Linker-Curvature Stabilized Zn-Rod Framework with Inverted C2 Hydrocarbon Adsorption

Abstract

a Zn-based rod MOFs are fundamentally limited by Zn-O lability and activation-induced structural collapse, accounting for their scarcity. Here, linker curvature rigidifies Zn-rod secondary building units in NTUniv-69A, preventing pore collapse. The framework overturns the conventional C2 hydrocarbon adsorption hierarchy (C₂H₂ > C₂H₆ > C₂H₄), enabling single-step ethylene purification.Metal-organic frameworks (MOFs) constructed from rodshaped secondary building units (rod-SBUs) represent a distinct structural class in which infinite metal-oxygen chains serve as one-dimensional inorganic backbones 1 . Since the early reports of MOF-69 and related sra-type networks, rod-based architectures have attracted attention owing to their topological modularity and resistance to interpenetration. However, Zn²⁺-based rod MOFs remain notably underrepresented compared to their Ni²⁺ and Co²⁺ analogues, largely because of the intrinsic lability of Zn-O coordination and the propensity of one-dimensional chains to undergo sliding, breathing, or pore closure upon guest removal 2, 3 . Indeed, members of the MOF-69 family were reported to exhibit negligible N₂ uptake after evacuation, behavior commonly attributed to framework flexibility and solvent-removalinduced structural rearrangement 4, 5 .MOF-74(Zn) represents a rare activation-stable Zn rod framework, whose robustness has been ascribed to strong μ₂-O bridging and chelating linker coordination that rigidly lock the metal-oxygen chain 3 . These contrasting behaviors raise a fundamental question: how can Zn-based rod SBUs be stabilized without relying exclusively on strongly chelating ligands?Herein we demonstrate that geometric regulation of linker curvature offers an alternative stabilization strategy. By employing a non-linear pyrrole-2,5-dicarboxylate (prdc) linker, we constructed a rod-type Zn-organic framework, NTUniv-69A,COMMUNICATION ChemComm 2