 Okay, so with that, how about we get started for today? I'm going to talk to you about pigments and colors and dyes, oh my, some of the chemistry behind the colors we see. I've got some photographs I've taken and then photographs I've rated from various places on the internet. This particular slide, I've got some daisies and a rose of Sharon from my own backyard. I had the flu last week, so I still got a bit of bronchitis this week. I apologize for coughing occasionally, but it's all for the best, believe me. Okay, so humans like art, we've been drawn graffiti in various places for thousands and thousands of years. Here's a lovely example. This is a bison drawn in red ochre from the famous Altamira Caves in Spain. It dates to about, oh, close to 18,000 years ago. And it's done mostly in red ochre, which is hematite or iron oxide, the regular old orange iron oxide, rust. And this image is public domain from Wikipedia, hopefully public domain. So we also have been doing pottery for a long time. One of the distinct types of pottery from ancient times are the black figure vases and the red figure vases from ancient Greece. And there's some wonderful chemistry associated with these pots. The red is essentially the same red that made up the bison in the last slide, iron oxide. The black is a slightly different iron oxide. It's an FE-304, which is the composition of magnetite. It's, you know, in FE-203 you got a pair of iron 3 pluses. In FE-304 you have a pair of iron 3 pluses and an iron 2. And the amalgamation of all of those ends up changing the color absorption profile. So it absorbs all the light instead of just the light that allows you to see red color. And these pots are wonderful. They basically show a very sophisticated knowledge of firing, basically taking the clay and baking it so that it chemically changes into a different state. So essentially, you know, to make one of these, first you have to make a clay pot. And then you have paint. I mean, I've got paint and quotes there. Figures on it with a slip. A slip is a dilute clay. It's got a larger particle size. It may be a different clay. It may have different pigment sand. For the black figure vases, there's a lot of scratching of details into the figures. And first what they do is they fire the pot in an oxygen-rich atmosphere at 800 degrees. That makes the entire pot bright red. You can't see any of the figures on it. And then they raise the temperature and throw in green wood. This makes carbon monoxide. And the entire pot turns black with the formation, the transformation of the rust iron 2 oxide into this magnetite. And I say almost smelting here because CO and carbon and low oxygen at these sorts of temperatures are very reminiscent of modern smelting techniques. So this is the knowledge that goes into them. Finally, they let the kiln that the stuff is done in cool back down. The thing about the 950 degrees Celsius is that the slip basically turns into a glass and it protects the black color from interacting with air. Whereas everywhere else on the pot, if it turns black, it reoxidizes to the red form. So this is very sophisticated stuff and here's this particular objects in the British Museum. Another example, it's called the siren vase. It's also in the British Museum. It's a more advanced technique but it's still the same sort of three-stage firing process. Notice how the figures here are red and have a little more fine detail. Why am I showing you pottery when this is a chemistry talk? Well, so far I think I convinced you that the potteries just developing the colors on these does involve a lot of knowledge of materials. In 2004-2005, I used to have a class, chemistry and art, that I taught to our honors students. It was a great class. The unfortunate thing is that I lost most of my content for that class when I had a high drive die on me. So this is an attempt to bring back a lot of the content that I used to have. So continuing, hey, let's get the question out of the way first. What is a pigment? What is a die? Well, they're both colored compounds and usually what people say is the difference is solubility. Does one dissolve, does another dissolve? Pigments are the ones that are generally not soluble, at least in water. Dyes are generally soluble, but they need to be anchored to whatever is being dyed, the cloth or whatever, through the use of additives. And these are called mordents often. I'm not really going to talk about the dyeing process in this particular talk. There's so much content for chemistry and art that I'm planning a series of talks in the next coming months for this. So here's some photos. This is from the St. Louis Art Museum in 2003. They had a lovely display of pigments from their Renaissance. And so I've got a few pigments. I think my laser pointer is showing up. That's actual silver. That little one is actual copper. I've got matter, coca chanel, carmine, gum, arabic, and indigo. We'll talk about indigo a little bit later in the talk. So, during the Renaissance, we had a variety of both organic dyes and pigments and inorganic dyes and pigments. The inorganic ones tend to be a bit more robust and might survive being put on pottery, for example, and firing up to 900 degrees Celsius. I don't think indigo would survive that. It would basically turn into carbon dioxide and water. I've got speed bumps. Here's some photos from my lab. This is cyclopentadienyl bistrofenolphosphine ruthenium chloride. Look at the beautiful orange crystals. Yeah, okay, it's a speed bump. So let's talk, and the speed bumps mark transitions in my talk. So one of the things that if we're going to talk about color, we have to talk about light. So light is just one form of electromagnetic radiation. And one way of quantifying the electromagnetic radiation is just to look at the wavelength of the photons. And photons can be emitted with wavelengths, radio waves. There's like 10 to the third meters. That's like a kilometer long. I don't know if any radio stations actually use that sort of wavelength, but it