scholarly journals Accelerating charge transfer via nonconjugated polyelectrolyte interlayers toward efficient versatile photoredox catalysis

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Tao Li ◽  
Chuang Feng ◽  
Boon Kar Yap ◽  
Xuhui Zhu ◽  
Biquan Xiong ◽  
...  

AbstractOne of the challenges for high-efficiency single-component-based photoredox catalysts is the low charge transfer and extraction due to the high recombination rate. Here, we demonstrate a strategy to precisely control the charge separation and transport efficiency of the catalytic host by introducing electron or hole extraction interlayers to improve the catalytic efficiency. We use simple and easily available non-conjugated polyelectrolytes (NCPs) (i.e., polyethyleneimine, PEI; poly(allylamine hydrochloride), PAH) to form interlayers, wherein such NCPs consist of the nonconjugated backbone with charge transporting functional groups. Taking CdS as examples, it is shown that although PEI and PAH are insulators and therefore do not have the ability to conduct electricity, they can form good electron or hole transport extraction layers due to the higher charge-transfer kinetics of pendant groups along the backbones, thereby greatly improving the charge transfer capability of CdS. Consequently, the resultant PEI-/PAH-functionalized nanocomposites exhibit significantly enhanced and versatile photoredox catalysis.

1996 ◽  
Vol 444 ◽  
Author(s):  
H. Okumoto ◽  
M. Shimomura ◽  
N. Minami ◽  
Y. Tanabe

AbstractSilicon-based polymers with σconjugated electrons have specific properties; photoreactivity for microlithography and photoconductivity for hole transport materials. To explore the possibility of combining these two properties to develop photoresists with electronic transport capability, photoconductivity of polysilanes is investigated in connection with their photoinduced chemical modification. Increase in photocurrent is observed accompanying photoreaction of poly(dimethylsilane) vacuum deposited films. This increase is found to be greatly enhanced in oxygen atmosphere. Such changes of photocurrent can be explained by charge transfer to electron acceptors from Si dangling bonds postulated to be formed during photoreaction.


2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Deepti Sharma ◽  
Louis De Falco ◽  
Sivaraman Padavattan ◽  
Chang Rao ◽  
Susana Geifman-Shochat ◽  
...  

AbstractThe poly(ADP-ribose) polymerase, PARP1, plays a key role in maintaining genomic integrity by detecting DNA damage and mediating repair. γH2A.X is the primary histone marker for DNA double-strand breaks and PARP1 localizes to H2A.X-enriched chromatin damage sites, but the basis for this association is not clear. We characterize the kinetics of PARP1 binding to a variety of nucleosomes harbouring DNA double-strand breaks, which reveal that PARP1 associates faster with (γ)H2A.X- versus H2A-nucleosomes, resulting in a higher affinity for the former, which is maximal for γH2A.X-nucleosome that is also the activator eliciting the greatest poly-ADP-ribosylation catalytic efficiency. The enhanced activities with γH2A.X-nucleosome coincide with increased accessibility of the DNA termini resulting from the H2A.X-Ser139 phosphorylation. Indeed, H2A- and (γ)H2A.X-nucleosomes have distinct stability characteristics, which are rationalized by mutational analysis and (γ)H2A.X-nucleosome core crystal structures. This suggests that the γH2A.X epigenetic marker directly facilitates DNA repair by stabilizing PARP1 association and promoting catalysis.


2021 ◽  
Vol 12 (11) ◽  
pp. 1692-1699
Author(s):  
Ji Hye Lee ◽  
Jinhyo Hwang ◽  
Chai Won Kim ◽  
Amit Kumar Harit ◽  
Han Young Woo ◽  
...  

New polystyrene-based polymers with high π-extended hole transport pendants were synthesized to obtain a low turn-on voltage and high efficiency in solution-processed green TADF-OLEDs.


2020 ◽  
pp. 104607
Author(s):  
Zeng-Jie Yang ◽  
Qing-Tian Gong ◽  
Yuan Yu ◽  
Wei-Fan Lu ◽  
Zhe-Ning Wu ◽  
...  

