After successful synthesis, the solution behavior was scrutinized first. In pure aromatic solvents like benzene, toluene, or pyridine and at low concentrations (ca. 10 -5 mol/L) green colored solutions are obtained for all derivatives 1-3. However, when inspecting the corresponding UV/vis spectra a distinct fine structure with several maxima around 700 nm and overall redshift of the absorptions is observed (see Supporting Information). This behavior served as first hint at possible aggregation behavior of the new PAT derivatives. After irradiation with 780 nm NIR light the solutions turned deep blue in color and the well-established smooth absorption of Z isomeric PAT was obtained in each case with one maximum at around 590 nm. Irradiation with 590 nm light turned the solutions green and produced the known absorption profile of E isomeric PAT with a maximum at around 760 nm in each case. After this initial photoswitching round the absorption profiles remained stable for each further irradiated state showing full dissolution of the chromophores in the aromatic solvents.