Circularly polarized luminescence (CPL) is a type of light emission that contains the differential emission intensity of left- and right-handed circularly polarized light, which can provide information about the structural and electronic properties of chiral luminescent systems in the excited state. Functional materials with CPL have shown promising prospects in diverse high-tech applications such as the displays, information storage, intelligent detection, optoelectronic devices, asymmetric synthesis, contrast imaging, and other fields. To meet the requirements of practical applications and meanwhile to enrich the structural diversity of CPL emitters, it is of great significance to design and construct novel CPL materials with efficientglumand highΦ. Chirality and luminescence are two preconditions for constructing CPL materials. Among various chiral materials, macrocycle-based chiral emitters have received increasing attention due to their unique structural features and excellent chiral properties. The luminescence performance of traditional planar luminophores tends to be diminished or even completely annihilated upon aggregation due to the presence of strong π-π stacking interactions. This aggregation-caused quenching effect greatly compromises the CPL performance of the corresponding supramolecular polymer materials in aggregate states and consequently limits their application scope. In practical applications such as security tags, biomedical applications in aqueous media, and photoelectric devices, CPL materials are preferred to be used as aggregate forms like nanoparticles and solid thin films. Therefore, it is highly desirable to develop chiral supramolecular polymers with efficient aggregate-state luminescence.
In light of this, Associate Professor Ting Han of Shenzhen University, in collaboration with Professor Ben Zhong Tang of Chinese University of Hong Kong (Shenzhen), developed a novel supramolecular coordination polymer system with efficient CPL in aggregate states based on the planar chirality and excellent fluorescence properties of the AIEgen-modified pillar[5]arenes.The introduction of pyridyl-TPE unit into pillar[5]arene endows the corresponding monomers and polymers with AIE properties and provide convenience for obtaining the planar chirality of pillar[5]arene monomers (pR-TPE-P5 andpS-TPE-P5) by chiral HPLC. Further coordination reaction between the pyridyl-TPE-pillar[5]arene monomers and silver ions affords supramolecular polymers with obviously enhanced CD signals and fluorescence intensity than their monomers. The CD signals in solution state increase by 1.5 folds and theΦvalues in solution state increase from∼0.9 to∼2.0 after polymerization. The dual enhancement in chiral and fluorescence properties induces the remarkable CPL signals ofpR-polymer andpS-polymer with |glum| values of 1.30 × 10−4and −0.65 × 10−4, respectively, at 510 nm in dilute solutions. Upon the formation of aggregates in aqueous media, theΦvalues of the polymer further increase from∼1.9% to∼49%, while the |glum| values significantly increased by∼21 folds to be 2.69 × 10−3at 510 nm forpR-polymer. The RIM effects of the multiple rotors in the AIEgen moiety and the pillar[5]arene unit together with the aggregation-induced conformation confinement collectively contribute to the boosting of glumvalues by polymerization and aggregation.These findings, titled "Synergistically Boosting the Circularly Polarized Luminescence of Functionalized Pillar[5]arenes by Polymerization and Aggregation", were published in the prestigious journalAdvanced Science. The first author of this article is Dr. Hewei Yan, a postdoctoral researcher at Shenzhen University.
Full article page：https://onlinelibrary.wiley.com/doi/full/10.1002/advs.202305149
