Reaction Vial Research Articles

Quenchers in advanced oxidation technologies for analysis of micropollutants by liquid chromatography coupled to mass spectrometry: Sodium sulphite or catalase?

This work aimed to investigate the possible effect of 2 quenchers commonly used in H2O2-based advanced oxidation technologies (AOTs), i.e. catalase and sodium sulphite (Na2SO3), on the analytical signal of 3 detectors coupled to liquid chromatography (LC): tandem mass spectrometry (LC-MS/MS), fluorescence detection (LC-FD) and LC-diode array detection (LC-DAD). The observation of analytical interferences for a group of compounds when studying the removal by continuous mode UV/H2O2 of 26 micropollutants (MPs) from a spiked surface water (SW), for which the residual H2O2 in the samples was quenched by Na2SO3, triggered the need of understanding these effects and thus catalase was used as comparative quencher. From the 26 MPs having a wide range of polarity and pKa, those monitored after electrospray ionization (ESI) under positive ionization (PI) mode and presenting a pKa higher than 5.9 revealed a great signal suppression, but only when using Na2SO3 as H2O2 quencher. In this sense, we further explored this effect by selecting 2 MPs, metoprolol and diclofenac, which had respectively signal suppression and no interference in the LC-MS/MS response. These MPs were analysed before and after addition of H2O2 and catalase or Na2SO3 in reaction vials, using: (i) different detectors coupled to LC, namely LC-MS/MS with ESI under PI and negative ionization (NI) modes, LC-FD and LC-DAD; (ii) different environmental matrices (SW, drinking water, wastewater) and ultrapure water; and (iii) different magnitude levels (0.1-10 mg L-1). The results demonstrated a remarkable signal suppression in LC-MS/MS analyses under PI mode for those compounds with pKa higher than 5.9, confirming the interfering effect of H2O2/Na2SO3. To the best of our knowledge, the analytical interference in the LC-MS/MS analysis, after adding Na2SO3 to quench H2O2 in AOTs experiments was never reported before and the results presented herein support the recommendation to use catalase instead of Na2SO3 as quencher in AOTs studies.

Convection-Flow-Assisted Preparation of a Strong Electron Dopant, Benzyl Viologen, for Surface-Charge Transfer Doping of Molybdenum Disulfide.

Transition metal dichalcogenides (TMDCs) have received attention as atomically thin post‐silicon semiconducting materials. Tuning the carrier concentrations of the TMDCs is important, but their thin structure requires a non‐destructive modulation method. Recently, a surface‐charge transfer doping method was developed based on contacting molecules on TMDCs, and the method succeeded in achieving a large modulation of the electronic structures. The successful dopant is a neutral benzyl viologen (BV0); however, the problem remains of how to effectively prepare the BV0 molecules. A reduction process with NaBH4 in water has been proposed as a preparation method, but the NaBH4 simultaneously reacts vigorously with the water. Here, a simple method is developed, in which the reaction vial is placed on a hotplate and a fragment of air‐stable metal is used instead of NaBH4 to prepare the BV0 dopant molecules. The prepared BV0 molecules show a strong doping ability in terms of achieving a degenerate situation of a TMDC, MoS2. A key finding in this preparation method is that a convection flow in the vial effectively transports the produced BV0 to a collection solvent. This method is simple and safe and facilitates the tuning of the optoelectronic properties of nanomaterials by the easily‐handled dopant molecules.

Fully Automated 89Zr Labeling and Purification of Antibodies.

