Discipline: Chemistry and Chemical Sciences
Subcategory: Chemistry (not Biochemistry)
Angelah Aminah Wilson - University of West Georgia
Co-Author(s): Jordan Davoll, University of West Georgia
Recently we have discovered that indole derivatives exhibit vivid color changes when exposed to select first-row d-block metal ions in acetonitrile solution. We hypothesize that when indole has interaction with certain metal ions, the electron excitation from the electron-rich indole to the metal ion’s orbital could cause the absorption of visible-range electromagnetic radiation. Colorimetric sensors are molecular compounds or materials that show color changes upon contact with specific analytes. Selective metal ion colorimetric sensors would have great potentials for applications in analyzing physiological and environmental samples. We have carried out systematic color response tests of 16 metal ions with 13 indole derivatives (10 commercially available and 3 synthesized in our lab) and photographed the color changes. We have discovered that (i) at least one electron-donating group at 1, 2 or 3 positions enhances the color; (ii) the 2 and 3 positions of indole are susceptible toward oxidation and thus need to be protected with substituents, and (iii) a 2-pyridyl group attached at either 2 or 7 position greatly enhance the metal ion binding and color response range of the indole. These learnings are reflected in our design of practical colorimetric sensors that utilize an indole as a color sensing unit. Future work will include computational studies of indole-metal ion complexes and their molecular orbitals to rationalize the UV-Visible absorption that we observe with certain combinations.
Funder Acknowledgement(s): LSAMP
Faculty Advisor: Megumi Fujita, firstname.lastname@example.org
Role: Synthesis of the lab-prepared indoles and the systematic colorimetric testing