A Sterically Congested Nitrogenated Benzodipentaphene with a Double π-Expanded Helicene Structure

Herein, we describe a series of three sterically congested nitrogenated benzodipentaphenes, one of which shows a highly distorted aromatic backbone with an unprecedented double π-expanded helicene structure.A.M.-A. acknowledge support of the Basque Science Foundation for Science (Ikerbasque), POLYMAT, the University of the Basque Country (Grupo de Investigación No. GIU17/054), Gobierno Vasco (No. PIBA 2019-09 and BERC program), and Gobierno de España (Ministerio de Economı́a y Competitividad No. CTQ2016-77970-R) and thank for technical and human support provided by SGIker of UPV/EHU and European funding (ERDF and ESF). F.C. and A.M.-A acknowledge that this project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme, under the Marie Skłodowska-Curie Grant Agreement No. 839626. A.M.-A. acknowledge that this project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme (Grant Agreement No. 722951). A.S. acknowledges the support of Japan Society for the Promotion of Science (JSPS) with the KAKENHI Grant-in-Aid for Scientific Research (A) (Grant No. JP16H02285). M.M.-F. acknowledges support from the Portuguese Foundation for Science and Technology (FCT), under the project IF/00894/2015, and the project CICECO-Aveiro Institute of Materials, FCT ref. UID/CTM/50011/2019, UIDB/50011/2020, and UIDP/50011/2020, financed by national funds through the FCT/MEC and, when appropriate, cofinanced by FEDER, under the PT2020 Partnership Agreement

Monodisperse N‐Doped Graphene Nanoribbons Reaching 7.7 Nanometers in Length

The properties of graphene nanoribbons are highly dependent on structural variables such as width, length, edge structure, and heteroatom doping. Therefore, atomic precision over all these variables is necessary for establishing their fundamental properties and exploring their potential applications. An iterative approach is presented that assembles a small and carefully designed molecular building block into monodisperse N-doped graphene nanoribbons with different lengths. To showcase this approach, the synthesis and characterisation of a series of nanoribbons constituted of 10, 20 and 30 conjugated linearly-fused rings (2.9, 5.3, and 7.7 nm in length, respectively) is presented.We are grateful to the Basque Science Foundation for Science (Ikerbasque), POLYMAT, the University of the Basque Country (SGIker), the Deutsche Forschungsgemeinschaft (MA 5215/4-1), Gobierno de Espana (Ministerio de Economia y Competitividad CTQ2016-77970-R and CTQ2015-71936-REDT), Gobierno Vasco (BERC program and PC2015-1-01(0637)), Diputacion Foral de Guipuzcoa (OF215/2016(ES)), CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT ref. UID/CTM/50011/2013), ON2 (NORTE-07-0162-FEDER-000086), and the FP7 framework program of the European Union (ERA Chemistry, Marie Curie Career Integration Grant No. 618247 (NIRVANA)). This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 664878. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 722951)

Halogen‐Free πupiupi‐Conjugated Polymers Based on Thienobenzobisthiazole for Efficient Nonfullerene Organic Solar Cells: Rational Design for Achieving High Backbone Order and High Solubility

In π-conjugated polymers, a highly ordered backbone structure and solubility are always in a trade-off relationship that must be overcome to realize highly efficient and solution-processable organic photovoltaics (OPVs). Here, it is shown that a π-conjugated polymer based on a novel thiazole-fused ring, thieno[2′, 3′:5, 6]benzo[1, 2-d:4, 3-d′]bisthiazole (TBTz) achieves both high backbone order and high solubility due to the structural feature of TBTz such as the noncovalent interlocking of the thiazole moiety, the rigid and bent-shaped structure, and the fused alkylthiophene ring. Furthermore, based on the electron-deficient nature of these thiazole-fused rings, the polymer exhibits deep HOMO energy levels, which lead to high open-circuit voltages (VOCs) in OPV cells, even without halogen substituents that are commonly introduced into high-performance polymers. As a result, when the polymer is combined with a typical nonfullerene acceptor Y6, power conversion efficiencies of reaching 16% and VOCs of more than 0.84 V are observed, both of which are among the top values reported so far for “halogen-free” polymers. This study will serve as an important reference for designing π-conjugated polymers to achieve highly efficient and solution-processable OPVs

USP8 prevents aberrant NF-κB and Nrf2 activation by counteracting ubiquitin signals from endosomes

K63-linked ubiquitin chains attached to plasma membrane proteins serve as tags for endocytosis and endosome-to-lysosome sorting. USP8 is an essential deubiquitinase for the maintenance of endosomal functions. Prolonged depletion of USP8 leads to cell death, but the major effects on cellular signaling pathways are poorly understood. Here, we show that USP8 depletion causes aberrant accumulation of K63-linked ubiquitin chains on endosomes and induces immune and stress responses. Upon USP8 depletion, two different decoders for K63-linked ubiquitin chains, TAB2/3 and p62, were recruited to endosomes and activated the TAK1-NF-κB and Keap1-Nrf2 pathways, respectively. Oxidative stress, an environmental stimulus that potentially suppresses USP8 activity, induced accumulation of K63-linked ubiquitin chains on endosomes, recruitment of TAB2, and expression of the inflammatory cytokine. The results demonstrate that USP8 is a gatekeeper of misdirected ubiquitin signals and inhibits immune and stress response pathways by removing K63-linked ubiquitin chains from endosomes.</p

