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Updated: Jul 4, 2026

Determination of the Photoisomerization Quantum Yield of a Hydrazone Photoswitch
Published on: February 7, 2022
Quantitative Photoswitching of Spin States in o-Fluoroazobenzene-Loaded Metal-Organic Frameworks
Kun-Peng Chen1, Dan Li1, Qiyi Miao1,2,3
1Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, Institute of Green Chemistry and Molecular Engineering, Guangdong Basic Research Center of Excellence for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, P.R. China.
Abstract:
The integration of photochromic guest molecules into spin-crossover (SCO) metal-organic frameworks (MOFs) offers a promising approach for optically regulating magnetic properties. Herein, we report a crystalline material, [Fe(bpn){Ag(CN)2}2]·E-F4AB (1-E) (bpn = 1,4-bis(4-pyridyl)naphthalene and E-F4AB = E-o-tetrafluoroazobenzene), which displays an asymmetric three-/four-step SCO behavior. At room temperature, the material undergoes efficient (90%) and reversible E/Z photoisomerization of guest molecules upon alternating irradiation with green (530 nm) and blue (410 nm) light. Following green-light irradiation, the crystal of 1-Z, containing 90% F4AB in the Z configuration, was obtained via a light-induced single-crystal-to-single-crystal transformation. The E-to-Z isomerization of F4AB introduces steric constraints within the pores, effectively locking the host framework into the high-spin (HS) state. Furthermore, by controlling the proportion of the Z isomer through variation of irradiation time, we achieve continuous and quantitative modulation of the HS fraction. This work provides the first direct structural evidence of guest-driven light-induced spin change (GD-LISC), establishing a robust strategy for designing photoswitchable materials.
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