New vulnerability discovered in the bacteria that causes the disease

Combining dynamic covalent bonds with photoswitches allows the kinetics and thermodynamics of exchange to be controlled with light. However, this two-component strategy introduces synthetic and compatibility challenges. Here, we present a single-component strategy using donor–acceptor Stenhouse adducts (DASAs) as both the photoswitch and the dynamic covalent bond. DASAs isomerize from “open” to “closed” forms with light and heat, respectively. We discovered that open DASA isomers undergo dynamic covalent exchange of their amine donor via two pathways, reversible dissociation and conjugate transamination. Exchange can then be arrested upon irradiation to form the closed DASA isomer, offering a handle to gate dynamic behavior. Consequently, incorporating DASAs as cross-linkers in PDMS-based networks yields covalent adaptable networks (CANs) with viscoelastic behavior that can be tuned by light. We also identify degradation pathways that limit the reversibility of this system under extended heating. Overall, DASA exchange represents a synthetically accessible platform for photocontrolled soft materials. More broadly, this work introduces DASAs as a new class of intrinsically photoswitchable dynamic covalent bonds and lays the foundation for the discovery of other stimuli-gated dynamic bonds that combine reactivity and responsiveness in a single molecular unit.

Strategy boosts spectral purity by 87%, paving the way for quantum technologies

Feinberg School of Medicine professor Jeffrey Savas has been funded by a U.S. Department of Defense grant to advance his work in hearing loss; circadian rhythm expert Fred Turek at the Weinberg Colleg...

New detector promises to lower the cost and increase the quality of nuclear medicine

Circularly polarized (CP) vibrations are the nuclear-motion analog of CP light, emerging in molecules with non-Abelian point-group symmetry that support orthogonal and degenerate vibrational normal mo...