exists. Microwaves are like seven meters long. Infrared are several microns long. Now the visible light is about half a micron, half a micron or so. If we use nanometers as our measuring unit, so a nanometer is one billionth of a meter. So there are 10 to the 9 nanometers in a meter. Well, 400 nanometers to 800 nanometers is what's visible light. So this little region down in here where you can see the familiar Lloyd G. Biv of the visible spectrum. So shorter than that we have ultraviolet, and there's a couple of different flavors of ultraviolet. UVA, UVB, UVC. Shorter than that we have x-rays and gamma rays. And interestingly, all of these frequencies can give you some chemical information. Okay, so Sysigie is telling me that radio waves in the AM band are 200 to 600 meters long. Awesome. So, okay, I circled down here. I circled down here where the visible region is, kind of in the middle of all of this electromagnetic radiation. If you could see in the UV, like bees do, flowers would look very much different. So essentially, everything you see is just in this tiny little region over here. 400 nanometers is the violet end of the spectrum. 800 nanometers is the red end of the spectrum. And many of the familiar primary colors you know are in the middle here. Okay, but that's not every color we actually can see. So, one thing to remember about color is that your perception of color is constructed within your brain. Okay, so there's a little bit of physics involved. The eyes focus an image on a retina. So, the retina is your detection device. Just like the diode array device, charge transfer device, I guess, in the cameras in your phone are, you know, what a lens focuses an image on. You know, that part of the physics is pretty similar. There's cells in the retina that react to light. They actually have dyes. Lodopsin is one dye and there's a variation on the theme of Lodopsin. What Lodopsin does is it changes shape when light interacts with it and eventually it changes back. The shape change causes the specialized cells to send signals to nerve cells. So eventually the photons falling on your retina cause nerve cells to fire. That transmits information to the brain and your visual centers process the image to perception. So, you know, besides just the physics of the outside world, your perception of color is individual to you and constructed within your brain. I know there's a lot of philosophical debate about whether what I see as red means the same sort of thing that you see as red to you. I usually sidestep that and say, well, you know, we're kind of constructed the same, so hopefully my red and your red are similar. Unless, of course, like my partner, you have red-green color blindness and then my red and my green might look the same to you. Okay, so color is constructed in your brain. Here's more of a view. Notice in all of these slides I've tried to be good about making attributions. If the text is too small to see easily, it's probably attribution text. You don't need to see it right now. I'll make a PDF of this available when my chat is over. I forgot to do that this week. So light falls on, let's see, light actually falls on the retina and the retina is constructed so that the light sensitive cells are contained in these rods and cones. And the light actually has to go through a set of nerve cells before it falls on the rods and cones and then the nerves take the signals to the main optic nerve. That surprised me. I would have thought it would have been easier to have the rods and cones on the outside. Yes, I agree with tagline here. So here's the thing with playing with your brain. So keep your microphone off. This is a freshman psychology experiment. If you could look at these words and name the colors. Do not read the words out. So the first one in the list is not red, it's green. There's a bit of a cognitive distortion that happens because the word red is screaming in your brain as you try to say green. So when I say green, purple, blue, brown, yellow, red and blue, that's fine as fast as I can do it even though I practice because it's screaming in my brain. Red, orange, yellow, green, blue, pink, brown. So the brain can be fooled. Perceptions of colors are something that we can play with. Yeah, it would help to be illiterate with this one. This is actually something I do for my freshman chemistry class when I'm trying to get them comfortable with maybe not knowing something or maybe not being able to find the right word. It's like, okay, everybody has brain fart moments. All right, moving on, moving on. Hey, the perception of colors constructed in your brain, but it has certain elements to it. The rods are sensitive to light, but they don't give so much wavelength information. They are very good for low level, low levels of light, and they give you kind of black and white information. There's three types of cone and each is sensitive to a different wavelength profile. And that's what I've shown here. So we've got on the x-axis of this graph, 400 to 800-ish, and the different profiles of the cones are shown. There's one that's very sensitive to the blue end, and there's two that have a surprising amount of overlap. So I think, you know, if you have anything long with either one of those, then it becomes difficult to distinguish between the red and green end of the spectrum. And, well, so I'm a chemist. There are several theories about how the brain assembles all of this information into the perception of color. I think this would be a wonderful talk for someone who actually knows what they're talking about. So, let's see, looking at the nearby chat, Susagee, I guess that the rods and cones are at the back to retina because those cells are sensitive to pressure. So it makes sense to protect them by not having, yes, okay, cool. My understanding of physiology and how things are put together in the body is, I mean, I can grind someone up and tell you what they're made of, you know, how all the bits are put together. That's beyond me. So, attributions for the