Photoluminescence and mechanism insights of isomers D- (-)-Arabinose and L-(+)-Arabinose crystals

Nonconventional luminophores have attracted extensive attention due to their unique photoluminescence (PL) properties, including excitation-dependent emission and persistent room temperature phosphorescence (p-RTP), intermolecular interactions play a key role in clustering-triggered emission (CTE). However, the diversity and complexity of atypical chromophores make it a significant challenge to accurately dissect the intrinsic structure of emissive clusters. In this work, D-(-)-arabinose (D-Arb) and L-(+)-arabinose (L-Arb) stereoisomeric pairs were selected as model systems to conduct comparative analysis of PL properties under controlled crystallization conditions. Experimental results show that D-Arb crystals exhibit a red-shifted emission, with relatively high photoluminescence quantum yield (PLQY) reaching 9.26%, while L-Arb crystals have a longer phosphorescence lifetime of 199.5ms. The study reveals that such differences in PL arise from the differentiated packing of D/L-Arb, which share a homologous molecular skeleton but exhibit distinct spatial configurations. Experimental and theoretical results revealed that D/L-Arb crystals form an abundant network of noncovalent interactions, including hydrogen bonds and short contacts between oxygen atoms. Analysis of key energy components intrinsic to the aggregates—such as electrostatic, polarization, dispersion, and exchange repulsion—indicates that these factors lead to varying degrees of electron delocalization in the emissive clusters. Combined with ab initio dynamics(AIMD), the intrinsic relationship between intermolecular interactions among D/L-Arb molecules and PL properties is more clearly revealed. These findings clarify the stereochemical control of emissive clusters through through-space interactions (TSI) and establish a refined structure-property relationship for the design of optical isomers in CTE engineering.