Modulating the Excited State Chirality of Dynamic Chemical Reactions in Chiral Micelles

Multiple Chirality Switching of a Dye-Grafted Helical Polymer Film Driven by Acid & Base

A stimuli-responsive multiple chirality switching material, which can regulate opposed chiral absorption characteristics, has great application value in the fields of optical modulation, information storage and encryption, etc. However, due to the rareness of effective functional systems and the complexity of material structures, developing this type of material remains an insurmountable challenge. Herein, a smart polymer film with multiple chirality inversion properties was fabricated efficiently based on a newly-designed acid & base-sensitive dye-grafted helical polymer. Benefited from the cooperative effects of various weak interactions (hydrogen bonds, electrostatic interaction, etc.) under the aggregated state, this polymer film exhibited a promising acid & base-driven multiple chirality inversion property containing record switchable chiral states (up to five while the solution showed three-state switching) and good reversibility. The creative exploration of such a multiple chirality switching material can not only promote the application progress of current chiroptical regulation technology, but also provide a significant guidance for the design and synthesis of future smart chiroptical switching materials and devices.

Chiroptically Active Host-Guest Composites Using a Terpene-Based Micellar Capsule

For the design of a new chiroptically active host-guest system, a bent amphiphilic compound was synthesized using cyclic monoterpenes as key biorelated chiral frameworks. In water, the bent amphiphiles form a terpene-based micellar capsule with a core diameter of ∼2 nm in a spontaneous and quantitative fashion. The resultant chiral capsule shows wide-ranging uptake abilities toward achiral fluorescent dyes in water. Notably, relatively strong CD bands are generated from the resultant host-guest composites, e.g., possessing AIE-active tetraphenylethene and sterically demanding BODIPY dyes, through efficient host-to-guest chirality transfer. The composites also display CPL, with moderate to high emission asymmetry factors (|glum| = up to 3.3 × 10-3).

Multicolor circularly polarized luminescence inversion of metal-organic supramolecular polymers

Metal-organic supramolecular polymers (MOSPs) with multicolor circularly polarized luminescence (CPL) and handedness inversion were constructed from the coordination-driven assembly of pyridine-cyanostilbene-cholesterol and metal salts by modulating the treatment modes, solvents, and metal ions.

Chiral Deep Eutectic Solvents Enable Full-Color and White Circularly Polarized Luminescence from Achiral Luminophores

Herein, chiral deep eutectic solvents (DES) are prepared by lauric acid as hydrogen bond donors (HBD) and chiral menthol as hydrogen bond acceptors (HBA). When achiral fluorescent molecules are dopedin the menthol-based chiral DES, they emit circularly polarized luminescence (CPL) with handedness controlled by the molecular chirality (l or d) of menthol. Remarkably, the strategy is universal and a series of achiral fluorescent molecules can be endowed with CPL activity, showing a full-color and white CPL upon appropriate mixing, which paves the way to prepare white CPL materials. Interestingly, CPL appears only in a certain temperature range in the DES. Variable-temperature spectra and other characterization methods reveal that the H-bond network in the chiral DES plays an important role in inducing CPL. This work unveils how the interior structure as well as the hydrogen-bond network of a chiral DES can transfer its chirality to achiral luminophores for the first time and realizes a full-color and white CPL in a DES.

Air-tolerant upconverted circularly polarized luminescence enabled by confined space of chiral micelle

Circularly polarized luminescence (CPL) has been widely demonstrated that the circular polarization in excited state can be significantly amplified through the triplet-triplet annihilation-based upconversion (TTA-UC) luminescence process in various chiral nano-assemblies. However, constructing such an upconverted circularly polarized luminescence (UC-CPL) system in the aqueous phase remains a challenge. In this work, a kind of amphiphilic chiral cationic gemini surfactant is utilized to construct chiral spherical micelle in the aqueous phase, whose internal chiral cavity can provide a hydrophobic and deoxygenated environment for air-sensitive TTA-UC system. In addition, due to the co-assembly process between the emitters and chiral micelles, achiral emitters of upconversion pairs exhibit induced chiroptical properties. More importantly, the luminescence dissymmetry factor (g_lum ) can be amplified by one order of magnitude through TTA-UC process. This work provides an effective and useful strategy for realizing UC-CPL in aqueous phase.

Induced CPL-Active Materials Based on Chiral Supramolecular Co-Assemblies

Circularly polarized luminescence (CPL) has attracted much interest due to its potential applications on chiral photonic techniques and optoelectronic materials science. As known, dissymmetry factor (g_em ) of CPL is one essential factor for evaluating the features of CPL-active materials. Much attention has focused on how to increase the g_em value, which is one of the most important issues for CPL practical applications. Recently, more and more works have demonstrated that chiral supramolecular could provide the significant strategy to improve the g_em value through the orderly helical superstructure of chiral building blocks. Normally, this kind of chiral supramolecular assembly process can be accompanied by chirality transfer and induction mechanism, which can promote the amplification effect on the induced CPL of achiral dyes. In this review, we fully summarized recent advances on the induced CPL-active materials of chiral supramolecular co-assemblies, their applications in circularly polarized organic light-emitting diodes (CP-OLEDs) and current challenges.