Multichannel Energy Convergence in Cellulose Cluster-From-Cluster by Enhanced Molecular Packing

Abstract

Embedding atomically precise nanoclusters into polymeric clusters enables the formation of nanomaterials with heterogeneous cluster coupling and multichannel energy transfer, providing a novel pathway for designing highly bright luminophores at the nanocluster level. Inspired by the excitation energy funneling mechanism of chlorophyll, a cellulose-based cluster-from-cluster structure with multichannel energy convergence was fabricated by embedding atomically precise gold nanoclusters into multichromophoric cellulose nanoclusters. The clusterization-triggered emission of the cellulose nanoclusters was activated through amino acid grafting, enhancing the molecular packing of dialdehyde cellulose. This enhancement could be attributed to the delocalization of lone-pair electrons on N or O atoms into the C═O/C═N π orbitals, promoting n→π* transitions and reducing the energy gap, thereby achieving strong luminescence from multiple emission centers in the 360–440 nm range, even at the lowest concentration of 0.03 wt% reported to date. Notably, the cellulose clusters formed a rigid microenvironment around the gold nanoclusters, effectively restricting the intramolecular motion of surface motifs. Moreover, the light energy from the multiple emission centers in the cellulose clusters was efficiently captured by the nearby nano-confined gold nanoclusters via multichannel energy convergence, resembling the energy transfer process in chlorophyll. Thus, this cluster-from-cluster exhibited excitation wavelength-dependent multicolor fluorescence with remarkable long-term stability, providing new design principles for cluster-level luminescent materials.