psychology section. I'm trying to be very good about making sure that, you know, I have no plagiarism here. I actually read the Creative Commons attribution licenses, and so authors and where it is, and the actual link that will be in the PDF, you can click on it when you get it. Here's another speed bump, some photos I've taken. The tree on the left is in my front yard. It's a maple tree. It turns this glorious red, orange, yellow, and green at times in the fall. Another orange speed bump, that's Seth, where my little laser pointer, he's asleep next to me. We made some elephant. This is something from my lab. One of my students made this stuff. It's something stirring around in ethanol. We filtered it off. Beautiful orange color. Here's some more orange stuff. The only stuff I'm making in my lab is orange and red. I really like it when I get a blue sometime. So I'm going to talk about blue stuff later in the talk. And again, the Daisy's Black Eyed Susan, I guess, is what we call them. That's from a backyard. So how do we get colors? Okay, so we can get colors from both more physical techniques or more chemical properties, physical properties of molecules. And I'll talk just a little bit about dispersion and interference. I do want to note there's a lovely video of how soap films give you rainbow colors by Paul Doherty. Paul was a giant here at Science Circle and we all miss him. So I've got two. Maybe I can hunt those down and put them in. Yes, got them. Okay, I'm hunting down the links and I'm going to copy them, put them in local chat so you can see them at your leisure. Moving on with the first thing I was going to talk about, dispersion. These are related to refractions, butterfly wings and other feathers and many other biological samples rely on dispersion to give you colors. Colloidal solutions can give you colors. So I was going to put the Pink Floyd album here, Dark Side of the Moon. And if you're lucky, I won't sing any of it for you. But I was also worried about copyright infringement and stuff like that. We don't want our videos to be taken off of YouTube for silly reasons like that. So here's one that's reminiscent. It's basically white light going through a prism being split into the different colors. Essentially each wavelength reacts a little bit differently to going from air to glass slows down and they're a little bit differently. And the angle that it gets deflected by is slightly different. So what comes out is the colors all spread together, spread apart rather than together. Dispersion can do some wonderful things. This is the Lysodris Cup. These are images from the British Museum site. And in fact I can copy those into local chat. So if you're interested, you can just grab the local chat later, enter. And the thing about the Lysodris Cup is that it looks different depending on where you put the lamp. So by reflected light, it looks like a greenish cup. So this cup was actually carved from a single block of glass. And it's got a couple of wonderful things about it. The colors are wonderful. Thus the craftsmanship in this carving because you can see the snakes on the side are almost completely detached. You can see it clearly on the right hand image. They're almost completely detached. But this was all carved from one single piece of glass. It wasn't, those snakes weren't attached later on. So that's a wonderful thing about this. It is worth a visit in real life. I'm hoping to get to the British Museum at some point. Iron dissolved in glass would make greenish glass. That's why I assume the reflected light looks greenish. The transmitted light looking red. Well, the light is dispersed by nanoparticles of silver and gold that are dispersed throughout this glass. I don't think that the Romans in the fourth century AD knew that they were making nanoparticles of silver and gold. However, the manufacturing process of this particular glass ended up giving us tiny, tiny particles that disperse light. And the least dispersed light I think is the red. And that ends up coming through. It ends up being exactly the same mechanism that results in sunsets being red. Very similar to why the sky is usually blue. Why the sky on Mars is red. You know, basically sort of Rayleigh scattering, I guess that's all. Beautiful example. One of the prime examples that I use in my class. Let's see where are we next slide. Okay, so that was dispersion. Dispersion can give us colors. Interference can give us colors. So this is the soap bubble type thing. You know, essentially, if we look at my little diagram on the left, we can see a light beam coming into an object. And say the object is a transparent film of some thickness. Some of the light can be reflected off of the surface. Some can penetrate, go through and then be reflected off the inner surface. Now, those two light beams have traveled different distances. They started off in phase. They started off with all the peaks of their photons and all the valleys of the photons in phase, especially if it was a laser. But after the reflections, one of these light beams has traveled a different distance. There's no guarantee that they'll be in phase anymore. So if it happens that their peaks and valleys still line up, they'll have what's called constructive interference. And you'll be able to see some light there. If they've traveled so that a peak of one light ray overlaps with the trough of another, then they will essentially destroy each other you won't be able to see. So we'll see a pattern of constructive interference and destructive interference. And you'll change, you know, as you move your head around. Yeah, this diagram is on Wikipedia actually. There's some really good stuff there. I was not so keen on Wikipedia in the early days, but I think there's been enough scientists going through the various pages to give very accurate stuff. So yes, it's not the distance, it's also the refractive index. So the angle that, the various angles that the light gets refracted at or comes out at, as well as the different distances