Tunable Circularly Polarized Luminescence from Single Crystal and Powder of the Simplest Tetraphenylethylene Helicate

Abstract

Tetraphenylethylene and its derivatives are a class of aggregation-induced emission (AIE) compounds that are most extensively and successfully studied. It has been found that the simplest TPE is easy to crystallize into homochiral M crystals or P crystals. However, no research on circularly polarized luminescence (CPL) of TPE solid is documented. In this paper, we report that TPE can grow into big and nonefflorescent single crystals in single helical conformation and has large birefringence that is comparative with commercially available products. The TPE single crystals can emit strong CPL with a very high g lum value up to 0.53. Moreover, the sense and magnitude of CPL signals can be willfully tuned by simple rotation of the single crystal due to anisotropy of the crystals. This simple and promising CPL photonic material integrates emission, chirality, and birefringence together in one single crystal without needing an additional chiral dopant or conjugate polymer that can produce linearly polarized light. After being ground into fine powder and pressed as KBr pellets, the obtained nanocrystals of TPE also emit strong CPL light. Exceptionally, by mixing other achiral luminescent dyes together with TPE powder in KBr pellets, induced CPL signals were obtained, which could give full-color CPL emission. Although there were no interactions between TPE and the dyes in the pellets, induced CPL signals were realized through radiative energy transfer, providing a very simple method for the tuning of CPL emission.

Structural Origin of Enhanced Circularly Polarized Luminescence in Hybrid Manganese Bromides

“…which could magnify the detected CPL intensity. [11,47] In addition, linearly polarized anisotropy of the crystals could contribute to the apparent circular polarized dissymmetry, resulting in the crystal size-dependent CPL signals (Figure S10a and c). [47] In summary, four pairs (R/S) of new enantiomorphic hybrid manganese bromides have been successfully synthesized using different chiral alkanolammonium cations.…”

Hindered Tetraphenylethylene Helicates: Chiral Fluorophores with Deep‐Blue Emission, Multiple‐Color CPL, and Chiral Recognition Ability

“…Single-crystal structures of the hindered TPE helicates were obtained and all the single crystals of helicate racemates showed M-and P-conformation existing in equal amounts in one crystal cell. [37] Compared with TPE molecule without any substituent, [16] there were larger dihedral angles between the double-bond plane and phenyl rings, indicating that these TPE helicates are more twisted (Figure 3). The average dihedral angle of TPE, 4 a and 4 b is 48.5°, 53.9°and 56.3°, respectively, demonstrating that the conjugation of the phenyl rings with double bond gradually decreases with the steric hindrance of the substituted phenyl rings.…”

“…[13][14][15] The obtained homochiral crystals not only show circular dichroism (CD) signals but also emit very strong CPL light in the crystal state and solid powders. [16] The second method is based on the intramolecular and intermolecular cyclization that immobilizes the propeller-like conformation of the TPE unit and enables the resolution of TPE helicates into M-and P-enantiomers. [17][18][19] These enantiomers are stable and display excellent chiroptical properties such as CD and CPL signals not only in the solid state but also in solution.…”

Helix‐Sense‐Selective Polymerization of Achiral Monomers for the Preparation of Chiral Helical Polyacetylenes Showing Intense CPL in Solid Film State

“…Circularly polarized luminescence (CPL) materials have attracted ever-increasing attention for their great potential applications in a wide variety of areas such as information storage, 3D optical displays, optoelectronic devices, etc. [1][2][3][4][5][6] Up to date, the main building blocks for constructing CPL materials include rare earth complex, [7] organic small molecules, [8,9] chiral polymers, [10][11][12] supramolecular self-assemblies, [13][14][15][16] and liquid crystals. [17,18] Of particular interest, chiral helical polymers have been widely used DOI: 10.1002/marc.202200111 to prepare CPL-active materials with high luminescence dissymmetry factor (g lum ) values due to their unique helical structure and chiral amplification effect.…”