Optical Properties of Artemisinin and Its Derivatives

Artemisinin and its derivatives are of great research value in biology. In this work, we study their chiral and optical properties. The multidimensional multifunction analysis method is used to analyze the linear and nonlinear optical processes (one-photon and two-photon absorption: OPA and TPA), electronic circular dichroism (ECD), and Raman optical activity (ROA) mechanisms under light excitation. Transition dipole moments (TDMs) and charge difference density (CDD) are used to describe the electromagnetic interaction between ECD and ROA when a substance is excited by light. The theoretical research results of the study show that the dioxygen atoms provide an intermediary for the transfer between charges and also enhance the role of the TDMs. This generalized chiral theory can not only explain the traditional sources of chirality but also distinguish whether the molecule has chirality when the chiral center is not obvious. By analyzing ROA and different vibration modes, we can clearly observe that each part of the molecule responds differently when excited.