Butterfly‐like Tetraazaacenequinodimethane Derivatives: Synthesis, Structure and Halochromic Properties

Abstract Two novel molecules TAP and TAH with pronounced reversible halochromic properties have been synthesized and fully characterized. Their butterfly‐like structures have been confirmed through single‐crystal X‐ray diffraction. Their UV‐Vis absorption after protonation dramatically red‐shifted with naked‐eye‐visible color change in a very dilute concentration of 10 −5 M. Note that the original color of the solution can be recovered after the neutralization with a base.