A Twisted Bay‐Substituted Quaterrylene Phosphorescing in the NIR Spectral Region

Abstract

The preparation of the first soluble quaterrylene derivative featuring peripheral tert‐butyl substituents and sterically hindering, core‐anchored triflate groups has been achieved. This involves a facile synthetic route based on an oxidative coupling of perylene precursors in the presence of H2O2 as oxidant. The steric hindrance between the TfO substituents at the central bay position of the quaterrylene board triggers a strong deformation of the central perylene planarity, which forces the quaterrylene platform to adopt a twisted geometry as shown by X‐ray analysis. Exceptionally, photophysical investigations show that the core‐twisted quaterrylene phosphoresces in the NIR spectral region at 1716 nm. Moreover, third‐order nonlinear optical measurements on solutions and thin film containing the relevant molecule showed very large second hyperpolarizability values, as predicted by theoretical calculations at the CAM‐B3LYP/6‐31G** level of theory, making this material very appealing for photonic applications.

Exciton Delocalization Counteracts the Energy Gap: A New Pathway toward NIR-Emissive Dyes

“…The emission quantum yields (Φ F ) of dihexylquaterrylene were determined to be 0.21 and 0.05, in C 2 H 2 Cl 4 and toluene, respectively. The latter goes in line with emission quantum yields previously observed for structurally rigid tetra- tert -butylquaterrylene derivatives, 32 , 41 and the increase in Φ F for the J-aggregate is therefore not likely to be due to aggregation-induced effects. Thus, Φ F increased by a factor of 4 in C 2 H 2 Cl 4 , despite the large red-shift of the emission.…”

“… 39 However, this strategy affects both intermolecular interactions that result in increased solubility and the electronic properties of the core. Introduction of bulky substituents such as tert -butyl 40 and triflate moieties 41 allowed obtaining soluble quaterrylenes, although with end-capping the ortho-positions, thus leaving no possibility for further elongation.…”

Helically Twisted Nanoribbons Based on Emissive Near-Infrared Responsive Quaterrylene Bisimides

“…In this regard, we would like to stress on the importance of the energy gap law that manifests an increased vibrational coupling between electronic states if they are energetically close. For this reason, it is indeed challenging to accomplish a decent NIR emission at wavelengths beyond 800 nm. − The fluorescence of planar QBIref has been previously investigated in chloroform solution, showing a emission maximum (λ em ) at 797 nm with an estimated quantum yield (Φ Fl ) by the Strickler–Berg analysis of about 5% . We took the effort to experimentally investigate all three QBIs in DCM with a state-of-the-art liquid-nitrogen-cooled NIR photomultiplier (with a good signal-to-noise ratio even in the NIR wavelength range) as well as a calibrated integration sphere setup.…”

“…These extended rylene dyes bearing four naphthalene subunits are known since 1995 and show extraordinary thermal- and photostability which allowed their use in organic electronics despite their poor solubility due to a strong pigment character. − So far, only decent solubility could be achieved by extensive side chain decoration . Hitherto reported twisted higher rylene dyes did not allow for the isolation of stable atropo-enantiomers. − Recent in-depth studies have focused on the singlet fission phenomenon of planar QBIs …”

Direct borylation of terrylene and quaterrylene

“…For instance, bay-bridging perylenes with long alkyl chains [12][13][14][15] and bay-alkoxy-substitution [16][17][18] enable us to prepare longer rylenes (Figure 1c and 1d). However, tying the bay regions with carbon or nitrogen atoms causes bowing of the oligorylene backbone without disrupting the planarity of the aromatic backbone to give a flat banana-shaped molecule [15].…”