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Buzuayehu Abebe ◽  
H. C. Ananda Murthy ◽  
Enyew Amare Zereffa

AbstractZinc oxide (ZnO) is a fascinating semiconductor material with many applications such as adsorption, photocatalysis, sensor, and antibacterial activities. By using a poly (vinyl alcohol) (PVA) polymer as a capping agent and metal oxides (iron and manganese) as a couple, the porous PVA-aided Zn/Fe/Mn ternary oxide nanocomposite material (PTMO-NCM) was synthesized. The thermal, optical, crystallinity, chemical bonding, porosity, morphological, charge transfer properties of the synthesized materials were confirmed by DTG/DSC, UV–Vis-DRS, XRD, FT-IR, BET, SEM-EDAX/TEM-HRTEM-SAED, and CV/EIS/amperometric analytical techniques, respectively. The PTMO-NCM showed an enhanced surface area and charge transfer capability, compared to ZnO. Using the XRD pattern and TEM image analysis, the crystalline size of the materials was confirmed to be in the nanometer range. The porosity and superior charge transfer capabilities of the PTMO-NCM were confirmed from the BET, HRTEM (IFFT)/SAED, and CV/EIS analysis. The adsorption kinetics (adsorption reaction/adsorption diffusion) and adsorption isotherm test confirmed the presence of a chemisorption type of adsorbate/methylene blue dye-adsorbent/PTMO-NCM interaction. The photocatalytic performance was tested on the Congo red and Acid Orange-8 dyes. The superior ascorbic acid sensing capability of the material was understood from CV and amperometric analysis. The noble antibacterial activities of the material were also confirmed on both gram-negative and gram-positive bacteria.


RSC Advances ◽  
2019 ◽  
Vol 9 (69) ◽  
pp. 40292-40300
Author(s):  
Anantharaj Gopalraman ◽  
Subbian Karuppuchamy ◽  
Saranyan Vijayaraghavan

VOC–JSC trade off is eliminated. Newly created surface states by OA in TiO2 facilitated the charge transfer kinetics.


2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Kunhua Song ◽  
Yuanbiao Zhao ◽  
Pilar Londono ◽  
Emily Sharpe ◽  
Joshua R Clair ◽  
...  

The mammalian heart is composed of ~30% cardiomyocytes which have limited capacity to regenerate and ~70% non-cardiomyocytes including endothelial cells and cardiac fibroblasts. Direct reprogramming of fibroblasts into cardiomyocytes by forced expression of cardiomyogenic transcription factors, GMT (GATA4, Mef2C, Tbx5) or GHMT (GATA4, Hand2, Mef2C, Tbx5), has recently been demonstrated, suggesting a novel therapeutic strategy for cardiac repair. Despite extensive efforts, the efficiency of direct reprogramming of embryonic or adult fibroblasts into cardiomyocytes has yet to exceed 20%, or 0.1% respectively, leading many in the field to question the clinical translatability of this method. Here, we demonstrate that pro-fibrotic signaling events governed by transforming growth factor-β (TGF-β) and Rho kinase (ROCK) are concomitantly activated in GHMT-expressing fibroblasts, leading to potent suppression of cardiac reprogramming ( Figure 1 ). Remarkably, pharmacological inhibition of TGF-β, or ROCK leads to conversion of ≥ 60% of fibroblasts into highly functional cardiomyocytes, displaying global cardiac gene expression, spontaneous contractility, action potentials and calcium transients. Furthermore, inhibition of TGF-β, or ROCK dramatically enhances the kinetics of cardiac reprogramming, with spontaneously contracting cardiomyocytes emerging in less than two weeks, as opposed to 4 weeks with GHMT alone. These findings provide new insights into the molecular mechanisms underlying cardiac conversion of fibroblasts, and should enhance efforts to generate cardiomyocytes for clinical applications.


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