Planar Chiral Organoboranes with Thermoresponsive Emission and Circularly Polarized Luminescence: Integration of Pillar[5]arenes with Boron Chemistry

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Date
2020-03-27
Authors
Chen, Pangkuan
Chen, Jin-Fa
Yin, Xiaodong
Wang, Bowen
Zhang, Kai
Meng, Guoyun
Zhang, Songhe
Shi, Yafei
Wang, Nan
Wang, Suning
Keyword
Pillar[5]arene , Organoborane , Circularly Polarized Luminescence , Planar Chirality , Thermochromic Emission
Abstract
Enantiopure molecules based on macrocyclic architecture are unique for applications in enantioselective host‐guest recognition, chiral sensing and asymmetric catalysis. Taking advantage of chiral transfer from the intrinsically planar chirality of pillar[5]arenes, we herein present an efficient and straightforward approach to achieve early examples of highly luminescent chiral systems ( P5NN and P5BN ). The optical resolution of their enantiomers has been carried out via preparative chiral HPLC, which was ascribed to the molecular functionalization of pillar[5]arenes with π‐conjugated, sterically bulky triarylamine (Ar 3 N) as an electron donor and triarylborane (Ar 3 B) an acceptor. This crucial design enabled investigations of the chiroptical properties, including circular dichroism (CD) and circularly polarized luminescence (CPL) in the solid state. Furthermore, the intramolecular charge transfer (ICT) nature in P5BN afforded an interesting thermochromic shift of the emission over a wide range of temperature.