Dual-Mode Induction of Tunable Circularly Polarized Luminescence from Chiral Metal-Organic Frameworks.

Tonghan Zhao,Jianlei Han,Minghao Zhou,Xue Jin,Pengfei Duan,Yan Liu,Minghua Liu

doi:10.34133/2020/6452123

Abstract

The general approach for fabricating solid-state materials showing circularly polarized luminescence (CPL) is still in its challenge. In this work, chiral metal-organic frameworks (MOFs) with full-color and white-color circularly polarized light emission are firstly achieved through a host-guest emitter-loading strategy. Chiral zeolitic imidazolate frameworks (ZIFs, a class of MOFs) are fabricated by a facile and simple mixed-ligand coassembly pathway. Meantime, achiral dyes, quantum dots (QDs), and upconversion nanoparticles (UCNPs) are easily loaded into the chiral ZIFs during the synthetic process. Size-matched dyes can be solely encapsulated into the chiral cages of ZIF, resulting in induced CPL and enhanced luminescence efficiency in solid-state ZIF⊃dye composites. Large-sized QDs, after embedding into the gap of the ZIF particles, also exhibited intense CPL activity. Furthermore, through modulating the blending ratio of colored dyes or QDs in chiral ZIFs, white light-emitting ZIFs with circular polarization could be constructed in a solid state. In addition, through loading rare earth element-based upconversion nanoparticles (UCNPs) into chiral ZIFs, upconverted CPL (UC-CPL) could be achieved with a high dissymmetry factor (glum). Thus, various achiral luminophores were endowed with CPL upon coupling with chiral ZIFs, which significantly deepened and enlarged the research scope of the chiroptical materials in a solid state.

Highlights

Chiral functional materials with circularly polarized luminescence (CPL) have risen to prominence in recent years due to their fascinating properties with wide potential applications in chiral sensors [1, 2], photoelectric devices [3,4,5], 3D optical displays [6, 7], encrypted storage of information [8, 9], and even dissymmetric synthesis [10,11,12]
Similar to the quantum dots (QDs)-loaded ZIF, transmission electron microscopy (TEM) images showed that upconversion nanoparticles (UCNPs):Er was distributed inside the ZIF particles (Figures 4(b) and S34), which indicated that the induced upconverted CPL (UC-CPL) was resulting from the chiral confinement effect of chiral ZIFs
The incorporation of L-/D-His in ZIF crystals makes the ZIFs with chirality, which can endow chirality to the encapsulated guest emitters

Summary

Introduction

Chiral functional materials with circularly polarized luminescence (CPL) have risen to prominence in recent years due to their fascinating properties with wide potential applications in chiral sensors [1, 2], photoelectric devices [3,4,5], 3D optical displays [6, 7], encrypted storage of information [8, 9], and even dissymmetric synthesis [10,11,12]. To endow achiral luminophores with CPL activity, an attracting approach is introducing the achiral luminescent guest emitter to a chiral host. Besides the noncovalent interaction, confined chiral space has been reported as a versatile chiral host for endowing achiral emitters with CPL activity through a host-guest encapsulation process. A large number of luminescent MOFs have been reported through loading guest emitters into host MOF matrixes Many applications such as multiphotonpumped lasing [37], white light-emitting diodes (WLEDs) [38], second-order nonlinear optics [39], and temperature sensing have been achieved [40]. We provide a facile and general pathway for fabricating CPLactive solid-state nanomaterials through chiral ZIF host loading guest emitters

Results

Discussion

Materials and Methods

Conflicts of Interest