Pillar[5]arene-Based Dual Chiral Organoboranes with Allowed Host–Guest Chemistry and Circularly Polarized Luminescence

Abstract

We first describe two examples of highly luminescent organoboranes (NP5BN1 and NP5BN2) with dual chirality that were achieved by molecular functionalization of planar chiral pillar[5]­arenes with naphthyls. Sufficiently strong steric effects are imposed by triarylamine (Ar3N) and triarylborane (Ar3B) moieties and further enhanced by the proximity of the chiral building blocks, leading to the isolation of multiple enantiomers via chiral high-performance liquid chromatography. The intramolecular charge transfer from N-donor to B-acceptor across both chiral subunits enabled the circularly polarized luminescence and thermally robust colorimetric responses in their emissions. Furthermore, their remarkable host–guest chemistry was allowed at no expense in the pursuit of advanced chiroptical properties using pillar[5]­arene-based supramolecular scaffolds.

Pillar[5]arene-based Neutral Radicals with Doublet Red Emissions and Stable Chiroptical Properties

“…Macrocyclic pillararenes have been widely explored for the chemistry in host–guest recognition and supramolecular self-assembly owing to their unique structures and accessible synthetic approaches. − Meanwhile, pillararenes are also planar chiral motifs as a result of the orientational alkoxy groups attached to macrocyclic rings (Scheme ). Although two of the stereoisomers ( p S and p R) can usually racemize under ambient conditions, many efforts have been made to sterically stabilize enantiomers by several research groups. , Although parent pillararenes with nonconjugated skeletons exhibit negligible emissions, π-conjugated luminophores and highly emissive functionalities can be employed to efficiently address these issues, and thus their CPL properties have been reported very recently by our group and others . Moreover, materials with lower energy emissions in the red and near-infrared (NIR) regions have received particular research attention due to their promising applications in (bio)­imaging.…”

Pillar[5]arene-based supramolecular gel: construction and applications

“…[36][37][38][39][40][41][42][43][44][45] Generally, the functional motifs introduced into the rim of pillar [5]arenes have largely governed the application potential of the corresponding gel materials to a large extent. [46][47][48][49][50] For example, Lin et al, 51 obtained stable organic SGs by effectively exploiting multiple supramolecular driving forces (e.g., C-H⋯π, π⋯π, van der Waals forces and hydrogen bonding interactions) stemming from the pillar [5]arene moiety and bis(hexadecyloxy)phenylfunctionalized acylhydrazone moiety acting as construction units. More importantly, these SGs displayed favourable blue aggregation-induced emission (AIE) properties and outstanding selectivity and high sensitivity to iodide as a result of the multiple hydrogen bond interactions between the bis(hexadecyl) phenyl group and I − anions.…”

“…36–45 Generally, the functional motifs introduced into the rim of pillar[5]arenes have largely governed the application potential of the corresponding gel materials to a large extent. 46–50 For example, Lin et al , 51 obtained stable organic SGs by effectively exploiting multiple supramolecular driving forces ( e.g. , C–H⋯π, π⋯π, van der Waals forces and hydrogen bonding interactions) stemming from the pillar[5]arene moiety and bis(hexadecyloxy)phenyl-functionalized acylhydrazone moiety acting as construction units.…”

Cyclic arrays of five pyrenes on one rim of a planar chiral pillar[5]arene

“…1c). 20–22 In 2020, Chen and co-workers introduced amine and borane substituents into one unit of a pillar[5]arene and attained CPL at around 455 nm ( 2 ). 20 a However, the emission largely relied on the functionalized terphenyl unit and hence limited chiral transfer from the chiral macrocycle core resulted in 10 −4 order of g lum value.…”