*2.2. General Procedure for the Synthesis of PP1–PP10:*

1*H*-Cyclopenta[b]naphthalene-1,3(2*H*)-dione **EA4** (0.5 g, 2.55 mmol) and the appropriate substituted benzaldehyde (2.55 mmol, 1. eq.) were dissolved in absolute ethanol (50 mL) and a few drops of piperidine were added. The reaction mixture was refluxed and progress of the reaction was followed by thin layer chromatography (TLC). After cooling, a precipitate formed. It was filtered off, washed several times with ethanol and dried under vacuum.
