Multi-interactive Coordination Network Featuring a Ligand with Topologically Isolated p Orbitals

Abstract

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.

Photoactive Hexaazaphenalene‐based Coordination Network as a Two‐Pathway Photosensitizer for Oxidation of Alkanes

“…[42][43][44] Due to the intramolecular charge transfer nature of this transition, the excitation energy and extinction coefficient could be modulated by modifying the substituent groups. [40,41,45] The possibility of formation of singlet oxygen ( 1 O 2 ) via the energy transfer pathway was considered. The existence of 1 O 2 was confirmed by photooxidation of 1,5-dihydroxynaphthalene (1,5-DHN), which is typically used as a selective trap (Scheme 2).…”

“…This quenching behavior indicated that TPHAP was acting as a photosensitizer and its excited state was able to transfer energy to oxygen molecules to generate reactive oxygen species (ROSs) [42–44] . Due to the intramolecular charge transfer nature of this transition, the excitation energy and extinction coefficient could be modulated by modifying the substituent groups [40,41,45] …”

“…N 2 sorption measurements at 77 K showed no appreciable uptake, thus confirming the structure likely changed to a non-porous phase (Figure S5). Nevertheless, when the solvent was kept inside the network, the porous structure could be maintained, [45,58,59] which is sufficient for photocatalysis experiments. In addition, absorption, excitation, and emission spectroscopies were carried out to ensure that TPHAP retained its photophysical properties while inside the network.…”

Atomic-resolution structure analysis inside an adaptable porous framework

“…Incorporating molecules into single crystalline porous materials could reveal a plethora of important information about guest structures 2 , 5 , 6 and host-guest interactions 7 – 10 , in addition to monitoring reaction intermediates 11 , 12 and detecting metastable species 13 , 14 . In particular, structure determination of complex organic molecules has garnered strong attention since this technique can be applied to non-crystalline solids 15 , oils 16 – 19 , and compounds that can only be obtained in trace amounts 20 – 24 .…”

“…Previously, we reported SXRD analysis of polycyclic aromatic hydrocarbons encapsulated into Co-3TPHAP MOF 7 . Interestingly, the host-guest crystal structures contained several solvent molecules in the pore, which were highly ordered and could be fully resolved by crystallography.…”