Planarisation or a twist? Using steric engineering to unlock the origin of mechanofluorochromic red-shifts

Abstract

Engineering the ground-state orientations of donor and acceptor groups through steric control of fluorophore conformations is an effective strategy for manipulating molecular electronics and, in turn, their emissive properties. Where strong emission is retained in the crystalline state, a correlation of structure with photophysical properties can be made, as is the case for the five pyridinium betaines reported herein. Our findings provide strong evidence that an increase in dihedral angle between N,N-diphenylamino donor and pyridinium acceptor induces a notable red-shift in emission maximum, with the mechanofluorochromic response also correlated with the same process. This research aims to ..