Aggregation-Dependent Photoreactive Hemicyanine Assembly as a Photobactericide.

Organic materials that show substantial reactivity under visible light have received considerable attention due to their wide applications in chemical and biological systems. Hemicyanine pigments possess a strong intramolecular donor-acceptor structure and thereby display intense absorption in the visible spectral region. However, most excitons are consumed via the twisted intramolecular charge-transfer (TICT) process, making hemicyanines generally inert to light. Herein, we describe the development of an amphiphilic hemicyanine dye whose aggregation could be easily regulated using salt or counterions. More importantly, its intrinsic photoreactivity was successfully induced by steric restriction and cofacial arrangement within the H-aggregate, thus creating an effective photobactericide. This strategy could be extended to the development of photocatalysts for photosynthesis and a photosensitizer for photodynamic therapy.

A donor-acceptor type macrocycle: toward photolyzable self-assembly.

A water-soluble macrocyclic host is reported, composed of alkoxyanthracene as the donor (D), and 4,4-bipyridinium as the acceptor (A). The intramolecular D-A structure renders the host highly photostable. However, the introduction of a strong electron-donating guest promotes the photodecomposition of alkoxyanthracene, yielding photolyzable host-guest complexes or aggregates.

Photolysis of polymeric self-assembly controlled by donor-acceptor interaction.

A photodegradable supramolecular polymer was constructed using cucurbit[8]uril (CB[8]) and an alkoxyanthracene guest. The monomeric unit was photostable because of the intramolecular donor-acceptor interaction. However, upon complexation with CB[8], the photolysis of alkoxyanthracene was enhanced, which endowed the supramolecular polymer with great photoreactivity.