plays a role in what you see. So butterflies take example or take advantage of this effect. Many of the colors that you see in butterflies are not dyes or pigments or anything that they've kind of had to biochemically synthesize to give them a color. They can use nanostructures. So take the butterfly and you keep looking at it under more and more expansion, more and more magnification, until eventually you need a scanning electron microscope. At the highest magnification you can see it's essentially a diffraction grating. This butterfly has grown scales on its wings that have the properties of diffraction gratings that give it the colors that you see. So this ends up being a mechanism by which we can see some really wonderful colors. And it doesn't really have a biochemical cost and the, well it does, I mean they have to grow the wings, but to change their colors all they have to do is change the spacing in the diffraction grating, which is a lot easier to do than coming up with a biochemical pathway to synthesize a different coloring agent. So from what I see here if I were to make a guess I would say that it would be fairly easy for generations of butterflies to be able to change their colors. And I think we've seen that in nature before, especially for moths. Hey a speed bump, here's some things I made in my lab. My students have made these wonderful little crystals. This is a, let's see, what is it? If you take ethylene diamine and salicylaldehyde and boil them up in ethanol and then let the solution cool, you get this lovely, it's called saline. We use it as scaffolding for our ruthenium compounds. And here's some of the final compounds. When you shove the ruthenium in there they turn dark blue and purple. In the middle, of course, there's my cat. Well, he passed away a few years ago, but it's a nice picture of him inside the planet glass set box. Okay, so dispersion and interference, physical ways of getting color. A more chemical way, or at least a way that involves the physical properties of actual molecules, is to look at things we call electronic transitions. Okay, I'm not going to try and scare anyone with this stuff. We're going to start simple. So hydrogen. You've got two hydrogen atoms, they share electrons to make a molecule. Essentially, you've got hydrogen, nucleus, two electrons kind of hanging out usually between the two nuclei and the other nuclei. And essentially, what electrons can do, where they can go in the molecule, that stuff's all quantized. When you get to very small objects, most of their properties end up being able to only take specific values. So for hydrogen, there's actually only two allowed spaces and energies that electrons can occupy. And when two hydrogen atoms get together, they make a bond, we basically have a shape that I've outlined here on the right that looks kind of like an egg. It has two full chi in it. Those are the actual nuclei. Most of the time, the electrons would hang out in between the nuclei and cause the plus charges of the nuclei to be attracted to them to keep the whole thing together as a unit. We call this thing an orbital. And in fact, this is not meant to be offensive, it's the highest occupied molecular orbital. Chemistry is a hurtful subject sometimes. The highest occupied molecular orbital is where the electrons are that have the highest energy in the molecule. In this case, there's only two orbitals. This other guy, lowest unoccupied molecular orbital. The lowest unoccupied molecular orbital has this shape. If electrons happen to be in this orbital, the nuclei can kind of see each other a bit better. The electrons, if they're out on either side, repel each other, this thing is destabilizing. If we think about where electrons can go, the probability of finding them as having wave properties, constructive interference and destructive interference end up being something important in the construction of these orbitals. Okay, that's where the orbitals come from, but why am I telling you this? Most of my students ask me that question at some point during lecture. Electronic transition is when an electron in one of these orbitals can absorb a photon and it can basically go up in energy to the higher orbital. So essentially what happens is that you get the electrons arranged like they are here, not in the same orbital anymore. This is a electronic transition. It's responsible for why things absorb energy. For hydrogen that happens in UV light, you cannot see 111 nanometers. So where do we go from now? Well, there's different molecules. Here's butadiene. Butadiene's got some orbitals. It's got lots of orbitals. It's got these things called p-orbitals. Each carbon has one. And we can put these atomic p-orbitals together. They are simply sitting in the molecule side by side. And we can basically look at four ways of putting them together. We can put them together with all the shading. This is phase information, all the shading happening on top of the molecule, all the unshading happen on the bottom of the molecule. And it turns out as you go up in energy, you get more of these nodal planes where the shading is on the top. Then the shading ends up going to the bottom. That's one nodal plane. This one, two nodal planes. And then finally three nodal planes. If we count them. You're allowed two electrons per orbital. So you start off with four because each carbon has one. One, two, three, four. You've got bonding happening up here. The word anti-bonding is not meant to be scary. It's meant to be, hey, this is in the shape of where electrons can go. But if you put electrons in, you get repulsive forces. This would be our highest occupied down here, our lowest unoccupied. The gap is only 258 nanometers now. Hydrogen was 111. This, oh, I'm sorry, this guy is, oh, I forget where it is. I think it's about 220. If you put another double bond, now you're at 258. The longer you make where the electrons can go. The longer you make the series of double bonds, the smaller that gap becomes. Or if you put a different type of