Dopant Effect on Phenalene Bandgap Control: A Hückel Molecular Orbital Perspective

Abstract

In this study, we investigate the effects of nitrogen and boron dopants on the properties of phenalene/phenalenyl systems based on the Hückel theory by using the Hueckel Molecular Orbital software. The dopants configurations are graphitic, pyridinic, and pyrrolic. The electronic configuration of bare phenalene confirms the delocalization of π electrons and the radical properties of the molecule, which is in good agreement with the results of previous studies. Dopant types and positions strongly affect the number of π electrons in the system, molecular orbital energy, total energy, average π-electron energy, and gap energy. The molecular energy level degeneracy strongly depends on the rotational symmetry of the system, in the order of graphitic, pyridinic, and pyrrolic. A preserved radical behavior and the number of π electrons are found for the pyridinic dopant type, while closed electronic configuration is observed for graphitic and pyrrolic types. A lower gap energy is typically found for B-doped phenalene compared to that for N-doped phenalene; this opens the possibility for the enhancement of photoluminescence intensity. This study, although qualitative, confirms the effects of dopants on the chemical and physical properties of phenalene/phenalenyl systems.

π-Extended 9b-Boraphenalenes: Synthesis, Structure, and Physical Properties

“…In this context, boraphenalene stands as a representative example of boron-doped polycyclic odd-alternant hydrocarbons, displaying an isoelectronic structure with a phenalenyl cation . Despite theoretical calculations predicting its electronic structure, including aromaticity/antiaromaticity, pancake π–π bonding, and singlet–triplet gap, the construction of boraphenalene skeletons remains challenging except for nitrogen incorporating boraphenalenes . Among the boraphenalenes, categorized into four types ( A – D ) based on the doping position of boron, type- B compounds (1-boraphenalene) have been independently reported by several research groups (Figure a) .…”