Utilizing Yellow Compounds to Introduce π-Conjugated Molecular Structures: A Harmony with Blue Compounds

The yellow–blue color pair has been used in creative artwork such as paintings and designs and in color engineering. Herein we present a method for using the yellow–blue combination in a chemistry lesson dealing with π-conjugated molecules for first-year undergraduate students who are not science majors. The lesson begins with an introduction to primary yellow compounds that contain π conjugation within their molecular structures and a demonstration of yellow dyeing using gardenia fruits or marigold petals. In addition to an overview of various yellow compounds, blue compounds with π-conjugated molecular structures are presented to enhance the perceived aesthetic stimulus. Yellow luminescence, blue luminescence, and intramolecular and intermolecular chemical reactions to produce yellow and blue compounds are exhibited. Through these demonstrations, students learn about basic π-conjugated molecular structure.