atom in there. So notice how there's an oxygen in this molecule taking the place of this CH2 essentially if you're just looking at how the double bonds are going. The oxygen has electrons and they actually sit in the gap between what would otherwise be the HOMO and the LUMO. That makes the gap a little bit smaller. This guy is 314 nanometers. That is still in the UV, but it's starting to get to the 400 zone where we can see. So a summary slide, there's different types of orbitals. Here's one type that's supposed to be one of the pi star anti-bonding orbitals. I made that model up in Second Life. The little thing there is actually a moon. The different types of orbitals, there's bonding ones where the bonding happens and the electrons are shared kind of head on between atoms. The pi is where you have sideways sharing of reasons of electron density between atoms and are when atoms are not actually sharing electrons, they just have a pair of electrons hanging out. And then you have these weird anti-bondings, these empty levels where electrons can go after they've absorbed a photon. The beautiful thing about organic compounds, the two transitions on the left in the blue end to pi star, pi to pi star. For just pure organic compounds, that's your colors. Because these purple lines, the four on the right, end to sigma star, all the way over to sigma to sigma star. The energies of those are just way too high for you to be able to see those wavelengths. Yay! So, as you make these molecules bigger and bigger with more double bonds, look at the pattern here. You've got a double bond, single bond. My pointer is acting up a bit. You've got double bond, single bond. Double bond, single bond. And that pattern goes all the way to the other end of the molecule. Essentially that pattern, double bond, single bond, double bond, gives electrons some mobility and ends up increasing the wavelength. Beta carotene is responsible for the orange color of carrots and basically has absorption in the visible. You have to have fairly large molecules with lots of, when you use the science word conjugation, which essentially means double bond, then single bond, then double bond, to be able to see colors. So how do we study color? I'll show you a UV-Vis spectrometer. Again, from Wikimedia, actually this one's from Libra Text. They're actually very good too. You have a source, some lamp. There's a slit or a shutter that some light goes through. The light beam goes through a sample. And then the light beam can hit some sort of grating, like the butterfly's wing. A grating, a diffraction grating, can take your colors and send them in different directions. And then the light, after it's hit the grating, all the different colors are separated and then they can hit an array of detectors, like a diode array detector, or something that's very much like the light sensing element of the camera in your cell phone. And then this information can be sent to a computer. There's some very nice, almost do-it-yourself spectrometers that are available these days that simply take advantage of diffraction gratings that you can get quite easily, 3D printing, and using your actual camera as the detector. And they do a pretty nice job actually of dispersing the color and giving graphs. And so essentially what we can do is, here's two graphs. We can look at which wavelengths get absorbed and which wavelengths get transmitted. So the top is a nickel solution just dissolved in water. The bottom one is a nickel solution with dissolved in water but with lots of ammonia around. And you can see similarities. There's three peaks. The peaks are where light is absorbed, so you don't actually see the light at the wavelengths that are associated with these peaks. What you see coming through the solution, what gives you the actual colors you see, are these troughs. Because the troughs are where those specific wavelengths can just make it through the solution to your eye. So if you have a solution that absorbs blue light, then the green and red light are going to make it through the solution and then you'll see whatever mixture of green and red, whatever your brain does to that. Interesting part here, going from water to ammonia ends up moving all of these transitions to slightly higher energy. And there's a reason for that and I'll get to that in a little bit. So here's some copper solutions. We have a lab where my students make, they start off with hexapaquo-copper. That's copper with six water molecules attached. That's not hard to do, you just dissolve copper in water and there you go, you've got your six water molecules attached. I haven't shown it because it's so pale that you don't actually see it. The leftmost going to the right, we've added progressively more ammonia to the solutions. So we've got a solution where essentially the major species has one ammonia on it. That's the leftmost, the rightmost. Essentially there's five ammonias attached if the students made up these solutions correctly. What's going on here? Well, I'll show you in a second. Hey, these are my cats. Cats through the ages, 30 years worth of cats. Let's see. This is Ishtar. She's on the left. She's two years old. This is Seth. He's actually sitting in exactly the same spot right now looking at me exactly the same way. He's five years old. The other cats are Tori, Sim, Burt, Manitoba, and Willow, and they've actually passed away. Burt passed away in December. He was 18 years old. So our cats tend to last. We tend to take good care of them, but they get old to get cancer, things like that. So we've got our two right now, asleep and not threatening the keyboard in any way. I'll stop talking about them in case they do. Here's another speed bump. Some more photos. These are actually all from my backyard. We've got dragonflies with colors from dispersion gradings. We've got tiger lilies of different sorts. There's a bee. I have no idea why bees are colored the way they are, but they are. That one is in a redbud tree. That's a tree that's local to the Midwest