Selective Vicinal Diiodination of Polycyclic Aromatic Hydrocarbons

Abstract

Vicinally diiodinated polycyclic aromatic hydrocarbons (I2‐PAHs) are accessible from the corresponding diborylated B2‐PAHs through boron/iodine exchange. The B2‐PAHs have been prepared via twofold electrophilic borylation reactions templated by a vicinally disilylated benzene. Our protocol is applicable to fluorenes, acenes, annulated acenes, oligoaryls, and even [5]helicene. Using B2‐naphthalene as the example, we have shown that the reaction scope can, in principle, be expanded to include the synthesis of vicinally dibrominated and dihydroxylated PAHs. The usefulness of the building blocks provided by our method in the field of optoelectronic materials was demonstrated by the successful conversion of I2‐fluoranthene to the analogous doubly alkynylated fluoranthene emitter.

π‐π Catalysis Made Asymmetric—Enantiomerization Catalysis Mediated by the Chiral π‐System of a Perylene Bisimide Cyclophane

“…While a dihedral angle of 30.4°was found for [5]helicene in the complex with the PBI cyclophane, this angle is, at 41.4°, significantly larger in the crystal structure of the free guest reported in literature. [46] Both values, as well as observed PBI core twists are in good agreement with those obtained from theoretical calculations (see below).…”

Enhanced N-directed electrophilic C–H borylation generates BN–[5]- and [6]helicenes with improved photophysical properties

“… 22 Comparison of the structure of 1-Br to that of the all carbon [5]helicene C is noteworthy. 23 In 1-Br the C9–C10–C11–C20 and C1–C10–C11–C12 torsion angles ( Fig. 5 ) are greater (34.6(5)° and 24.1(5)°, respectively) than the analogous angles in C (32.3(2)° and 20.2(2)°).…”

Effect of [n]-Helicene Length on Crystal Packing

“…Of the molecules studied in this paper, crystal structures of naphthalene and [ n ]­helicenes with n = 3–7 and 9–11 have been synthesized − with more than one polymorph obtained for [5]­helicene − and [7]­helicene. , With the exception of [3]­helicene, X-ray crystal structures were deposited to the CSD, which we used to compare with the structures within our CSP landscapes. We found that the CSP landscapes (Figure ) were able to reproduce most of the experimentally known crystal structures.…”