Fluorous Separation Techniques
March 2010 Fluorous Technical Newsletter
CEOverture
How would you describe yourself in only a few words? That can be a challenge for anyone, or any company, especially when your company markets and sells products relating to a broadly enabling technology platform. At Fluorous Technologies, we sell tools for synthesis, purification, enrichment, and immobilization. Simple and robust fluorous separations are at the heart of our technology, supporting a nearly endless array of applications. In this Technical Newsletter, we highlight the three major approaches to fluorous separations and provide a few recent literature examples. Hopefully these will get you to thinking about the separation challenges in your own work and how a fluorous technique might just solve one of the biggest problems you face.
Cheers,
Philip E. Yeske
President & CEO
Fluorous Technologies Inc.
Fluorous Liquid-Liquid Extraction (FLLE)
FLLE was the initial embodiment of fluorous separations. Perfluorocarbon solvents were found to be immiscible with organic and aqueous phases, creating a unique fluorous phase. Furthermore, compounds with multiple fluorous chains were found to partition preferentially into the fluorous phase. Biphasic catalysis was the initial application, but since that time fluorous tagged reagents, scavengers, and substrates have all been separated from non-fluorous materials using FLLE. In 2005, we reported a significant advance in FLLE through the use of solvent tuning, a process that increases partition coefficients by adjusting the extraction solvents. With solvent tuning, it is now possible to separate compounds with only one or two fluorous tags from non-fluorous compounds by FLLE. You can read more about solvent tuning and FLLE on our website.
A recent report in the Journal of Fluorine Chemistry uses solvent tuning and FLLE in conjunction with anion exchange solid phase extraction for the detection and analysis of perfluorinated compounds from food matrices at the ppb level. Without FLLE the perfluorinated compounds were not detectable at these levels using MS detection. Increased sensitivity was a direct result of using FLLE to selectively enrich the original sample. Find additional discussion of this paper at F-Blog.
Fluorous Solid Phase Extraction (FSPE)
FSPE was developed as a quick and simple method for the separation of fluorous compounds from complex mixtures. It was initially applied to small molecule synthesis, but has since been used in a variety of applications such as peptide purification, oligonucleotide purification, proteomics, and analytical sample prep. FSPE has proven time and again to be a robust, simple, and fast method to execute fluorous separations. Learn more at our FSPE technology page.
An example of FSPE in action from the recent peer-reviewed literature was reported by Prof. Xuefei Huang and co-workers at Michigan State University for the one-pot synthesis of oligosaccharides. The researchers’ approach was to prepare the oligosaccharide in a single pot through sequential addition of the appropriate monomer units. The desired oligosaccharide was then captured using a fluorous scavenger and separated from other reaction components including all reagents and excess monosaccharides using FSPE. Removal of the fluorous tag provided the final oligosaccharide. As an example the authors prepared branched trisaccharide LewisX in 62% over five steps in ~4h from start to finish including FSPE purification. Further details about this oligosaccharide catch and release work can be found here.
Fluorous HPLC (F-HPLC)
The third major fluorous separation technique is F-HPLC. Unlike FLLE and FSPE, which separate fluorous molecules from non-fluorous molecules, F-HPLC separates compounds based on their fluorine content. Compounds with a greater percentage of fluorine content elute later from the F-HPLC column than compounds with a lower percentage. Historically, a molecule’s fluorine content varied with the length of the fluorous tag. This is the basis for fluorous mixture synthesis (FMS) which has been used for the synthesis of small molecule libraries.
Prof. Bruce Yu at the University of Maryland used an innovative FMS approach to prepare fluorinated dendrimers for diagnostic 19F imaging. He and his co-researchers still used F-HPLC to separate compounds, but they modified fluorine content by adding branching and surface units while using the same fluorous t-butyl tag for all the molecules in their mixture. The fluorine content of the molecules changed substantially after each iteration even though the fluorous tag itself remained constant. As in all FMS, F-HPLC enabled Prof. Yu to synthesize and purify more compounds for less effort. Read more about this original use of FMS at F-Blog.
The examples cited above highlight the various means by which fluorous based separations can be used. Whether you are looking to use fluorous techniques in an analytical, preparative, or diagnostic setting, Fluorous Technologies can help you choose, design, and execute the separation that’s best for you. We can provide all the expertise and materials you’ll need including fluorous tags, reagents, and separation media. Please contact us to get started.
The Fine Print
Fluorous Technologies is a chemical technology company devoted to the development and commercialization of fluorous products for the life science market. The company uses its patented technology to solve synthesis and separation problems spanning the entire drug discovery and development process. Fluorous chemistry enhances a wide range of applications, including medicinal chemistry, combinatorial chemistry, catalysis, biomolecule production, and proteomics. For more information, please visit: http://fluorous.com
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