4-(3,5-dichloro-2-pyridylazo)-1,3-diaminobenzene as a metallochromic indicator for the complexometric determination of Cu(II) with EDTA

Synthesis, Structure and Solvatochromism Studies on Copper(II) Complexes Containing Ethylenediamine, Pyridine and Imidazol Ligands

“…Among the former whose color changes are due to those of d-d transitions, copper(II) complexes with a strong JahnTeller effect can be anticipated to show simple and regular changes in their electronic spectra according to the strength of interactions with solvent molecules at the axial sites. [6][7][8] There are many applications for this phenomenon such as Lewis acid-base color indicator, 9 imaging, [10][11][12][13] photoswitching, [14][15][16] and sensor materials. 17 It has been known that wave numbers corresponds to absorption maxima of the compounds in solvents of used correlate well with the solvent parameters.…”