An investigation of Solid‐State Emission of Halogenated Diphenyl Phosphanyl Anthracenes

Abstract

are hardly predictable. It often happens that the strong emission observed in solution is completely quenched in the solid state. This phenomenon is known as aggregation-caused quenching (ACQ) and is mostly attributed to the strong, unfavorable intermolecular interactions present in the crystalline phase. [5] On the other hand, one may tailor aggregation in such a way that the photoluminescence may not only be observed in a solid state, but in fact can be significantly enhanced. Such an effect is called aggregationinduced emission (AIE) and was first described by Tang et al. in 2001. [6] It is an interesting and important phenomenon especially in view of its technological perspective, as it allows to control, up to a certain extent, the self-assembly of molecules via known intermolecular interactions, leading to introduction of light emission upon aggregation. Since the introduction of this concept, particular focus has been paid to single-component crystals and cocrystals in which the fine-tuned solid-state luminescence is controlled via π-π interactions, hydrogen and halogen bonds. [7,8] By selective reorganization of such synthons, it is possible to alter the molecular structure and thus also control the emission behavior. As a result, one may observe excimer/exciplex formation between two conjugated molecules one being the electron donor and another the electron acceptor building block. These form an intermolecular dimer/complex in the excited state which usually leads to the situation that the energy level of an excited complex is below that of the respective molecules involved, resulting in a red shift of emission compared to the original emission of the individual molecules. [9] Such a behavior was observed in recently published studies on a series of phosphanyl anthracenes and their sulfur oxidized analogues. [10,11,12] The presence of carefully targeted dominant face-to-face interactions between anthracene rings and lack of other strong noncovalent interactions (NCIs) resulted in excimer formation and promoted the solid-state AIE effect. Moreover, it was shown that in order to maximize the solid-state emission, the overlap between anthracene rings should be kept at around 45% and possibly the distance between the rings should be reduced to further shift the emission band.As mentioned above, also halogen bonds may play a major role in solid-state luminescence, in particular the so-called heavy atom effect. [7] It promotes intersystem crossing, thus enhances spin-orbit coupling between excited state electrons In today's world, the development and research of optoelectronic materials and devices based on solid-state luminescence is essential. Due to their versatile application possibilities, e.g. as light-emitting diodes or lasers, they are already indispensable. This work presents three halogenated anthracene derivatives [9-PPh 2 -10-X-(C 14 H 8 )] and their respective photoluminescent behavior in solution and in the solid state. The formation of halogen-π interactions in the solid state leads to unanti...

Current developments and trends in quantum crystallography

“…Racioppi et al, 2020;Sorbara et al, 2022;Montisci et al, 2023: Stachowicz et al, 2023, structure-property correlation (e.g. Tchon ´et al, 2021;Gajda et al, 2020Gajda et al, , 2023Milas ˇinovic ´et al, 2021;Molc ˇanov et al, 2019;Stanic ´et al, 2023;Patten et al, 2023), QSAR (e.g. Vigneau et al, 2022), etc.…”

Full-color emission of fluorinated benzothiadiazole-based D–A–D fluorophores and their bioimaging applications

“…Moreover, compounds 3a-3p display two or three maximum absorption peaks. Among them, the absorption peak at 280-400 nm is attributed to the p-p* transition from the aromatic rings in FBTD derivatives, 29 and the absorption peak at above 400 nm is assigned to the ICT of D-A-D systems. 30 As depicted in Fig.…”

“…However, for each compound, especially for 3j-3m, the solid-state emission has varying degrees of bathochromic shift relative to that in the solution state, which may be the formation of excimers and strong p-p interactions in the solid state. 29,31 Most of the compounds 3a-3p have high F F in the solid state (clearly, F F , 3m 4 F F , 3n), which helps to develop low-cost solid-state organic luminescent materials. Therefore, we further tested the fluorescence spectra of the thin film state prepared by mixing compounds 3a-3p with poly(methyl methacrylate) (PMMA) and then dissolving them.…”