Chemistry in Pictures

Grainbow colors

This is a close-up photo of a piece of stainless steel from a large spring, meant to support 5000 lbs (around 2200 kg) of weight, that failed during testing. Russell Rohloff, a chemist in the materials and surface engineering group at Woodward Inc., captured the image while preparing a sample of the metal for scanning electron microscopy analysis to look at the composition and distribution of carbides in the material. Excess carbides at grain boundaries can cause metals to break more easily. After vacuum etching the sample at 3500 °C to expose the metal’s internal grain structure, Rohloff cleaned the surface with a mixture of alcohol and acetone. During the cleaning step, he accidentally contaminated it with oils from his skin—which gave the surface an iridescent rainbow sheen. Though he couldn’t use the contaminated sample, Rohloff used the image, taken at 2500x magnification under white light, in an assignment for an art appreciation class he was taking at the local community college (and got an A). —Brianna Barbu

Submitted by Russell Rohloff

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Not Tang

The inorganic crowd gets the lion’s share of pretty colors in synthetic chemistry circles, but every now and then the organic chemists get a piece. These sparkling orange crystals appeared during a reaction work-up in Ivana Jevtić’s lab at the University of Belgrade. Jevtić says this derivative of 2-nitroaniline is part of a synthetic pathway she’s developing to new anilidopiperidines, a class of molecules that includes the opioid painkiller fentanyl.—Craig Bettenhausen  

Submitted by Ivana Jevtić

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A scent-ual sketch

The online art shop n.p.ainting released this chemistry-themed watercolor last year, which will surely please many a natural products chemist. What might not be obvious to most viewers is that Nadine Peez, the artist behind n.p.ainting, is a PhD chemist who often features molecules in her work. This piece features linalyl acetate, the fragrance industry’s go-to molecule for the scent of lavender and one of the many fragrant molecules produced by the plant. Peez shows both enantiomers in this work, although the R enantiomer (shown on the right) is present at a higher concentration in the plant and contributes more strongly to its scent. n.p.ainting released a series of these molecular watercolors that highlight the chemical details of other everyday plants and foods, which can be admired on n.p.ainting’s Instagram and Etsy shop.—Manny I. Fox Morone  

Credit: n.p.ainting/Nadine Peez

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The color of life

Xiaolin Liu calls porphyrins “the colors of life” because they’re brightly colored and the molecular motif shows up in some very important biomolecules. A porphyrin is the backbone of the heme that binds oxygen in red blood cells, for example. In her work as a postdoc in the Moore group at the University of Illinois Urbana-Champaign, Liu makes porphyrin derivatives in the lab and studies their ability to conduct electricity. She took this photo of an emulsion that formed while she was trying to perform an extraction procedure on a porphyrin that she’d made that included both hydrophilic and hydrophobic parts. The water-loving and water-averse segments of the molecule caused it to behave as a surfactant. What resulted was not a clean extraction with distinct layers but an emulsion with large, emerald-colored bubbles reminiscent of plant cells, whose photosynthesis relies on another porphyrin-based molecule: chlorophyll.—Brianna Barbu  

Submitted by Xiaolin Liu

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Drug delivery in bloom

The molecules found inside this rose could be potent antiviral agents. Not because they’re newly discovered natural products—rather, they’re small interfering RNA (siRNA) sequences designed to target and silence key genes in chikungunya virus, a mosquito-borne pathogen which currently has no approved vaccine or treatment. And the flower is a porous metal-organic framework (MOF) meant to deliver the siRNA into cells.

Shakil Polash is investigating the nucleic acid delivery properties of MOFs as part of his PhD work in Ravi Shukla’s lab at the Royal Melbourne Institute of Technology. In addition to targeting viruses, Polash is also looking into MOF delivery of siRNA and other nucleic acids, such as plasmid DNA and CRISPR sequences, for cancer treatment. Polash and his colleagues published a paper on their MOF-delivered chikungunya virus gene silencing efforts last December (Front. Bioeng. Biotechnol. 2022, DOI: 10.3389/fbioe.2022.1003448).—Brianna Barbu  

Submitted by Shakil Ahmed Polash

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Is there anything porphyrins can’t do?