region in Illinois. The buds actually come. They erupt out of the bark of the main trunk. It's kind of a cool thing, and that's the same dragonfly. So I'll get back to why copper is colored the way it is at the end of my talk here, but do some show and tell. This is my blue period. All of these little round dots are supposed to be the RGB colors of these various dyes. All of these various pigments and indigos are dye. Starting off, we've known about blue for a long time. This is an example of a shabti. It's a small figurine that would be put in a tomb. Evidently, the small figurines were supposed to come to life and do chores that were necessary instead of having your dead loved one doing chores in the afterlife. So this little guy would go and harvest crops or something, having Fethi the first to harvest the crops. Fence, that's the type of ceramic that this is usually called. And this is an example of Egyptian blue. It's thought to be the first synthetic pigment. Its formula would be calcium, copper, tetra-silicate. Pretty much sand is silica, and the recipe apparently they used in later times bronze, which is a mixture of copper and tin to make their Egyptian blue. Interestingly, in Roman times, the recipe fell out of favor and was lost for a long time. And in modern times, it has been rediscovered. This is supposed to be the RGB look of the Egyptian blue. But I think from this particular object it looks a little lighter. I've tried to make the titles of these slides reflect which blue it is. Keep in mind that what your monitor is made of may or may not be able to reproduce colors accurately. So there may be some colors that when you see them in person are subtly different from anything you can see on a monitor. You've probably seen this before. A Starry Night by Vincent van Gogh. There's two blues here. One of them is Prussian blue. And hey, Prussian blue is... Prussian blue has this structure as it's, and I'm going to bring down this model I've been using a few times. Well, maybe I'll just bring it down there. That's Prussian blue. Hopefully I haven't crushed anyone under it. It's iron cyanide. It's got iron 3 pluses. It's got iron 2 pluses. Let's see. All of the iron 2 pluses are attached to the carbon ends of the CN that makes the cyanide. All of the iron 3 pluses are attached to the nitrogen ends. And here the nitrogen ends are these grey areas on this representation. Let me move that back out of the way. Up we go. I'll move my camera so I can see what I'm doing. So Prussian blue is one. Cerulean blue is a cobalt stanate. So it's actually a cobalt 2 with a tin oxide The Prussian blue is a little darker than the Cerulean blue. Cobalt has a bad reputation for being toxic. It's well deserved. Prussian blue, even though it's called all the cyanide and it's not particularly toxic. And I've got some more pictures. There you go. There's the Prussian blue skeleton. And in fact in the lower left and the lower left I've got a more faithful representation. Inside each of the boxes there should be a water molecule. I've deleted that from the second life version of it because it's not totally necessary to have it. But you know essentially it's a very cubic looking structure and you can see that the cyanides are very strong. The cyanides are very strongly bound in the structure. They can't get out. So in fact a Prussian blue itself is non-toxic and there have been some research done with making magnetic nanoparticles of Prussian blue onto which you can graft drugs and hopefully use magnetism to concentrate the drug after it's been given to somebody in a particular area in the body. I don't think those are gone to anything clinical yet but it was an idea that was very popular for a while. There's the water molecule stabilized a lot. I actually think it does. For a lot of these lattices when you look at different metals like chromium and cobalt versions of these you have to adjust charge and sometimes you have potassium ions that take the place of waters to stabilize the charge. Otherwise it's a big void and as you know nature abhors the vacuum. If there isn't something in the void those may just collapse. Another famous painting here's a Renoir. He used cobalt blue and that's a cobalt aluminate and again cobalt is kind of toxic. It's nicer to go with things like Prussian blue. One of the things I noticed when I was visiting my colleagues in their art building before they had a new art building with safety built in was that they were doing many of the same things that my colleagues and I in chemistry were doing except with let's say less safety going on. So yeah that scared me. So I'd be worried about just using really really toxic chemicals as pigments. Things that are much less toxic are much nicer. Oh here's one of the cross-eyed stereograms of the cobalt blue crystal structure. Again when you look at the PDF of this you bust your eyes right now and see if you can get the images to overlap. Some people can do this, some people can't. It's a fairly complicated structure. The pink is either cobalt or aluminum. They randomly substitute for each other. The red are oxygen atoms. The thing about how the oxygen atoms are arranged each cobalt is attached to six in an octahedral fashion. Testing of artists for metal toxicity. I don't know if anyone's done it but I'm pretty sure that especially in the older days when safety seemed to be less of a concern that there are a lot of people whose lives were shortened. Yeah especially the yellow pigments would be chromium based a lot. Lead based, chromium based yes. So everything I've talked about so far that's blue has been pretty inorganic. Here's a indigo example. This is a kimono. It was made in Japan around 1820. This particular kimono is an example of some fabulous dyeing of silk in the 1820s. The indigo has been used in traditional cultures for many, many hundreds of years if not thousands of years. Let's see. I'm going to cut and paste some things soon so I'll get that ready. Quick. Okay. So what's indigo? Well it's actually a