Dozens of monoclonal antibodies (mAbs) have been approved for clinical use, and hundreds more are under development. To support these developments and facilitate a personalized medicine approach, PET imaging and quantification of mAbs, after chelation with desferrioxamine B (DFO) and radiolabeling with 89Zr, has become attractive. Also, the use of 89Zr-mAbs in preclinical and clinical studies is expanding rapidly. Despite these rapid developments, 89Zr radiolabeling is still performed manually. Therefore, we aimed to develop a simple, fully automated, good-manufacturing-practice (GMP)-compliant production procedure for the 89Zr labeling of mAbs. Such procedures should increase the robustness and capacity of 89Zr-mAb production while minimizing the radiation dose to the operator. Here, the procedures for fully automated 89Zr-mAb production are described and applied to produce batches of 89Zr-DFO-N-suc-cetuximab and 89Zr-DFO-N-suc-rituximab suitable for clinical use. Both products had to meet the GMP-compliant quality standards with respect to yield, radiochemical purity, protein integrity, antigen binding, sterility, and endotoxin levels. Methods: Automated 89Zr labeling of mAbs was developed on a Scintomics GRP 2V module and comprised the following steps: reagent transfer to the 89Zr-containing reaction vial, mixing of the reagents followed by a 60-min reaction at room temperature to obtain optimal radiolabeling yields, and product purification using a PD-10 desalting column. Results: Radiochemical yields of 89Zr-DFO-N-suc-cetuximab and 89Zr-DFO-N-suc-rituximab were all more than 90% according to instant thin-layer chromatography. Isolated yields were 74.6% ± 2.0% and 62.6% ± 3.0% for 89Zr-DFO-N-suc-cetuximab and 89Zr-DFO-N-suc-rituximab, respectively, which are similar to isolated yields obtained using GMP protocols for manual 89Zr labeling of mAbs. To meet the GMP-compliant quality standards, only the radiochemically pure fractions were collected from PD-10, resulting in a lower isolated yield than the radiochemical yield according to instant thin-layer chromatography. The radiochemical purity and protein integrity were more than 95% for both products, and the antigen binding was 95.6% ± 0.6% and 87.1% ± 2.2% for 89Zr-DFO-N-suc-cetuximab and 89Zr-DFO-N-suc-rituximab, respectively. The products were sterile, and the endotoxin levels were within acceptable limits, allowing future clinical production using this procedure. Conclusion: Procedures for fully automated GMP-compliant production of 89Zr-mAbs were developed on a commercially available synthesis module, which also allows the GMP production of other radiolabeled mAbs.

Synthesis of 99m Tc-roxithromycin: A novel diagnostic agent to discriminate between septic and aseptic inflammation.

Roxithromycin is a second-generation macrolide antibiotic derived from erythromycin. In the current study, roxithromycin (ROX) was successfully labeled with technetium-99m for early diagnosis of bacterial infection and discrimination between septic and aseptic inflammation. The highest radiochemical purity of ≥95% was achieved by investigating different labeling parameters such as pH, ligand/reducing agent concentration, temperature, and amount of stabilizing agent. For this purpose, 0.3-0.5mg ligand, 2-6μg SnCl2 ·2H2 O as a reducing agent at basic pH (8-10 pH) and 2mg mannitol used as a stabilizing agent, in the end, 370MBq 99m Tc added into the reaction vials and incubated for a wide range of temperature (-4 to 65°C). The percent radiochemical purity of 99m Tc-roxithromycin was assessed with the help of the radio-thin-layer chromatography technique. The characterization studies were carried out using electrophoresis and Radio-HPLC techniques as well as saline stability and serum stability studies were also performed. Furthermore, biodistribution study was also performed in an inflamed animal model to discriminate between septic (heat-killed Staphylococcus aureus) and aseptic (turpentine oil) inflammatory lesions. The results were elaborated that 99m Tc-roxithromycin (99m Tc-ROX) was clearly bounded at the septic inflammation site (T/NT ratio of 7.08±1.14) at 30min postadministration, and maximum accumulation was seen in heart, lungs, liver, stomach, kidneys, and intestine. The results were suggested that 99m Tc-ROX might be used to discriminate between septic and aseptic inflammatory lesions at an early stage.

Photoinduced Miniemulsion Atom Transfer Radical Polymerization.

