Copy of VoE_Cristo Sevov YouTube === Cristo Sevov: We've been very interested in polyvinyl chloride. And so this is PVC that a lot of people have heard of. It's everywhere. And so it's just a long hydrocarbon chain. So it's just carbon and hydrogen with chlorides coming off of it every three carbons. And so this polymer is completely useless. PVC is the world's worst polymer. David Staley: Useless! Cristo Sevov: It's been known... David Staley: Because it seems to be used in so many ways. Cristo Sevov: It is. It is now. But PVC has been known for a hundred years. It's only since the late fifties that we've started using it as a plastic material, as a polymer in plastics. And it's because PVC itself in pure form is incredibly unstable. Jen Farmer: From the heart of The Ohio State University on the Oval, this is Voices of Excellence from the College of Arts and Sciences, with your host David Staley. Voices focuses on the innovative work of Arts and Sciences faculty and staff with departments as wide ranging as art, astronomy, chemistry and biochemistry, physics, emergent materials and mathematics and languages, among many others. The college always has something exciting happening. Join us to find out what's new, now. David Staley: Joining me today in the ASC Marketing and Communications Studio is Christo Sevov,  Associate Professor in the Department of Chemistry and Biochemistry, The Ohio State University College of the Arts and Sciences. His lab develops strategies at the interface of homogeneous catalysis and electrochemistry for the sustainable utilization of electricity that is generated from renewable sources. He received the American Chemical Society Catalysis Lectureship Award for the advancement of catalytic science for his group's contributions to homogeneous catalysis. Dr. Sevov, welcome to Voices Cristo Sevov: Thank you. Thank you, David. David Staley: And congratulations on the award. Cristo Sevov: Thank you. It was a fantastic surprise. David Staley: Well, and you'll have to help me tell us what catalysis is. I was just saying I was practicing this all weekend saying homogeneous catalysis. What are we talking about when we say catalysis? Cristo Sevov: Catalysts are these really I think elegant little reagents that we add to chemical reactions where you can take two molecules that you're trying to stitch together into maybe a drug or some other material that we value, and you can mash them together. You can heat them for years and nothing can happen. And you can add this little catalyst, this chemical that can completely change how fast this reaction works. And so you can go from years to minutes for this reaction. And so So, a catalyst really just merges compounds together, it accelerates reactions that don't otherwise work, and so we have catalysts everywhere in our lives. David Staley: And pretty basic to chemistry, I seem to recall that from my high school chemistry many many years ago. This is pretty standard in chemistry. Cristo Sevov: Yes, it is now. It is now I mean, we've been looking for catalysts for just about every single reaction that we run. We're always looking for a catalyst, something that can accelerate the reaction so that we don't have to wait as long; we don't have to use as much energy to push this reaction forward. Catalysts sort of help us with with every facet David Staley: So what specifically do you work on what sorts of catalysts? Cristo Sevov: So we try to use abundant catalysts so catalysts made out of You really inexpensive metals. So nickel, iron, copper compared to the transition metals that come from meteorites and asteroids like iridium and rhodium, right? That are very, very very, very expensive, very rare. And so we try to use these abundant catalysts and try to use them for reactions that people in the pharmaceutical industry would be interested in. So that they can make drugs more inexpensively. We also have a lot of different applications for plastics upcycling that again, use cobalt, which is a relatively inexpensive metal, again, compared to its more expensive brothers of rhodium and iridium. So you can use catalysts for just about everything. David Staley: You also correct me if I'm wrong. You also use electricity as part of this process. Cristo Sevov: That's our secret sauce. David Staley: Well, I'm really eager to hear more about this. Cristo Sevov: Yeah. So, for the longest time, the way people have used catalysts is they kind of sprinkle in these metals and then those metals interact with each of the molecules that they're looking to combine. And the way that they push these reactions forward is by heating them. So it's sort of thermal energy that they're introducing into the system and you can heat it to hundreds of degrees. That's kind of how the Haber-Bosch process works for us to make ammonia from nitrogen and hydrogen. And that's how I think 5 percent of the global energy that we use is used just for this heating process to then make fertilizers for all of our crops, right? So our approach is instead of heat or thermal energy as the way to push reactions forward, we use electrical energy, which we can harvest from solar power, wind power. And when you use electricity, you can do some things that you can't normally do with just heat alone, because electricity moves electrons around by definition. And so you can get to some really unusually reactive catalyst intermediates that you wouldn't be able to make otherwise by just heating something to death. And so our