Multivariate Sulfate‐Pillared Metal Azolate Frameworks with Tunable Flexibility for CO₂ Capture from C2 Hydrocarbons

Abstract A series of sulfate‐pillared metal azolate frameworks (MAFs) were synthesized via a multivariate (MTV) strategy to systematically tune framework flexibility and gas separation performance. The monotonic sulfate‐pillared MAF, Zn 2 (daTz) 2 SO 4 (where daTz = 3,5‐diamino‐1,2,4‐triazolate), exhibits pronounced structural dynamics upon adaptive guest inclusions, driven by triazolate linker rotation and reversible Zn─O bonds rearrangement, enabling dynamic pore modulation for efficient CO 2 , C 2 H 4 , and C 2 H 6 uptakes. Incorporation of an asymmetric, non‐amino linker effectively suppresses framework flexibility by reducing intraframework hydrogen bonding, resulting in a locked structure with enhanced selectivity for CO 2 over light hydrocarbons. Gas adsorption and breakthrough experiments demonstrate that the MTV approach enabled structural control, leading to exceptional CO 2 /C 2 H 6 and CO 2 /C 2 H 4 separation performance. Notably, Zn 2 (mTz) 0.74 (daTz) 1.26 SO 4 (where mTz = 3‐methyl‐1,2,4‐triazolate) achieves 17‐fold enhancement in ethylene purification. Comprehensive structural analyses and interaction energy calculations reveal the molecular basis of flexibility regulation, offering valuable insights for designing next‐generation porous materials for selective gas separation.