Chemistry and the Environment
Image Source: Crow, James Mitchell. “A Lightning Burst of Chemistry.” Chemistry World, Chemistry World, 10 June 2024, www.chemistryworld.com/features/a-lightning-burst-of-chemistry/4015883.article
Molecule of the Week:
Coronene
Coronene perhaps has the least-needed 3-D structure of all the molecules I have covered. Coronene is entirely planar and is a quintessential polyaromatic cyclic hydrocarbon (PAH). Coronene fluoresces under UV light which should come as no surprise due to its delocalized electrons; anthracene with only three fused aromatic rings fluoresces under UV. Coronene is surprisingly interesting beyond this, however. Coronene occurs naturally as an organic mineral (quite rare) called carpathite. When I say mineral, I don’t just mean coronene is some impurity; carpathite consists of tiny crystals of almost entirely pure coronene. In the field of organic synthesis, coronene also is useful as a nucleation seed for graphene, an interesting and useful material consisting of a one-layer sheet of carbon, much like an infinite sheet of coronene (graphite is actually stacks of graphene sheets, interestingly). Finally, coronene is interesting theoretically in terms of aromaticity. The two 2-D Chemdraw structures represent different visualizations of this. The first is the more classical method of drawing an aromatic compound as a series of alternating double and single bonds. Although these structures are accurate for benzene and other small aromatic molecules, larger and polycyclic aromatic hydrocarbons present a challenge: in terms of reactivity and other chemical properties, not all these double bonds are equal. Hence, Clar’s rule.
Clar’s rule states that the resonance structure that is the largest contributor to the actual structure (the drawn structure that most accurately predicts the real physical and chemical properties) is the one with the most pi sextets (Clar sextets), which are depicted instead as circles. In less complicated language, more non-adjacent hexagons with circles inside = better depiction of actual molecule and its properties, including, but not limited to, reactivity. You can (correctly) imagine that if more circles = good, then these electrons are less likely to react in comparison with the electrons depicted as double bonds. Clar’s rule is actually one of the greatest chemistry rules because it is almost entirely perfect, as supported by experimental evidence regarding polycyclic aromatic hydrocarbons. The only limitations are that Clar’s rule only really works for hexagons and there may be multiple nontrivial resonance structures with the same number of sextets. In fact, coronene has two resonance structures such that there are three Clar sextets, but the other one is equivalent (imagine shifting the circles and double bonds clockwise by 1 ring and notice how it is the same structure, just rotated by a hexagon). Overall, coronene is theoretically, geologically, and chemically intriguing in a multitude of ways. Who could have guessed that from a compound only made of carbon and hydrogen?
Interesting Recent Chemistry Publications With Environmental Applications:
Diffusion-Induced Redox Gradients for the Concurrent Synthesis of MoS2 and MoO3 in a Single Reactor: A Green Pathway for Hydrogen Evolution
Prasad C. Walimbe, Preeti S. Kulkarni, and Sunil D. Kulkarni
Inorganic Chemistry 2025 64 (39), 19582-19597
DOI: 10.1021/acs.inorgchem.5c02517
Photo-Catalyzed Synthesis of Indanones from Aromatic Aldehydes and Terminal Alkynes
Florence Babawale, Indrajit Ghosh, and Burkhard König
The Journal of Organic Chemistry 2025 90 (39), 13885-13890
DOI: 10.1021/acs.joc.5c01749
Rapid Electrochemical Assessment of Excited-State Quenching Dynamics
Tobia Casadei, Alberto Piccoli, Davide Zeppilli, Laura Orian, Abdirisak A. Isse, and Marco Fantin
ACS Catalysis 2025 15 (19), 16938-16952
DOI: 10.1021/acscatal.5c02778
Podcast
First Episode with Dr. Zoerb, Cal Poly
My Story
I am currently a chemistry major at Rice University, and I am deeply passionate about organic chemistry and the environment, especically concerning climate change. My favorite element is sulfur and my favorite molecule is grapefruit mercaptan (yes, that is actually its name). Here’s a few things I am interested in or have already done.
Nuclear and Radiochemistry
After a brief stint at Brookhaven National Laboratory as part of the Nuclear Chemistry Summer School this past summer, I am certainly more interested in nuclear chemistry than before. Much of this revolves around my initial interest in organometallic and inorganic complexation chemistry. I am interested in extending the traditions of organometallic and non-covalent complexation chemistry to the actinides, a woefully under-studied subject. The interactions of actinides in terms of covalent bonding, host-guest chemistry, and other ionic complexation is interesting theoretically for understanding actinides and has potential uses in separation of actinides, such as in nuclear reprocessing. I hope to continue to develop my techniques with non-radioactive d and f block metals before potentially looking at actinide chemistry.
(Synthetic Organic) Electrochemistry
As the first image shows, I really enjoy a good storm. In fact, back in February 2024, I had the pleasure of witnessing an intense line of thunderstorms plow through coastal central California. In fact, two EF1 tornadoes (both with winds of 95 mph) came within a few miles of me. The chemistry of thunderstorms is equally as fascinating as the physics and meteorology. Due to the extremely high current from lightning, molecules like water and dinitrogen, are blasted apart and smashed together, forming some interesting radicals that bearly last a tenth of a second before they react. In fact, two of these radicals, hydroperoxyl and hydroxyl, actually destroy greenhouse gases when they violently react. These atmospheric radicals are currently being investigated for their role in the climate and in climate change. Interestingly as well, electrochemistry is now being applied to the field of synthetic organic chemistry, producing the new and upcoming field of synthetic organic electrochemistry. With synthetic organic electrochemistry, useful molecules, like drug precursors and agrochemicals, can be produced more selectively, better, and without the need of redox reagents by using electricity. Oxidations and reductions are done using a range of anodes and cathodes to precisely create the exact redox potential needed for a reaction to occur. The electricity basically does the chemistry for you!
Covalent Organic Frameworks
Image Source: Woojung Ji, et al. “COF-300 Synthesis and Colloidal Stabilization with Substituted Benzoic Acids.” RSC Advances, Royal Society of Chemistry, 12 May 2023, pubs.rsc.org/en/content/articlehtml/2023/ra/d3ra02202a
My research project at Cal Poly involved Covalent Organic Frameworks (COFs), a class of porous, crystalline polymers. They have interesting applications in gas storage, carbon capture, water filtration, and more. I tackled the depolymerization of an imine-linked COF, COF-300 (shown above). This was quite difficult due to the strength of the imine bonds. Additionally, because the idea is to use this for recycling of COFs, we tried to avoid unnecessarily complex and hazardous methods. I discovered that this COF can be depolymerized somewhat in a dilute solution of aniline with scandium(iii) triflate as a Lewis acid catalyst. While I am now at Rice, the Hamachi group will continue to work on covalent organic frameworks and I would recommend checking out their latest work.