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

A zinc boron-oxo cluster-based structure ({Zn2(μ2-OH)(Dmg)4[B3O3(OH)] [B6O7(OH)2]}, BOC-23) was synthesized solvothermally using a dioxime (DmgH2) ligand. Two polyboroxole units ([B3O7(OH)] and [B6O11(OH)2]) are linked to Dmg via oxygen-sharing, forming an organic-inorganic hybrid macrocyclic cluster coordinating two Zn2+ 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.