naturally occurring organic dye. We make it artificially today because it's in blue jeans. I mean essentially we use so much indigo that rowing it is unfeasible. Okay. I'm going to cut and paste these links into nearby chat. There's some beautiful traditional processing of indigo. From a site in India that is on Google Arts and Culture. If you haven't played with Google Arts and Culture I suggest that you do so. It's a great way of spending an afternoon. Essentially what these photos show is indigo leaves of the plant. Indigo tinctoria. I'm sorry. Indigo for tinctoria. This comes from Uttarakhand, India. Basically the leaves are put in a pot in the earth. They are allowed to ferment and this allows the indigo to come out of the leaves into the solution. The fermentation gives you a reducing environment. So one in which electrons are available gives you a basic environment. Under those conditions the indigo can be dissolved in its colorless form. Even though it looks blue there's a lot of the colorless form dissolved. And then you can soak cloth in there. Once you take the cloth out the next photo here. Once you take the cloth out and just hang it to dry the air can oxidize the indigo into a totally insoluble form that is color fast and stays in the fabric. So I've given you the structure of indigo here. There's a lot of this conjugation I mentioned earlier. The nitrogens have their own pairs of electrons. The blue form is what is on the left in this diagram. This is known as a redox dye. If you give this thing two more electrons those electrons end up hanging out on the oxygen. This disrupts the conjugation a little bit and just changes the properties of the molecule so that it's no longer blue. The charge allows it to dissolve in water. You have to make sure that the pH is right otherwise if hydrogen is attached to those oxygens it will be colorless but also not soluble. And the little equation at the bottom shows what happens with oxygen. Essentially you get back to the blue form. Firmantation is wonderful. We're actually getting a bioprocessing specialization in our chemistry program happening soon. At least I hope we've got the paperwork and it's going through the system. It'll basically a whole set of fermentation classes and quality control of fermentation classes that are going through now. How does the UV light affect the dye chemically? This particular one is more stable to UV. There are orange dyes called azodies that have two nitrogen atoms attached to each other. And essentially what can happen there is that nitrogen-nitrogen bond can end up getting cleaved. And when that happens your molecule falls apart and your orange color goes away. Azodies, reds, oranges, this is kind of why many of the orange dyes in the mid-20th century were not so color fast. I wonder how this was discovered. So in the UK in hundreds of years ago the plant that's called Wode-W-O-A-D also has indigo in it. So I actually think that it's fairly obvious when walking leaves of these plants are all around. I think that you actually do see the blue color and that would have attracted some attention because blue is very hard to get. So here's our newest blue, the Yin-Ming Blue discovered 2008-2009 by Maz Subramian at Oregon State University as part of NSF-sponsored research. They were looking for materials with high reflectivity in the near-infrared region. That's actually a little longer than the visible region, 900 to 2,000 nanometers. This color has been commercialized. It's close to cobalt blue. It's going to be a lot less toxic, I think. It says non-toxic but I'm going to keep that with a grain of salt. I don't know what yitrim indigo and manganese would do to you. I think I tried getting some examples but the examples seem to be copyrighted. So in lieu of examples, here's a crystal structure. I believe the yitrim atoms form layers separated from layers of manganese by the red oxygen atom. So this is the nice layered type structure. And again, this is a cross-eyed 3D sort of model. Look. And inorganic pigments for stained glass. This is at the end of my talk here, I think, rather than going on for another five hours about orbital structure for the orbitals and the like. Basically, I'll wrap up in the next few minutes. This is actually a stained glass piece that's in the church in my hometown. That's Cowinsville, Quebec, in Canada. And it's a memorial to a World War I soldier. Stained glass is a whole topic that really interests me and I think I'll probably try and do a whole talk on it in the future so I can learn more about it. Yellow colors and gray colors end up being well suited for using things like silver sulfide. You'd apply a paste of silver sulfide to glass. You'd heat the glass up. Some of the silver and sulfide ions would penetrate into the glass depending on what else is in the glass. You might get a yellow color or shades of gray. So finally, I'm going to actually just talk about orbitals just a tiny, tiny bit. Where do the inorganic colors come from? Well, they come from transitions in d-orbitals. So d-orbitals are these four leaf clover looking things. And this is a view of one of the landscapes I made in unity. Why would d-orbitals do this? I've got a little animation I've made in Second Life. I'll bring it forward. Essentially, if you've got six things attached to a d-orbital, or I'm sorry, six things attached to a metal, it's in an octahedral arrangement. What does that mean? You've got a metal that dates in at the origin of a XYZ Cartesian coordinate system. So there would be a... If it's octahedral, you'd have something on top, on bottom, to the left, to the right, in front and in back. But essentially, if you look at the left mo... I'm sorry, the rightmost little orbital I've got here, there's a box around it. And the little wooden spheres on the box correspond to places where an atom could be if it were in an octahedral coordination environment. There's two types of d-orbitals if you're considering left, right, top, bottom, front, back. There's the d-orbitals