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  • Quinoline Photobasicity: Investigation within Water-Soluble Light-Responsive Copolymers.

Quinoline Photobasicity: Investigation within Water-Soluble Light-Responsive Copolymers.

Chemistry (Weinheim an der Bergstrasse, Germany) (2020-09-29)
Maria Sittig, Jessica C Tom, Johanna K Elter, Felix H Schacher, Benjamin Dietzek
ABSTRACT

Quinoline photobases exhibit a distinctly higher pKa in their electronically excited state than in the ground state, thereby enabling light-controlled proton transfer reactions, for example, in molecular catalysis. The absorption of UV light translates to a pKa jump of approximately 10 units, as established for small-molecule photobases. This contribution presents the first synthesis of quinoline-based polymeric photobases prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization. The integration of quinolines as photobase chromophores within copolymers offers new possibilities for light-triggered proton transfer in nanostructured materials, that is, in nanoparticles, at surfaces, membranes and interfaces. To exploit the light-triggered reactivity of photobases within such materials, we first investigated how the ground- and excited-state properties of the quinoline unit changes upon polymer integration. To address this matter, we combined absorption and emission spectroscopy with time-resolved transient-absorption studies to reveal photoinduced proton-transfer dynamics in various solvents. The results yield important insights into the thermodynamic and kinetic properties of these polymeric quinoline photobases.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Methacryloyl chloride, 97%, contains ~200 ppm monomethyl ether hydroquinone as stabilizer
Sigma-Aldrich
5-Aminoquinoline, 97%