A tridentate 3-pyridyl-based ligand containing a hexaazaphenalene skeleton (3-TPHAP − ) with topologically isolated p orbitals was prepared by a onepot reaction. It was successfully reacted with a Co 2+ salt and a 1,4benzenedicarboxylic acid co-ligand to give a porous coordination network. In the structure, the hexaazaphenalene skeleton interacts with water to form an internal hydrogen bonding network, allowing the entire pore space to be revealed by single-crystal X-ray diffraction (SXRD). The network structure consists of dimeric Co clusters featuring labile sites occupied by solvent molecules. Several guest molecules, namely, anthracene, triphenylene, and iodine, were incorporated inside the network. The resultant encapsulated structures were elucidated by SXRD, revealing unusual host−guest interactions with a subtle structural modulation.

A tris(4-pyridyl) hexaazaphenalenyl anion (TPHAP À ) exhibited both energy and charge transfer processes to oxygen molecules under UV irradiation resulting in the production of reactive oxygen species (ROSs). The existence of ROSs was confirmed by spectroscopic characterization and photooxidation of a standard compound selective for the singlet oxygen, 1,5dihydroxynaphthalene (1,5-DHN). In addition, a porous coordination network (PCN) consisting of TPHAP À , cadmium ions and fumarate co-ligand was synthesized and used as a heterogeneous photosensitizer capable of ROSs generation. To take advantage of this ability, photooxidation of various saturated hydrocarbons including cyclohexane, cyclooctane and n-octane was investigated. TPHAP-based PCN demonstrated excellent photosensitizing ability achieving more than a hundred times higher turnover frequency than other reported coordination networks based on photoactive ligands.

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