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Chemical Engineering Journal

The hot injection technique for the synthesis of quantum dots (QDs) is a well-established and widely used method in the lab. However, scale-up rules do not exist. One reason is that in particular the role of process parameters like mixing on particle formation is largely unknown, as systematic examination of the latter is impossible for the laborious and complex manual synthesis. Herein we studied the mixing induced self-focusing of particle size distributions (PSDs) of CdSe QDs using automation in combination with a defined stirrer geometry. Basis for our study is a platform that allows parallelization with inline temperature monitoring, defined injection rate, accurate sampling times as well as controlled stirring. Reproducibility in terms of optical product properties was analyzed by absorption and emission whereas reproducibility in terms of the PSD was verified by deconvolution of UV/Vis absorbance spectra and especially by analytical ultracentrifugation (AUC) complemented by transmission electron microscopy (TEM). In line with previous results, AUC confirmed that even QDs made by hot injection in an automated setup are polydisperse with multimodal size distributions. Finally, reproducibility in combination with early stage sampling and controlled mixing allowed us for the first time to analyze the influence of stirring on focusing and defocusing of PSDs, that has been expressed in terms of the evolution of the relative standard deviation (RSD). Our work paves the way to gain in-depth understanding of often forgotten process-structure relationships of colloidal nanoparticles which eventually is a first step in the direction of the development of scalable synthesis and reliable application of high-quality QDs in technical applications.

September 3, 2019
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ChemRxivTM Journal

Organic molecules tend to close pack to form dense structures when they are crystallized from organic solvents. Porous molecular crystals defy this rule: they typically crystallize with lattice solvent in the interconnected pores. However, the design and discovery of such structures is often challenging and time consuming, in part because it is difficult to predict solvent effects on crystallization. Here, we combine crystal structure prediction (CSP) with a high-throughput crystallization screening method to accelerate the discovery of stable hydrogen-bonded frameworks. We exemplify this strategy by finding new phases of two well-studied molecules in a computationally targeted way. Specifically, we find a new porous polymorph of trimesic acid, δ-TMA, that has a guest free hexagonal pore structure, as well as three new solvent-stabilized diamondoid frameworks of adamantane-1,3,5,7-tetracarboxylic acid (ADTA).

September 3, 2019
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Organic Process Research & Development Journal

High-throughput experimentation is a technique for screening multiple reaction conditions in parallel at micro or nanoscale without depleting precious starting materials. However, assembling a comprehensive screening set often involves the distribution of large number of solid reagents with diverse physical properties in small quantities. Automated solid dispensing, especially at submilligram scale, has long been a challenge with no practical and reliable solutions. This paper describes the use of our newly developed chemical-coated beads technology to provide a universal approach to the solid handling problem. This technology, when combined with an automated solid dispensing platform or calibrated scoops, can dispense submilligram quantities of a variety of solids with efficiency and adequate accuracy.

September 3, 2019
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The Royal Society of Chemistry Journal

Most developments in the chemistry and applications of metal–organic frameworks (MOFs) have been made possible thanks to the value of reticular chemistry in guiding the unlimited combination of organic connectors and secondary building units (SBUs) into targeted architectures. However, the development of new titanium-frameworks still remains limited by the difficulties in controlling the formation of persistent Ti-SBUs with predetermined directionality amenable to the isoreticular approach. Here we report the synthesis of a mesoporous Ti-MOF displaying a MIL-100 topology. MIL-100(Ti) combines excellent chemical stability and mesoporosity, intrinsic to this archetypical family of porous materials, with photoactive Ti3 (μ3-O) metal-oxo clusters. By using high-throughput synthetic methodologies, we have confirmed that the formation of this SBU is thermodynamically favored as it is not strictly dependent on the metal precursor of choice and can be regarded as an adequate building block to control the design of new Ti-MOF architectures. We are confident that the addition of a mesoporous solid to the small number of crystalline, porous titanium-frameworks available will be a valuable asset to accelerate the development of new porous photocatalysts without the pore size limitations currently imposed by the microporous materials available.

August 8, 2019
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Chilly-Mazarin, France

Watch this inspiring video:

Sanofi – High-Throughput Experimentation (courtesy of Sanofi)

 

For more information about the solution applied:

ISYNTH REACTSCREEN

 

For details please contact [email protected]

July 4, 2019
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Molecules Journal

Due to the lack of approved vaccines against human leishmaniasis and the limitations of the current chemotherapy inducing side effects and drug resistance, development of new, effective chemotherapeutic agents is essential. This study describes the synthesis of a series of novel oxadiazoles and indolizine-containing compounds. The compounds were screened in silico using an EIIP/AQVN filter followed by ligand-based virtual screening and molecular docking to parasite arginase. Top hits were further screened versus human arginase and finally against an anti-target battery to tag their possible interactions with proteins essential for the metabolism and clearance of many substances. Eight candidate compounds were selected for further experimental testing. The results show measurable in vitro anti-leishmanial activity for three compounds. One compound with an IC50 value of 2.18 µM on Leishmania donovani intramacrophage amastigotes is clearly better positioned than the others as an interesting molecular template for further development of new anti-leishmanial agents. 

June 6, 2019
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The Royal Society of Chemistry Journal

Automated kinetic profiling is a valuable tool for providing insights into key mechanistic features of complex catalytic systems. In an attempt to optimize a palladium-catalyzed Suzuki cross-coupling reaction, automated kinetic profiling was utilized with offline liquid chromatography to monitor reaction progress. Upon uncovering analytical sample instability issues, an online HPLC capability was developed and implemented through integration of a Chemspeed liquid handling robot with an Agilent HPLC to facilitate automated reaction set-up and monitoring. Application of this capability resulted in the observation that precatalyst activation was a key factor influencing the reaction rate. Leveraging this mechanistic insight, a more efficient method to access the active catalyst was developed. This change resulted in a five-fold increase in the reaction rate.

May 6, 2019
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Angewandte Chemie Journal

Technologies that enable rapid screening of diverse reaction conditions are of critical importance to methodology development and reaction optimization especially when molecules of high complexity and scarcity are involved. The lack of a general solid dispensing method for chemical reagents on micro- and nanomole scale prevents the full utilization of reaction screening technologies. We herein report the development of a technology in which glass beads coated with solid chemical reagents (ChemBeads) enable the delivery of nanomole quantities of solid chemical reagents efficiently. By exploring the concept of preferred screening sets, the flexibility and generality of this technology for high throughput reaction screening was validated.

May 1, 2019
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University of Georgia

Nature Chemistry Journal

An automated platform that can synthesize a wide range of complex carbohydrates will greatly increase their accessibility and should facilitate progress in glycoscience. Here we report a fully automated process for enzyme-mediated oligosaccharide syn-thesis that can give easy access to different classes of complex glycans including poly-N-acetyllactosamine derivatives, human milk oligosaccharides, gangliosides and N-glycans. Our automated platform uses a catch and release approach in which glycos-yltransferase-catalysed reactions are performed in solution and product purification is accomplished by solid phase extraction. We developed a sulfonate tag that can easily be installed and enables highly efficient solid phase extraction and product release using a single set of washing conditions, regardless of the complexity of the glycan. Using this custom-built synthesizer, as many as 15 reaction cycles can be performed in an automated fashion without a need for lyophilization or buffer exchange steps.

April 1, 2019