Hierarchical nanogap-lattice coupling transduces molecular chirality into collective optical modes

Molecular chirality produces intrinsically weak far-field optical signals, limiting the translation of local chiral interactions into measurable nanophotonic responses. Existing enhancement strategies rely on either nanogap hotspots or lattice resonances, but architectures combining both are rare. Here, we present nanocube cluster lattices (NCCLs), hierarchical nanogap-lattice platforms where Au nanocube clusters are periodically arranged. NCCLs retain open, molecule-accessible intracluster nanogaps while hybridizing dressed cluster plasmons with lattice diffraction to form a narrow surface lattice resonance (SLR). Chiral molecules incorporated in situ during NCCL formation selectively transduce molecular handedness into a circular dichroism response at the collective mode with minimal change in extinction. Simulations link this selectivity to homochiral optical helicity localized in nanogaps and SLR-mediated dissipation across the cluster volume. This work provides a design principle for coherence-enhanced chiral readout by coupling accessible nanogap interaction volumes to narrow collective resonances.