program is kind of studying what happens when you rip out an electron, what happens when you jam an electron into these metals: are they going to do something different and access some new reactivity that we haven't seen before? David Staley: Wow, I want to hear more about that process. How do you move electrons or what do you say, jam them in? That that sounds, oh, man, that sounds like Oppenheimer type stuff. Cristo Sevov: Yeah, not really. So, electrochemistry is actually one of the first reactions that has been developed in the late 19th century. People have been using electrochemistry. We use it for some of our largest scale processes. So, any time you make chlorine gas, people are taking salt water and electrolyzing it. These are all these electrolyzers. But really what you're doing is you have two electrodes, a positive and a negative electrode, and you use some form of energy to make one electrode positive and the other one very negative. And so at the very negative electrode, anything that bumps into it is going to start accepting electrons from it. Anything at the very positive electrode, anything that bumps into it will have its electrons taken out. So it's just this kind of polarization that allows you to push electrons around as you wish. David Staley: You had mentioned some of the specific applications we're working on. I'd like to hear more about these pharmaceuticals and plastics. Give us. Cristo Sevov: Yeah. So we have quite a few different programs. We have different subgroups, but all of it is kind of focused around this core concept of electrochemistry or electricity pushing catalysis around. And so for the pharmaceutical side of things, we're really developing the tools for pharmaceutical companies to then be able to make molecules inexpensively. So we like to think of chemistry as Legos, where we have this molecule and this molecule, and we want to snap them together and make something that might be physiologically active. You kind of have to test a million different Lego combinations before you find the right drug that doesn't give you all the side effects that you're trying to avoid, but fits perfectly into this binding site. And so we developed those Legos, those Lego strategies for connecting and disconnecting molecules. And so one of the things that we're really working towards is taking compounds that are shelf stable or that you can buy off of any supplier company very inexpensive, stable, abundant molecules and be able to use those directly for pharmaceutical drug design. Instead of having to take those molecules that you can commercially access, those inexpensive ones, and then you have to change them through some series of reactions into a more reactive form, and then use it. So, all of these additional steps generate waste, they waste time, not just chemical waste, but user time. All of that adds cost. And so if we can go straight from the supplier chemistry chemicals directly to the end product and skip all of those steps in between, that would be a very elegant and attractive and sustainable way of performing chemistry. David Staley: So does this mean as you develop these strategies, are you doing this sort of at a theoretical level or through trial and error in an experimental way? Cristo Sevov: Both. So we start with a theoretical concept. We say, this would be a fantastic reaction, if we could combine these two things, that would really skip these four steps in between and get us to the same place. That's as far as our theory goes. And, you know, we'll look at and say, well, this molecule might react with this type of metal catalyst. And so that gives us an idea of whether we should choose copper or nickel or iron. But that's about where it stops. And then from there, it's really just kind of trial and error, ideally using a good chemist's intuition of saying, well, this solvent should work best. These electrolysis conditions might be the first place to start. So. It's both, but it's certainly a lot of trial and error. We run thousands of reactions before we publish a paper. And in that paper, there are maybe 50 reactions that we show of we've figured it all out. Here's the end result. You can use this godspeed. David Staley: Can you mention one of these pharmaceuticals or something specific? Is that, are you at liberty to do that? Cristo Sevov: Yeah. So our job isn't to make the pharmaceutical. Our job is to make the tools to make the pharmaceutical, right? So, we have recently developed, in addition to these catalytic processes, we've developed this strategy that we're very excited about, where we mount a metal complex directly onto some drug like molecule or a prodrug. And so, these molecules are very complex. They have atoms everywhere, all sorts of different functional groups, and we can install a metal complex as kind of just a placeholder, that then allows you to stitch on just about any other functional group onto that site where that metal complex is. And so the idea is we can make these metallo drug combinations where the metal is bound to the pro drug. It's in a bottle. It's a solid. A pharmaceutical company can then take it, weigh it out into maybe a 96 well plate where there are 96 wells, and then add 96 different molecules that you want to stitch onto that site where the metal is. And then using electricity, you activate the metal that's bound to the prodrug, and it stitches on the second reagent that you've added. And so in one shot, you now have 96 new variants of the