Tuning carboxylate coordination as a molecular gearshift to optimize interfacial electron transfer for ultrafast...

The rational design of smart materials requires precise control over interfacial electron transfer, which remains a fundamental challenge. Herein, we demonstrate that a subtle shift in carboxylate coordination mode acts as a molecular gearshift, triggering optimized supramolecular π-stacking, hydrogen bonding, and lone-pair···π interactions. This cascade constructs a continuous electron-transfer pathway, leading to dramatically enhanced efficiency in coordination polymer (CPs). This subtle change at the coordination interface triggers a cascade of optimizations in key supramolecular interactions (shorter π···π stacking, stronger hydrogen bonds, more effective lone-pair···π contacts), collectively constructing a highly efficient and continuous electron-transfer (ET) pathway. Consequently, compound 2 exhibits benchmark-breaking performance, including ultrafast photochromism (with a rate constant 20 times greater than that of 1) and highly sensitive "turn-on" fluorescence sensing of hazardous N₂H₄·H₂O (limit of detection = 0.43 ± 0.03 μM). This work establishes a direct causal link from primary coordination geometry, through optimized interfacial interactions, to superior macroscopic function, offering a novel and broadly applicable design principle for engineering next-generation stimuli-responsive materials.