| 研究実績の概要 |
In the past year, continuous efforts have been made to synthesize new types of metal-organic frameworks (MOFs) that contained both electron-donating and accepting moieties. Using donor ligands derived from anthracene and naphthalene, a class of cadmium(II) MOFs has been successfully synthesized and characterized. Careful optimization of the synthetic conditions has resulted in the preparation of single crystals, allowing the observation of the structure and packing of the MOFs via X-ray diffraction studies. Upon variation of the nature of the ligands as well as fine-tuning of the solvents for the synthesis, different arrangements and packing in the crystal structures of the MOFs, ranging from two-dimensional structures to three-dimensional interpenetrated networks, have been successfully obtained. It is interesting to observe that in all of the MOF structures, the donor and acceptor groups are arranged in a cofacial fashion with slight π-π stacking interactions between adjacent moieties.
In addition, the photochemical properties of the MOFs have been investigated in detail. In the solid-state absorption spectra, the MOFs were observed to show a lower-energy absorption band originated from the intraligand transition, as well as a higher-energy band tentatively assigned to originate from intramolecular charge transfer. Preliminary studies with flash-photolysis time-resolved microwave conductivity (FR-TRMC) experiments revealed that the porous materials are photoconductive in nature.
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