Preparation, spectroscopic, cyclic voltammetry and DFT/TD-DFT studies on fluorescein charge transfer complex for photonic applications

The solid charge transfer (CT) complexes of fluorescein (Flu) with definite acceptors (tetrafluoro para benzoquinone (Fla); 7,7,8,8-tetracyanoquinodimethane (TCNQ); 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and iodine) were prepared. Several characteristic analytic procedures such as transmission (FT-IR), diffuse reflectance, UV-Vis absorption, and cyclic voltammetry were used to determine the structural and optical properties of the prepared fluorescein charge transfer complex. Kubelka Munk model (K-M) and the absorption spectral fitting (ASF) methods were used to obtain the optical transitions of the solid fluorescein charge transfer complex and fluorescein CT complexes in methanol solution. The cyclic voltammetry method has been presented as capable of obtaining valuable information on quasi-reversible redox systems in the fluorescein CT-complexes. The electrochemical gap of the fluorescein CT complex was successfully determined from the cyclic voltammetry technique. Theoretical calculations (density functional theory) were made to corroborate experimental results for the synthesized CT complexes. KEY WORDS: Fluorescein charge transfer complex, Optical spectroscopy, Cyclic voltammetry Bull. Chem. Soc. Ethiop. 2023, 37(2), 515-532. DOI: https://dx.doi.org/10.4314/bcse.v37i2.19