Boosted Circularly Polarized Luminescence of a Chiral Metallacage Through Co-Assembly in Confined Microfluidic Environments

Chiral metallacages, with their precisely distributed luminescent and chiral units and inherent adaptive chirality, represent an ideal framework for developing circularly polarized luminescence (CPL)-active materials. Despite their potential, enhancing the luminescence dissymmetry factor (g_lum) of metallacage-based materials remains a significant challenge. In this study, a useful approach is proposed by co-assembling the chiral donor metallacage Δ₄/Λ₄-Zn₄A₄ with the achiral acceptor Nile red (NiR), achieving efficient energy and chirality transfer and resulting in enhanced CPL in these co-assemblies. More importantly, microfluidic laminar flow is utilized, known for providing stable driving forces and confined spaces, to achieve a marked improvement in the g_lum values of these co-assemblies within polymethyl methacrylate (PMMA) films. Computational fluid dynamics (CFD) simulations and small-angle X-ray scattering (SAXS) experiments confirm that films containing Δ₄/Λ₄-Zn₄A₄/NiR, prepared via microfluidic chips, display well-defined distributions of metallacages and NiR due to the controllable assembly process facilitated by microfluidic laminar flow. This work pioneers a new methodology to significantly enhance the g_lum of metallacage-based CPL materials, opening new avenues in the field of chiral photonics.