Have you ever wondered how people build such crazy structures with LEGOs? Rube Golderberg machines, the Eiffel Tower, the Taj Mahal—these are just a few of the things that individuals have created. Perhaps surprisingly, LEGO architects and chemists have quite few similarities. The same inquisitiveness that we all remember from our childhoods playing with LEGOs goes a long way towards advancing a chemist’s work. Patience, dedication, and planning are all required to pull off the successful completion of both kinds of projects. They both work with tiny building blocks, too, although chemists take the cake there. Chemists can work with materials 200,000-times smaller than a standard LEGO brick!
The workhorses of a chemist’s reaction repertoire are catalysts. These materials make chemical reactions run faster. In fact, catalysts are essential to life as we know it. Many of the things we take for granted—plastics, clean water, fertilizer for our farms and the catalytic converters that make sure our automobiles don’t suffocate us—are all possible thanks to catalysts. In many chemical reactions, the catalyst gives an assist so the star player can score all the points.
While they may not seem related at first glance, chemistry and LEGOs have something important in common: both material systems and LEGO towers are built from basic building blocks that have order and structure. But to look into the structured world of chemical reactions, we will have to shrink ourselves. This is because the length of individual molecules is on the order of nanometers—or about 10,000 times smaller than the tip of a needle. (A lot of times, things that have a huge impact can come in little packages.)
Now, when building LEGO castles that large, flat, green LEGO sheet serves as our foundation. It provides stability and allows us to build amazing structures on its surface. Trying to build without this part—say, trying to build a tower directly on the carpet—will make the structure very unstable. Chemists also need foundations upon which to build their material structures. These are called substrates. A substrate helps to make a chemical compound stable so that all sorts of interesting reactions can take place. (Chemists that work with catalysts a lot call the substrate a catalyst support.)
Think of it like DUPLOs and LEGOs. DUPLOs and LEGOS can be used together to build things, but not arbitrarily.
When connecting blocks, LEGOs can only be stacked on top of other LEGOs, and are rotated at certain angles. (A LEGO brick will never stick to another if it’s upside down, for instance.)
Also, a DUPLO baseplate has different surface properties than a LEGO baseplate (the trademark “nubs” that lock the blocks are bigger). This means a DUPLO board can only be used for DUPLO blocks and not LEGO blocks.
While a classic, green LEGO board can be used for DUPLO blocks, the fit is not snug and the pieces can be easily knocked off. This base instability isn’t helpful when you’re trying to build impenetrable castles, but it can be detrimental when trying to design stable, safe chemical reactions.
The size of the nubs, which differentiate LEGO and DUPLO—and which also dictate how they connect or interact with other blocks and the base surface—are intrinsic properties. In chemistry, intrinsic properties also limit which materials we can combine.
In chemistry, the substrate, like the LEGO baseplate, will dictate what can go on it. The substrate also determines the orientation and stability of the catalyst. For real catalysts, we must carefully select and assemble compatible materials. We want stable, sturdy combinations and for all our pieces—substrates, catalysts, and reactive chemicals. If we don’t, it could be dangerous or even toxic! We need to choose carefully for everything to work together.
Once you’ve selected the right substrate material, it’s time to start building. As a LEGO architect, you have a lot of artistic leeway, constrained only by the baseplate you choose. As a chemist, there is an equally expansive blank canvas constrained by the substrate you choose. An infinite set of possibilities is out there, waiting to be explored. And the same things that make a great LEGO architect—creativity, good hands and an understanding of how the building blocks work together—also make a great chemist.
Each and every day, chemists and their (often microscopic) work play a big role in making our world run. Although you can’t see their handiwork directly, there are many benefits we enjoy thanks to the development of catalysts. The food you buy at the grocery store was almost certainly grown using fertilizer made with catalysts. When you step on the gas to pull away from the stoplight, your car’s catalytic converter is hard at work keeping the air clean. So think about that unusual, mostly invisible LEGO kit the next time you’re on the way home from the store. The building blocks of catalytic reactions—catalysts, substrates, and chemicals—make it all possible.