Porous physisorbents are attractive candidates for selective capture of trace gas or volatile compounds due to their low energy footprints. However, many physisorbents suffer from insufficient sorbate-sorbent interactions, resulting in low uptake or inadequate selectivity when gases are present at trace levels. Here, we report a strategy of programmed fluorine binding engineering in anion-pillared metal-organic frameworks to maximize C
2
H
2
binding affinity for benchmark trace C
2
H
2
capture from C
2
H
4
. A robust material (ZJU-300a) was elaborately designed to provide multiple-site fluorine binding model, resulting in an ultrastrong C
2
H
2
binding affinity. ZJU-300a exhibits a record-high C
2
H
2
uptake of 3.23 millimoles per gram (at 0.01 bar and 296 kelvin) and one of the highest C
2
H
2
/C
2
H
4
selectivity (1672). The adsorption binding of C
2
H
2
and C
2
H
4
was visualized by gas-loaded ZJU-300a structures. The separation capacity was confirmed by breakthrough experiments for 1/99 C
2
H
2
/C
2
H
4
mixtures, affording the maximal dynamic selectivity (264) and C
2
H
4
productivity of 436.7 millimoles per gram.
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