Abstract:

A new approach to rapidly obtain a stable topological structure of a reverse micelle was investigated using a mathematical method combined with a Monte Carlo simulation. The vibrational frequency shift and the spectral distribution of I2, which was confined in a water pool of two different sizes in reverse micelles (RMs), were calculated by mixed quantum-classical molecular dynamics simulations. Results indicate that the vibrational frequency is blue-shifted for both RMs studied compared to the vibrational frequency for I2 in bulk water. This difference is not obviously related to RM size. By analysis of the interactions of I2 with its surroundings, the instantaneous frequency shift of I2 may consist of contributions from the water pool, the surfactant, and the organic solvent while the data provide detailed mechanistic information. The induced contribution and spatial distribution of water molecules confined in the water pool suggest that the induced frequency shift of I2 mainly originates from the first solvation layer, which is composed of contributions from 4 blue-shifted and 2 red-shifted water molecules.

Key words: Vibrational frequency shift, Mixed quantum-classical molecular dynamics, Reverse micelle, Confined water pool, Spectrum distribution