Nature uses porphyrins for all kinds of things. The aromatic, disc-shaped molecules form the functional core of systems that transport oxygen, catalyze biochemical transformations, and harvest light, among other things. Sukrit Tantrawong, a professor at Thammasat University, studies porphyrins as components of dye-sensitized solar cells, where the molecules’ famously rich colors are used to expand the range of light that an inorganic semiconductor can transform into useable electrons. He captured this image while analyzing a thin film of a porphyrin derivative using an optical polarizing microscope.—Craig Bettenhausen    

Submitted by Sukrit Tantrawong

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Laser cut

Hitendra Kumar of the University of Calgary and Zhangkang Li, a PhD student in his lab, are creating hydrogels like this one that can house cells and maybe one day mimic living organs. But before they do that, they still need to make systems where they can run experiments to see how cells grow and interact in various 3D gel environments. So the team is working on a 3D printing technique for creating small, intricate shapes out of hydrogels filled with cells. To create this grid, they mixed cells with a solution of a monomer that can spontaneously crosslink when exposed to blue laser light. And by using a 3D printer whose printhead was replaced with a laser, they traced small, intricate designs in the solution using the laser and created a tiny 3D object. Originally, the grid had straight lines and right angles, but after the gel soaked up a solution with dye in it, the lines crinkled and turned teal.—Manny I. Fox Morone

Submitted by Hitendra Kumar and Zhangkang Li

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Trypophilia

Trypophobia, an aversion to things with semi-regular textures of small holes, has been an on-again off-again internet darling in recent years. But on the microscale, such patterns are an active area of research as membranes and scaffolds for novel materials. Chandrashekhar Bobade, a researcher at MIT World Peace University, prepared this holey sample from poly(lactic-co-glycolic acid) using a technique called “breath figure” that uses humidity to form ordered arrays of aqueous and organic solvent phases. Evaporation of both phases leaves behind just the polymer, which formed along the way. Bobade collected this image of the result using scanning electron microscopy.—Craig Bettenhausen  

Submitted by Chandrashekhar Bobade

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O Chemistree

Andres Tretiakov, a physics technician at St. Paul’s School in London, made this density column chemistree as part of a demonstration for students using a few kitchen staples and a tree-shaped glass bottle. The bottom layer of the column is Karo corn syrup, followed by blue food coloring in water, then olive oil, then acetone with “a pinch of turmeric powder”—each successive layer of liquid lower in density than the one below it. And, as a bonus, each layer is fluorescent under 365 nm light. Curcumin in the turmeric emits a “joyous yellow-green colour.” Olive oil glows blue thanks to polyphenols, vitamins, and chlorophyll derivatives (the exact hue depends on the type of olive oil—Tretiakov used light refined oil). The blue food coloring is made with spirulina, an edible blue-green algae which produces red-fluorescing phycocyanin pigments. Finally, the source of the blue fluorescence in the corn syrup likely comes from a blend of fluorescent polysaccharides.—Brianna Barbu

Credit: Andres Tretiakov

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Holey hohlraum, Batman!

Researchers at the US National Ignition Facility made energy history on December 5. For the first time, humans caused a controlled nuclear fusion reaction that yielded more energy than the laser power it took to get started. This widget is where it happened. It’s called hohlraum, and it holds a millimeter-sized sphere of deuterium and tritium that’s bombarded by lasers with enough juice to fuse the atoms. There’s plenty of room for improvement; counting all the way back to the electricity needed to power the equipment, the process is still a net energy loss. To read more about the experiment and its ramifications, see our more in-depth story at cenm.ag/fusion2022.—Craig Bettenhausen

Credit: US National Ignition Facility

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Secret message

Although she’s still perfecting how neatly she can write with a paintbrush, Shaista Lone sends invisible notes like this one to her labmates using solutions of fluorescent compounds she’s working with in lab. Under ultraviolet light, the message appears, but the paper looks blank in ambient light (shown). Lone, a researcher at the University of Kashmir under the mentorship of Aijaz A. Dar, is working on making smart materials using these nontoxic organic molecules that can sense things like pH and various biological molecules in solution. In the vials shown below, you can see how amino acids (left) change the yellow fluorescence of the pure sensor (center) to green upon mixing (right).—Manny I. Fox Morone

Credit: Shaista Lone

Submitted by Shaista Lone

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Holiday light

This festive fluorescence photo was taken by Andrea Nikolić, a researcher in Igor Opsenica lab at the University of Belgrade. It shows Nikolić’s labmate Ljiljana Koračak’s hand holding a pear-shaped flask containing an organic molecule she had modified to fluoresce under ultraviolet light. The flask’s shape and shining contents give it a strong resemblance to a Christmas light or tree ornament. By taking natural products and modifying them to make them fluorescent, Nikolić says that she and her coworkers in the Opsenica lab are trying to create molecules that can be used for diagnostic imaging as well as therapies for diseases such as cancer.—Brianna Barbu

