Large, Tunable, and Reversible pH Changes by Merocyanine Photoacids
Artikel i vetenskaplig tidskrift, 2021

Molecular photoswitches capable of generating precise pH changes will allow pH-dependent processes to be controlled remotely and noninvasively with light. We introduce a series of new merocyanine photoswitches, which deliver reversible bulk pH changes up to 3.2 pH units (pH 6.5 to pH 3.3) upon irradiation with 450 nm light, displaying tunable and predictable timescales for thermal recovery. We present models to show that the key parameters for optimizing the bulk pH changes are measurable: the solubility of the photoswitch, the acidity of the merocyanine form, the thermal equilibrium position between the spiropyran and the merocyanine isomers, and the increased acidity under visible light irradiation. Using ultrafast transient absorption spectroscopy, we determined the quantum yields for the ring-closing reaction and found that the lifetimes of the transient cis-merocyanine isomers ranged from 30 to 550 ns. Quantum yields did not appear to be a limitation for bulk pH switching. The models we present use experimentally determined parameters and are, in principle, able to predict the change in pH obtained for any related merocyanine photoacid.


Laura Wimberger

University of New South Wales (UNSW)

Shyamal K.K. Prasad

University of New South Wales (UNSW)

Martin D. Peeks

University of New South Wales (UNSW)

Joakim Andreasson

Chalmers, Kemi och kemiteknik, Kemi och biokemi

Timothy W. Schmidt

University of New South Wales (UNSW)

J. E. Beves

University of New South Wales (UNSW)

Journal of the American Chemical Society

0002-7863 (ISSN) 1520-5126 (eISSN)

Vol. 143 49 20758-20768


Atom- och molekylfysik och optik

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