Manipulation of charge carrier flow in Bi₄NbO₈Cl nanoplate photocatalyst with metal loading

Separation of photoexcited charge carriers in semiconductors is important for efficient solar energy conversion and yet the control strategies and underlying mechanisms are not fully established. Although layered compounds have been widely studied as photocatalysts, spatial separation between oxidation and reduction reaction sites is a challenging issue due to the parallel flow of photoexcited carriers along the layers. Here we demonstrate orthogonal carrier flow in layered Bi₄NbO₈Cl by depositing a Rh cocatalyst at the edges of nanoplates, resulting in spatial charge separation and significant enhancement of the photocatalytic activity. Combined experimental and theoretical studies revealed that lighter photogenerated electrons, due to a greater in-plane dispersion of the conduction band (vs. valence band), can travel along the plane and are readily trapped by the cocatalyst, whereas the remaining holes hop perpendicular to the plane because of the anisotropic crystal geometry. Our results propose manipulating carrier flow via cocatalyst deposition to achieve desirable carrier dynamics for photocatalytic reactions in layered compounds

A Wavy Two-Dimensional Covalent Organic Framework from Core-Twisted Polycyclic Aromatic Hydrocarbons

A high degree of crystallinity is an essential aspect in two-dimensional covalent organic frameworks, as many properties depend strongly on the structural arrangement of the different layers and their constituents. We introduce herein a new design strategy based on core-twisted polycyclic aromatic hydrocarbon as rigid nodes that give rise to a two-dimensional covalent organic framework with a wavy honeycomb (chairlike) lattice. The concave–convex self-complementarity of the wavy two-dimensional lattice guides the stacking of framework layers into a highly stable and ordered covalent organic framework that allows a full 3D analysis by transmission electron microscopy revealing its chairlike honeycomb facets and aligned mesoporous channels. Remarkably, the waviness of the framework does not disrupt the interlayer π–π stacking that shows charge transporting properties similar to those of planar covalent organic frameworks. The implementation of core-twisted aromatics as building blocks for covalent organic frameworks brings new possibilities in the design of highly ordered organic materials

Soft chromophore featured liquid porphyrins and their utilization toward liquid electret applications

Optoelectronically active viscous liquids are ideal for fabricating foldable/stretchable electronics owing to their excellent deformability and predictable π-unit-based optoelectronic functions, which are independent of the device shape and geometry. Here we show, unprecedented 'liquid electret' devices that exhibit mechanoelectrical and electroacoustic functions, as well as stretchability, have been prepared using solvent-free liquid porphyrins. The fluidic nature of the free-base alkylated-tetraphenylporphyrins was controlled by attaching flexible and bulky branched alkyl chains at different positions. Furthermore, a subtle porphyrin ring distortion that originated from the bulkiness of alkyl chains was observed. Its consequences on the electronic perturbation of the porphyrin-unit were precisely elucidated by spectroscopic techniques and theoretical modelling. This molecular design allows shielding of the porphyrin unit by insulating alkyl chains, which facilitates its corona-charged state for a long period under ambient conditions

Two distinct modes of DNMT1 recruitment ensure stable maintenance DNA methylation

Stable inheritance of DNA methylation is critical for maintaining differentiated phenotypes in multicellular organisms. We have recently identified dual mono-ubiquitylation of histone H3 (H3Ub2) by UHRF1 as an essential mechanism to recruit DNMT1 to chromatin. Here, we show that PCNA-associated factor 15 (PAF15) undergoes UHRF1-dependent dual mono-ubiquitylation (PAF15Ub2) on chromatin in a DNA replication-coupled manner. This event will, in turn, recruit DNMT1. During early S-phase, UHRF1 preferentially ubiquitylates PAF15, whereas H3Ub2 predominates during late S-phase. H3Ub2 is enhanced under PAF15 compromised conditions, suggesting that H3Ub2 serves as a backup for PAF15Ub2. In mouse ES cells, loss of PAF15Ub2 results in DNA hypomethylation at early replicating domains. Together, our results suggest that there are two distinct mechanisms underlying replication timing-dependent recruitment of DNMT1 through PAF15Ub2 and H3Ub2, both of which are prerequisite for high fidelity DNA methylation inheritance

Understanding charge transport in wavy 2D covalent organic frameworks

Understanding charge transport in 2D covalent organic frameworks is crucial to increase their performance. Herein a new wavy 2D covalent organic framework has been designed, synthesized and studied to shine light on the structural factors that dominate charge transport