Professor Leon Tilley Offers a Lesson in the Chemistry of Life

It is my greatest honor to be standing up here today before you, because I hope receiving the award means I am able to use my own journey through life to make a positive impact by helping you all to enjoy learning and be part of the congenial atmosphere of Stonehill, our wonderful sciences, and especially our amazing chemistry department, which has been like a family to me these many years.   

I really don’t want to spend too much time talking about myself. Let me just say a few things and then I’ll tell you a story about some chemistry. To graduating seniors: you have the privilege of getting to graduate. I’ve been at Stonehill since 1996 and I haven’t graduated yet. Truth be told, I haven’t left school since 1974! To juniors: I really think junior year is the hardest year (the steepest part of the hill at Stonehill – Go Hill!), and to sophomores – hopefully you enjoyed your first year here and are looking forward to another great year at Stonehill and you can pass it forward to incoming students. 

To incoming first-year and transfer students: I’m pretty confident that your first semester at Stonehill will be smoother than mine. I cried when I got my teaching evaluations then! Since I’m standing up here now, I hope that’s a sign that my teaching must have gotten at least a bit better since then. How did I get to Stonehill and how am I up here now? I made some changes, made some choices and chose some pathways to take.

What does that have to do with my chemistry story? I must admit that my colleagues and students would be sulfurious with me if I didn’t say something about chemistry and make some chemistry jokes. But I’ll try not to be too silicon because I don’t want to be fluorine anyone with my bad puns. By the way, silicon and fluorine are two of my favorite elements. Silicon is carbon’s doppelganger and fluorine hides in the shadow of hydrogen and pounces when it’s too late. OK – enough for now – I know I’m triene too hard at any rate. Speaking of rate, what I’d really like to tell you all about is reaction rates and pathways. So, let’s talk about physical organic chemistry. I’m sure that’s all your favorite topic! 

Physical organic chemistry (which, in addition to bicyclobutanes and nitroxyl radicals, is one of my favorite things to talk about) is the study of reaction mechanisms for organic chemistry. Organic chemistry is the study of compounds of carbon (and often their relationship to living systems). Organic chemists study how to manipulate and make those compounds, but a really important aspect of doing so is studying how these processes occur, otherwise known as the reaction mechanism. As part of the mechanism, molecules must interact with each other in the right way – just like we can interact with each other. They must also have enough energy so that when they interact with each other, they can react to form new molecules, otherwise they will just bounce off each other and go their separate ways. This energy is called activation energy. Another important aspect of reaction mechanisms is that when molecules interact, there are often multiple pathways by which one molecule can react with another and become something else – often something new and unique. 

Indeed, you each are on your own pathways to becoming new and unique. You’ve been on your path since you’ve been born; when you look backwards into the past you may see only one path you have followed (there are really many barely visible branches of then-possible tomorrows that have all but disappeared) but when you look into the future there are many new branched pathways – first-years as you start at Stonehill, and seniors as you look forward to careers ahead. 

Since you all have the misfortune at the moment to be my captive audience, let me introduce you to another concept in physical organic chemistry (really a broader chemistry concept): that of the kinetic product and the thermodynamic product. While there are many outcomes of a chemical reaction, two of the most recognized are the kinetic product and the thermodynamic product. The kinetic product describes the compound that is formed by overcoming the lowest activation energy barrier – climbing up the lowest hill and taking the easiest path. It is formed the fastest but is not necessarily the most stable product (or the desired outcome). The thermodynamic product, on the other hand, describes the compound that is the most stable product, but it is not necessarily formed by the easiest route, and greater activation energy may be required to achieve it. However, sometimes a reaction can go backwards and forwards many times (what we call equilibration) so the thermodynamic product can be formed even if not by the easiest route. 

So, do you want to take the path to the kinetic or the thermodynamic product? Sometimes the thermodynamic and kinetic product are the same, sometimes not. Sometimes the kinetic product is desired, sometimes it is not. The right path isn’t necessarily the easiest or the hardest one. How do we know? The answer is, we don’t, the best we can do is try and see what happens. That’s what chemists often do with a new reaction – try just for fun to see what happens. And it is often fun because you never know what will happen. Sometimes good, sometimes bad, but we still have to try. Some of us will find our way right away, others may have to equilibrate several times before getting where we want to go because we won’t know until we get there.  

If you are a first-year student, I would encourage you to explore many different pathways to see where you end up. Try different classes, join clubs, explore different majors and minors. You may find some of these pathways have an easy hill to climb, but you may not find them to be the most interesting; some may be more challenging but more rewarding. You may find something you really want to pursue but there will be difficult barriers to overcome – a high activation energy – you may have to try a few times to get where you want to go. 

But never fear! Help is there in the form of a catalyst! A catalyst is something that speeds up a reaction (in both the forward and reverse directions) by lowering the activation energy. Indeed, we all need catalysts in our lives. Outcomes aren’t always the most important part of the pathway. Just like those molecules that have to collide in the right way, we should consider it important who we meet, who we help, and how we mold ourselves by helping others along the way, as they shape our paths as well. Your parents, your friends, your professors, your coaches, the Holy Cross Fathers, all of the staff and administration and the entire Stonehill community are here to help to make it easier for you to overcome those tough activation barriers (and facilitate going backward if necessary). We never know who will catalyze some of our best experiences in life and who will teach us the most.

If you talk to any of the upper-class students and ask them what the most important thing to do as you start your journey at Stonehill, I am certain many of them will answer that it is to get to know your professors. Please don’t let me sit alone and bored in my office! Come see me! If you talk to any of my students, they will tell you that I love to help and that I’m “diene” to chat about chemistry or anything else! Indeed, I hope my role here has been and will continue to be to make the activation barrier lower for you all. 

Just keep in mind as you start climbing up the activation energy barrier that any goal is achievable, but the pathway often defines and thereby is just as important as the goal. Our Stonehill motto, Lux et Spes, is especially suitable for our journey since you should let light and hope guide you on your way wherever you may go.