Enhancement of Mechanophore Activation in Mechanochromic Dendrimers by Functionalization of Their Surface

Abstract

The mechanochemical reactions of a series of dendrimers with a mechanochromic core were systematically investigated, and drastic enhancement of their reactivity was observed after their surface functionalization. We recently reported the quantitative and qualitative mechano-responsive behavior characteristic of a radical-type mechanophore for mechanochromic dendrimers (MDs) with defined structures in the bulk. In the present study, we systematically investigated the mechanochemical response of a series of dendrimers with different functional groups on their surfaces by mechanical grinding in the bulk. Effective activation of the mechanochromic core was achieved in higher-generation MDs with hydrogen-bonding amide groups on their surfaces. A comparison of the degree of activation of the MDs with that of linear analogues revealed that the chain overlap, molecular size, and polarity affect the efficiency of the transmission of the grinding force to the mechanochromic core.