Light-Driven Generation of Air-stable Zn(I) Under Ambient Conditions

Research on the synthesis and stabilization of air-stable monovalent zinc (Zn⁺) species under mild conditions remains relatively unexplored. This article reports the synthesis of a new zinc coordination polymer, [Zn₂(PA)₄(bipy)₂]_n·nH₂O (1) (PA = propionate; bipy = bipyridine), which generates stable Zn⁺ species upon photoirradiation under ambient conditions. Compound 1 features a metalloviologen structure built by 1-D ladder-like chains. Upon Xe lamp irradiation, it changes from colorless to light brown, which is accompanied by the emergence of new electron absorption bands assigned to bipy radical anions and Zn⁺ species by UV-vis and EPR tests. PXRD, Raman, and IR analyses indicate that the crystalline framework remains but distortion happens during photoirradiation. The photoinduced Zn⁺ species remains stable under ambient conditions for at least 7 days. This work demonstrates that air-stable Zn⁺ species can be easily prepared through the coordination assembly of Zn²⁺ ion, carboxylate and bipyridine and further light stimulation, which will help to understand the chemical bonding nature or find catalytic and other applications of Zn⁺-based materials.