Cyclodextrins with Multiple Pyrenyl Groups: An Approach to Organic Molecules Exhibiting Bright Excimer Circularly Polarized Luminescence

Abstract

We report asimple and effective approach to organic molecules exhibiting bright circularly polarized luminescence (CPL) by combining ac hiral cyclic molecular scaffold and multiple excimer-enabling moieties.A na-cyclodextrin (CyD) scaffold was modified with six pyrenyl groups to obtain pyrene-cyclodextrins (PCDs) in ao ne-step synthesis from commercially available compounds.The PCDs exhibited high molar extinction coefficients (e % 10 5 M À1 cm À1 ), polarized emission with ag ood dissymmetry factor (j g lum j % 10 À2 ), and quantum yield (F f % 0.5). Owing to the excellent photophysical properties of the PCDs,t he circularly polarized luminescence brightness (B CPL )r eached 340 M À1 cm À1 .P hotophysical and chiroptical studies of the PCDswith only five pyrene units and with linkers of various lengths connecting the CyD with the pyrene units revealed that the formation of apyrene excimer in aspatially crowded environment is crucial for CPL anisotropy. This study paves the way for the development of bright CPL organic molecules.

Tailor‐Made PdnL2n Metal‐Organic Cages through Covalent Post‐Synthetic Modification

“…A plausible explanation is that the pyrene chromophore is in a chiral microenvironment surrounded by BINOL groups, which induces chirality through steric interaction, and then makes the product emit a pyrene-based CPL signal. [65][66][67] These intriguing results suggest that it is possible to obtain MOCbased materials with CPL activity by introducing both chirality and luminescent moieties into one MOC through PSM. In addition, it is also possible to gradually introduce a variety of different functional groups into MOCs, and consequently acquire new functions.…”

Steroid-Aromatics Clathrates as Chiroptical Materials with Circularly Polarized Luminescence and Phosphorescence

“…An alternative manner to realize chirality to the achiral species is cocrystallization or coassembly, which is achieved by the ordered molecular packing between a chiral component and other species that can be chiral or achiral . The noncovalent forces such as hydrogen bonds, − coordination, − halogen bond, − aromatic stacking, , and host–guest inclusion − could anchor or induce the chirality to the achiral species that realize helicity or chiroptical activities. In this regard, organic dyes and inorganic species, such as gold nanoparticles and quantum dots, have been incorporated into helical structures through a templating effect driven by noncovalent forces, which generate versatile chiroptical properties such as Cotton effects and circularly polarized luminescence (CPL).…”

“…Host–guest inclusion is an emerging protocol to enable chirality to the achiral guest species. The natural chiral hosts such as cyclodextrin and synthesized chiral hosts endow achiral guests with a chiral environment to realize chiroptical activities. − , In spite of the development, developing chiral guests with universality toward achiral luminophores to realize chiroptical activities still remains a major challenge.…”

Monomer and Excimer Emission in a Conformational and Stacking‐Adaptable Molecular System

“…[9] However, numerous luminogens exhibit only single-mode fluorescence emission, including monomer or excimer emission. [10,11] Monomer mainly exists in dilute solution or the doped state, [12] such as when doping organic dyes into polymethyl methacrylate (PMMA). It is worth noting that, the monomer can also exist in the solid state when the intermolecular stacking of the central luminophore is not closed.…”

“…Organic luminescent materials have been highly desired in many areas such as bioimaging, [1–3] sensors, [4–6] drug release, [7, 8] and security protection [9] . However, numerous luminogens exhibit only single‐mode fluorescence emission, including monomer or excimer emission [10, 11] . Monomer mainly exists in dilute solution or the doped state, [12] such as when doping organic dyes into polymethyl methacrylate (PMMA).…”