drug that you're trying to develop of this prodrug. And so then you can take an assay it. So it's a very rapid way for drug diversification to then explore what we call new chemical space. So we think of, chemistry as, oh, we can make these molecules with the synthetic tools that we have. With this pro drug metal combination that we have, we can now do a lot newer reactions that you can't otherwise do. So now you can maybe access that top right corner of chemical space that we've never been able to make those compounds before. Maybe they'll have new activity that we don't see before. So this is something that we've been working on with a few different pharmaceutical companies. David Staley: Chemical space, almost like a map of possibilities. Cristo Sevov: And we map it in a two dimensional map. That's right. David Staley: Like you're an explorer. Cristo Sevov: Yes. We like to think so. David Staley: So in a sense, you're not making the pharmaceuticals. You're making the design, as it were. Is that a fair statement? Cristo Sevov: The tools. The tools to make the pharmaceutical. David Staley: Are those tools patentable I mean, is that the commercializable product? Cristo Sevov: Right. They are. They are. So it's kind of a balance because we obviously want to protect a lot of the work that we develop but at the same time we're in academic chemistry because we want people to use the chemistry. And so we have patented and protected the IP of the pro drug this strategy and what complex it is that you mount onto the drug but , we share a lot of it. We give a lot of different companies when they ask us, we sort of like trial packs for them to use. So yes, it is certainly patentable. We have protected a lot of it, but it's a fine line between use and protection and red tape and things like that. So David Staley: How about your work with plastics? Cristo Sevov: Yeah, that's something that we recently have started, maybe in the last three years or so. And so there, we think of plastics as large organic molecules. So plastics are polymerized organic molecules. David Staley: Polymers. Cristo Sevov: Yes, exactly.* *Polyethylene. Ethylene is a small organic molecule. So we've been very interested in polyvinyl chloride. And so this is PVC that a lot of people have heard of. It's everywhere. And so it's just a long hydrocarbon chain. So it's just carbon and hydrogen with chlorides coming off of it every three carbons. And so this polymer is completely useless. PVC is the world's worst polymer. David Staley: Useless! Cristo Sevov: It's been known David Staley: Because it seems to be used in so many ways. Cristo Sevov: It is. It is now. But PVC has been known for a hundred years. It's only since the late fifties that we've started using it as a plastic material, as a polymer in plastics. And it's because PVC itself in pure form is incredibly unstable. These chlorides, if they're exposed to a lot of heat or a lot of UV radiation, the chloride starts to pop off and then the whole polymer sort of falls apart, releasing all sorts of nasty chlorides and acids and things like that. It's only once you start adding plasticizers, stabilizers, impact modifiers, other sorts of additives to this polymer. So these are all organic molecules that you kind of mix in with the PVC polymer. You melt it all together. And then you now have this new formulation of a plastic that has these other molecules embedded in it. And so that's what gives it the stability. It doesn't fall apart because these additives are there to sort of protect it. So that's all great. And because of that, we use it for medicinal applications or storage of blood and for toys and car parts. But the problem is all of these additives that you've mixed in, they can start to leach out. They sort of migrate within this mixture. And that's what gives you the nice new car smell. Those are all volatile organics that are coming out of your dashboard. David Staley: You just spoiled it for me. Cristo Sevov: I'm sorry. That's why eventually it disappears. They've sort of from the surface, they've all sort of evaporated. And so this leads to quite a few problems because as those, critical additives leach out over time, the PVC plastic sort of regresses back to what it was, which is pure PVC. And then you start getting sloughing off of that pure PVC layer to then expose a fresh layer of the additive mixture. Those additives leach out and then PVC kind of falls apart. So you get all of these microplastics that come off. You get just a shortening of the lifetime of PVC. So, one solution that we've thought of and that others have been working towards is how do you directly or can you directly attach the plasticizers, all of these critical components? Can you with a bond attach them to the PVC polymer so that they can't run away, right? Can't migrate away. And so because there are all these chloride sites on PVC, it gives us sort of a perfect site to modify and functionalize using the same catalysts that we had developed for pharmaceutical modification, where we take alkyl chlorides, these are organic chloride molecules, and we functionalize them. We make new drugs out of them. Well, now we have the ultimate alkyl chloride, the ultimate organochloride, which is this poly chlorinated polymer that we use our catalyst on. And with electricity, we can activate the catalyst. It clips off a chloride and then stitches on one of these additives, a stabilizer, a plasticizer. And so we have this great control over how