Summer Hanson

Document Type

Honors Thesis

Degree Name

Bachelor of Science in Biological Sciences

Date of Award

Spring 2023


This study was used to determine the significance of substituents placed on aromatic molecules and how electron-donating groups (EDG) and electron-withdrawing groups (EWG) affect the strength of the halogen bond. Each study involved the same substituents, each differing in electron-withdrawing and electron-donating capability. Five different systems were created on computational software to evaluate the distance between the halogen bond donor and halogen bond acceptor. In two studies, the goal was to find the best electron-donor on the halogen bond acceptor (donor of electron density) while the halogen bond donor remained constant. For one study, the goal was to determine the best electron-acceptor on the halogen bond donor, which changed its electron density. For a fourth study, a nitro group was utilized as the electron donor. For the final study, substituents of varying electron-donating and withdrawing ability were studied on both the halogen bond donor and acceptor to allow for pairing the best substituents. Hammett plots were utilized to correlate substituent σ values and the halogen bond distance. Halogen bonding is a relatively newly discovered type of intermolecular attraction under the branch of supramolecular chemistry that has been used to drive molecular self-assembly in crystal engineering. This project may contribute to a goal of developing sensors for explosives. Nitro groups are part of many explosives (ex. TNT) and a halogen bond could be used to attract, and therefore detect nitro containing compounds. Halogen bonding could also be used to develop sensor applications containing anions and amines. Anions have the potential to be environmental contaminants/pollutants and amines are in many narcotics. Developing sensors for these may contribute to decreasing the abundance in the environment or aid in drug detection or drug detoxification.


Stephen Starnes

Included in

Chemistry Commons