So it begins, the story begins in 1864, so a little bit more than 150 years ago, where our ancestors were trying to make CH2.

And to do this, they started from methanol, which is a very simple molecule, and of course if you remove water from methanol, you end up with CH2. And what is interesting, at that time, it was not clear that carbon is always tetravalent,

so CH2 could be stable. It turned out it was not stable, of course. And then they realized, in fact, only at the beginning of the 20th century, that carbon cannot have only two neighbors

with the remaining lone pairs. This is a work by Staudinger here in Germany. However, even if the carbines are not stable, people use them a lot. In the 40s, in the 50s, here in Marburg,

this is a CH insertion reaction, so it started from a carbine, a transient carbine of course, something which has a very, very short life, let's say some nanoseconds, and it trapped it inside a CH bond. So this is a CH bond insertion.

And then some other reactions, just like cyclopropanation reactions that you learn, I guess, in the first year of your study. And then in the 60s, chemists tried to visualize these carbines. And to do so, they have to work at a very, very low temperature. Of course, if you work at a very low temperature,

you can stabilize these species, because they cannot move, and they cannot meet their neighbor, and so they are kind of stable. So if you work at a few K, let's say 4K, 10K, you can see the carbines. And then came the work by A.O. Fisher in Munich,

and he got the Nobel Prize, as you might know, where he was able to stabilize a carbine in the coordination sphere of a metal. So this is the history. And then for many, many years, nobody tried to make a stable carbine,

or those we tried, like Wenzlich in Germany, in Berlin, failed. And then we came, and by accident, I guess, we made the first stable carbines. What is interesting, at the end of the 80s,

when we did this, everybody thought that carbines were curiosities, just toys. And myself, I was the first guy to say it's a curiosity. And it turned out that in 2010, so that means, what, 20 years later, every year,

more than 3,000 papers are published with a carbine. So this is a tremendous expansion of this field. And now, people use carbines in catalysis, transition metal catalysis, organic catalysis, to stabilize reactive species, and this is kind of fun.

You use a carbine which was supposed to be a reactive intermediate for more than a century, and now you use this carbine to stabilize other unstable species. So I think it's very fun. You can stabilize radicals, you can stabilize many, many things. There are even some medical applications.

So, for instance, carbines are used to transport silver in the body, and this is a new important application of carbines. So you think about this. In, let's say, 20 years, we went from laboratory curiosities

up to something that you can find everywhere. Yeah, there are several types of carbines, and it turns out that, in contrast to the first carbine that we prepared in my group,

and it turned out not to be useful, Arduengo's carbines, or the NHCs, the N-heterocyclic carbines, are by far those we are using today. However, there are new generations of carbines coming from different labs, including my lab, of course,

which might be more powerful. The problem is that when a community starts to use a tool, everybody uses this tool, and it's very difficult to explain that there are new tools. You know, there is a good example in chemistry,

not about carbines, but a perfect example. And this is for the polymerization of ethylene, the Zigonata catalyst, all this kind of thing. There are new, extremely powerful catalysts, which are on the market, but no company at all wants to change a process which is 60 years old.

And with a carbine, it's exactly the same thing. In the literature, you have thousands of papers, tens of thousands of papers using N-heterocyclic carbines, and they are commercially viable, and what else? Nothing else. This is just, they are used because some other people used it.

And I think it's really striking. When something becomes fashionable, you have X labs that go to this topic.

And they don't want to go out the mainstream. Having said that, I do believe that some of the carbines coming from my group right now are by far more interesting for many types of applications. And so what we need is to have two or three groups starting to use them,

and then I'm absolutely convinced that hundreds of groups will use them. I mean, this is a human being. Everybody wants to be in the mainstream. That's the only reason I can see.

What is fascinating for me, again, is that carbon chemistry 20 years ago was just a fundamental research. And nowadays, you find this everywhere. So this is what is most important for me.

I think what is really interesting is that 20 years ago, so, carbine was supposed to be unstable. And then came the first stable carbine, the second stable carbine, the third stable carbine, and so on and so forth. And nowadays, you realize that many, many, many types of carbines are stable. It seems that once somebody has discovered a type of species,

then this species becomes available for everybody, stable for everybody. And as I mentioned at the beginning, carbon is supposed to be tetravalent, and there are some rules. For instance, if you have an sp hybridized carbon, it's supposed to be linear.

This is the case for alkynes, this is the case for allenes. Okay, now you can play some tricks. And so, for instance, we recently reported what we call bent allenes.

And the idea is, how is it possible to transform a compound which seems to be rigid, which has to be linear, into something which is very flexible, and which is bent. And once you discover this, then it's easy for everybody to make bent allenes.

So, it seems that you have a kind of energy barrier to find something new, and once this barrier is over, then it's open, and everything seems very simple.

I'm sure there are many examples, for instance, of rare gases. For many years, everybody thought, okay, these guys are not reactive at all. And then if somebody finds a reaction with xenon, or whatever, then thousands of reactions will be discovered.

It seems just like if Mother Nature put a key on a problem, and then, when you open the door, the problem is over. And I think it's something which appeared to me really fascinating for scientists,

to open this door. Think about something else. I mean, the first time somebody walked on the Moon, it was something phenomenal, right? And now I'm quite sure that if the US, or the Russians, or the Japanese, whatever, send a new guy on the Moon, maybe two minutes on the TV,

maybe three minutes, I don't know, and that's all. Just because that has been done. It's open. So, I think this is something fascinating for scientists. So, carbon is just an example. But for me, the most important is this. You have a door, you have a key, or you have to find the right key to the door,

and then you open the door, and the story is over. And my story is over.