Abstract
<jats:p> Controlling the spatial distribution of photoluminescent molecules within constrained microenvironments remains a fundamental challenge in enhancing their photophysical properties. Herein, we demonstrate that the differential adsorption behaviors of enantiopure and racemic octahedral iridium(III) complexes on clay nanosheets can be exploited to modulate their photophysical and chiroptical properties, particularly circularly polarized luminescence (CPL). Two structurally related chiral complexes, [Ir(ppy) <jats:sub>2</jats:sub> (phen)](PF <jats:sub>6</jats:sub> ) ( <jats:bold> Ir1-PF <jats:sub>6</jats:sub> </jats:bold> ) and [Ir(piq) <jats:sub>2</jats:sub> (phen)](PF <jats:sub>6</jats:sub> ) ( <jats:bold> Ir2-PF <jats:sub>6</jats:sub> </jats:bold> ), were investigated. Upon adsorption onto colloidal clay, the pseudo- <jats:italic toggle="yes">C</jats:italic> <jats:sub>3</jats:sub> -symmetric <jats:bold>Ir1</jats:bold> <jats:sup>+</jats:sup> cation exhibited UV–vis, photoluminescence (PL), and electronic circular dichroism (ECD) spectra distinctly different from those in solution, a phenomenon absent for the sterically bulkier <jats:bold>Ir2</jats:bold> <jats:sup>+</jats:sup> complex. Crucially, <jats:bold>Ir1</jats:bold> <jats:sup>+</jats:sup> displayed distinct photophysical properties between its enantiopure and racemic forms, stemming from contrasting, optical-purity-dependent packing modes. While the racemate was proposed to form stable heterochiral pairs irrespective of loading density, the enantiopure complex underwent dense packing and concentration quenching at higher loadings. Furthermore, despite having the same absolute configuration, <jats:bold>Ir1</jats:bold> <jats:sup>+</jats:sup> and <jats:bold>Ir2</jats:bold> <jats:sup>+</jats:sup> exhibited opposite CPL signs in solution—an inversion computationally attributed to ligand-dependent changes in orbital topologies. Upon confinement within the clay matrix, the CPL intensity of enantiopure <jats:bold>Ir1</jats:bold> <jats:sup>+</jats:sup> was significantly amplified, whereas that of <jats:bold>Ir2</jats:bold> <jats:sup>+</jats:sup> decreased. This enhancement of the CPL intensity of <jats:bold>Ir1</jats:bold> <jats:sup>+</jats:sup> upon clay adsorption closely parallels the effects of cryogenic cooling. Furthermore, molecular dynamics (MD) simulations revealed that, although both <jats:bold> Ir1 <jats:sup>+</jats:sup> </jats:bold> and <jats:bold> Ir2 <jats:sup>+</jats:sup> </jats:bold> adsorb onto the clay, <jats:bold> Ir1 <jats:sup>+</jats:sup> </jats:bold> adsorbs at a position closer to the clay surface and, relative to <jats:bold> Ir2 <jats:sup>+</jats:sup> </jats:bold> , tends to direct part of its ligands toward the hexagonal cavities of the clay surface; that strong interactions operate between the opposite-handed enantiomers of the racemate in both cases; and that the bulkier <jats:bold> Ir2 <jats:sup>+</jats:sup> </jats:bold> experiences weaker electrostatic repulsion and thus tends to aggregate—observations that were consistent with the experimental results. These findings establish clay nanosheets as powerful structural scaffolds for transforming weakly emissive molecules into highly functional chiral luminescent materials. </jats:p>