Decades-long research culminates in a new way of creating left- and right-handed molecules

May 1, 2017
Mark Davis. Credit: Caltech

An international team of researchers, led by Mark E. Davis at Caltech, has succeeded in making the first chiral molecular sieves. This discovery opens new areas of investigation in both chemistry and biology, and has broad implications for pharmaceutical companies and other specialized chemical manufacturers.

A trait common amongst the molecules in cells is chirality. Objects that have chirality are mirror images of one another. Just as humans have two hands that are of one another, molecules exhibit handedness and have left and right versions called enantiomers. Since the molecules of life, namely proteins, sugars and DNA, are chiral, the enantiomers of molecules such as drugs have completely different functions when they interact with cells.

Specialty chemicals industries like the pharmaceutical industry have had difficulties in producing . The challenges lie in either separating left-handed from right-handed versions or directly creating only the desired enantiomer through a chemical reaction.

Davis and his team have now invented molecular sieves that are able to both sort and create chiral molecules. With this development, manufacturers may be able to produce more specific and desired forms of drugs and other products. An example of a medication that could be improved upon, Davis says, is the drug ibuprofen, also known by one of its brand names—Advil. Ibuprofen contains both left- and right-handed forms, but only the left-handed version is therapeutic.

"In order to minimize side effects associated with ibuprofen—such as stomach pain, ulcers, and other health issues—it would be helpful to just take the left-handed version," says Davis, the Warren and Katharine Schlinger Professor of Chemical Engineering at Caltech and principal investigator of the new research, which appears in the May 1 issue of Proceedings of the National Academy of Sciences. "The goal for the future is to create specific chiral forms of molecules, not mixtures. Chiral molecular sieves will let us do this in new ways that most likely will be less cost-prohibitive. These sieves can be robust and reusable, and don't require special temperatures and other operating conditions."

Molecular sieves are silicon-based crystal lattices used in multibillion-dollar commercial applications ranging from the production of gasoline and diesel fuel to the purification of oxygen from air. The sieves, many of which are a class called "zeolites," look like Swiss cheese under a microscope, with interconnected pores smaller than 2 nanometers in size. The pores are what make these solids so useful: they let molecules of only a certain size and shape pass through. In addition, the pores can act as catalytic reaction chambers to spur the production of specific chemical products.

To create molecular sieves that can selectively let a specific form of a chiral molecule pass through, the researchers made several advances. First, co-authors at Rice University designed and implemented computational methods to help guide the design of chiral organic molecules that direct the synthesis of the chiral molecular sieves. Second, Caltech researchers—who spent decades learning what the properties of the guiding organic molecules should be, and how to then use them to assemble molecular sieves—prepared the designed, chiral organic molecules and synthesized the chiral molecular sieves. Third, scientists now at ShanghaiTech University developed a new, high-resolution transmission electron microscopy method that was used to confirm that the sieves were indeed either the left- or right-handed versions. The Caltech researchers also demonstrated that the sieves could either separate chiral molecules or create them by catalyzing chiral reactions.

"What we're able to do here by design is let researchers pick which form they want: if you want the right-handed molecule, you use the right molecular sieve and you make that one. If you want the other one, you use the other molecular sieve," says Davis, who has been working on the problem of creating chiral molecular sieves for 30 years. "Now, we can synthesize with chirality using molecular sieve catalysts for the first time."

Explore further: Researchers' work in catalysis could aid drug development

More information: Stephen K. Brand el al., "Enantiomerically enriched, polycrystalline molecular sieves," PNAS (2017). www.pnas.org/cgi/doi/10.1073/pnas.1704638114

Related Stories

Nanoscopic golden springs could unravel twisted molecules

April 3, 2017

University of Bath scientists have used gold spring-shaped coils 5,000 times thinner than human hairs and powerful lasers to enable the detection of twisted molecules, and the applications could improve pharmaceutical design, ...

New catalysts mimic human vision

March 21, 2017

Photoreceptors in vertebrates typically consist of two separate colourless parts: an organic pigment and a protein. Combined, they create a colourful, light-sensitive molecule called an iminium ion that triggers vision upon ...

Recommended for you

World first: New polymer goes for a walk when illuminated

June 28, 2017

Scientists at Eindhoven University of Technology and Kent State University have developed a new material that can undulate and therefore propel itself forward under the influence of light. To this end, they clamp a strip ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

FredJose
5 / 5 (1) May 02, 2017
Wow, wow, wow!!!!
This is brilliantly excellent news!
The possibilities are vast - from biomedical applications to increased efficiency in power engineering. This is indeed a wonderful end-result of 30 years of research.

Watch this space for some truly mind-blowing new creative applications.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.