Computational Analysis of Chlorophyll Structure and UV-Vis Spectra: A Student Research Project on the Spectroscopy of Natural Complexes

ABSTRACT

Chlorophyll was extracted from fresh spinach leaves (Spinacia L.) and its absorption spectrum was recorded. Computational methods were used to optimize the geometry and energy of chlorophyll as well as to compute UV-Vis spectra of chlorophylls a and b and to compare them with the spectrum of chlorophyll extract. Chlorophyll bands are well predicted, especially with B3LYP/CIS and TD-B3LYP methods. This research project forms a modern approach to the process of spectroscopy teaching—students can apply quantum-mechanics calculations for understanding of reaction mechanisms with the involvement of biologically active compounds and learn to interpret the absorption spectra of chlorophyll extract obtained by themselves.

KEYWORDS:

• chlorophyll
• computational methods
• extraction
• UV-Vis spectrophotometry
• X-ray structure

ACKNOWLEDGMENTS

The computational part of this work was performed during a postdoctoral stay of Agnieszka A. Kaczor at the Department of Pharmaceutical Chemistry II at the Faculty of Chemistry and Pharmacy of the University of Regensburg, Germany, founded by Deutscher Akademischer Austausch Dienst (DAAD). Calculations with Gaussian 09 were performed under a computational grant by the Interdisciplinary Center for Mathematical and Computational Modeling (ICM), Warsaw, Poland, Grant No. G30-18.

Notes

This paper was submitted as a contribution representing work done primarily by undergraduate researchers; Dorota Kukier and Anna Gasior, supervised by Magdalena Makarska-Bialokoz and Agnieszka Kaczor.