Leveraging Fluorescent Emission to Unitary Yield: Dimerization of Polycyclic Aromatic Hydrocarbons

Abstract

We report on the synthesis and characterization of novel substituted 1,1′‐biperylene‐2,2′‐diols in which the dihedral angle between the two polycyclic aromatic hydrocarbon (PAH) units is tailored from ca. 60° to ca. 90° in the solid state by introduction of cyclo‐etheric straps or sterically hindered groups such as the triisopropylsilyl (TIPS) group. Depending on the type of substitution, we lock the dihedral angle between the perylenyl moieties enabling fine‐tuning of the molecular optoelectronic properties, with the molecules displaying the smallest angles acting as exceptionally strong emitters with unitary quantum yields.

Orbital Mapping of Semiconducting Perylenes on Cu(111)

“…In Figure 4a, the relative intensity associated with the tertbutyl groups is not compatible with the strongly non-planar structure of the BPOL isolated molecule in the gas phase with the two perylene arms tilted by 63°with respect to each other. 24 By looking carefully at the tert-butyl protrusions (six per molecule), we see a rather small difference in the height Δz MAX = 25−30 pm (see height distribution analysis in Supporting Information, Figure S11), also suggesting that perylenes should arrange in a flatter configuration than in the isolated gas-phase molecule. This refined analysis also matches the assumption of a more planar configuration described in the ARPES simulations, discussed below.…”

“…In the case of BPF (Figure 7a,b), the intrinsic chirality does not clearly display different chiral domains by STM, and this is probably due to the square lattice adsorption geometry. Moreover crystallographic data reported for BPF and BPOL show a large decrease of the dihedral angle from 63°for BPOL to 17°f or BPF, where the dihedral angle between the aryl moieties is drastically reduced by planarity of the furanyl framework, 24 thus making BPF molecules adsorb flat on the surface with a further suppression of chirality-related effects.…”

“…While the crystal structures of BPOL and BPF were established previously by single-crystal X-ray diffraction analysis, , the growth of single crystals of BPPP suitable for single-crystal X-ray diffraction turned out to be difficult. Thus, we have carried out structure determination of BPPP directly from powder X-ray diffraction (XRD) data.…”