Strategies to Enhance the Photosensitization: Polymerization and the Donor-Acceptor Even-Odd Effect

A particular challenge in the design of organic photosensitizers (PSs) with donor-acceptor (D-A) structures is that it is based on trial and error rather than specific rules. Now these challenges are addressed by proposing two efficient strategies to enhance the photosensitization efficiency: polymerization-facilitated photosensitization and the D-A even-odd effect. Conjugated polymers have been found to exhibit a higher O-1(2) generation efficiency than their small molecular counterparts. Furthermore, PSs with A-D-A structures show enhanced photosensitization efficiency over those with D-A-D structures. Theoretical calculations suggest an enhanced inter-system crossing (ISC) efficiency by these strategies. Both in vitro and in vivo experiments demonstrate that the resulting materials can be used as photosensitizers in image-guided photodynamic anticancer therapy. These guidelines are applicable to other polymers and small molecules to lead to the development of new PSs.