Credit: Andrea Nikolić

Warp drive

Raman spectroscopy is a powerful analytical technique in part because of the high signal-to-noise ratio. If regular absorption spectroscopy is like viewing the noonday sky through a stained glass window, Raman is like riding a bicycle around your neighborhood at night looking for houses lit up for the holidays. There’s less total information, but almost all of it is exactly what you came for. Avery Blockmon, a chemistry graduate student at the University of Tennessee, Knoxville, captured this image while calibrating a Raman spectrometer; a 532 nm green laser focused on a silicon wafer gives a sharp Raman peak at 520.7 cm-1, Blockmon says.—Craig Bettenhausen

Submitted by Avery Blockmon

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Quinoline quills

As the weekend approached, Chayut Thongdeelert had to put his experiments on hold. So after he evaporated most of the solvent from his round-bottom flask, he left the flask sitting out for a few days. When he got back to the lab, he saw that the rest of the solvent had evaporated leaving behind these spiky crystals of the quinoline derivative he’d made. Thongdeelert is master’s student at Mahidol University in the lab of Tienthong Thongpanchang, a synthetic chemist who works on organic materials. One day, the compounds he synthesizes could be used in organic light-emitting diodes or dye-sensitized solar cells.—Manny I. Fox Morone  

Submitted by Chayut Thongdeelert and Tienthong Thongpanchang

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An LED’s polar bear plunge

Light-emitting diodes shine in a spectrum of colors thanks to semiconductors inside them: materials that can easily shuffle electrons between two discrete energy levels when they’re connected to a power source. The color of an LED is directly connected to the gap between the semiconductor’s two energy levels. In this demo, YouTuber Tommy Technetium shows how that gap can change when an LED is dipped in –78 °C liquid nitrogen, changing a yellow LED to green. The low temperature increases the gap between semiconductors’ two energy levels. Specifically, it makes the lower energy level even lower and makes LEDs release higher energy photons, which are “bluer” than the room-temperature color.—Manny I. Fox Morone      

Credit: Tommy Technetium (videos, Subscribe to his YouTube channel, follow @pchemstud on Twitter and on TikTok)

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A little nudge

All it takes is a few taps on the side of this vial and—like magic—a ring of fluffy white solid suddenly appears inside, seemingly out of nowhere But a closer look reveals a few drops of a clear, colorless liquid, pooled almost invisibly at the bottom of the vial, that rapidly crystallize under when the vial is tapped.

The stuff in the vial is a ligand that Jaime Martin, a postdoc in Cristina Nevado’s group at the University of Zurich, synthesized as part of his research quest to make a library of stable gold(III) complexes and study their properties and reactivity. Gold(III) tends to undergo reduction easily, and a good ligand is essential for keeping the metal happy in the desired oxidation state. Martin says that most of the ligands he makes are liquids after purification, but the higher molecular weight ones can crystallize under the right conditions—given a little nudge. It’s “very very satisfying” to see the solid pop up under vacuum, he says.—Brianna Barbu

Credit: Jaime Martin. Follow him on Twitter @Jaime_Chem.

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Let there be light

In the beginning, there was darkness: a nonfluorescent solution of cesium bromide, lead(II) bromide, and a metal-organic framework dispersed in dimethyl sulfoxide. But all it takes is the addition of some hexanes as an “antisolvent” to get the metal ions to assemble themselves into bright green fluorescent perovskite quantum dots inside the MOF’s nanosized pores.

Nima Tabatabaei Rezaei, a PhD student in mechanical engineering at the University of Calgary, captured the luminous transformation on video as part of his research on ways to stabilize quantum dots for biological imaging applications. The goal is to prevent the perovskites from shedding toxic lead ions inside cells. Tucked inside the MOF framework, the nanoparticles are shielded from degradation by moisture and oxygen for months, compared to mere hours for quantum dots made by traditional ligand-assisted methods. Tabatabaei Rezaei envisions that stable quantum dot–carrying MOFs could also be loaded with drugs for targeted delivery.—Brianna Barbu    

Submitted by Nima Tabatabaei Rezaei

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