Investigating the Complexation and Release Behaviors of Iodine in Poly(vinylpyrrolidone)-Iodine Systems through Experimental and Computational Approaches

Abstract

Poly(vinylpyrrolidone)-iodine (PVPI)-based materials have attracted significant attention, owing to their effective inhibition of COVID-19 However, the complexation and release manner of iodine in PVPI are not fully understood This article reveals the role of halogen bonding in PVPI chemistry through a combination of experimental and computational approaches, including ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, electronic structure calculations, electronically excited-state analysis, electrostatic potential mapping on molecular van der Waals surfaces, halogen bond energy calculations, and thermodynamic equilibrium analysis Our research shows that, in both the solid state and solution, PVPI contains iodine molecules bonded with carbonyl groups as well as polyiodides derived from the ionization and assembling of iodine molecules The iodophors (i e , PVP, iodide, and polyiodides) interact with iodine molecules through halogen bonds The halogen bond energy is as low as 2-8 kcal/mol, enabling the easy release of iodine by the iodophors In PVPI solutions, the complexation and release of iodine reach a chemical equilibrium that is susceptible to temperature and other iodophors Raising the temperature favors the release of iodine Some synthetic polymers, biological proteins, and phospholipids can extract iodine molecules from solutions of PVPI, demonstrating good iodophor abilities © 2020 American Chemical Society