Inducing Circularly Polarized Luminescence by Confined Synthesis of Ultrasmall Chiral Carbon Nanodot Arrays in Pyrene-Based MOF Thin Film
Yihong Xiao, Zhi‐Zhou Ma, Xuexian Yang, Dong‐Sheng Li, Zhi‐Gang Gu, Jian Zhang
Abstract
Combining the features of the host–guest system and chirality is an efficient strategy to achieve circularly polarized luminescence (CPL). Herein, well-defined chiral carbon nanodot (chirCND) arrays were confined-synthesized by low-temperature calcination of a chiral amino acid loaded metal–organic framework (MOF) to induce high CPL. An achiral porous pyrene-based MOF NU-1000 thin film as the host template was prepared by a liquid-phase epitaxial layer-by-layer fashion, and chiral amino acids as the carbon sources could be confined in the porous MOF and carbonized to homogeneous and ultrasmall chirCND arrays, resulting in a chirCNDs@NU-1000 thin film ( l -CNDs x @NU-1000; x = l -cysteine (cys), l -serine, l -histidine, l -glutamic acid, and l -pyroglutamic acid). The results show the pristine chirCNDs by directly carbonizing chiral amino acids hardly endow them with a CPL property. By contrast, benefiting from the arrayed confinement and coordination interaction between chirCNDs and NU-1000, the chirality transfer on the excited state of chirCNDs@NU-1000 is enabled, leading to strong CPL performance (a high luminescence dissymmetry factor g lum of l -CNDs cys @NU-1000 thin film reached 1.74 × 10 –2 ). This study of chirCNDs encapsulated in fluorescent MOF thin films provides a strategy for developing uniform chiral carbon nanoarrays and offers chiral host–guest thin-film materials for optical applications.