Chemistry in Pictures: Complicated crystals

If perfectly dipole parallel–aligned organic molecular crystals sound like complex things to study, well, you’re right. Rainer Glaser’s group, now at Missouri University of Science and Technology, has been making them and interrogating their optical properties since 1995, when it first synthesized 4-bromoacetophenone 4-methoxyacetophenone azine. You’d expect a polar molecule to crystalize with the negatively charged end of one adjacent to the positively charged end of the next, but Glaser’s students found the opposite arrangement. The counterintuitive crystal packing yields polar materials that interact with polarized light in interesting and potentially useful ways. Students currently preparing butadiene derivatives of the original Glaser-lab workhorse molecule noticed an unexpected ultraviolet fluorescence from their target molecule, so they grabbed these two photos, in normal light (top) and under UV light (bottom), as they were weighing a sample.

Submitted by Harmeet Singh Bhoday

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