Resumen de Integrating a Smartphone and Molecular Modeling for Determining the Binding Constant and Stoichiometry Ratio of the Iron(II)–Phenanthroline Complex: An Activity for Analytical and Physical Chemistry Laboratories
Camilo de L. M. de Morais, Sérgio R. B. Silva, Davi S. Vieira, Kassio M. G. de Lima
The binding constant and stoichiometry ratio for the formation of iron(II)–(1,10-phenanthroline) or iron(II)–o-phenanthroline complexes has been determined by a combination of a low-cost analytical method using a smartphone and a molecular modeling method as a laboratory experiment designed for analytical and physical chemistry courses. Intensity values were obtained from the digital images by measuring the RGB (red, green, blue) values (on a scale of 0–255 in intensity) of the samples between Fe(II) and o-phenanthroline using a digital camera from a smartphone. The R channel showed the best linearity for predicting the binding constant. For computational studies, iron(II) complexes using water molecules and 1,10-phenanthroline were used to evaluate the stability of the complex by varying the number of ligands. Complexes have been optimized by reaching a minimum amount of energy. It was possible to observe how stable the complexes are from the optimization calculations, including aspects about the achieved geometries. The approach provides a simple method for performing stability constants over a wide range of complexes, from the undergraduate chemistry laboratories, in the field, and in the research laboratory.
