title: Localization/delocalization of charges in bay-linked perylene bisimides.
abstract: The copper-mediated Ullmann coupling of 1,7-dibromoperylene bisimides afforded structurally perfect singly-linked perylene bisimide (PBI) arrays, whilst the homo-coupling of 1,12-dibromoperylene bisimides gave doubly-linked and triply-linked diperylene bisimides. The interactions of three bay-linked diperylene bisimides that differed in their linkage (singly, doubly, and triply) were investigated in their neutral and reduced forms (mono-anion to tetra-anion). UV/Vis absorption and fluorescence spectroscopy revealed different degrees of interaction, which was explained by exciton coupling and conjugation effects. The electrochemical properties and spectroelectrochemistry also showed quite-different degrees of PBI interactions in the reduced mixed-valence species, which was apparent by the observation of CT bands. The interpretation of the experimental findings was supported by spin-restricted and -unrestricted DFT and time-dependent TD-DFT calculations with the long-range-corrected CAM-B3LYP functional. Accordingly, the degree of interaction in both the neutral and reduced forms of the bay-linked PBIs was qualitatively in the order doubly linked<singly linked << triply linked, owing to the different degrees of twisting and flexibility between the two PBIs moieties. Only triply linked diPBI showed completely delocalized wavefunctions over the entire π-system.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P.R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Jiang
authors.forename: Chengyi
authors.initials: C
authors.lastname: Xiao
authors.forename: Linxiao
authors.initials: L
authors.lastname: Hao
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Wang
authors.forename: Harald
authors.initials: H
authors.lastname: Ceymann
authors.forename: Christoph
authors.initials: C
authors.lastname: Lambert
authors.forename: Simone
authors.initials: S
authors.lastname: Di Motta
authors.forename: Fabrizia
authors.initials: F
authors.lastname: Negri