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Richard J. Hooley
Assistant Professor
Department of Chemistry
University of California, Riverside
Chirality and the Origins of Life: A Case Study in Organic Chemistry

In this case study, students are guided through an example of how the amplification of enantiomeric excess in prebiotic amino acids may have contributed to the occurrence of only L-amino acids in nature. By studying the mechanism of racemization of amino acids and their derivatives and applying the concepts of crystallization and equilibrium, students can critically analyze a recent (2008) article in the Journal of the American Chemical Society on chirality enhancement under conditions that mimic the prebiotic environment. The article provides a possible cause of single enantioforms of amino acids, and the case study extends this to critically investigate whether this is a viable theory for the existence of L amino acids as the sole natural constituents of natural macromolecules. This case study is designed for a first semester/first quarter organic chemistry course, and is generally presented in the middle of the course after the topics of stereochemistry and acid/base reactions are taught.

Organic Chemistry and Your Cellphone: Organic Light-Emitting Diodes

This case study guides students through a systematic exploration of the synthesis and properties of poly(phenylene vinylene) (PPV), the first conjugated polymer applied as an organic light-emitting diode (OLED). Students determine how to synthesize a conducting polymer from basic organic chemicals, how to vary its structure to alter the color of emitted light (essential for the creation of color displays), and determine how and why it functions. A classic article from Nature is used to introduce students to the synthesis and properties of PPV, while extracts from more popular sources are used to explain the concepts of electroluminescence and the construction of OLEDs. This case study is designed for a second semester/second quarter organic chemistry course, and is generally presented in the middle of the course. Students will need to be familiar with nucleophilic substitution and elimination, conjugation and UV spectroscopy, aromaticity, electrophilic aromatic substitution, and polymers. An optional PowerPoint presentation, available from the Supplementary Materials tab, can be used to provide a framework for running the class activity, which involves answering questions in small groups.