many grafts or how many attachments we make by just how long do we electrolyze. So with the computer we have this ultimate control. And again, the key is the catalyst. You can mix the plasticizer and the PVC, they stay together for years. They never make a bond. It's only once you add this tiny bit of cobalt with electricity that allows the metal to clip the cobalt and then stitch on the plasticizer directly to it. So that's kind of the, again, catalysis in a nutshell. David Staley: And is the idea to make PVC more useful? Cristo Sevov: To make it more robust, David Staley: More robust. Cristo Sevov: There are a lot of applications where you can't use the best types of PVCs, the most stable forms of PVC, because maybe it comes in contact with our food, or it comes in contact with blood or it comes in contact with other sort of medicinal or physiological applications that we can't have a lot of these plasticizers that work really well. We can't have them leaching into our food, leaching into our pharmaceuticals. And so if you covalently bind them, you now have more robust PVCs that you can use for these applications that have to use the sort of second and third rate additives that might be less harmful But they also create a less robust plastic David Staley: A moment ago, you said you use computers and I don't know, it might strike some listeners as odd that a chemist is using a computer. In what ways do you use computation? Cristo Sevov: So, it's not really computation. We do some computation where we try to model how the catalyst might interact with maybe the vinyl chloride or with a pharmaceutical. We really just use computers to tell our electrolyzing machines how many electrons to move around. This is control that a chemist doesn't usually have. Usually you mix things together, you heat things and you kind of hope for the best. But now we can say, okay, you pass exactly this many electrons. And when it's done, the reaction is stopped. There's no more reaction. So the computer is really just a way to control our electrolyzer and other instruments. David Staley: This new, or is this a recent development or is this something that chemists have always relied upon. Cristo Sevov: So we've always used computers for, electrolysis. In fact, since electrochemistry is a pretty old field in general, and it's been really interesting how it's kind of come back. It's now in vogue, even though it had been done for years and years, the French, the Soviets were fantastic electrochemists kind of in the 70s and 80s, and chemistry just kind of has this sort of spiraling way of coming back to itself where we learn something new, a new technology opens up or a new field is developed, and then we kind of spiral back and we say, what happens if we apply electrochemistry to this new thing that we learned? And so in the 2000s, I think we really got a great grasp of how metals work as catalysts. We really understood them. In fact, when I was a graduate student, that was my entire PhD. And after that, I was like, okay, I kind of get what metals are going to do. It's pretty predictable at this point. But now what happens if you start moving electrons around? And that really sort of drew me back to electrochemistry to, combine the two things together. So it's a very old field, and computers have always been the tool to kind of control these electrolyzers. David Staley: A moment ago you used the term a chemist's intuition. And I'd like you to say a little more about that. What is the chemist's intuition? Again, I'm a little surprised you're a scientist talking in terms of intuition. Cristo Sevov: Yeah, you kind of, it's interesting, you kind of get a feel for things that It's sort of the magic of doing something for 10, 000 hours. David Staley: Again, I'm not expecting to talk about magic. Cristo Sevov: Well, there is a lot of magic, where you just hope, there's a lot of hope when you run 1, 000, 2, 000 reactions and you're hoping that one of them will come together. It's really the result of working in a field for a long time and seeing and learning from your mistakes, learning from the literature. It's incredibly important for my students to read the literature so that they can say, this works best with that. I should try these conditions for this, et cetera, et cetera. So that's the intuition is really, really experience, right? There's nothing more than that. David Staley: So is this something you can teach your students or is it is it really just you have to give them the experiences? Cristo Sevov: They have to go through it. You can't tell them every single condition in the world. I mean I can stand during group meetings for the next year spouting out different conditions. None of it's going to stick until they read it themselves, until they try it themselves, until they see the impact of this and this and this combination, how that works, and those don't. So it's really their responsibility to figure it out. They have to build it themselves. I can guide them, but they really have to put in the work. David Staley: Tell me a little bit more about your lab. Both well, everything about it, I suppose, not just the kind of work that goes on, but we're not in your lab right now, our listeners, of course can't be there. Help us visualize what your lab is and how it works, how it functions. Cristo Sevov: Yeah. So it's a beautiful space. First of all, we're in the nice new building at Ohio State. So, the lab, it's completely run by my graduate students