Vapor triggered fluorescent color changes among solvates of Emodin

Abstract

The reversible vapochromic phenomenon of Emodin (EM), which is an eco-friendly, naturally occurring and metal-free organic MCL material, was investigated, and six new EM solvates were synthesized. Vapor and mechanical force triggered reversible fluorescent color changes, which occurred during solid-state transition processes, were fully studied. It was found that different types of H-bonds and π–π interactions highlighted the reasons why EM solvates exhibited significantly different fluorescent colors. This study provides a new approach to find a vapor sensitive MCL material without metal elements and chemical synthesis.