Gas Selective Ultrathin Organic Covalent Networks Synthesized by iPECVD: Does the Central Metal Ion Matter?

The potential of porphyrin‐derived metal organic covalent networks (OCN) thin films on light gas separations has been recently demonstrated. However, whether or not the central metal ion of the porphyrin plays a key role on separation performance has yet to be elucidated. Here, one metal‐free and three metal‐containing (zinc(II), manganese(III), and cobalt(II)) porphyrin‐derived OCN thin films are successfully deposited on various substrates via an easily scalable initiated plasma‐enhanced chemical vapor deposition approach. Among these four porphyrin‐derived OCN thin films exhibiting superior light gas separation performances, three of them are synthesized for the first time. The gas permeation properties of these four OCN thin films suggest that the central metal ions neither significantly alter the packing structure of resulting OCN thin films, nor introduce facilitated transport phenomena favoring oxygen transmission. This observation is further validated by density functional theory calculations. Additional aging tests are also carried out to evaluate the physical aging behavior of the OCN thin films.