Dual-Function, Light Switchable Cobalt Catalysis via Active Site Metamorphosis

2019 ◽  
Author(s):  
Enrico Bergamaschi ◽  
Frédéric Beltran ◽  
Christopher Teskey
Keyword(s):  
Visible Light ◽  
Active Site ◽  
Catalytic Site ◽  
Dual Function ◽  
Catalytic Systems ◽  
Hydride Complex ◽  
Dual Functional ◽  
Multiple Processes ◽  
Olefin Migration

<p></p><p></p><p>Switchable catalysis offers opportunities to control the rate or selectivity of a reaction <i>via</i> a stimulus such as pH or light. However, few examples of switchable catalytic systems that can facilitate multiple processes exist. Here we report a rare example of such dual-functional, switchable catalysis. Featuring an easily prepared, bench-stable cobalt(I) hydride complex in conjunction with pinacolborane, we can completely alter the reaction outcome between two widely employed transformations – olefin migration and hydroboration – with visible light as the sole trigger. This dichotomy arises from ligand photodissociation which leads to metamorphosis of the active catalytic site, resulting in divergent mechanistic pathways.</p><p></p><p></p>

Dual-Function, Light Switchable Cobalt Catalysis via Active Site Metamorphosis

2019 ◽  
Author(s):  
Enrico Bergamaschi ◽  
Frédéric Beltran ◽  
Christopher Teskey
Keyword(s):  
Visible Light ◽  
Active Site ◽  
Catalytic Site ◽  
Dual Function ◽  
Catalytic Systems ◽  
Hydride Complex ◽  
Dual Functional ◽  
Multiple Processes ◽  
Olefin Migration

<p></p><p></p><p>Switchable catalysis offers opportunities to control the rate or selectivity of a reaction <i>via</i> a stimulus such as pH or light. However, few examples of switchable catalytic systems that can facilitate multiple processes exist. Here we report a rare example of such dual-functional, switchable catalysis. Featuring an easily prepared, bench-stable cobalt(I) hydride complex in conjunction with pinacolborane, we can completely alter the reaction outcome between two widely employed transformations – olefin migration and hydroboration – with visible light as the sole trigger. This dichotomy arises from ligand photodissociation which leads to metamorphosis of the active catalytic site, resulting in divergent mechanistic pathways.</p><p></p><p></p>

scholarly journals Catalytic systems mimicking the [FeFe]-hydrogenase active site for visible-light-driven hydrogen production

2021 ◽  
Vol 448 ◽  
pp. 214172
Author(s):  
Juan Amaro-Gahete ◽  
Mariia V. Pavliuk ◽  
Haining Tian ◽  
Dolores Esquivel ◽  
Francisco J. Romero-Salguero ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Visible Light ◽  
Active Site ◽  
Catalytic Systems ◽  
Visible Light Driven

scholarly journals Improved Visible Light-Based Indoor Positioning System Using Machine Learning Classification and Regression

2019 ◽  
Vol 9 (6) ◽  
pp. 1048 ◽  
Author(s):  
Huy Tran ◽  
Cheolkeun Ha
Keyword(s):  
Machine Learning ◽  
Visible Light ◽  
Noise Reduction ◽  
Indoor Positioning ◽  
Computational Time ◽  
Dual Function ◽  
Positioning System ◽  
Positioning Accuracy ◽  
Positioning Systems ◽  
Machine Learning Classification

Recently, indoor positioning systems have attracted a great deal of research attention, as they have a variety of applications in the fields of science and industry. In this study, we propose an innovative and easily implemented solution for indoor positioning. The solution is based on an indoor visible light positioning system and dual-function machine learning (ML) algorithms. Our solution increases positioning accuracy under the negative effect of multipath reflections and decreases the computational time for ML algorithms. Initially, we perform a noise reduction process to eliminate low-intensity reflective signals and minimize noise. Then, we divide the floor of the room into two separate areas using the ML classification function. This significantly reduces the computational time and partially improves the positioning accuracy of our system. Finally, the regression function of those ML algorithms is applied to predict the location of the optical receiver. By using extensive computer simulations, we have demonstrated that the execution time required by certain dual-function algorithms to determine indoor positioning is decreased after area division and noise reduction have been applied. In the best case, the proposed solution took 78.26% less time and provided a 52.55% improvement in positioning accuracy.

Cascade GaN-based blue micro-light-emitting diodes for dual function of illumination and visible light communication

2020 ◽  
Vol 53 (35) ◽  
pp. 355103 ◽  
Author(s):  
Huamao Huang ◽  
Haocheng Wu ◽  
Cheng Huang ◽  
Tianxiang Lan ◽  
Qingyuan Han ◽  
...  
Keyword(s):  
Visible Light ◽  
Light Emitting Diodes ◽  
Visible Light Communication ◽  
Dual Function ◽  
Light Emitting

scholarly journals Photo-triggered hydrogen atom transfer from an iridium hydride complex to unactivated olefins

2020 ◽  
Vol 11 (32) ◽  
pp. 8582-8594
Author(s):  
Mirjam R. Schreier ◽  
Björn Pfund ◽  
Xingwei Guo ◽  
Oliver S. Wenger
Keyword(s):  
Hydrogen Atom ◽  
Visible Light ◽  
Electron Donor ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Hydride Complex ◽  
Proton Source

Upon irradiation with visible light, an iridium hydride complex undergoes hydrogen atom transfer (HAT) to unactivated olefins in presence of a sacrificial electron donor and a proton source.

scholarly journals Activation and selectivity of OTUB-1 and OTUB-2 deubiquitinylases

2020 ◽  
Vol 295 (20) ◽  
pp. 6972-6982
Author(s):  
Dakshinamurthy Sivakumar ◽  
Vikash Kumar ◽  
Michael Naumann ◽  
Matthias Stein
Keyword(s):  
Active Site ◽  
Electrostatic Interactions ◽  
Active Form ◽  
Cysteine Proteases ◽  
Binding Pocket ◽  
Catalytic Triad ◽  
Catalytic Site ◽  
Dynamics Simulation ◽  
Active Site Residues ◽  
Catalytically Active

The ovarian tumor domain (OTU) deubiquitinylating cysteine proteases OTUB1 and OTUB2 (OTU ubiquitin aldehyde binding 1 and 2) are representative members of the OTU subfamily of deubiquitinylases. Deubiquitinylation critically regulates a multitude of important cellular processes, such as apoptosis, cell signaling, and growth. Moreover, elevated OTUB expression has been observed in various cancers, including glioma, endometrial cancer, ovarian cancer, and breast cancer. Here, using molecular dynamics simulation approaches, we found that both OTUB1 and OTUB2 display a catalytic triad characteristic of proteases but differ in their configuration and protonation states. The OTUB1 protein had a prearranged catalytic site, with strong electrostatic interactions between the active-site residues His265 and Asp267. In OTUB2, however, the arrangement of the catalytic triad was different. In the absence of ubiquitin, the neutral states of the catalytic-site residues in OTUB2 were more stable, resulting in larger distances between these residues. Only upon ubiquitin binding did the catalytic triad in OTUB2 rearrange and bring the active site into a catalytically feasible state. An analysis of water access channels revealed only a few diffusion trajectories for the catalytically active form of OTUB1, whereas in OTUB2 the catalytic site was solvent-accessible, and a larger number of water molecules reached and left the binding pocket. Interestingly, in OTUB2, the catalytic residues His224 and Asn226 formed a stable hydrogen bond. We propose that the observed differences in activation kinetics, protonation states, water channels, and active-site accessibility between OTUB1 and OTUB2 may be relevant for the selective design of OTU inhibitors.

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