# Structural Characteristics, Electronic Properties, and Coupling Behavior of 12-4-12, 12-3-12, 12-2-12 Cationic Surfactants: A First-Principles Computational Investigation and Experimental Raman Spectroscopy

## TL;DR

This paper uses computational methods and Raman spectroscopy to study the structure, electronic properties, and interactions of three cationic Gemini surfactants with varying central spacers.

## Contribution

The study provides new insights into the coupling mechanisms and structural variations of Gemini surfactants based on their central spacer lengths.

## Key findings

- The structural and electronic properties of the surfactants depend on the number of carbon atoms in the central spacer.
- Different conformers (parallel, wing, bent) show distinct stability and molecular arrangements.
- Experimental Raman spectroscopy confirmed the computational findings on surfactant behavior.

## Abstract

In this study, we present a comprehensive first-principles computational investigation focused on the structural characteristics, electronic properties, and coupling integrations of three cationic Gemini surfactants: 12-4-12, 12-3-12, and 12-2-12 ((CH3(CH2)11)(CH3)2-N+-(CH2)n-N+(CH3(CH2)11)(CH3)2, where n = 2, 3, or 4). By employing Density Functional Theory (DFT) computations, we aimed to gain insights into the fundamental aspects of these surfactant molecules, and the intermolecular interactions among these surfactant molecules. We examined different conformers of each surfactant, including parallel, wing, and bent conformers, and compared their relative stability and properties. We elucidated that the complex structural characteristics, electronic properties, and molecular arrangements of the surfactants vary according to the number of carbon atoms in the central spacer. We also conducted experimental Raman spectroscopy on the three surfactants to compare the results with our computational findings. Furthermore, we computed the coupling behaviors of different conformers of 12-4-12 surfactants in order to gain insights into their coupling mechanism.