2.2]Paracyclophane-Based Chiral Platforms for Circularly Polarized Luminescence Fluorophores and Their Chiroptical Properties: Past and Future.

Ken-Ichi Sugiura

doi:10.3389/fchem.2020.00700

Abstract

Quality of CPL fluorophore is defined by the vectors of electric dipole transition moment and imaginary magnetic dipole transition moment. The aim of this review is to introduce readers to a chiral moiety applicable to CPL studies focusing on chiral cyclophanes because the rigid cyclophanes are able to hold the vector directions of electric dipole transition moment and imaginary magnetic dipole transition moment.

Highlights

Polarized luminescence (CPL) is both an old and a new research field
As far as the author knows, the first Circularly polarized luminescence (CPL) observation could be the spectrum for a chiral crystal of uranyl acetate (Na[UO2(CH3COO)3]) recorded at liq
Basic theoretical background was already established in 1970’ (Richardson and Riehl, 1977), the lack of a commercially available CPL apparatus hindered the progress of this research field and only a limited number of researchers who could make the apparatus were able to conduct research of CPL

Summary

INTRODUCTION

Polarized luminescence (CPL) is both an old and a new research field. As far as the author knows, the first CPL observation could be the spectrum for a chiral crystal of uranyl acetate (Na[UO2(CH3COO)3]) recorded at liq. The author introduces reported chiral cyclophanes such as pyrenophanes, which show great potential in CPL science. This information is expected to benefit readers. The connection of two fluorescent arenes at the hindered position to restrict free rotation induces axial chirality Based on this consideration, the author reported bipyrenol 4 having an improved quantum yield (Hassan et al, 2015). The two terphenyls in and the two quaterphenyls in are arranged in a chiral manner, and the termini of these fluorophores interact strongly through the [2.2]paracyclophane skeletons Their quantum yields are dependent on the introduced para-phenylenes, i.e., Φ = 0.20 and 0.64 for 14 and 15, respectively. The rigidity of cyclophane and the strong interaction of the chromophore via the cyclophane unit would contribute to these chiroptical properties

MULTILAYERED CYCLOPHANE

CONCLUSION