“A Journey to Pure Hexagonal Crystals” received an honourable mention at ChemiSTEAM 2021.

Every time that I show this type of picture to lab mates and friends they are intrigued by the shape of the crystals. It leads to a conversation about crystals that can be visualized at the macro or microscopic level. It’s fascinating how the observation of crystals leads to interesting questions that most of the time require an intricate answer, discussion that is attractive not only for scientists, but also for the general public. I have noticed that such tangible observation calls the attention of the observers very easily, sparking their curiosity about the composition of the material and how it was obtained, making me believe that this process of elaborating questions and searching for accurate answers can help us to learn about a specific topic, improve critical thinking, and most importantly, it can expand our own horizons, leading to a potentially new hobby, an interesting career path, or new research proposal.

During my career I had the opportunity to learn and explore the process of crystallization and I am always pleased to observe how matter can arrange in such organized geometric bodies, and I am confident to say that working with crystals is what led me to follow a career in the chemical sciences.

When starting my graduate studies at Concordia University under the supervision of Dr. Ashlee J. Howarth, I had as an objective the synthesis of novel metal-organic frameworks (MOFs) using rare-earth (RE) metals, and a particular linker with interesting optical properties that make it look yellow under white light. Once I met the required conditions to synthesize a novel MOF named RE-CU-10 (CU: Concordia University) I was striving for the opportunity to characterize this material by single crystal X-ray diffraction, a powerful technique that allows us to understand the molecular structure of the material and relate it with its physicochemical properties such as surface area, gas adsorption, catalysis, among others. That being said, I was pursuing the synthesis of single crystals suitable for such intricate characterization, and after several attempts I was delighted to obtain crystallites large enough to be isolated and analysed by single crystal X-ray diffraction, where the observation through an optical microscope is very useful. However, at the beginning the product was not completely pure, something that can be observed in the left figure, where the large hexagonal shaped crystals belong to the terbium-CU-10 MOF but is accompanied by another type of solid that grows in a relatively more disordered way, with a shape like a rosette. This observation allowed me to realize that I have not succeeded yet in the synthesis of a pure product, but by manipulating different reaction parameters such as temperature, amount of solvent and the presence of different reagents, I was able to make some progress. In the middle figure these rosette-like particles are not present, but agglomerated rods are observed, leading me to think that the material could still be potentially contaminated. Not satisfied with this result, I persevered in the optimization of the reaction conditions until the sample only shows pure hexagonal crystals when looked under the microscope, like the figure at the right, telling me that the procedure was working, and the purity of the material was confirmed by powder X-ray diffraction.

As a MOF scientist, is very important to design a synthesis procedure that is reproducible and will yield the desired material without any other impurities that can be amorphous, and in some cases crystalline. This allows me to proceed to the large-scale synthesis of the material and its complete characterization.

It’s a fact that for many people learning chemistry or science in general can be very tedious, and difficult most of the time, and its here where the creation of artistic images is of paramount importance, since it will attract the interest of the new generation of scientist, calling their attention first and make them think latter, allowing people to learn about science in and enjoyable way, fueled by their own curiosity.