Hello! My name is Laura Jane, and I’m a PhD candidate hailing from Stellenbosch, South Africa, here to show you what a week in my #RealTimeChem life entails!
One of the things our group is working on is a class of molecules called dithiadiazolyls (see this paper for more). Dithiadiazolyls (or DTDAs) are sulphur- and nitrogen-containing heterocycles that exist as neutral radicals. (It is interesting to note that the SOMO, in which the unpaired electron resides, is nodal at the carbon of the DTDA ring, so it is possible to alter the nature of the R-group without significantly altering the nature of the DTDA ring.) Thiazyl radicals have been investigated as potential building blocks for the design of molecular materials with interesting and desirable physical properties, such as conductivity and magnetism. Their magnetic and electrical conducting properties relate directly to their solid state structure. Unfortunately, many DTDAs tend to diamerise in the solid state, which results in spin pairing and, consequently, loss of any magnetic or conductive properties. We therefore look into ways to override this diamerisation and direct the structure of these materials in the solid state. My project involves the use of porphyrins as supramolecular scaffolds to create novel materials.
Monday morning starts like any other, with a cup of tea and `n Ouma beskuit while I read the news, then a breakfast of fresh fruit while I check up on what’s new in the Chemistry world. After checking my email, it’s off to my supervisor’s office, to discuss my plans for the week, but more importantly – to discuss our group’s plans regarding data backups (and storing data off-campus), spurred on by the previous day’s fire at one of our neighbouring buildings. Today ended up being an office day, not a lab day. First, backing up my data. While that’s running (my laptop tends to crash if you try giving it two things to do at once), I head off on a library run. When I return, it’s time to go play catch-up by going through some data from the last two weeks that I collected, but didn’t process, as I had fallen ill.
On Tuesday afternoons I have to demonstrate (“demi”) for an undergraduate practical session. First though, marking a stack of my class’s lab reports (nothing like leaving your marking to the last moment!). By the time that is finally done, there’s only an hour or two to spend in the lab, so I catch up on the always-fun tasks such as cleaning the never-ending pile of dirty glassware, sweeping the floor, taking inventory and so on. After a quick lunch at my desk while I catch up with what’s happening on Twitter, I haul myself and my giant stack of books across the road and around the block to one of the other Chemistry buildings for my demi duty. (The Department of Chemistry and Polymer Science at SU is spread over five buildings). This semester I’m involved in second year Inorganic Chemistry, a fun course to demi for as the pracs involve fundamental concepts and lots of pretty colours! Today’s practical involves introducing the students to the concept of qualitative analysis. South Africa has a very diverse population and consequently has 11 official languages – so language policy is a very important topic. While SU has traditionally been an Afrikaans university, undergraduate programs are now mostly bilingual (with postgraduate programs typically run only in English), so it’s quite a challenge constantly switching between the two languages when explaining to the students if your brain isn’t fully engaged.
Wednesday arrives and it’s time to hit the lab for some DTDA synthesis! DTDAs are very moisture sensitive, so it’s all about the Schlenk line. I work in a tiny little synthesis lab, where currently only myself and a MSc student are working in the fume hoods. Today it’s just step one of the DTDA synthesis, first creating LiHMDS in situ (it arrives in an unusable state when purchased as-is), then – no, wait, load shedding has kicked in again. Luckily, our building can get power from back-up generators (otherwise it’s 2.5 hours without power each time), but it’s still a minute of standing around in the dark waiting for electricity to return. Once the lights are back on and the stirrer plate is working again, it’s on adding the desired aromatic nitrile to form a silylated amidine. While those reactions are stirring away until completed, I turn my attention to my DTDA – metalloporphyrin complexations. These tend to take (what seems like) forever to form diffraction-quality crystals, so there are normally lots of these running in the background. Because of the moisture-sensitive nature of the DTDA radicals, I tend to set up these crystallizations in skinny Schlenk tubes rather than crystallization vials – it turns out that old-school test tube racks are perfect for holding these flasks when there’s only so much room to clamp flasks in your fume hood!
Thursday brings step two, condensation of the silylated amidine with SCl2 to form a dithiadiazolylium chloride salt. SCl2 is another reagent that we have to synthesise ourselves (from powdered sulphur and chlorine gas), and smells just about as lovely as you can guess, so luckily I don’t have many lab-mates to irritate! Once the product has formed, it’s time to filter and wash it – inertly of course. After drying in vacuo, the dithiadiazolylium chloride salt is obtained as a yellow powder. Halfway through the day, there’s a short break from the lab for group meeting. Typically, our group meetings involve one student presenting their current research and another presenting a paper in a relevant field. This week, however, was something a little bit different as our group was hosting Prof. Wais Hosseini (University of Strasbourg), who was given the opportunity to discuss some of his group’s work in molecular tectonics.
The last thing to do for Friday is reduce the dithiadiazolylium chloride salt to the dithiadiazolyl radical. There are several ways to do this, but my favourite is a solid-state reduction using triphenylantimony. (Zinc-Copper couple in THF is another option.) If the reaction is successful, a drastic colour change from yellow to purple is observed. Purification is then achieved by means of sublimation to get shiny dark purple crystals, all ready to meet up with some porphyrins next week.
Finally, the week comes to an end and it’s time to enjoy the late afternoon sun with a glass of cold Sauvignon Blanc on the lawns of a wine farm just up the road! Life in Stellenbosch isn’t all too bad!
Laura van Laeren is a PhD candidate at Stellenbosch University in South Africa. She is currently investigating novel thiazyl radical – metalloporphyrin complexes under the supervision of Prof Delia Haynes and Dr Katherine de Villiers. Her passions include the written word, scientific education and the Cape Winelands.
Blogs at Whimsical Science (http://www.whimsicalscience.com/) & Whimsy Is Forever (http://www.whimsyisforever.com/)