文献类型：期刊文献

英文题名：Regulating Reversible Untwisting and Twisting Motions in Helical Dynamic Molecular Crystals

作者：Qiu, Xiao-Dong[1,2];Chen, Lin[1,2];Hou, Jia-Wang[1,2];Lin, Hui-Yao[1,2];Xu, Tian-Yi[1,2];Tong, Fei[1,2];Tian, He[1,2];Qu, Da-Hui[1,2]

机构：[1]East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Frontiers Sci Ctr Materiobiol & Dynam Chem, Inst Fine Chem,Sch Chem & Mol Engn,Key Lab Adv Mat, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Frontiers Sci Ctr Materiobiol & Dynam Chem, Inst Fine Chem,Sch Chem & Mol Engn,Joint Int Res L, Shanghai 200237, Peoples R China

年份：2025

卷号：147

期号：21

起止页码：17772

外文期刊名：JOURNAL OF THE AMERICAN CHEMICAL SOCIETY

收录：;EI(收录号：20251718279883);WOS:【SCI-EXPANDED(收录号:WOS:001469202800001)】；

基金：This work wassupported by the National Natural Science Foundation of China (22375063, 22025503, 22220102004, 22405089), the Science and Technology Commission of Shanghai Municipality (24DX1400200, 23JC1401700, 22ZR1417100),the Innovation Program of Shanghai Municipal Education Commission(2023ZKZD40), the Programme of Introducing Talents of Discipline to Universities (grant no. B16017), and the Fundamental Research Funds for the Central Universities.

语种：英文

外文关键词：Dimers - Elastomers - High modulus textile fibers - Ionomers - Laser beams - Molecular crystals - Nanocrystalline alloys

摘要：Dynamic molecular crystals with a desirable morphology and controllable responses to external stimuli are highly desired but remain challenging. Here, we present a new photoactive molecular crystal (MCA) featuring a naphthalene backbone linked with a vinyl structure and an asymmetric tail. It can undergo reversible head-to-tail [2 + 2] photodimerization under visible light illumination and heating. Helicoidally twisted crystalline fibers can be easily prepared by drop-casting an MCA ethanol solution onto a glass surface. The thread length and fiber width can be regulated by changing the solvent evaporation temperature. An MCA fiber untwists upon light irradiation and twists back under mild heating due to the dissociation of the metastable photodimer (d-MCA), enabling a highly reverse transformation. Crystallinity and overall helical morphology can be reserved well during the untwisting and twisting cycles, allowing multiple repetitions of the dynamic motions. Under interval light excitation and continuous heating, an MCA fiber can perform cyclical untwisting-twisting motions over 200 times for 5 h. The amount of photodimer significantly affects the photoresponse, resulting in fully reversible cycles, partial reverse twisting, or complete untwisting at different dimer fractions. We found that about 10% of d-MCA is enough to drive the circular movements. Higher photoproduct conversion makes the fibers prone to fatigue and lose the cyclic responses. Our results provide an excellent example for fabricating new dynamic organic crystals for soft robotics and photoactuators based on spiral twisting movements.