title: Photoinduced transformations of stiff-stilbene-based discrete metallacycles to metallosupramolecular polymers.
abstract: Control over structural transformations in supramolecular entities by external stimuli is critical for the development of adaptable and functional soft materials. Herein, we have designed and synthesized a dipyridyl donor containing a central Z-configured stiff-stilbene unit that self-assembles in the presence of two 180° di-Pt(II) acceptors to produce size-controllable discrete organoplatinum(II) metallacycles with high efficiency by means of the directional-bonding approach. These discrete metallacycles undergo transformation into extended metallosupramolecular polymers upon the conformational switching of the dipyridyl ligand from Z-configured (0°) to E-configured (180°) when photoirradiated. This transformation is accompanied by interesting morphological changes at nanoscopic length scales. The discrete metallacycles aggregate to spherical nanoparticles that evolve into long nanofibers upon polymer formation. These fibers can be reversibly converted to cyclic oligomers by changing the wavelength of irradiation, which reintroduces Z-configured building blocks owing to the reversible nature of stiff-stilbene photoisomerization. The design strategy defined here represents a novel self-assembly pathway to deliver advanced supramolecular assemblies by means of photocontrol.
authors.affiliation: State Key Laboratory of Chemical Engineering, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China;Department of Chemistry, University of Utah, Salt Lake City, UT 84112; and.
authors.forename: Xuzhou
authors.initials: X
authors.lastname: Yan
authors.affiliation: Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
authors.forename: Jiang-Fei
authors.initials: JF
authors.lastname: Xu
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112; and.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Cook
authors.affiliation: State Key Laboratory of Chemical Engineering, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China; fhuang@zju.edu.cn qzyang@mail.ipc.ac.cn stang@chem.utah.edu.
authors.forename: Feihe
authors.initials: F
authors.lastname: Huang
authors.affiliation: Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China fhuang@zju.edu.cn qzyang@mail.ipc.ac.cn stang@chem.utah.edu.
authors.forename: Qing-Zheng
authors.initials: QZ
authors.lastname: Yang
authors.affiliation: Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
authors.forename: Chen-Ho
authors.initials: CH
authors.lastname: Tung
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, UT 84112; and fhuang@zju.edu.cn qzyang@mail.ipc.ac.cn stang@chem.utah.edu.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Stang
mesh_terms: D032701:Biomimetics; D008024:Ligands; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008422:Materials Testing; D008670:Metals / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D055668:Photochemical Processes; D017785:Photons; D011108:Polymers / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013267:Stilbenes / Q000737:chemistry*; D013696:Temperature
chemical_list: D008024:Ligands; D008670:Metals; D011108:Polymers; D012997:Solvents; D013267:Stilbenes
keywords: dynamic materials; metal coordination; photoirradiation; reversibility; supramolecular coordination complex