Self-regulating photochemical Rayleigh-Bénard convection using a highly-absorbing organic photoswitch.

Seshadri, Serena; Gockowski, Luke F; Lee, Jaejun; Sroda, Miranda; Helgeson, Matthew E; Read de Alaniz, Javier; Valentine, Megan T · Nat Commun · 2020

basic_science · Level V

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Abstract

We identify unique features of a highly-absorbing negatively photochromic molecular switch, donor acceptor Stenhouse adduct (DASA), that enable its use for self-regulating light-activated control of fluid flow. Leveraging features of DASA's chemical properties and solvent-dependent reaction kinetics, we demonstrate its use for photo-controlled Rayleigh-Bénard convection to generate dynamic, self-regulating flows with unparalleled fluid velocities (~mm s<sup>-1</sup>) simply by illuminating the fluid with visible light. The exceptional absorbance of DASAs in solution, uniquely controllable reaction kinetics and resulting spatially-confined photothermal flows demonstrate the ways in which photoswitches present exciting opportunities for their use in optofluidics applications requiring tunable flow behavior.