Related Experiment Video
Updated: Aug 13, 2026

Determination of the Photoisomerization Quantum Yield of a Hydrazone Photoswitch
Published on: February 7, 2022
A multi-state photoswitch regulated by higher excited states
Shuang Xu1, Le Yu2, Yang Cheng1
1Key Laboratory of Applied Surface and Colloid Chemistry of Ministry of Education, Shaanxi Provincial Key Laboratory of New Concept Sensors and Molecular Materials, School of Chemistry and Chemical Engineering, Shaanxi Normal University Xi'an 710119 China majiani@snnu.edu.cn.
None:
Integrating multiple photoswitching units into a single molecule is a challenging way to achieve the manipulation of molecule geometry by selectively activating individual photoresponsive moieties. A lack of understanding from a mechanism viewpoint obstructs the advancement and realization of such systems. Herein, we construct a new hybrid ionic photoswitch (PZ-SP-MeSO4) that combines spiropyran (SP) and the ionic arylazopyrazolium (PZ) counterpart. Independent modulation of PZ (E/Z) and SP (closed/open) moieties via specific irradiation wavelengths has been achieved. The photostationary state composition (>66% Z-isomer content), fatigue resistance (>15 cycles), thermal stability of the Z-isomer (t 1/2 = 717 days in water) and pH -dependent behavior enabled PZ-SP-MeSO4 to act as a potential hybrid photoswitch for molecular logic gate application, in addition to excellent water solubility (18.4 mM). More importantly, we elucidated the wavelength-gated regulating mechanisms for PZ-SP-MeSO4: 450 nm (S1) excites E → Z isomerization primarily and 365 nm (S3) triggers the SP → MC transformation. Uniquely, upon 420 nm excitation (S2), soon after the E → Z isomerization, the relay SP → MC transformation occurs from the hot ground state species due to excess vibrational energy. The understanding of the multi-state photoswitch regulated by higher excited states in this work establishes a blueprint for designing advanced light-responsive molecules.
Related Concept Videos
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Deactivation Processes: Jablonski Diagram
The Photochemical Reaction Center
Photosystem I
Both these photosystems work in concert. An excited electron from PSII is relayed to PSI via an electron transport chain in the thylakoid membrane of the chloroplast, which is comprised of the carrier molecule plastoquinone, the dual-protein cytochrome complex, and plastocyanin. As electrons move between PSII and PSI, they lose energy and must be re-energized...
Photoluminescence: Fluorescence and Phosphorescence
A pair of electrons in a...
Photosystems
Functioning of Photosystems
Photosystems contain many pigment molecules, such as chlorophylls and carotenoids, arranged in a particular organization across two domains — the antenna complex and the reaction center. The main aim of the pigment molecules...
