Cation−π Interaction Induced Excimer Formation: A New Strategy for High‐Efficiency Organic Solid‐State Luminescence

Abstract

Organic solid‐state luminescence materials have shown great promise in many forefront areas of modern chemistry. However, the well‐developed organic luminescent solids usually provoke a mass of synthetic steps. To better utilize their performances, the development of simple strategies for host materials is a goal of general concern. Herein, a series of highly efficient solid‐state luminescence materials are attained with aid of one‐step acidification of commercially available molecules. The mechanism demonstrates that the luminous efficiency of the solid‐state molecules is efficiently improved due to the synergy from the emergence of cation–π interaction and the formation of excimer. The cation–π interaction replaces π–π packing, leading to the formation of dimers with higher rigidity in solid state accompanied by red‐shifted emissions. Therefore, this one‐step acidification design concept will light the great passion of scientists for the fabrication of cation−π‐triggered analogous organic solid‐state luminescence materials with different colors by changing the substituents on benzene moieties.

Control of Multicolor and White Emission by Triplet Energy Transfer

“…It shows distinctive dimers, where the pyridinium hydrogens form a pair of noncovalent intermolecular interactions with an aromatic ring with short intermolecular stacking distances of 3.7206 and 3.7406 Å (Figure C,D). According to our previously reported work, the driving force of the dimer formation was attributed to cation-π interaction. , Therefore, we conclude the existence of cation-π interaction between the DMP dimers, which will be studied in detail in the next section.…”

“…According to our previously reported work, the driving force of the dimer formation was attributed to cation-π interaction. 32,33 Therefore, we conclude the existence of cation-π interaction between the DMP dimers, which will be studied in detail in the next section.…”

Photoluminescent and Chromic Nanomaterials for Anticounterfeiting Technologies: Recent Advances and Future Challenges

“…The smart characteristics observed for the fluorescent cyanostilbene derivative is due to its interactions with surface molecules of the substrate, which confirms the effect of different interactions on optical properties of a fluorophore. A similar strategy was reported by Shi and co-workers to form stilbene derivative excimers in the solid state via one-step acidification reaction, which lead to multiple cation−π interactions and lack of π–π stacking between the fluorophore molecules . The cation−π interaction of the molecules could induce formation of molecular dimers with higher rigidity, lower band gap in the solid state, and shorter interplanar distance in the solid state, resulting in higher luminescence efficiencies and red-shifted emissions.…”

“…A similar strategy was reported by Shi and co-workers to form stilbene derivative excimers in the solid state via one-step acidification reaction, which lead to multiple cation−π interactions and lack of π−π stacking between the fluorophore molecules. 166 The cation−π interaction of the molecules could induce formation of molecular dimers with higher rigidity, lower band gap in the solid state, and shorter interplanar distance in the solid state, resulting in higher luminescence efficiencies and red-shifted emissions. Such approaches could be used for other organic fluorophores to design authentication systems with higher security in future studies.…”

Aggregation induced emission of chalcones

“…The design and synthesis of π-conjugated organic luminescent small molecules with inherent AIE or AIEE property have progressed as a dynamic realm in materials science research (Mei et al 2015). Several mechanisms were proposed to understand the AIE phenomenon such as conformational planarization, H/J-aggregation, RIR, RIV, excimer formation (Cui et al 2020), non-covalent intermolecular interactions (Leduskrasts et al 2019), hindrance to intramolecular charge transfer (ICT), twisted intramolecular charge transfer (TICT), and inhibition of photo-cyclization or photo-isomerisation (Gao et al 2010;Aldred et al 2012). RIR is established to be the vital parameter among all for the fascinating and highly useful AIEE/AIE behavior (Li et al 2007;Zhao et al 2010).…”