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.

Synthesis and Characterisation of 1,7‐Di‐ and Inherently Chiral 1,12‐Di‐ and 1,6,7,12‐Tetraarylperylenetetracarbox‐3,4:9,10‐diimides

“…Recently, compound 6a , possessing two chlorine atoms in the bay positions 1 and 12, has been described 51,52. When compounds such as 5a are transformed under Ullmann‐type reaction conditions in a basic reaction medium, condensation of two or three perylenediimides occurs 52–55. Highly selective transformations have been carried out with CuI and proline in dimethyl sulfoxide (DMSO).…”

Synthesis of Alternative Electron Acceptor Compounds

“…similar to the values found in the trans (less stable) bis-diimide conformation. (More strongly coupled bis-diimides have been reported but for very different structure containing a chemical bond between carbon atoms of two perylene units [19]). …”

Arylphosphonylation and Arylazidation of Activated Alkenes

“…Under similar reaction conditions, 1,6,7,12‐tetrachloroperylenetetracarboxlic 3,4:9,10‐dianhyride ( 4 ) was transformed into the corresponding diimides 5a and 5b 41,49,50. Recently, compound 6a , possessing two chlorine atoms in the bay positions 1 and 12, has been described 51,52. When compounds such as 5a are transformed under Ullmann‐type reaction conditions in a basic reaction medium, condensation of two or three perylenediimides occurs 52–55.…”