Aurora de Tagyos

ELUCIDATING THE REVERSION MECHANISM OF DONOR ACCEPTOR STENHOUSE ADDUCT (DASA) PHOTOCHROMIC MOLECULES

Aurora de Tagyos, Marvin Santiago, Julie Peterson, Javier Read de Alaniz, Craig J. Hawker

Donor-acceptor Stenhouse adducts (DASAs) are a class of visible light-activated photochromic molecules. These molecules are composed of three elements: an electron donor, a triene backbone, and an electron acceptor. Upon activation, they transform from a colored "open" form to a colorless "closed" form with different properties. These molecules have found applications in photothermal agents, amine sensing, and photopharmacology. DASAs have a thermal equilibrium between their open and closed forms and have been observed to favor the closed form in polar solvents. It is possible to adjust this equilibrium by attaching a methyl group to the triene but then a reversion to the DASA starting materials is observed. This reversion is studied in various conditions using UV-Visible spectroscopy (UV-Vis) and Nuclear Magnetic Resonance (NMR) techniques to gain a better understanding of the general reversion mechanism. It has been observed that these DASAs break apart and recombine with each other in a dynamic exchange equilibrium. This is leading to further investigation regarding the feasibility of DASA incorporation into covalent adaptable networks.