately equal strength. These emitters show green to orange emission with high photoluminescence quantum yields in toluene solution (0.75–1.0) and are TADF-active in doped films. In addition, each of the donor–acceptor dyads is found to display mechanochromic luminescence as neat powders. Analysis of X-ray diffraction data shows that the changes in optical properties upon mechanical stimulation are associated with a crystalline to amorphous transition, which may be due to disruption of weak intermolecular interactions in the crystalline powder. [ABSTRACT FROM AUTHOR]

The first synthesis of hierarchical porous metal–organic frameworks (HP‐MOFs) is reported through a solvent evaporation‐induced co‐assembly of polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) and MOF building blocks. The growth of MOFs is restricted to confined spaces formed by self‐assembled PS‐b‐PEO, and mesopores and/or macropores are created after removing PS‐b‐PEO by solvent rinsing. This approach avoids phase separation and competitive interactions between templates and MOF building blocks. Both amorphous and crystalline HP‐MOFs can be synthesized by finely controlling MOF growth conditions. Additionally, HP‐MOFs (ZIF‐L sheets) with honeycomb‐like channels show significantly enhanced incorporation of large guest molecules compared to microporous MOFs. This study establishes an efficient synthetic strategy for preparing HP‐MOFs with highly accessible mesopores and macropores for applications involving large molecules. [ABSTRACT FROM AUTHOR]

Here we describe a facile approach to preparing cationic bottlebrush brush polymers via sequential surface‐initiated (SI) ring‐opening metathesis polymerization and SI activators regenerated by electron transfer atom transfer radical polymerization. These techniques afforded both bottlebrush polymer brushes and their linear polymer brush analogues with cationic triphenylphosphonium pendant groups. Utilization of two controlled polymerization techniques with orthogonal requirements for monomers and additives allowed the polymerization of the backbone and the pendant side chains to be controlled independently. Grafting polymer side chains to a polymer brush backbone resulted in a thickness increase of ca 70%, indicating that the polymers are forced into a stretched conformation with greater surface coverage than was afforded by the linear brush polymers. As a result of the stretched conformation, greater ionic conductivity in the bottlebrush brush architectures was observed. © 2022 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]