G. Salinas, S. Arnaboldi, P. Garrigue, G. Bonetti, R. Cirilli, T. Benincori, A. Kuhn

Faraday Discussions (2023) in press

Chemistry on-the-fly is an interesting concept, extensively studied in recent years due to its potential use for recognition, quantification and conversion of chemical species in solution. In this context, chemistry on-the-fly for asymmetric synthesis is a promising field of investigation, since it can help to overcome mass transport limitations, present for example in conventional organic electrosynthesis. Herein, the synergy between a magnetic field-enhanced self-electrophoretic propulsion mechanism and enantioselective redox chemistry on-the-fly is proposed as an efficient concept to boost the stereoselective conversion. We employ Janus swimmers as redox-active elements, exhibiting a well-controlled clockwise or anticlockwise motion with a speed that can be increased by one order of magnitude in the presence of an external magnetic field. While moving, these bifunctional objects convert spontaneously on-the-fly a prochiral molecule into a specific enantiomer with high enantiomeric excess. The magnetic field-enhanced self-mixing of the swimmers, based on the formation of local magnetohydrodynamic vortices, leads to an significant improvement of the reaction yield and the conversion rate.

2023 5

C. Zhang, X. Zhang, Y. Fu, L. Zhang, A. Kuhn

J. Catal. 421(2023) 95-100

Free download

Electrochemical regeneration of the cofactor nicotinamide adenine dinucleotide (NADH) is crucial for the enzymatic synthesis of a variety of valuable chemicals. [Rh(Cp*)(bpy)Cl]+ has been reported as one of the most efficient non-enzymatic catalysts for electrochemical regeneration of NADH, but the efficiency of the existing systems is still far from satisfying. Here we propose to suspend metal-organic framework functionalized glassy carbon beads in a bipolar electrochemical cell under mechanical stirring for bulk electroenzymatic synthesis. The beads are modified with a metal-organic framework NU-1000 shell, in which [Rh(Cp*)(bpy)Cl]+ catalyst is incorporated via the solvent-assisted ligand incorporation approach. Enzymatically active 1,4-NADH is electrochemically regenerated, and finally bipolar electrochemical bulk conversion of pyruvate into L-lactate is performed in the presence of NADH dependent L-lactate dehydrogenase as a model system. The very high turnover frequency (TOF) of 3100±106 h-1 opens up promising perspectives for employing this concept also for various other electroenzymatic bulk processes.

2023 4  

Y. Zhao, J. Descamps, Y. Léger, L. Santinacci, S. Zanna, N. Sojic, G. Loget

Electrochimica Acta, 2023, 444, 142013

n-Si/SiOx/Ni photoanodes are investigated for upconversion photoinduced electrochemiluminescence (PECL) employing the 3-aminophthalhydrazide (luminol)-hydrogen peroxide (H2O2) model electrochemiluminescent (ECL) system at pH 13. We show that IR excitation of the photoanode at 850 nm produces PECL emission at 440 nm resulting in an anti-Stokes shift of -410 nm at biases higher than 0 V vs Ag/AgCl. Due to the alkaline pH value of the electrolyte that prevents Ni dissolution, this upconverting system is active for a longer period (several hours) than reported durations for similar photoanodes operating at neutral pH. The PECL intensity can be controlled by the applied potential and the power density of the incident IR light. This new PECL system opens up promising perspectives for light-addressable electrodes, microscopy, and imaging.


J. Descamps, C. Colin, G. Tessier, S. Arbault, N. Sojic

Angew. Chem. Int. Ed., 62, 2023

Here we report on a label-free electrochemiluminescence (ECL) microscopy using exceptionally low concentrations of the [Ru(bpy)3]2+ luminophore. This work addresses the central point of the minimal concentration of the ECL luminophore required to image single entities. We demonstrate the possibility to record ECL images of cells and mitochondria at concentrations down to nM and pM. This is 7 orders of magnitude lower than classically used concentrations and corresponds to a few hundreds of luminophores diffusing around the biological entities. Yet, it produces remarkably sharp negative optical contrast ECL images, as demonstrated by structural similarity index metric analyses and supported by predictions of the ECL image covering time. Finally, we show that the reported approach is a simple, fast, and highly sensitive method, which opens new avenues for ultrasensitive ECL imaging and ECL reactivity at the single molecule level.

ACIE 2023 2

X. Huang, B. Li, Y. Lu, Y. Liu, S. Wang, N. Sojic, D. Jiang and B. Liu

Angew. Chem. Int. Ed., 62, 2023, 135, e202215078

Nanoconfinement in mesoporous nanoarchitectures could dramatically change molecular transport and reaction kinetics during electrochemical process. A molecular-level understanding of nanoconfinement and mass transport is critical for the applications, but a proper route to study it is lacking. Herein, we develop a single nanoreactor electrochemiluminescence (SNECL) microscopy based on Ru(bpy)32+-loaded mesoporous silica nanoparticle to directly visualize in situ nanoconfinement-enhanced electrochemical reactions at the single molecule level. Meanwhile, mass transport capability of single nanoreactor, reflected as long decay time and recovery ability, is monitored and simulated with a high spatial resolution. The nanoconfinement effects in our system also enable imaging single proteins on cellular membrane. Our SNECL approach may pave the way to decipher the nanoconfinement effects during electrochemical process, and build bridges between mesoporous nanoarchitectures and potential electrochemical applications.

ACIE 2023 1