*3.2.2 Redox-complexation (oxidation:reduction reactions)*

These reactions involve a transfer of electrons between two species and a change in the oxidation number of species by gaining or losing an electron, generating a colored species. Many scientific published papers indicated oxidation-reduction reactions, that include; valganciclovir hydrochloride with iron (III) and KMnO4 [30], amoxycillin, ampicillin, and cloxacillin with iodate [17], Olanzapine with N-Bromosuccinimide and Cerium (IV) sulfate [56], captopril with a mixture of KBrO3 and KBr [57], to name a few.


#### **Table 3.**

*The wavelengths of the visible and ultraviolet regions.*

#### *3.2.3 Charge-transfer complexation*

The charge-transfer complex is formed from a combination of two molecules, one of which acts as an electron donor and the other as an electron acceptor. Based on the charge-transfer complexation, albendazole with picric acid [58] (**Figure 4**), chloranilic with tyrosine [59], carvedilol with iodine [60] to name a few, were determinates using spectrophotometric techniques.
