title: Extending photoinduced charge separation lifetimes by using supramolecular design: guanine-perylenediimide G-quadruplex.
abstract: We report here a potassium-induced guanine quadruplex as a supramolecular platform for controlled assembly of electron donor-acceptor systems. A monodisperse, C4-symmetric octamer of a guanine-perylene-3,4,9,10-bis(dicarboximide) conjugate (GPDI) was prepared in tetrahydrofuran. The two layers of cyclic guanine tetramers have the same direction of rotation, and the PDI moiety between the layers adopts a nearly eclipsed relationship (H-aggregation), as revealed by small- and wide-angle X-ray scattering, NMR spectroscopy, and steady-state UV/vis absorption. Following photoexcitation of the PDI moiety in the quadruplex, charge separation occurs in τCS = 98 ± 12 ps to give G(+•)-PDI(-•) that recombines in τCR = 1.2 ± 0.2 ns, which is >100 times longer than that in the monomeric GPDI dyad. The transient absorption spectrum of G(+•)-PDI(-•) within the GPDI quadruplex suggests the formation of a radical anion delocalized over the neighboring PDI units, and this result is consistent with the more favorable electrochemical reduction potential for PDIs in the quadruplex relative to the monomer.
authors: Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University , Evanston, Illinois 60208-3113, United States.
authors: Yi-Lin
authors: YL
authors: Wu
authors: Kristen E
authors: KE
authors: Brown
authors: Michael R
authors: MR
authors: Wasielewski
mesh_terms: D054856:G-Quadruplexes; D006147:Guanine / Q000737:chemistry*; D007094:Imides / Q000737:chemistry*; D046911:Macromolecular Substances / Q000138:chemical synthesis / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D010569:Perylene / Q000031:analogs & derivatives* / Q000737:chemistry; D055668:Photochemical Processes
chemical_list: D007094:Imides; D046911:Macromolecular Substances; C521332:perylenediimide; D010569:Perylene; D006147:Guanine