Molecule

Intramolecular force

Conjugated system

Nanorod

Polymer

Alkyl

Nanotechnology

Organic chemistry

Photothermal therapy

Chemical physics

Intermolecular force

Nanoparticle

Chemistry

Materials science

Photochemistry

Journal of the American Chemical Society

Planar donor and acceptor (D–A) conjugated structures are generally believed to be the standard for architecting highly efficient photothermal theranostic agents, in order to restrict intramolecular motions in aggregates (nanoparticles). However, other channels of extra nonradiative decay may be blocked. Now this challenge is addressed by proposing an "abnormal" strategy based on molecular motion in aggregates. Molecular rotors and bulky alkyl chains are grafted to the central D–A core to lower intermolecular interaction. The enhanced molecular motion favors the formation of a dark twisted intramolecular charge transfer state, whose nonradiative decay enhances the photothermal properties. Result shows that small-molecule NIRb14 with long alkyl chains branched at the second carbon exhibits enhanced photothermal properties compared with NIRb6, with short branched chains, and much higher than NIR6, with short linear chains, and the commercial gold nanorods. Both in vitro and in vivo experiments demonstrate that ...

Molecular Motion in Aggregates: Manipulating TICT for Boosting Photothermal Theranostics