Photomediated atom transfer radical polymerization (photoATRP) of (meth)acrylic monomers was conducted in miniemulsion media. The polymerization procedures took advantage of an ion-pair catalyst formed by interaction of Cu/TPMA2 (TPMA = tris(2-pyridylmethyl)amine) and an anionic surfactant, sodium dodecyl sulfate (SDS). The ion-pair catalyst was efficient in controlling ATRP reactions with catalyst loadings as low as 100 ppm. The effect of different polymerization parameters, such as the size of the reaction vial, amount of surfactant, and solids content influencing the photoATRP in miniemulsion, was studied. The polymerization was conducted with solids content ranging from 5 to 50 vol % under a moderate surfactant loading (<5 wt % relative to monomer). Excellent temporal control was achieved upon switching the UV light on and off multiple times, and the polymer was successfully chain extended, indicating high retention of chain-end fidelity.

Methane oxidation in industrial biogas plants—Insights in a novel methanotrophic environment evidenced by pmoA gene analyses and stable isotope labelling studies

A broad methanotrophic community consisting of 16 different operational taxonomic units (OTUs) was detected by particulate methane monooxygenase A (pmoA) gene analyses of reactor sludge samples obtained from an industrial biogas plant. Using a cloning-sequencing approach, 75% of the OTUs were affiliated to the group of type I methanotrophs (γ-Proteobacteria) and 25% to type II methanotrophs (α-Proteobacteria) with a distinct predominance of the genus Methylobacter. By database matching, half of the total OTUs may constitute entirely novel species. For evaluation of process conditions that support growth of methanotrophic bacteria, qPCR analyses of pmoA gene copy numbers were performed during a sampling period of 70 days at varying reactor feeding scenarios. During the investigation period, methanotrophic cell counts estimated by qPCR fluctuated between 3.4 × 104 and 2 × 105 cells/mL with no distinct correlation to the organic loading rate, the amount of CH4, O2 and NH4-N. Methanotrophic activity was proofed even at low O2 levels (1%) by using stable carbon isotope labelling experiments of CH4 in batch experiments inoculated with reactor sludge. Supplementation of 13C labelled CH4 in the headspace of the reaction vials unambiguously confirmed the formation of 13C labelled CO2. Thus, industrial biogas reactors can be considered as a further methanotrophic habitat that exhibits a unique methanotrophic community which is specifically adapted to high CH4 and low O2 concentrations. To the best of our knowledge, our study is the first accurate detection and quantification of methanotrophic bacteria in industrial biogas reactors.

Fast automated online xylanase activity assay using HPAEC-PAD.

In contrast to biochemical reactions, which are often carried out under automatic control and maintained overnight, the automation of chemical analysis is usually neglected. Samples are either analyzed in a rudimentary fashion using in situ techniques, or aliquots are withdrawn and stored to facilitate more precise offline measurements, which can result in sampling and storage errors. Therefore, in this study, we implemented automated reaction control, sampling, and analysis. As an example, the activities of xylanases on xylotetraose and soluble xylan were examined using high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The reaction was performed in HPLC vials inside a temperature-controlled Dionex™ AS-AP autosampler. It was started automatically when the autosampler pipetted substrate and enzyme solution into the reaction vial. Afterwards, samples from the reaction vial were injected repeatedly for 60min onto a CarboPac™ PA100 column for analysis. Due to the rapidity of the reaction, the analytical method and the gradient elution of 200mM sodium hydroxide solution and 100mM sodium hydroxide with 500mM sodium acetate were adapted to allow for an overall separation time of 13min and a detection limit of 0.35-1.83mg/L (depending on the xylooligomer). This analytical method was applied to measure the soluble short-chain products (xylose, xylobiose, xylotriose, xylotetraose, xylopentaose, and longer xylooligomers) that arise during enzymatic hydrolysis. Based on that, the activities of three endoxylanases (EX) were determined as 294U/mg for EX from Aspergillus niger, 1.69U/mg for EX from Bacillus stearothermophilus, and 0.36U/mg for EX from Bacillus subtilis. Graphical abstract Xylanase activity assay automation.

