Trying to identify phases can be frustrating, especially when you leave the comfort zone of materials you have a solid understanding of. This happened to us recently as we moved more into the area of calamitic (rod-shaped) molecules. These molecules form a variety of liquid crystals, the most common ones being nematic, smectic A and smectic C phases. These are relatively easy to identify, as they exhibit a range of standard textures. We were working with molecules that had been reported to form either smectic B or smectic G phases. After extensive microscopy and x-ray diffraction studies, we concluded that the literature reports were wrong; the molecules form smectic F phases. I will go into more details on this over the next few posts, but for the time being, here is one of the textures that lead us to this conclusion.
Here's today's fun fact: the majority of organic solids are birefringent. Take, for example, urea:
I took a couple weeks off from blogging as I was getting caught up on other things. I have also started a new side project for myself: microscopy of natural product solids. This falls under the heading of "chemistry outreach." Finding ways to engage the wider public about chemistry is always challenging, so lately I've been taking a different approach: posting pictures of compounds like caffeine, cholesterol, etc. I'll post some of these here in the days to come. For those who just want to look at liquid crystals, don't worry, I'll keep posting those too. For now, here's some morning caffeine: