Acid-Induced Structural Diversity of Stable Mn(II) Metal-Organic Framework Photocatalysts for Effective Visible...

Rational structural engineering of metal-organic frameworks (MOFs) through dimensionality modulation enables the precise tailoring of light-matter interactions and reaction kinetics. Herein, we successfully obtained a one-dimensional (1D) metal-organic chain (MOC) with [Mn(ADBA)(DMA)]_n (XAIU-2) and a three-dimensional (3D) metal-organic framework (MOF) with [Mn(ADBA)(H₂O)(DMA)]_n (XAIU-3) by using 4,4'-(anthracene-9,10-diyl)dibenzoic acid (H₂ADBA) and MnCl₂·4H₂O, which regulate the acidity of the synthetic environment. XAIU-2 features isolated MnO₆ octahedral units, with each MnO₆ unit being bridged by two ADBA^2- ligands. In contrast, XAIU-3 has MnO₆ units that are not only bridged by ADBA^2- ligands but also connected to adjacent MnO₆ units via the COO^- group of the ADBA^2- ligand. XAIU-2 and XAIU-3 exhibited high activity for the trifluoromethylation reaction under visible light. XAIU-2 with oriented continuous electron transfer channels can reduce carrier recombination and extend carrier lifetime, which showed much higher activity for the trifluoromethylation reaction than that of XAIU-3. This study demonstrates that dimensionality modulation in MOFs serves as a potent strategy to engineer electron transport pathways and carrier dynamics, which provides a new strategy for designing high-performance photocatalysts toward selective C-H functionalization in organic synthesis.