Researchers at Shandong University have developed a method to control macroscopic symmetry breaking and photomechanical movement in self-assembled materials by selectively introducing protic solvent guests, according to a study published in Nature Communications on August 14, 2026.
The team found that achiral nitro-conjugated cyanostilbenes self-assemble into macroscopic helices in the absence of protic guests. When trace amounts of protic solvents are present, hydrogen bonding anchors the molecular arrangement. This interaction suppresses symmetry breaking, directing the system to form achiral crystals instead of helical structures. The structural preference between helices and crystals responds selectively to protic guests such as water, alcohols, and acids.
Single crystal structures identified packing nanopockets across the matrices. The authors propose that whether these nanopockets are filled determines the presence of screw dislocations in the self-assembled framework. Building on this structural control, the researchers triggered photomechanical motion via [2 + 2] photodimerization of the stilbene units. This photoinduced reaction drives physical crystal deformation and enables the in-situ generation of macroscopic helices.
The peer-reviewed paper was submitted on January 8, 2026, and accepted on July 30, 2026, by authors Xinde Zhou, Aiyou Hao, and Pengyao Xing at the School of Chemistry and Chemical Engineering in Jinan. Funding came from the National Natural Science Foundation of China under grant numbers 22171165, 22371170, and 22571184, as well as the National Natural Science Foundation of Shandong Province under grant ZR2025QA15.
