About
22
Publications
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Introduction
Additional affiliations
April 2016 - present
Position
- PostDoc Position
Description
- Ultrafast vibrational spectroscopy of catalytic intermediates in photodriven reductions and small-molecule activation (proton/carbon dioxide reduction)
March 2012 - April 2016
September 2009 - February 2012
FutureChemistry BV
Position
- Researcher
Description
- Flow chemistry for education, research and industrial applications.
Publications
Publications (22)
The identification and optimization of electrode materials is of great importance in the study of (flow and solid state) batteries, industrial electrocatalysis and analytical devices such as sensors. To identify useful materials from a virtually unbound set of metals, alloys and semiconductors, high-throughput techniques are of vital importance. In...
Artificial photosynthesis ‐ the direct photochemical generation of hydrogen from water ‐ is a promising but scientifically challenging future technology. Since nature employs membranes for photo‐driven reactions, we aim to elucidate the effect of membranes on artificial photocatalysis. To do so, we report a combination of electrochemistry, photocat...
In this study we describe the design of a biomimetic and fully base‐metal photocatalytic system for photocatalytic proton reduction in a homogeneous medium. A synthetic pyridylphosphole‐appended [FeFe]hydrogenase mimic is encapsulated inside a supramolecular zinc porphyrin‐based Fe4(Zn‐L)6 metal‐organic cage structure. The binding is driven by the...
Highly branched-selective hydroformylation of propene is an industrially important transformation, which now can be achieved using a novel caged rhodium catalyst. The catalyst encapsulation is based on a ligand-template approach in which the second coordination sphere around the encapsulated catalyst is generated by coordination of the catalyst's l...
In this study unprecedented regio-selectivity to the branched aldehyde product in hydroformylation of propene is attained upon embedding a rhodium complex in a supramolecular assembly, L2, formed by coordination-driven self-assembly of tris-(meta-pyridyl)-phosphine and zinc(II) porpholactones. The design of the new capsule is based on the ligand-te...
Supplementary
There is broad interest in molecular encapsulation as such systems can be utilized to stabilize guests, facilitate reactions inside a cavity, or give rise to energy-transfer processes in a confined space. Detailed understanding of encapsulation events is required to facilitate functional molecular encapsulation. In this contribution, it is demonstr...
![Figure 1. The active [FeFe]H 2 ase biomimetic supramolecular assembly...](profile/Rene-Becker-2/publication/331973676/figure/fig17/AS:740317389156356@1553516828287/The-active-FeFeH-2-ase-biomimetic-supramolecular-assembly-formed-under-photo-reductive_Q320.jpg)
Hydrogen gas is a viable, sustainable alternative to fossil fuels, but only when produced from sustainable resources such as water and sunlight. Devices that can perform the photocatalytic splitting of water are colloquially called ‘artificial leaves’ and should contain at least a light-absorbing entity and water splitting catalysts. In this thesis...
The transition from a fossil-based economy to a hydrogen-based economy requires cheap and abundant, yet stable and efficient, hydrogen production catalysts. Nature shows the potential of iron-based catalysts such as the iron-iron hydrogenase (H2ase) enzyme, which catalyzes hydrogen evolution at rates similar to platinum with low overpotential. Howe...
We present a synthetic strategy for the efficient encapsulation of a derivative of a well-defined cobaloxime proton reduction catalyst within a photoresponsive metal-organic framework (NH2- MIL-125(Ti)). The resulting hybrid system Co@MOF is demonstrated to be a robust heterogeneous composite material. Furthermore, Co@MOF is an efficient and fully...
Broader theoretical insight on organic reactions in driving them automatically opens the window towards new technologies particularly to flow chemistry. This emerging concept promotes the transformation of present day's organic processes into a more rapid continuous set of synthesis operations, more compatible with the envisioned sustainable world....
Photoinduced electron transfer in a supramolecular ZnTPP·Fe2S2 complex is investigated using femtosecond infrared spectroscopy, infrared spectro-electrochemistry, and DFT calculations. We find that the electron density is delocalized over the diiron core and the naphthalimide ligand, which explains the photocatalytic properties of this complex. The...
A phosphoramidite modified [FeFe]H2ase mimic is studied as a model for photodriven production of H2. On cathodic activation, the pyridyl-phosphoramidite complex exhibits a strongly enhanced rate of proton reduction over the previously reported pyridylphosphine model at the same overpotential. Analysis of the cyclic voltammograms shows an apparent H...
To expand the knowledge base for fundamental organic reactions in continuous flow, the α-bromination of aceto-phenone was successfully transformed from a known batch procedure to a continuous flow process in 99 % yield through D-optimal optimisation and subsequent scale-up of the validated optimum. Using a preparative scale system, a space–time yie...
With the commercial availability of integrated microreactor systems, the numbers of chemical processes that are performed nowadays in a continuous flow is growing rapidly. The control over mixing efficiency and homogeneous heating in these reactors allows industrial scale production that was often hampered by the use of large amounts of hazardous c...
The Vilsmeier-Haack formylation of aromatic compounds is a well-established process in organic synthesis, largely driven by the fact that the resulting aldehydes are generally useful intermediates for the synthesis of fine chemicals and pharmaceutical products. Industrial-scale production, however, is often hampered by laborious procedures requirin...
Epoxidation of both terminal and non-terminal olefins with peroxy acids is a well-established and powerful tool in a wide variety of chemical processes. In an additional step, the epoxide can be readily converted into the corresponding trans-diol. Batch-wise scale-up, however, is often troublesome because of the thermal instability and explosive ch...
A general methodology is presented as a practical approach to the design of a continuous flow process and its subsequent optimisation and up scaling. Three examples of such designs are shown. The continuous flow Swern-Moffatt oxidation shows that even for ultrafast reactions, the same methodology is still feasible, resulting in an 8.5 g/h synthesis...
In this study, the excellent scalability of flow chemistry was shown. Selective formation of mono-a-bromoketones was chosen as a model reaction. In a full multivariate optimization experiment, 60 different settings for reaction parameters such as temperature and reaction time were screened, requiring only small amounts of chemicals. A mathematical...
Questions
Questions (2)
I'd like to solve the following non-autonomous, non-linear first order differential equation, which is a result of (quite straightforward) chemical kinetics:
dy/dt = a*exp(-k*t) - b*y^2 - c*y with a,b,c,k > 0 and y(0) = 0.
Is there an algebraic solution? I tried all general methods including Laplace transforms, to no avail. WolframAlpha gives a solution using Bessel and Gamma functions, which is completely unstable in my region of interest.
I'm interested in the binding constants between pyridine and zinc tetraphenylporphyrin (ZnTPP) in dichloromethane. For neutral ZnTPP, the binding constant is around 7000 /M (from UV-vis titration).
For the anion and cation, I derived the binding constants from running cyclic voltammetry on ZnTPP (host H) in presence of increasing amounts of pyridine (guest G). The half-wave potentials then converge from the E_H potentials to the E_HG potentials, and from the difference I can get the anionic binding constant through: E_H - E_HG = RT/nF*ln(K+/K) (and the cationic binding constant in the same way).
Although I now have all the information I wanted to have, I'm puzzled by the graph [G]/[H] versus E_1/2. For the oxidation wave, this one is very steep. For the reduction wave, this one is very shallow. What does this plot tell me? What information is hidden in this plot? If I fit it to a supramolecular model analogously to UV-vis titrations, it does give me some value, but this is neither one of the association constants, nor a ratio thereof...
Anyone??
