Revealing Topological Influence of Phenylenediamine Unit on Physicochemical Properties of Donor-Acceptor-Donor-Acceptor Thermally Activated Delayed Fluorescent Macrocycles.

A new thermally activated delayed fluorescence (TADF)-displaying macrocyclic compound  m-1  comprising of two electron-donors ( N,N'- diphenyl- m -phenylenediamine) and two electron-acceptors (dibenzo[ a,j ]phenazine) has been synthesized. The macrocycle developed herein is regarded as a regioisomer of the previously reported TADF macrocycle  p-1 , which has two  N,N '-diphenyl- p- phenylenes as the donors. To understand the influence of the topology of the phenylenediamine donors on physicochemical properties of TADF-active macrocycles, herein the molecular structure in the single crystals, photophysical properties, electrochemical behavior, and TADF properties of  m-1  have been investigated compared with those of  p-1 . The substitution of  p- phenylene donor with  m -phenylene donor led to distinct positive solvatoluminochromism over the full visible-color range, unique oxidative electropolymerization, and slightly lower contribution of TADF, due to the lower CT character in the excited states.