Diameter of the vial plays a crucial role in the amyloid fibril formation: Role of interface area between hydrophilic-hydrophobic surfaces

Number of incurable diseases associated with neurodegenerative syndromes like Alzheimer’s, and Parkinson’s, are owing to protein aggregation which leads to amyloid fibril formation. In vitro, such fibrillation depends on concentration, temperature, pH, ionic strength, organic solvents, agitation, and stirring, which play a crucial role in understanding the mechanism of fibrillation as well as to identify potential inhibitors for fibrillation. Although these parameters were considered, the precise repeatability of amyloid fibrillation kinetics between laboratories remains challenging. Herein, we have demonstrated that another important parameter such as diameter of the vial in which protein undergoes fibrillation play a key role in the amyloid fibrillation. The various biophysical analyses indicated that the lag time, elongation, and the amount of fibril formation was significantly reduced with decreasing the diameter of the reaction vial from 24 to 15mm. Further, the minimum amount of protein required for fibrillation was determined by the diameter of the vial. The observed fibrillation difference in different vials is most likely due to the variation in the interface area between hydrophobic (air) and hydrophilic (water) surfaces as the diameter of the vial changes. The current results have a major role in the design of drug screening assays for amyloid inhibition.

Proteomics reveals the effects of sustained weight loss on the human plasma proteome.

Sustained weight loss is a preferred intervention in a wide range of metabolic conditions, but the effects on an individual's health state remain ill‐defined. Here, we investigate the plasma proteomes of a cohort of 43 obese individuals that had undergone 8 weeks of 12% body weight loss followed by a year of weight maintenance. Using mass spectrometry‐based plasma proteome profiling, we measured 1,294 plasma proteomes. Longitudinal monitoring of the cohort revealed individual‐specific protein levels with wide‐ranging effects of losing weight on the plasma proteome reflected in 93 significantly affected proteins. The adipocyte‐secreted SERPINF1 and apolipoprotein APOF1 were most significantly regulated with fold changes of −16% and +37%, respectively (P < 10−13), and the entire apolipoprotein family showed characteristic differential regulation. Clinical laboratory parameters are reflected in the plasma proteome, and eight plasma proteins correlated better with insulin resistance than the known marker adiponectin. Nearly all study participants benefited from weight loss regarding a ten‐protein inflammation panel defined from the proteomics data. We conclude that plasma proteome profiling broadly evaluates and monitors intervention in metabolic diseases.

A Nested PCR Assay to Avoid False Positive Detection of the Microsporidian Enterocytozoon hepatopenaei (EHP) in Environmental Samples in Shrimp Farms.

Hepatopancreatic microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP) is an important disease of cultivated shrimp. Heavy infections may lead to retarded growth and unprofitable harvests. Existing PCR detection methods target the EHP small subunit ribosomal RNA (SSU rRNA) gene (SSU-PCR). However, we discovered that they can give false positive test results due to cross reactivity of the SSU-PCR primers with DNA from closely related microsporidia that infect other aquatic organisms. This is problematic for investigating and monitoring EHP infection pathways. To overcome this problem, a sensitive and specific nested PCR method was developed for detection of the spore wall protein (SWP) gene of EHP (SWP-PCR). The new SWP-PCR method did not produce false positive results from closely related microsporidia. The first PCR step of the SWP-PCR method was 100 times (104 plasmid copies per reaction vial) more sensitive than that of the existing SSU-PCR method (106 copies) but sensitivity was equal for both in the nested step (10 copies). Since the hepatopancreas of cultivated shrimp is not currently known to be infected with microsporidia other than EHP, the SSU-PCR methods are still valid for analyzing hepatopancreatic samples despite the lower sensitivity than the SWP-PCR method. However, due to its greater specificity and sensitivity, we recommend that the SWP-PCR method be used to screen for EHP in feces, feed and environmental samples for potential EHP carriers.