and I haven't run a reaction in five years. I sit in my office. They give me results. I get excited. So the lab has separate office spaces where they work on their computers, planning out their reactions and writing up results. And then when they're set with what they're going to test, they go just outside of the office and there they have hoods, which , imagine your kitchen where the vent is always sucking up air and there's kind of a sash, a screen that prevents stuff from splashing onto you. And in those hoods, that's where they set up a lot of these reactions. That's classically how you do it, but we of course need electricity. And so we have a bunch of wires that drop into the back of these hoods so that students can clip on positive and negative leads. And then all of those wires get plumbed into sort of almost like an audio jack, like an audio system from the pre wireless days, where you have all these plugs and you then use the computers that I spoke about to program exactly how many electrons to pass into your reactions. So we have a lot of equipment for doing all sorts of chemistry. David Staley: You said you haven't conducted a reaction in five years. So, what do you do? What does the director of the lab do? Cristo Sevov: My job at this point is more to check base with students to provide guidance. We have weekly subgroup meetings where the plastics subgroup gets together and I oversee what they've been doing. They have PowerPoint presentations on these are the things that I tested and I say, well, what about this? Maybe you should try that. And we kind of have this discussion about results, good and bad. It's very important to talk about negative results. Those are probably more important than the positive results. David Staley: Why do you say that? Cristo Sevov: Well, it sort of shows you the limits of your current chemistry, right? If you just have a bunch of positives, that's not enough. You need to know just how far can you go. How fast can this reaction go? How low of a catalyst loading can you use? What is the bare minimum that you can get away with so that you can make this process as efficient as possible as renewable and sustainable as possible? David Staley: Hmm. We sometimes say in design that we learn a lot from failure. We're not afraid of failure. Cristo Sevov: Yeah David Staley: Sounds like it's something similar. Cristo Sevov: Yeah, it's incredibly important. That's actually one of the main frustrations with publishing because publications really have just the results that work. I told you we run thousands of reactions and then publish 50 but chemists are getting into machine learning about trying to do predictable chemistry to almost augment this intuition that I talked about. Instead of me , having some idea of maybe this will work without being able to properly articulate it, now you can have a neural network that provides some guidance to, oh, you have this reaction that you want to try? Well, here are the first ten things that you should try. But in order to build that conceptually, you need negative results. Right? Otherwise, this system that you feed all the data to, all the publications that get fed into this, it's just gonna say, well, everything works, so everything's gonna work. You need the negative results for it to be able to identify the limits of each process. David Staley: I'm very interested to know, did you know when you were a boy that you were going to be a chemist? Cristo Sevov: No. David Staley: You didn't. Cristo Sevov: No. I always loved to make things. I started off as a math major math and physics. And then I just loved the chemistry research because I loved working with my hands. I loved making things. I loved getting instant results and seeing things work or not work. So it's all about just making things. That's what we do all day. And I didn't really have that access in the other sciences, I guess. David Staley: So that's why you're not a mechanical engineer. So Cristo Sevov: I guess not. I also love sort of the basic science of it. Engineering is sort of taking chemistry to the next level and optimizing a lot of what we do. I think of it as like math is the first thing, and then physics takes math into the scientific realm and then chemistry takes physics into the practical area. And then engineering takes chemistry into the actual industrial age. So I like that chemistry level where it's not too applications oriented, not too basic science. We get to make things, and then the engineers can make them better. David Staley: Why the particular problems that you work on? I'm curious to know where the idea came from to work on the problems that you do, of all the problems you could work on in chemistry. Cristo Sevov: Yeah. Yeah. So as I said as a graduate student, I worked in catalysis which I thought was this really elegant field of designing something that makes reactions happen that don't usually happen, and we got to the what I thought was maybe the kind of the edge of catalysis, where we have a great understanding of it, now what? And at that point some new technology started coming out where people started using light and these sort of secondary catalysts to move electrons around to again, pull electrons out, push electrons into metal catalysts. And the catalyst started doing completely unpredictable things that I thought I'd understood catalysis, and clearly I have not, and I had not. That was all light driven, and so I started thinking about what are other ways