Direction Switching and Self‐Recovering Mechanochromic Luminescence of Anthracene‐Modified o‐Carboranes

Abstract

AbstractLuminochromic behaviors regarding mechanochromic luminescence (MCL) of o‐carborane‐modified anthracene derivatives are reported. We have previously synthesized bis‐o‐carborane‐substituted anthracene and found that its crystal polymorphs show dual‐emission properties composed of excimer and charge transfer (CT) emission bands in the solid state. Initially, we observed the bathochromic MCL behavior from 1 a originating from emission mechanism alteration from dual emission to CT emission. By inserting the ethynylene spacers between anthracene and o‐carboranes, compound 2 was obtained. Interestingly, 2 showed hypsochromic MCL originating from the emission mechanism alteration from CT to excimer emission. Furthermore, luminescent color of ground 1 a can be recovered to the initial state by allowing to stand at room temperature, meaning that self‐recovery proceeds. Detailed analyses are described in this study.