Anomalous deep-red luminescence of perylene black analogues with strong π-π interactions

Abstract

Perylene bisimide (PBI) dyes are known as red, maroon and black pigments, whose colors depend on the close π−π stacking arrangement. However, contrary to the luminescent monomers, deep-red and black PBI pigments are commonly non- or only weakly fluorescent due to (multiple) quenching pathways. Here, we introduce N-alkoxybenzyl substituted PBIs that contain close π stacking arrangement (exhibiting dπ−π ≈ 3.5 Å, and longitudinal and transversal displacements of 3.1 Å and 1.3 Å); however, they afford deep-red emitters with solid-state fluorescence quantum yields (ΦF) of up to 60%. Systematic photophysical and computational studies in solution and in the solid state reveal a sensitive interconversion of the PBI-centred locally excited state and a charge transfer state, which depends on the dihedral angle (θ) between the benzyl and alkoxy groups. This effectively controls the emission process, and enables high ΦF by circumventing the common quenching pathways commonly observed for perylene black analogues.

Excited-State Odd–Even Effect in Through-Space Interactions

“…On the contrary, the face-to-face TSI with a large POA corresponding to odd TPAs is nonemissive (dark state) (Figure e). Such kind of intramolecular face-to-face TSI is quite similar to the well-studied intermolecular H-aggregate which is always nonemissive. , Once again, these results prove the important role of molecular packing in photophysical properties. Since the different kinds of TSI (staggered and face-to-face) were revealed to induce the ESOEE, why can the different lengths of the alkyl chain regularly generate these two kinds of intramolecular packing?…”

Boron-, carbon-, and silicon-bridged 1,12-dihydroxy-perylene bisimides with tuned structural and optical properties

“…This intriguing observation, however, needs to be further analysed by advanced spectroscopic studies. 51…”

Unlocking the sensing potential of phenyl-substituted perylene diimides under extreme conditions

“…Notably, the Φ value strictly depends on various factors, such as the functional substituents at atom N1, type of aggregation, solvents and concentration. 75–78 Despite the low Φ value, the application of PTCDI-Ph as a sensor material is advantageous owing to the large shift value and excellent sensitivity parameter for the investigated temperature and pressure conditions.…”