to move electrons around? Well, electricity, how can I learn about electricity? And I got into a post doc working on batteries, and these large scale flow batteries, where the idea was to learn about electrochemistry, learn about electricity properly, but kind of keep my ear to the ground of chemistry. So the group that I worked with, they were pure catalysis oriented students and the PI I kind of had my sort of separate subgroup where I could work on batteries and then still kind of keep an eye on everybody else. And the idea was always to merge the two things together to do this electric catalysis that we're doing currently. David Staley: At least a couple of times in our conversation, you've described catalysis as elegant. Mm hmm. Could you say a little more about what that means to you? Cristo Sevov: It allows you to perform a reaction that is otherwise impossible or would take years. Okay, fine. But the more interesting thing I find is that once this tiny bit of metal, or it could be some organic catalyst or whatever, once this catalyst activates one of these reagents and then spits out a product, the catalyst regenerates itself so that it can do it again and it can do it again. And so with ideally with one molecule of catalyst, you can convert all of your starting materials to product and it'll have just done that reaction tens of millions of times. And so I think that's the elegance where it regenerates itself. Not only does it completely accelerate this reaction that you couldn't do before, but it also regenerates itself at the end and you can collect it at the end. So designing something, a catalyst that can do all of these steps in order to make the product that you're after and then spit itself back out to do it again, I think is just very, very beautiful. David Staley: Tell us what's next for your research. Cristo Sevov: Oh, we've been doing this now for seven years, which is kind of remarkable how time flies. We have a lot of work to do with designing new reactions that people might be interested in. And we really want to push this plastics idea of just what can we do with these new materials that we make? What are the properties of these new materials? And then we also have a energy storage program where we've been building this new concept for grid scale energy storage. So they're the David Staley: Electric grid. Cristo Sevov: Electric grid, right. Where we harvest a lot of renewable energies, but we actually can't use all of them when they are available. So the real goal is to, to dump all of that extra electricity into a battery and then use it at night when the sun isn't shining, but people want to turn their lights on. And so we've been developing some organic batteries some new concepts for very inexpensively making batteries bigger, scaling them, so that somebody can basically implement these in a stationary place, not try and put it in your car. But that's something that we really want to push forward with. And again, it sort of uses this concept of catalysis where something is regenerated and it charges this external solid material. David Staley: Why has this been such a challenge? Building batteries like this. I mean, all know that we need, storage batteries. What's the source of the challenge? Cristo Sevov: The chemistry still needs to be developed. The physics is there. Now, the chemistry of finding the right molecules that can store this electricity, store this energy for long periods of time without decomposing. Those molecules need to be sourced from a sustainable source, so they can't be metals There are some of these stationary batteries that are currently commercial or based on vanadium. Vanadium is a metal. But even though it's a relatively inexpensive and abundant metal, there isn't enough vanadium in the world to power most of the major cities in the U S. So ideally these storage materials would be from organic compounds that you could get from petroleum by products or from refinery by products. So designing molecules with these very strict limits of you have to use these molecules. The molecules that you make have to operate at these voltages. They have to have these lifetimes in the charge state. They can't just decompose. That's a, pretty major challenge. So then once you do find candidates that might satisfy these requirements, then it has to go up to the next level of engineering. So that people can make this on a huge scale, test these in flow. Sorry, I should say these are flow batteries where we take the organic compounds and they're in solution and you actually flow them through a big reactor and that's how you extract the electricity back out. It's much easier to explain with a, PowerPoint. I've never had to do this. discussion only. The challenge though is really designing the chemistry that can be robust enough for, a worker making this on a huge scale and then having it sit out in the Arizona sun for years, charging, discharging, heat cycling without decomposition. There are a lot of challenges to that. David Staley: Are you optimistic? Cristo Sevov: Yeah, absolutely. I wouldn't be in this if I wasn't optimistic. David Staley: Cristo Seboff. Thank you. Cristo Sevov: Thank you. Jen Farmer: Voices of Excellence is produced and recorded at The Ohio State University College of Arts and Sciences Marketing and Communications studio. More information about the podcast and our guests can be found at go.osu.edu/voices. Voices of Excellence is produced by Doug Dangler. I'm Jen Farmer.