Based on the parent structure 9,10-AQ, the hydroxyanthraquinone derivatives were classified into π-plane backbone is not only essential for the photosensitizing ability but also enables hydrophobic interactions with the β-sheet in oligomeric and fibrillar Aβ. Hydroxyl groups and the neighboring ketone functionality are envisioned to serve as potential metal-binding sites that can interact with other metal ions bound to Aβ. Upon photoactivation, anthraquinones are reported to generate singlet oxygen ( 1 O2), which are highly reactive towards diverse biological substrates. As such, we anticipated that AQ derivatives could readily oxidize amino acid residues in Aβ. We evaluated 1 O2 production of compact molecules in the AQ series with mechanistic investigations and their reactivities towards both metal-free Aβ and metal-Aβ, as depicted in Figure .