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18 HEALTH AND LABORATORY MAGAZINE

NEW LIGHT-POWERED

CATALYST DESIGN MAY

AID IN MANUFACTURING

When coated onto plastic
tubing, the catalysts could act
on chemicals flowing through,
helping to synthesize drugs and
other compounds.

A new type of photore- process of accelerating a two main classes of pho- could incorporate about a the reactants in the poly-
dox catalyst, designed by reaction by using a cata- toredox catalysts, which dozen different homoge- mer make for faster and
MIT chemists, may make lyst. Photoredox catalysts are known as homogene- neous catalysts into their more efficient reactions
it easier to incorporate work by absorbing photons ous and heterogeneous new hybrid material, but than are possible in pure
light-driven reactions into and then using that light catalysts. Homogeneous they believe it could work solution processes.”
continuous flow manufac- energy to power a chemi- catalysts usually consist of more many more.
turing processes. The key cal reaction. organic dyes or light-ab- HIGHER EFFICIENCY
is their insolubility, which sorbing metal complexes. “These hybrid catalysts
allows them to be used “Being able to recycle These catalysts are easy have the recyclability and The researchers also
over and over again. the catalyst is one of the to tune to perform a durability of heteroge- showed that they could
biggest challenges to specific reaction, but the neous catalysts, but also tune the physical prop-
Light-driven chemical re- overcome in terms of being downside is that they dis- the precise tunability of erties of the polymer
actions provide a powerful able to use photoredox solve in the solution where homogeneous catalysts,” backbone, including its
tool for chemists devel- catalysis in manufacturing. the reaction takes place. Liu says. “You can incorpo- thickness and porosity,
oping novel methods of We hope that by being This means they can’t be rate the dye without losing based on what applica-
producing pharmaceuticals able to do flow chemis- easily removed and used its chemical activity, so, you tion they want to use the
and other important mole- try with an immobilized again. can more or less pick from catalyst for.
cules. Harnessing this light catalyst, we can provide a the tens of thousands of
energy requires photore- new way to do photoredox Heterogeneous catalysts, photoredox reactions that As one example, they
dox catalysts, which can catalysis on larger scales,” on the other hand, are are already known and get showed that they could
absorb light and transfer says Richard Liu, an MIT solid minerals or crystalline an insoluble equivalent of make fluorinated poly-
the energy to a chemical postdoc and the joint lead materials that form sheets the catalyst you need.” mers that would stick to
reaction. author of the new study. or 3D structures. These fluorinated tubing, which is
materials do not dissolve, The researchers found that often used for continuous
Now, MIT chemists have The new catalysts, which so they can be used more incorporating the catalysts flow manufacturing. During
designed a new type of can be tuned to perform than once. However, these into polymers also helped this type of manufacturing,
photoredox catalyst that many different types of catalysts are more difficult them to become more chemical reactants flow
could make it easier to reactions, could also be to tune to achieve the efficient. One reason is that through a series of tubes
incorporate light-driven incorporated into other desired reaction. reactant molecules can be while new ingredients are
reactions into manufac- materials including textiles held in the polymer’s pores, added, or other steps such
turing processes. Unlike or particles. To combine the benefits ready to react. Addition- as purification or separa-
most existing photoredox of both of these types of ally, light energy can easily tion are performed.
catalysts, the new class HYBRID MATERIALS catalysts, the researchers travel along the polymer to
of materials is insoluble, decided to embed the find the waiting reactants. Currently, it is challenging
so they can be used over Photoredox catalysts work dyes that make up ho- to incorporate photoredox
and over again. Such by absorbing photons mogeneous catalysts into “The new polymers bind reactions into continuous
catalysts could be used to and then using that light a solid polymer. For this molecules from solution flow processes because
coat tubing and perform energy to power a chem- application, the research- and effectively preconcen- the catalysts are used up
chemical transformations ical reaction, analogous ers adapted a plastic-like trate them for reaction,” quickly, so they have to be
on reactants as they flow to how chlorophyll in plant polymer with tiny pores Swager says. “Also, the continuously added to the
through the tube. cells absorbs energy from that they had previously excited states can rapidly solution. Incorporating the
the sun and uses it to build developed for performing migrate throughout the new MIT-designed cata-
A catalyst is a substance sugar molecules. gas separations. In this polymer. The combined lysts into the tubing used
that speeds up a chemical study, the researchers mobility of the excited for this kind of manufactur-
reaction. Catalysis is the Chemists have developed demonstrated that they state and partitioning of ing could allow photoredox