title: Visible Light-Driven Artificial Molecular Switch Actuated by Radical-Radical and Donor-Acceptor Interactions.
abstract: We describe a visible light-driven switchable [2]catenane, composed of a Ru(bpy)3(2+) tethered cyclobis(paraquat-p-phenylene) (CBPQT(4+)) ring that is interlocked mechanically with a macrocyclic polyether consisting of electron-rich 1,5-dioxynaphthalene (DNP) and electron-deficient 4,4'-bipyridinium (BIPY(2+)) units. In the oxidized state, the CBPQT(4+) ring encircles the DNP recognition site as a consequence of favorable donor-acceptor interactions. In the presence of an excess of triethanolamine (TEOA), visible light irradiation reduces the BIPY(2+) units to BIPY((•+)) radical cations under the influence of the photosensitizer Ru(bpy)3(2+), resulting in the movement of the CBPQT(2(•+)) ring from the DNP to the BIPY((•+)) recognition site as a consequence of the formation of the more energetically favorable trisradical complex, BIPY((•+)) ⊂ CBPQT(2(•+)). Upon introducing O2 in the dark, the BIPY((•+)) radical cations are oxidized back to BIPY(2+) dications, leading to the reinstatement of the CBPQT(4+) ring encircled around the DNP recognition site. Employing this strategy of redox control, we have demonstrated a prototypical molecular switch that can be manipulated photochemically and chemically by sequential reduction and oxidation.
authors.affiliation: †Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.
authors.forename: Junling
authors.initials: J
authors.lastname: Sun
authors.affiliation: †Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.|‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.
authors.forename: Yilei
authors.initials: Y
authors.lastname: Wu
authors.affiliation: †Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.
authors.forename: Zhichang
authors.initials: Z
authors.lastname: Liu
authors.affiliation: †Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.
authors.forename: Dennis
authors.initials: D
authors.lastname: Cao
authors.affiliation: †Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.
authors.forename: Yuping
authors.initials: Y
authors.lastname: Wang
authors.affiliation: †Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.
authors.forename: Chuyang
authors.initials: C
authors.lastname: Cheng
authors.affiliation: †Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.
authors.forename: Dongyang
authors.initials: D
authors.lastname: Chen
authors.affiliation: †Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.|‡Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Wasielewski
authors.affiliation: †Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.
authors.forename: J Fraser
authors.initials: JF
authors.lastname: Stoddart