Walking Down the Chalcogenic Group of the Periodic Table: From Singlet to Triplet Organic Emitters

Abstract

The synthesis, X-ray crystal structures, ground- and excited-state UV/Vis absorption spectra, and luminescence properties of chalcogen-doped organic emitters equipped on both extremities with benzoxa-, benzothia-, benzoselena- and benzotellurazole (1X and 2X ) moieties have been reported for the first time. The insertion of the four different chalcogen atoms within the same molecular skeleton enables the investigation of only the chalcogenic effect on the organisation and photophysical properties of the material. Detailed crystal-structure analyses provide evidence of similar packing for 2O -2Se , in which the benzoazoles are engaged in π-π stacking and, for the heavier atoms, in secondary X⋅⋅⋅X and X⋅⋅⋅N bonding interactions. Detailed computational analysis shows that the arrangement is essentially governed by the interplay of van der Waals and secondary bonding interactions. Progressive quenching of the fluorescence and concomitant onset of phosphorescence features with gradually shorter lifetimes are detected as the atomic weight of the chalcogen heteroatom increases, with the tellurium-doped derivatives exhibiting only emission from the lowest triplet excited state. Notably, the phosphorescence spectra of the selenium and tellurium derivatives can be recorded even at room temperature; this is a very rare finding for fully organic emitters.

Deoxygenation Increases Photoluminescence Lifetime of Protein-Responsive Organic Probes with Triplet–Singlet Resonant Energy Transfer

“…31 Furthermore, a clear heavy-atom effect was shown recently for two families of organic bis-benzoazole luminophores doped with oxygen, sulfur, selenium, or tellurium. 32 We have detected significantly higher luminescence intensities for selenophene-containing ARC-Lum probes in complex with a …”

Concurring Chalcogen‐ and Halogen‐Bonding Interactions in Supramolecular Polymers for Crystal Engineering Applications

“…This suggests that once a pyrid‐4‐yl moiety contacts a DITFB, it seemingly depletes the Se‐CGP moiety, raising the strength of the double EBIs. This observation is in accordance with previous results, for which CF 3 ‐bearing Se‐CGP derivatives form doubly EB‐bonded dimers …”

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

“…X‐ray diffraction clearly showed that 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, twisting the naphthyl portions of each perylene units. Remarkably, this unique core‐twisted quaterrylene was found to emit in the NIR spectral region, with a phosporescence maximum centered at 1716 nm at 77 K. Considering that, up to now, the library of NIR‐emissive organic materials that emit beyond 750 nm is truly limited and it is mostly based on metal complexes and chalcogen‐containing hybrids, [ ][ ] this finding is very promising in the design of efficient organic NIR‐emitting materials. Moreover, third‐order NLO measurements on solutions and thin film containing the relevant dye showed considerably high NLO second hyperpolarizability values (15.7 ± 0.2 × 10 −31 esu) in comparison with those reported in the literature for parent π ‐extended PAHs.…”