Frontispiece: In Situ Tracking of Dynamic NO Capture through a Crystal‐to‐Crystal Transformation from a Gate‐Open‐Type Chain Porous Coordination Polymer to a NO‐Adducted Discrete Isomer

Selective NO adsorption is intriguing from the viewpoint not only of environmental issues, but also of the control of the medical/biological NO‐transmission mechanism and electronic applications that exploit the redox‐active nature of NO. Optimal control of gas adsorption properties in metal–organic frameworks (MOFs) or porous coordination polymers (PCPs) remains a great challenge in the field of materials science. In their Full Paper on page 3020, H. Miyasaka et al. evaluate selective NO capture in a Ru dimer chain porous compound through strong host–guest magnetic/electronic interactions by using in situ techniques of powder magnetic and permittivity measurements, IR spectroscopy, and X‐ray diffraction. A dynamic change with respect to the NO trapping in pores was followed, which underwent a crystal‐to‐crystal transformation from a gate‐opened NO adsorbed form to an NO‐adducted form.