that point directly at those sites, and then there's the d-orbitals that point in between the sites. If you point at the sites, electrons in those d-orbitals are going to be raised in energy because they'll experience more repulsion. So this box is going to grab any d-orbital that has... that points directly at those left, right, front, back, top, bottom objects, and then is going to raise it in energy. So let's see if it actually does so. Oh, yes! The two of them go up, and then the rest are left alone. And this just loops over and over again. So essentially we get two sets of orbitals, one at lower energy, one at higher energy, and the blue colors, the nice colors we see for transition metal compounds, arise from different energies, or I'm sorry, from the promotion of electrons from the lower set to the upper set. So I have a question here. Will dye contributing to ADHD? I don't know. I kind of doubt it, but then I have no idea. And then I'm not sure which blue was used in the Federal Union. So sorry for not getting to that just a little earlier. So I think that's a good place to stop for now. I'm going to continue this kind of chemistry and arts sort of talk for probably a few talks in the future. So right now I'll throw it open to questions. I see some are violent in blue dyes, more sensitive to oxidation. It depends. Blue, like the blue pigments I showed you that are inorganic, they're pretty robust. Like the Egyptian blue is something that can survive being in a fire. Organic dyes, they tend to be more subject to oxidation. So yes, I'd say the organic ones are. Modern dyes, the ones that have been developed recently would be one of the things we've looked for are oxidation stability. So if something was developed in the early 20th century, it's probably going to be sensitive. If it's developed like last year then it's probably going to be less sensitive. One wonders how artificial dyes might affect epigenetic markers and genetic expression. Yeah, the dyes are organic compounds and we know that there's lots of organic compounds in our modern conveniences. I mean, when you look at the plasticizers in plastics a lot of them, like BPA apparently have hormonal activity or mimicry. Or mimic hormone activity. So yeah, there's a possibility that epigenetic markers can be affected. I'd say with the azo dyes and things that are a little more sensitive and might give you more radicals and the like, when they react with light you could even get genetic damage. My mother used to keep some dark blue black paper in with some antique fabrics to protect them from oxidation. Yes, I have that stuff too. What is it? I don't even know what that stuff is but I think it's essentially I got some metal particles in it that absorb sulfur because it's not so much you couldn't really have so much that it would affect oxidation from air but oxidation by sulfur leads to tarnishing. So in fact I have some of that stuff in with my silver. Let's see, does the mordant use to set the dye influence to color? Yes, it does. So essentially you can have an organic molecule that's soluble and it is it gets like permanently attached to maybe a transition metal ion or more commonly an aluminum 3 plus ion that's sitting attached to a fabric and when the organic molecule wraps itself around the metal there are changes in the energies of the orbitals and that does change the color. And how does the mordant affect the life and deterioration of the pigment? Well it varies if the mordant is anchored really well to the fabric then the pigment will be set really well but the pigment, the organic part of it has to remain attached to the metal. Now factors that influence whether it's attached are you know when you wash this fabric what sort of pH does your water have is H plus competing with the dye that's attached to the transition metal or aluminum ion that's anchored to the fabric. So yeah I mean basically what we've tried to develop is dyes and mordants that stay in a fabric like forever but it's there's always fading. No, pigments in paint since you don't wash paintings so much or at least I hope no one's taking like a power sprayer to their local art gallery those issues are a little less intense so pigments in paints for paintings usually you have to worry about oxidation from air and exposure to UV light. The inorganic pigments are usually very stable sometimes when you mix two pigments together and you might have some electron transfer happening one is an oxidant and one is a reductant that may mean that there's some pigments that are incompatible with each other or they might make some fabulous new shade that can't get any other way. But also worrying about organic pigments with oxidation and UV if you make the molecules and break them up into smaller trunks they're not so conjugated and you don't see their colors anymore. One should not restore paintings with cats around. Oh my god, yeah, oh yeah. I try to keep anything of value like in my office at work because I know my cats if there's anything of value that they can destroy they will destroy it. I think that's a corollary to Murphy's law. I think Murphy had cats. Let's see, did I miss any questions? I like the fermentation reference because those are a very cool area of chemistry these days. I think I got everyone's questions. Okay, who buys Sizzigie? Excellent. Well with that I think I'll call it quits then. I am going to continue using the art world as an inspiration for some of these chemistry talks that I give from now on. Yay, thank you Shantel. Excellent, well very pleased to be here. Thank you all for your time and attention. I should probably also zoom through some slides blah blah blah. Here's what I haven't shown you but I should get to the acknowledgement slides somewhere where we have NSF thanked. Yes, somewhere NSF has been thanked. Okay. Well I would still like to thank NSF for their support and all of my colleagues and SIUE for its support as well. Thank you all for coming. I'm going to sign off soon. Okay, going radio silent. Click.