Translating π-adsorptive sites across reticular chemistries for water-tolerant CO2 capture

Metal-organic frameworks (MOFs) are among the most versatile platforms for CO2 capture, yet their performance under realistic, humid conditions remains a major limitation. Strategies that enhance CO2 affinity often rely on highly polar adsorption sites, which simultaneously promote water uptake and compromise selectivity and stability. Overcoming this trade-off between adsorption strength and operational robustness remains a central challenge in the field. Here we show that this limitation can be addressed by translating a π-based CO2 recognition motif from a carboxylate MOF into a denser pyrazolate framework. In the resulting material, MUV-92, structural confinement reconfigures the adsorption energy landscape, redistributing CO2 binding over several energetically similar sites rather than concentrating it in a single dominant environment. This redistribution leads to homogeneous adsorption energetics and enhanced uptake without introducing additional polar functionalities. Framework densification also creates a more confined pore environment dominated by weakly interacting polyaromatic surfaces, which limits water access to the adsorption cavities. As a result, MUV-92 maintains efficient CO2 capture under humid conditions. Dynamic breakthrough and competitive adsorption experiments demonstrate sustained performance even under saturated humidity, a regime in which benchmark materials typically suffer severe performance losses.