Comparative Study of the Optoelectronic, Reactivity Descriptors, and Thermodynamic Properties for Derivatives of Fluorene, and its Hetero-Analogous (Si, NH, O, S, and Se) by Employing the DFT and TD-DFT Approaches. Mal. J. Fund. Appl. Sci. 2024;20(4):871-887. doi:10.11113/mjfas.v20n4.3538