Session: Undergraduate Research Posters: Analytical Chemistry:

The creation of azo dyes is a fun and engaging experiment for sophomore organic chemistry students. It can be done in a combinatorial fashion to demonstrate the effects of substituents on the color of the dye. In this project, the azo dye experiment has been expanded to include NMR spectroscopic analysis and X-ray crystallography. The 1D and 2D NMR spectra of the azo dyes include a sharp, highly deshielded peak (~14-16 ppm) which provides evidence for a charged tautomeric form of the azo dyes with an intramolecular hydrogen bond. The crystal structures show that the hydrogen is more closely associated with the nitrogen of the diazo functional group rather than the phenolic oxygen. NMR spectra (¹H, ¹³C, COSY, HMQC, HMBC) and crystal structures for over 12 azo dyes have been collected that can be used at other universities. This allows students to utilize crystallography for structure determination and highlights the interesting tautomeric forms of azo dyes that have not been addressed previously.

Ian McTamaney

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