Boron-Oxo Cluster-Based Hydrogen-Bonded Framework for Luminescent Tuning

A zinc boron-oxo cluster-based structure ({Zn 2 (μ 2 −OH)(Dmg) 4 [B 3 O 3 (OH)] [B 6 O 7 (OH) 2 ]}, BOC-23 ) was synthesized solvothermally using a dioxime (DmgH 2 ) ligand. Two polyboroxole units ([B 3 O 7 (OH)] and [B 6 O 11 (OH) 2 ]) are linked to Dmg via oxygen-sharing, forming an organic−inorganic hybrid macrocyclic cluster coordinating two Zn 2+ ions. Peripheral hydroxyl groups of the cluster facilitate the formation of a 3D hydrogen-bonded network in BOC-23 through intermolecular O−H···O interactions, forming a rigid framework that enhances stability and modulates guest luminescence via confinement. Systematic studies on host−guest interactions via in situ encapsulation of distinct luminescent guests reveal luminescence tuning from blue to cyan and red, alongside distinct synergistic luminescence enhancement in specific host−guest pairs. Notably, BOC-23 is a crystalline boron-oxo cluster host that enables in situ encapsulation of multiple luminescent guests─a feature not observed in prior boron-oxo clusters. This capability is exemplified by DEAC@BOC-23, which exhibits a quantum yield of 18.8% and a lifetime of 2.99 ns, representing 25 times and 6 times enhancements over pristine DEAC, respectively.