Optimizing labelling conditions of 213Bi-DOTATATE for preclinical applications of peptide receptor targeted alpha therapy

Background213Bismuth (213Bi, T1/2 = 45.6 min) is one of the most frequently used α-emitters in cancer research. High specific activity radioligands are required for peptide receptor radionuclide therapy. The use of generators containing less than 222 MBq 225Ac (actinium), due to limited availability and the high cost to produce large-scale 225Ac/213Bi generators, might complicate in vitro and in vivo applications though.Here we present optimized labelling conditions of a DOTA-peptide with an 225Ac/213Bi generator (< 222 MBq) for preclinical applications using DOTA-Tyr3-octreotate (DOTATATE), a somatostatin analogue. The following labelling conditions of DOTATATE with 213Bi were investigated; peptide mass was varied from 1.7 to 7.0 nmol, concentration of TRIS buffer from 0.15 mol.L-1 to 0.34 mol.L-1, and ascorbic acid from 0 to 71 mmol.L-1 in 800 μL. All reactions were performed at 95 °C for 5 min. After incubation, DTPA (50 nmol) was added to stop the labelling reaction. Besides optimizing the labelling conditions, incorporation yield was determined by ITLC-SG and radiochemical purity (RCP) was monitored by RP-HPLC up to 120 min after labelling. Dosimetry studies in the reaction vial were performed using Monte Carlo and in vitro clonogenic assay was performed with a rat pancreatic tumour cell line, CA20948.ResultsAt least 3.5 nmol DOTATATE was required to obtain incorporation ≥ 99 % with 100 MBq 213Bi (at optimized pH conditions, pH 8.3 with 0.15 mol.L-1 TRIS) in a reaction volume of 800 μL. The cumulative absorbed dose in the reaction vial was 230 Gy/100 MBq in 30 min. A minimal final concentration of 0.9 mmol.L-1 ascorbic acid was required for ~100 MBq (t = 0) to minimize radiation damage of DOTATATE. The osmolarity was decreased to 0.45 Osmol/L.Under optimized labelling conditions, 213Bi-DOTATATE remained stable up to 2 h after labelling, RCP was ≥ 85 %. In vitro showed a negative correlation between ascorbic acid concentration and cell survival.Conclusion213Bismuth-DOTA-peptide labelling conditions including peptide amount, quencher and pH were optimized to meet the requirements needed for preclinical applications in peptide receptor radionuclide therapy.

A biosensor platform for rapid detection of E. coli in drinking water

There remains a need for rapid, specific and sensitive assays for the detection of bacterial indicators for water quality monitoring. In this study, a strategy for rapid detection of Escherichia coli in drinking water has been developed. This strategy is based on the use of the substrate 4-methylumbelliferyl-β-d-glucuronide (MUG), which is hydrolyzed rapidly by the action of E. coli β-d-glucuronidase (GUD) enzyme to yield a fluorogenic 4-methylumbelliferone (4-MU) product that can be quantified and related to the number of E. coli cells present in water samples. In this study, the detection time required for the biosensor response ranged between 20 and 120min, depending on the number of bacteria in the sample. This approach does not need extensive sample processing with a rapid detection capability. The specificity of the MUG substrate was examined in both, pure cultures of non-target bacterial genera such as Klebsiella, Salmonella, Enterobacter and Bacillus. Non-target substrates that included 4-methylumbelliferyl-β-d-galactopyranoside (MUGal) and l-leucine β-naphthylamide aminopeptidase (LLβ-N) were also investigated to identify nonspecific patterns of enzymatic activities in E. coli. GUD activity was found to be specific for E. coli and no further enzymatic activity was detected by other species. In addition, fluorescence assays were performed for the detection of E. coli to generate standard curves; and the sensitivity of the GUD enzymatic response was measured and repeatedly determined to be less than 10 E. coli cells in a reaction vial. The applicability of the method was tested by performing multiple fluorescence assays under pure and mixed bacterial flora in environmental samples. The results of this study showed that the fluorescence signals generated in samples using specific substrate molecules can be utilized to develop a bio-sensing platform for the detection of E. coli in drinking water. Furthermore, this system can be applied independently or in conjunction with other methods as a part of an array of biochemical assays in order to reliably detect E. coli in water.

