Fig. 2

Adsorbent and proposed cooperative adsorption process. a Representative structure of M₂(dobpdc) (dobpdc^4- = 4,4′-dioxidobiphenyl-3,3′-dicarboxylate). Light blue, red, and gray spheres represent M, O, and C atoms, respectively; H atoms are omitted for clarity. The inset shows an expanded view of an open metal site appended with the diamine N,N-dimethylethylenediamine (mm-2). b Proposed reversible process for cooperative CS₂ adsorption in mm-2–M₂(dobpdc), illustrating insertion of CS₂ into the M–N bonds, proton transfer, and formation of electrostatically paired ammonium dithiocarbamate chains