Vibrational properties of inclusion complexes: the case of indomethacin-cyclodextrin

TL;DR

This study investigates how the vibrational properties of indomethacin change upon forming inclusion complexes with cyclodextrins, using Raman spectroscopy and simulations to understand the molecular interactions involved.

Contribution

It combines experimental Raman spectroscopy with ab initio and molecular dynamics simulations to elucidate the vibrational changes and geometric details of indomethacin-cyclodextrin inclusion complexes.

Findings

Notable Raman spectral shifts in the 1600-1700 cm$^{-1}$ range upon complex formation

Correlation between vibrational changes and inclusion geometry

Disentangling effects of solid state structure and dimerization

Abstract

Vibrational properties of inclusion complexes with cyclodextrins are studied by means of Raman spectroscopy and numerical simulation. In particular, Raman spectra of the non-steroidal, anti-inflammatory drug indomethacin undergo notable changes in the energy range between 1600 and 1700 cm$^{-1}$ when inclusion complexes with cyclodextrins are formed. By using both \emph{ab initio} quantum chemical calculations and molecular dynamics, we studied how to relate such changes to the geometry of the inclusion process, disentangling single-molecule effects, from changes in the solid state structure or dimerization processes.