Nucleoside Azide–Alkyne Cycloaddition Reactions Under Solvothermal Conditions or Using Copper Vials in a Ball Mill

Novel nucleoside analogues containing photoswitchable moieties were prepared using ‘click’ cycloaddition reactions between 5′-azido-5′-deoxythymidine and mono- or bis-N-propargylamide-substituted azobenzenes. In solution, high to quantitative yields were achieved using 5 mol% Cu(I) in the presence of a stabilizing ligand. ‘Click’ reactions using the monopropargylamides were also effected in the absence of added cuprous salts by the application of liquid assisted grinding (LAG) in metallic copper reaction vials. Specifically, high speed vibration ball milling (HSVBM) using a 3/32″ (2.38 mm) diameter copper ball (62 mg) at 60 Hz overnight in the presence of ethyl acetate lead to complete consumption of the 5′-azido nucleoside with clean conversion to the corresponding 1,3-triazole.

QuickTox™ Kit for QuickScan DON3 (Vomitoxin) Method Modification.

Lateral flow technology and a reader-based system are used for quantitative determination of deoxynivalenol (DON), also known as vomitoxin, residues in cereal grain commodities by the QuickTox Kit for QuickScan DON (Vomitoxin). The assay has been modified, and a study was conducted in support of a Performance Tested MethodSM (PTM) Modification. The modified assay employs identical biologic reagents as used previously (PTM No. 121202). Compared to the PTM certified product, the new assay uses modified device architecture. Multiple kits and catalog numbers were required in the original kit reflecting the necessity for matrix specific calibration curves affixed to assay strips. A single calibration curve and kit are utilized in the new product; extraction volumes used in sample preparation are varied to accommodate multiple sample types. Extracts are clarified by filtration or settling depending on the sample type. Filtration was used for matrixes examined in these studies. With the original product, the extract was mixed 1:1 with DB1 buffer followed by the addition of the strip which was developed for 10 min. The new product dilutes extracts five-fold offline in DB6 buffer; an aliquot of the dilution is moved to a reaction vial followed by strip development time for 3 min. The new assay performance was evaluated for linearity, robustness, selectivity (inclusivity), lot-to-lot consistency, and both internal and third party matrix studies. All DON positive samples yielded results within previously defined acceptable ranges with dose-dependent correlation values of R2 greater than 0.97 in linearity and internal and external matrix studies. Inclusivity data indicated detection of DON along with acetyl derivatives, glucoside-conjugate, and Nivalenol. Robustness studies showed within range results upon co-variation of multiple user interface parameters, and lot-to-lot consistency challenges demonstrated acceptable results across five manufactured lots.

Indirect chiral ligand exchange chromatography for enantioseparation: a modification of conventional techniques

Indirect chiral ligand exchange chromatography (ICLEC) was facilitated by substituting chiral ligands from the bidentate Cu(II) complex via racemic analytes in reaction vial. In-vial ligand exchange does not require the potentially harmful Cu(II)-containing mobile phase for HPLC separation, as it facilitates better pH control for improved complexation of enantiomers with the chiral Cu(II)–ligand complex. Resulting Cu(II)–analyte–ligand complexes have higher stability constants and show better chromatographic resolution than conventional (CLEC). The new technique also eliminates background noise, a problem with conventional CLEC due to higher concentrations of Cu-containing selector due to the Cu-free mobile phase. The new technique was found successful in determining enantiomeric purity of drugs in pharmaceutical formulations. The technique can be regarded as a novel surrogate for conventional CLEC and has the potential for biological and pharmaceutical applications.

One-pot multi-tracer synthesis of novel (18)F-labeled PET imaging agents.

