Qiu, Q., Usuba, J., Koay, W. L., Conrad, V. J. O., Wu, N. M.-W., Zheng, S.-L., Truong, V. X., & Han, G. G. D. (2026). Visible photon energy storage by [2+2] cycloaddition of Pd-oxazolones. Chemical Science, 17(6), 3066–3074. https://doi.org/10.1039/d5sc07833d
Abstract:
We report a new class of ortho-palladated oxazolone complexes that capture and release solar energy through visible-light-triggered [2 + 2] photocycloaddition reactions. The free oxazolone ligands weakly absorb near 400 nm and undergo slow and incomplete intermolecular dimerization, yielding multiple stereoisomers of cycloadducts. Upon ortho-palladation, the resulting Pd (II) complexes exhibit strong charge-transfer absorption bands in the visible range (430–570 nm) and adopt a clamshell geometry that preorganizes the reactive alkenes in close spatial proximity. This unique coordination environment facilitates fast, near-quantitative, and reversible [2 + 2] photocycloaddition in both solution and amorphous solid state under the irradiation of green light or standard sunlight. The cycloadducts formed are stable, isolable solids with long thermal half-lives (up to 504 days at 298 K), enabling long-term energy storage. The combination of visible-light responsiveness, robust reversibility, and solid-state reactivity demonstrates the potential of transition metal complexes as a promising molecular platform for molecular solar thermal energy storage applications.
License type:
Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Funding Info:
This research / project is supported by the Agency for Science, Technology and Research (A*STAR) - A*STAR Industry Alignment Fund—Pre- Positioning Programme
Grant Reference no. : H23J2a0130