(18)F labeled phosphonium salts are increasingly important molecular probes for targeting the mitochondrial membrane potential depletion during apoptosis and for detecting myocardial perfusion deficit. Here, we introduce three new tracers, [(18)F]MitoPhos_04, [(18)F]MitoPhos_05, and [(18)F]MitoPhos_07, that have the potential to act as mitochondrial imaging agents. Moreover, they have the added advantage of being synthesized in the same reaction vial from one radiolabeled synthon, demonstrating a new approach to synthesizing multiple tracers in one-pot, which is a highly useful means for increasing the throughput of radiotracer development. The radiosynthesis of the tracers was carried out on a fully automated system via a facile two-step reaction. Utilizing the radiolabeling of an ethyl azide, a copper-mediated 1,3-cycloaddition reaction and isolation via semiprep high-performance liquid chromatography (HPLC) allowed for the simultaneous synthesis of two or three tracers with a total synthesis time of less than 1 h.

Polyol synthesis of silver nanocubes via moderate control of the reaction atmosphere

Silver nanocubes were successfully synthesized at high yield in variously controlled reaction atmospheres by balancing etching of O2/Cl− and reduction of glycolaldehyde. There have been efforts to control the O2 content in reaction atmospheres by purging of O2 or Ar gas for the balancing, but we found that moderate control of reaction atmosphere, just by careful timing of the opening and the capping of the reaction vial, greatly enhanced reproducibility. Enhanced reproducibility is attributed to alleviation of evaporation and condensation of glycolaldehyde (b.p.=131°C) by using capping at reaction temperatures higher than the b.p. of glycolaldehyde rather than purging with gas. The most important finding is that seeding is initiated by HNO3 induced deoxygenation reaction in the gas phase. O2 is consumed by oxidation of NO generated from the silver etching reaction by HNO3, which effectively controls the reaction atmosphere without introduction of gas. Our simple method to control reaction atmosphere reduces the overall reaction time to one fifth of the previous result and provides excellent size and distribution selectivity of the Ag nanocube product.

Light‐Driven Organocatalysis Using Inexpensive, Nontoxic Bi2O3 as the Photocatalyst

AbstractThe development of enantioselective catalytic processes that make use of sunlight as the energy source and nontoxic, affordable materials as catalysts represents one of the new and rapidly evolving areas in chemical research. The direct asymmetric α‐alkylation of aldehydes with α‐bromocarbonyl compounds can be successfully achieved by combining bismuth‐based materials as low‐band‐gap photocatalysts with the second‐generation MacMillan imidazolidinone as the chiral catalyst and simulated sunlight as a low‐cost and clean energy source. This reaction also proceeded with high efficiency when the reaction vial was exposed to the morning sunlight on a clear September day in Tarragona, Spain.

Light-driven organocatalysis using inexpensive, nontoxic Bi2O3 as the photocatalyst.

The development of enantioselective catalytic processes that make use of sunlight as the energy source and nontoxic, affordable materials as catalysts represents one of the new and rapidly evolving areas in chemical research. The direct asymmetric α-alkylation of aldehydes with α-bromocarbonyl compounds can be successfully achieved by combining bismuth-based materials as low-band-gap photocatalysts with the second-generation MacMillan imidazolidinone as the chiral catalyst and simulated sunlight as a low-cost and clean energy source. This reaction also proceeded with high efficiency when the reaction vial was exposed to the morning sunlight on a clear September day in Tarragona, Spain.

Instrumentation and Hardware

Asynt has updated the design of its products for parallel synthesis to share standard parts (inserts) for reaction tube, vial, and round-bottom flask-based reactions and now also can be upgraded to a parallel reaction station using standard round-bottom flasks, by using the appropriate DrySyn MULTI inserts. In this configuration, facilities can be added such as directly driven stirring with the Asynt Vortex stirrer system. Available in a choice of configurations, the Asynt DrySyn SnowStorm system provides controlled cooling and heating for subambient parallel chemistry without the need for jacketed reaction vessels or ice baths and is now available in new sizes.